10.1. Alphabetical Listing of Keywords [A-E]

Table 10.1: Alphabetical Listing of Keywords [A-E]

Keyword	Definition
ABFR Solver	This keyword serves as a switch to turn on an empirical active surface area factor when surface reaction rates on the particle surface are calculated. The concept is that not all surface area (or sites) on the particle surface is active. The active surface area during the particle formation phase is found to be a function of total particle mass and gas temperature. The form and the model parameters of this empirical formulation are obtained by fitting predictions to measured data from premixed flames. By default this factor is turned off.
	Parameters	Optional/Reqd.	Units	Examples
	--	--	--	ABFR
	Keyword Usage	Optional keyword. By default this factor is turned off.
	Reactor Models	Cylindrical Shear Flow Reactor Planar Shear Flow Reactor Perfectly-stirred Reactor (PSR) Plug-flow Reactor (PFR)
ABSLSolver	This keyword is used to override the default value for the absolute perturbation in the solution variable used in the determination of the numerically derived Jacobian.
	Parameters	Optional/Reqd.	Units	Examples
	Absolute perturbation	Required	--	ABSL 1.E-15
	Keyword Usage	Optional keyword. By default, if the ATOL keyword is given, then the absolute perpetuation is set equal to the ATOL value. ATOL is not specified, then the absolute perturbation is set equal to the square root of the unit round-off error of the machine.
	Reactor Models	Closed Plasma Reactor Non-reactive Gas Mixer Perfectly Stirred Reactor (PSR) Plasma PSR
ACHG Solver	Maximum absolute change in the surface site fractions (over one time step) for which the preliminary, fictitious transient equations can be considered to have converged to steady state. The convergence test is made against the sum of the ACHG value plus the product of RCHG multiplied by the old site-fraction value. Therefore, if ACHG is set to zero (by default) then only RCHG is used to control the convergence criteria.
	Parameters	Optional/Reqd.	Units	Examples
	Absolute relative change	Required	--	ACHG 1.0E-7
	Keyword Usage	Optional keyword. By default, only RCHG is used to determine convergence.
	Reactor Models	Honeycomb Reactor Plasma Plug Flow Reactor Plug Flow Reactor
ADAM Solver	Flag indicating the implicit Adams method of the DVODE solver is used to integrate the equations.
	Keyword Usage	Optional keyword. By default, the DASPK solver will be used.
	Reactor Models	Closed Partially Stirred Reactor (PaSR) Partially Stirred Reactor (PaSR)
ADAP Solver	Flag indicating the saving of additional adaptive points for improved resolution of the solution data (for example, for post-processing and plotting) for transient simulations. ADAP is the default. ADAP inserts extra solution points when your solution is changing rapidly (for example, a steep transient or engine ignition occurs). How and when the points are inserted is controlled by the AVALUE, AVAR and ASTEPS keywords. The companion keyword, NADAP, can be used to turn off adaptive time-stepping during continuations, if desired.
	Keyword Usage	Optional keyword. ADAP is the default.
	Reactor Models	Closed Plasma Reactor Closed Homogeneous Reactor Honeycomb Reactor IC HCCI Engine Model Multi-Zone HCCI Engine Simulator Plasma Plug Flow Reactor Multiphase PSR Plug Flow Reactor SI Engine Zonal Simulator
ADD Reactor or Inlet Property	Mole fractions of species that should be added to the inlet or initial composition but excluded from the equivalence-ratio calculation. This keyword is only valid when the equivalence-ratio option is used to specify the inlet or initial composition. These species do not enter into the equivalence ratio computations. One species is entered per line.
	Parameters	Optional/Reqd.	Units	Examples
	Inlet stream name	Optional (PSRs only) If there is no stream name than the product species applies to the default or all defined streams.	--	ADD mixture1 AR 0.2
	Species name	Required	--	ADD AR 0.2
	Additive fractions	Required	mole fractions	ADD AR 0.2
	Keyword Usage	Optional keyword. By default, ADD is not used. But either REAC or EQUI / FUEL / OXID / CPROD is required for each inlet stream or to define initial conditions for a closed system.
	Reactor Models	Closed Homogeneous Batch Reactor IC HCCI Engine Plasma PSR Plug Flow Reactor SI Engine Zonal Simulator
	Notes	The ADD keywords must be changed as a set, not individually for a restart run. The ADD keywords must be changed as a set, not individually for a continuation run.
ADIA Reactor Property	Turns on the adiabatic wall condition for plug-flow or for planar, symmetric, shear-flow models. For planar, non-symmetric shear flow, an adiabatic wall is the default, but for symmetric (planar or cylindrical) shear-flow cases, the ADIA keyword is required for the adiabatic condition.
	Keyword Usage	Optional keyword. By default, the specified (temperature) condition is used for shear-layer flow. The default behavior for plug-flow depends on the problem type; if the energy equation is being solved, the default is for adiabatic conditions.
	Reactor Models	Cylindrical Shear Flow Reactor Honeycomb Reactor Planar Shear Flow Reactor Plasma Plug Flow Reactor Plug Flow Reactor
AEXT Reactor Property Profiles	External surface area (for 0-D Homogeneous systems) or surface area per unit length (for Plug Flow Models) used to control heat transfer to the external environment. AEXT is usually used to specify area profiles as a function of time (0-D Homogeneous systems) or distance (Plug Flow Models). However, if the AEXT value is only provided at a single point, then the surface area is assumed to be constant as a function of time (for transient 0-D Homogeneous systems) or distance (for Plug Flow Models). See also AREAQ.
	Parameters	Optional/Reqd.	Units	Examples
	Time or Distance, depending on Reactor Model	Required	^{sec or cm}	AEXT 0.0 1.0
	External surface area or surface area per unit length, depending on Reactor Model	Required	cm^{2 or cm}	AEXT 0.0 1.0
	Keyword Usage	Optional keyword. If not specified, the external area is assumed equal to the internal surface area (see AINT or AREA).
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Honeycomb Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Plasma PSR SI Engine Zonal Simulator
AFLO Reactor Property Profiles	Cross-sectional area profile as a function of distance. If only a single AFLO entry is provided, the cross-sectional area is assumed to be a constant at that specified value. See also AREAF and DIAM.
	Parameters	Optional/Reqd.	Units	Examples
	Distance from inlet	Required	cm	AFLO 0.0 1.0
	Cross-sectional area	Required	cm²	AFLO 0.0 1.0
	Keyword Usage	Optional keyword. If none of DIAM, AFLO, or AREAF keywords are included, then an attempt will be made to use the GEOM user subroutine to determine the flow area.
	Reactor Models	Honeycomb Reactor Plasma Plug Flow Reactor Plug Flow Reactor
AFLW Reactor Property	Fraction of the total lower wall surface area that corresponds to a surface material. For example, "AFLW WAFER 0.001" indicates that the material "WAFER" makes up 0.1% of the lower wall surface area. The material name must correspond to a material name declared in the Surface Kinetics input file or an error will occur.
	Parameters	Optional/Reqd.	Units	Examples
	Surface material name	Required	--	AFLW WAFER 0.001
	Fraction of total surface area	Required	--	AFLW WAFER 0.001
	Keyword Usage	Optional keyword. By default, 1.0 is used for all materials in all PSRs.
	Reactor Models	Non-symmetric Planar Shear Flow Reactor
AFRA Reactor Property	Fraction of the total surface area that corresponds to a surface material (see the multiple surface material capability under Surface Kinetics). For example, "AFRA WAFER 0.001" indicates that the material "WAFER" makes up 0.1% of the total reactor surface area. The material name must correspond to a material name declared in the Surface Kinetics input file or an error will occur.
	Parameters	Optional/Reqd.	Units	Examples
	Surface material name	Optional	--	AFRA WAFER 0.001
	Fraction of total surface area	Required	--	AFRA WAFER 0.001
	Reactor number (PSR clusters only)	Optional If no number is given, the keyword is assumed to apply to all reactors in a cluster.	--	AFRA WAFER 0.001 2
	Keyword Usage	Optional keyword. By default, 1.0 is used for all materials in all PSRs.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Cylindrical Shear Flow Reactor Honeycomb Reactor Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma Plug Flow Reactor Plasma PSR Plug Flow Reactor
AFRMX Reactor Property/Model	Maximum air entrainment mass flow rate into the spray parcel.
	Parameters	Optional/Reqd.	Units	Examples
	Max air entrainment rate	Required	g/sec	AFRMX 200.0
	Keyword Usage	Optional keyword. Default is 50 g/sec.
	Reactor Models	Direct Injection Diesel Engine Simulator
AGGA Reactor Property	The pre-exponential factor of the Arrhenius-like expression for characteristic fusion time.
	Parameters	Optional/Reqd.	Units	Examples
	Material name	Required	--	AGGA SOOT 1.0E10
	Pre-exponential factor	Required	sec	AGGA C(B) 1.0E7
	Keyword Usage	Optional keyword. By default, the pre-exponential factor is 1.0E-30.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Diffusion or Premixed Opposed-flow Flame IC HCCI Engine Multi-Zone HCCI Engine Simulator Perfectly Stirred Reactor (PSR) Plasma PSR Premixed Laminar Burner-stabilized Flame SI Engine Zonal Simulator
AGGB Reactor Property	The temperature exponent of the Arrhenius-like expression for characteristic fusion time.
	Parameters	Optional/Reqd.	Units	Examples
	Material name	Optional	--	AGGB SOOT 1.0
	Temperature exponent	Required		AGGB C(B) 0.5
	Keyword Usage	Optional keyword. By default, the temperature exponent is 0.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Diffusion or Premixed Opposed-flow Flame IC HCCI Engine Multi-Zone HCCI Engine Simulator Perfectly Stirred Reactor (PSR) Plasma PSR Premixed Laminar Burner-stabilized Flame SI Engine Zonal Simulator
AGGD Reactor Property	The exponent of the primary particle diameter in the Arrhenius-like expression for characteristic fusion time.
	Parameters	Optional/Reqd.	Units	Examples
	Primary particle name	Optional	--	AGGD C(B) 1.0
	Keyword Usage	Optional keyword. By default, the primary particle diameter is 1.0.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Diffusion or Premixed Opposed-flow Flame IC HCCI Engine Multi-Zone HCCI Engine Simulator Perfectly Stirred Reactor (PSR) Plasma PSR Premixed Laminar Burner-stabilized Flame SI Engine Zonal Simulator
AGGE Reactor Property	The activation temperature of the Arrhenius-like expression for characteristic fusion time.
	Parameters	Optional/Reqd.	Units	Examples
	Material name	Required	--	AGGE SOOT 0.0
	Activation temperature	Required	K	AGGE C(B) 800
	Keyword Usage	Optional keyword. By default, the activation temperature is 0.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Diffusion or Premixed Opposed-flow Flame IC HCCI Engine Multi-Zone HCCI Engine Simulator Perfectly Stirred Reactor (PSR) Plasma PSR Premixed Laminar Burner-stabilized Flame SI Engine Zonal Simulator
AGGFD Reactor Property	The fractal dimension of the aggregate.
	Parameters	Optional/Reqd.	Units	Examples
	Material name	Required	--	AGGFD SOOT 1.0E3.0
	Fractal dimension	Required	--	AGGFD C(B) 1.8
	Keyword Usage	Optional keyword. By default, the fractal dimension is 3.0.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Diffusion or Premixed Opposed-flow Flame IC HCCI Engine Multi-Zone HCCI Engine Simulator Perfectly Stirred Reactor (PSR) Plasma PSR Premixed Laminar Burner-stabilized Flame SI Engine Zonal Simulator
AGGMN Reactor Property	The threshold value to include the sintering effect in particle aggregation. For the Moments Method, this indicates the ratio of the collision to the fusion time scale, whereas for the Sectional Method, this indicates the minimum value of the characteristic fusion time.
	Parameters	Optional/Reqd.	Units	Examples
	Material name	Required	--	AGGMN SOOT 1.0E10
	Threshold	Required	-- (Moments)sec (Sectional)	AGGMN SOOT 1.0E-4
	Keyword Usage	Optional keyword. By default, the threshold is 1.0E-3 for the Moments Method and 1.0E-06 for the Sectional Method.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Diffusion or Premixed Opposed-flow Flame IC HCCI Engine Multi-Zone HCCI Engine Simulator Perfectly Stirred Reactor (PSR) Plasma PSR Premixed Laminar Burner-stabilized Flame SI Engine Zonal Simulator
AINL Inlet Property	The radial velocity spreading rate. At the inlet x = L , v/r = AINL.
	Parameters	Optional/Reqd.	Units	Examples
	Radial velocity divided by radius	Required	1/sec	AINL 2.3
	Keyword Usage	Optional keyword. By default, the radial velocity spreading rate is 0.0.
	Reactor Models	Diffusion or Premixed Opposed-flow Flame Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
	Notes	Supersedes previous AFUE and AOXI keywords.
AINT Reactor Property Profiles	Internal surface area (for 0-D Homogeneous systems) or surface area per unit length (for Plug Flow models) that is considered active for surface chemistry. AINT is usually used to specify area profiles as a function of time (0-D Homogeneous systems) or distance (Plug Flow models). However, if the AINT value is only provided at a single point, then the surface area is assumed to be constant as a function of time (for transient 0-D Homogeneous systems) or distance (for Plug Flow models). See also AREA.
	Parameters	Optional/Reqd.	Units	Examples
	Time or distance, depending on Reactor Model	Required	sec or cm	AINT 0.0 1.0
	Internal surface area or area per unit length, depending on Reactor Model	Required	cm2 or cm	AINT 0.0 1.0
	Keyword Usage	Optional keyword. If not specified, the internal surface area is determined based on the hydraulic diameter for a plug-flow, as specified through AFLO, AREAF, or DIAM keywords. For 0-D Homogenous systems, a value of 0.0 is assumed by default.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Honeycomb Reactor Perfectly Stirred Reactor (PSR) Plasma PSR Plasma Plug Flow Reactor Plug Flow Reactor
ALL Output	Turns default output on for all of Surftherm’s tables.
	Keyword Usage	Optional keyword. By default, the all output will be printed. See also NONE.
	Reactor Models	Mechanism Analyzer
APRO Reactor Property Profiles	Use of the APRO keyword(s) allow the user to specify a piece-wise linear profile as a function of distance for the stream-tube area. The stream-tube area is given relative to the burner area and is therefore dimensionless. Each input provides a pair and the x coordinates must be in ascending order. For example, APRO 0.1 1.2 assigns a relative area of 1.2 at a position 0.1 cm from the burner surface.
	Parameters	Optional/Reqd.	Units	Examples
	x-coordinates	Required	cm	APRO 0.1 1.2
	Relative area	Required	dimensionless	APRO 0.1 1.2
	Keyword Usage	Optional keyword. By default, the area ratio is constant at 1.0.
	Reactor Models	Premixed Laminar Burner-stabilized Flame
	Notes	This keyword can be changed for a restart run.
AREA Reactor Property	The total internal surface area (for 0-D homogeneous reactors) or surface area per unit length (for plug-flow) in the reactor. The internal surface area represents the area available for surface chemistry. See also AINT.
	Parameters	Optional/Reqd.	Units	Examples
	Total surface area or surface area per unit length, depending on Reactor Model	Required	cm² or cm	AREA 200
	Reactor number (PSR clusters only)	Optional If no number is given, the keyword is assumed to apply to all reactors in a cluster.	--	AREA 200 1
	Keyword Usage	Optional keyword. By default, the total surface area is set to 0.0 for 0-D homogeneous reactor models and is determined based on the hydraulic diameter (set using DIAM, AREAF, AFLO) for plug-flow.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Honeycomb Reactor Perfectly Stirred Reactor (PSR) Plasma PSR Plasma Plug Flow Reactor Multiphase PSR Plug Flow Reactor
AREAF Reactor Property	The total cross-sectional flow area. See also AFLO.
	Parameters	Optional/Reqd.	Units	Examples
	Cross-sectional flow area	Required	cm²	AREAF 200
	Keyword Usage	Optional keyword. Either DIAM or AREAF must be set, unless the user has implemented the GEOM user subroutine.
	Reactor Models	Honeycomb Reactor Plasma Plug Flow Reactor Plug Flow Reactor
AREAM Reactor Property	Contact area for mass exchange or reactions between two phases or bulks.
	Parameters	Optional/Reqd.	Units	Examples
	Contact area for mass transfer and reactions	Required	cm²	AREAM catalyst Gas 50.0
	Keyword Usage	Required for multiphase systems. Two bulk phase names must follow the keyword indicating the bulks in contact. "Gas" indicates the gas phase. Default value of 0 is used for combination of bulks for which the area is not specified.
	Reactor Models	Closed Multiphase Reactor Multiphase PSR
AREAQ Reactor Property	The total external surface area (for 0-D homogeneous reactors) or surface area per unit length (for plug-flow) in the reactor. The external surface area represents the area available for heat transfer to the external environment. See also AEXT.
	Parameters	Optional/Reqd.	Units	Examples
	Total surface area or surface area per unit length, depending or Reactor Model	Required	cm² or cm	AREAQ 200
	Reactor number (PSR clusters only)	Optional If no number is given, the keyword is assumed to apply to all reactors in a cluster.	--	AREAQ 200 1
	Bulk name (multiphase reactors only)	Optional	--	AREAQ Gas AMBIENT 0.5
	Keyword Usage	Optional keyword. By default, the total external surface are is set equal to the internal surface area ( AREA, AINT), unless AREAQ or AEXT are included. For the multiphase reactors, the keyword is effective for the phase name following the keyword. The name of the bulk phase should be used. "Gas" indicates the gas phase.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Honeycomb Reactor Perfectly Stirred Reactor (PSR) Plasma PSR Plasma Plug Flow Reactor Multiphase PSR Plug Flow Reactor
AROP Output	Determine the rate-of-production coefficients for all species and print results to the diagnostic output file of the reactor simulation.
	Keyword Usage	Optional keyword. By default, no rate-of-production values are printed.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Closed Multiphase Reactor Honeycomb Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Plasma Plug Flow Reactor Plasma PSR Multiphase PSR Plug Flow Reactor SI Engine Zonal Simulator
	Notes	This keyword can be added but not removed from a continuation run.
ASEN Output	Calculate the first-order, A-factor sensitivity coefficients (that is, with respect to the gas-phase and surface chemistry rate constants) for species fractions and for other dependent variables in the system. Sensitivity results will be included in the XML Solution File. For 0-D and Plug Flow systems, sensitivity results will also be printed to the diagnostic output file.
	Parameters	Optional/Reqd.	Units	Examples
	String indicating for which variables sensitivity coefficients will be saved or printed. The string is a space-delimited list containing species names and any one of the following: ALL, AVEL, RVEL, CVEL, FLRT, or TEMP (see Notes)	Optional If no string is given, then ALL is assumed.	--	ASEN H2O ASEN TEMP
	Keyword Usage	Optional keyword. By default, no sensitivity coefficients are computed or printed. See also SENG.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Closed Multiphase Reactor Diffusion or Premixed Opposed-flow Flame Honeycomb Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Plasma Plug Flow Reactor Plasma PSR Multiphase PSR Plug Flow Reactor Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation Rotating Disk CVD Reactor SI Engine Zonal Simulator Stagnation Flow CVD Reactor
	Notes	This keyword can be added but not removed from a continuation run. See also EPSS, EPSG, EPST, SENG, and HSEN for other sensitivity options The optional parameter strings are defined as follows: `ALL`: all species and all other dependent variables in the solution `AVEL`: axial velocity (Plug Flow, Diffusion or Premixed Opposed-flow Flames, Rotating Disk, and Stagnation Flow CVD Reactors only) `CVEL`: circumferential velocity (Rotating Disk and Stagnation Flow CVD Reactors only) `RVEL`: radial velocity (Diffusion or Premixed Opposed-flow Flames, Rotating Disk, and Stagnation Flow CVD Reactors only) `FLRT`: mass flow rate (Premixed Laminar Flame-speed Calculation only) `TEMP`: gas temperature
ASTEPS Output	Uses the integrator steps to adaptively insert extra solution data points in addition to those specified by the DTSV option whenever the solver takes the number of integration steps specified by this option. The default is 20, the value used if no argument is provided. The purpose of the ASTEPS keyword is to ensure that during a transient solution, sufficient solution data points are available around the time of a fast transient, for example a rapidly increasing temperature, so that an accurate analysis of the problem is possible (to allow a good plotting resolution).
	Parameters	Optional/Reqd.	Units	Examples
	Integration steps	Optional.	--	ASTEPS 20
	Keyword Usage	Optional keyword. By default ASTEPS is set to 20.
	Reactor Models	Closed Homogeneous Reactor Closed Plasma Reactor Honeycomb Reactor IC HCCI Engine Multi-Zone HCCI Engine Simulator Perfectly Stirred Reactor (PSR) Plasma Plug Flow Reactor Plasma PSR Plug Flow Reactor SI Engine Zonal Simulator
	Notes	For further details, see the description of DTSV.
ASWH Reactor Property	Crank angle at which the simulation switches from fixed-temperature condition to using energy equation with Woschni correlation as the heat transfer model. By default the energy equation is used starting at zero crank angle.
	Parameters	Optional/Reqd.	Units	Examples
	Crank angle in degrees.	Required	degree	ASWH 5.0
	Keyword Usage	Optional keyword.
	Reactor Models	Multi-Zone HCCI Engine Simulator SI Engine Zonal Simulator
ATIM Solver	Absolute tolerance for convergence of Newton iteration as it is used in the pseudo time stepping procedure for steady-state problems employing the Twopnt solver. Since we are not seeking accuracy in a transient solution, this convergence criteria typically does not need to be as stringent as for the Newton iteration on the actual steady-state solution.
	Parameters	Optional/Reqd.	Units	Examples
	Absolute tolerance	Required	--	ATIM 1.E-6
	Keyword Usage	Optional keyword. By default, the absolute tolerance is 1.E-9. See also RTIM.
	Reactor Models	Closed Plasma Reactor Cylindrical Shear Flow Reactor Diffusion or Premixed Opposed-flow Flame Honeycomb Reactor Non-reactive Gas Mixer Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma PSR Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
	Notes	For a precise definition, see the description of ATOL.
ATLM Solver	ATOL is used for all variables.
	Parameters	Optional/Reqd.	Units	Examples
	Tolerance	Required	--	ATLM 1.0E-6
	Keyword Usage	ATOL.
	Reactor Models	Closed Plasma Reactor Cylindrical Shear Flow Reactor Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma PSR Multiphase PSR
ATLRE Reactor Property/Model	The absolute tolerance to determine the energy fluxes at the droplet surface are balanced. This is one of the convergence criteria for solving the droplet surface temperature. This parameter is associated with the "Solve for Surface T" option of the vaporization model.
	Parameters	Optional/Reqd.	Units	Examples
	Tolerance	Required	--	ATLRE 1.0E-6
	Keyword Usage	Optional keyword.
	Reactor Models	Direct Injection Diesel Engine Simulator
ATLS Solver	Absolute tolerance used by the transient DASPK solver, as an indicator of the accuracy desired in the solution for the sensitivity coefficients only. Generally, the sensitivity coefficients need not be solved to a great degree of accuracy, so these tolerances could be lower than the tolerances placed on the physical variables.
	Parameters	Optional/Reqd.	Units	Examples
	Absolute tolerance	Required	--	ATLS 1.E-3
	Keyword Usage	Optional keyword. The default absolute tolerance is 1.E-5.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Honeycomb Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Plasma PSR Plasma Plug Flow Reactor Plug Flow Reactor SI Engine Zonal Simulator
ATLTS Reactor Property/Model	The absolute tolerance for the droplet surface temperature. A droplet surface temperature is considered found when the change in the droplet surface temperature of two consecutive iterations is less than the tolerance. This parameter is associated with the "Solve for Surface T" option of the vaporization model.
	Parameters	Optional/Reqd.	Units	Examples
	Temperature change	Required	K	ATLTS 0.01
	Keyword Usage	Optional keyword. Default is 0.001 K.
	Reactor Models	Direct Injection Diesel Engine Simulator
ATOL Solver	Absolute tolerance used by the solvers as an indicator of the accuracy desired in the physical solution. Typically ATOL should be less than the smallest meaningful value of a species mass fraction.
	Parameters	Optional/Reqd.	Units	Examples
	Absolute tolerance	Required	--	ATOL 1.E-9
	Keyword Usage	Optional keyword. The default values are: CVD, Partially Stirred Reactor (PaSR), Plug Flow Reactor, Shear Flow Reactor: 1.E-8 Open 0-D Reactors run in steady-state mode, Opposed-flow Flame, Premixed Laminar Burner-stabilized Flame, Premixed Laminar Flame-speed Calculation: 1.E-9 Normal Incident Shock, Normal Reflected Shock: 1.E-10 Closed 0-D Reactors and Open 0-D Reactors run in transient mode: 1.E-20 See also RTOL.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Partially Stirred Reactor (PaSR) Closed Plasma Reactor Cylindrical Shear Flow Reactor Diffusion or Premixed Opposed-flow Flame Honeycomb Reactor IC HCCI Engine Non-reactive Gas Mixer Normal Incident Shock Normal Reflected Shock Opposed-flow Flame Partially Stirred Reactor (PaSR) Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma PSR Multiphase PSR Plug Flow Reactor Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation Rotating Disk CVD Reactor SI Engine Zonal Simulator Stagnation Flow CVD Reactor
AVALUE Output	Uses the integrator steps to adaptively insert extra solution data points in addition to those specified by the DTSV option whenever the variable specified by the AVAR keyword moves by ±x since the last time an extra data point was generated. You must specify a value for AVALUE; there is no default and you must also specify the AVAR keyword. The purpose of the AVALUE keyword is to ensure that during a transient solution, sufficient solution data points are available around the time of a fast transient, for example a rapidly increasing temperature, so that an accurate analysis of the problem is possible (to allow plotting a resolution).
	Parameters	Optional/Reqd.	Units	Examples
	Integration steps	Required	--	AVALUE 10
	Keyword Usage	Optional keyword. AVAR is required.
	Reactor Models	Closed Plasma Reactor Closed Homogeneous Reactor Honeycomb Reactor IC HCCI Engine Model Multi-Zone HCCI Engine Simulator Perfectly Stirred Reactor (PSR) Plasma Plug Flow Reactor Plasma PSR Multiphase PSR Plug Flow Reactor SI Engine Zonal Simulator
	Notes	See also ASTEPS and AVAR is required when AVALUE is used.
AVAR Output	Determines which variable is used for the AVALUE keyword. Parameter <string> should be "temperature" or the name of a particular species to serve as the time-stepping monitor species. There is no default species value. AVAR is required when the AVALUE keyword is used.
	Parameters	Optional/Reqd.	Units	Examples
	String	Required	--	AVALUE temperature AVALUE CH4
	Keyword Usage	Optional keyword.
	Reactor Models	Closed Plasma Reactor Closed Homogeneous Reactor Honeycomb Reactor IC HCCI Engine Model Multi-Zone HCCI Engine Simulator Perfectly Stirred Reactor (PSR) Plasma Plug Flow Reactor Plasma PSR Multiphase PSR Plug Flow Reactor SI Engine Zonal Simulator
AXIS Reactor Property	Use a radial, axisymmetric coordinate system.
	Keyword Usage	Optional keyword. By default, the coordinate system is radially axisymmetric.
	Reactor Models	Diffusion or Premixed Opposed-flow Flame
AZFAC Reactor Property/Model	The maximum portion of the initial cylinder volume that can be assigned to the spray parcels.
	Parameters	Optional/Reqd.	Units	Examples
	Maximum total initial parcel volume	Required	--	AZFAC 0.33
	Keyword Usage	Optional keyword. Default is 0.5.
	Reactor Models	Direct Injection Diesel Engine Simulator
BDF Solver	Flag indicating the backward differentiation formulas of the DVODE solver is used to integrate the equations.
	Keyword Usage	Optional keyword. By default, the DASPK solver will be used.
	Reactor Models	Closed Partially Stirred Reactor (PaSR) Partially Stirred Reactor (PaSR)
BDUR Solver	Specifies the value of the "duration of combustion," Dq_c, in the Wiebe function. Dq_c must be greater than 0.
	Parameters	Optional/Reqd.	Units	Examples
	Duration of combustion in number of crank angles	Required	degree	BDUR 45.6
	Keyword Usage	Optional keyword.
	Reactor Models	SI Engine Zonal Simulator
BEFF Solver	Specifies the mass fraction of the fresh fuel-air charge being consumed by the premixed flame, that is, the combustion efficiency. The combustion efficiency must be > 0.0 and ≤ 1.0 and is set to 1.0 (complete combustion) by default.
	Parameters	Optional/Reqd.	Units	Examples
	Combustion efficiency	Optional	--	BEFF 0.85
	Keyword Usage	Optional keyword.
	Reactor Models	SI Engine Zonal Simulator
BETA Reactor Property	This is a combined correction factor to the coalescent collision between particles. The van der Waals forces can enhance the collision frequency while non-coalescent collision can reduce the frequency. The default value is 1.0, that is, van der Waals effect is off and collisions are 100% coalescent.
	Parameters	Optional/Reqd.	Units	Examples
	Material name	Required	--	BETA C(B) 0.9
	Enhance factor	Required	--	BETA C(B) 0.9
	Keyword Usage	Optional keyword.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Cylindrical Shear Flow Reactor Honeycomb Monolith Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma PSR Plasma Plug Flow Reactor Plug Flow Reactor SI Engine Zonal Simulator
BINI Solver	Specifies the value of the "duration of combustion," q_c, in the Wiebe function.
	Parameters	Optional/Reqd.	Units	Examples
	Start of combustion crank angle	Required	degree	BINI -15.3
	Keyword Usage	Optional keyword.
	Reactor Models	SI Engine Zonal Simulator
BLKEQ Reactor Property	Toggle to turn on or off solution of bulk activities for bulk species.
	Parameters	Optional/Reqd.	Units	Examples
	String "on" or "off" to turn on or off solution of the bulk-species equations	Required	--	BLKEQ ON BLKEQ OFF
	Keyword Usage	Optional keyword. By default, bulk-activity equations are solved when there is more than one bulk species in one or more bulk phases on a material. Otherwise the bulk activities are presumed constant at their initial value.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Honeycomb Reactor Perfectly Stirred Reactor (PSR) Plasma Plug Flow Reactor Plasma PSR Plug Flow Reactor
BMCOE Reactor Property / Model	A multiplier, when set to a value greater than 0, that enables the spray parcels to pass their contents (composition and enthalpy) indirectly to other spray parcels via the air zone for the multi-injection simulations.
	Parameters	Optional/Reqd.	Units	Examples
	Parcel back-mixing coefficient	Required	--	BMCOE 1.0
	Keyword Usage	Optional keyword. Default value = 0.0.
	Reactor Models	Direct Injection Diesel Engine Simulator
BLTK Reactor Property	Specifies a boundary-layer thickness. When BLTK is declared, a parabolic velocity profile is specified with a zero velocity at each wall increasing to the velocity specified by VEL at a distance of BLTK from the wall. A flat (constant) velocity profile is used for distances greater than BLTK from the wall. In addition, if the initial gas temperature differs from the initial surface temperature the application linearly interpolates the gas-phase temperature profile between the wall temperature and the bulk gas temperature over the distance BLTK.
	Parameters	Optional/Reqd.	Units	Examples
	Boundary-layer thickness	Required	cm	BLTK 0.05
	Keyword Usage	Optional keyword. By default, the boundary-layer thickness is set to 0 and a full parabolic velocity is assumed.
	Reactor Models	Cylindrical Shear Flow Reactor Planar Shear Flow Reactor
BPWR Reactor Property	RF bias power at a specified material. The energy that the ions gain in the sheath is estimated as this power divided by the total ion current to that material as calculated in the plasma-reactor model. For example, "BPWR material1 200" specifies an applied bias of 200 W to the material boundary, material1. The ion energy gain calculated from the sheath model results in a reduced effective power deposition to the electrons (unless ELSH is also specified), as described in Homogeneous 0-D Reactor Models of the Chemkin Theory Manual .
	Parameters	Optional/Reqd.	Units	Examples
	Material name	Optional If there is no material name than the multiplier applies to all materials.	--	BPWR material1 200 1
	RF bias power	Required	watts	BPWR 200
	Reactor number (PSR clusters only)	Optional If no number is given, the profile described by the first two values is assumed to apply to all reactors in a cluster.	--	BPWR material1 200 1
	Keyword Usage	Optional keyword. By default, the RF bias power is set to 0.0.
	Reactor Models	Closed Plasma Reactor Plasma PSR Plasma Plug Flow Reactor
BTMIN Reactor Property/Model	The minimum value of the Spalding heat transfer number to prevent numerical issues at the beginning of liquid vaporization.
	Parameters	Optional/Reqd.	Units	Examples
	Spalding heat transfer limit	Required	--	BTMIN 0.01
	Keyword Usage	Optional keyword. Default is 0.1
	Reactor Models	Direct Injection Diesel Engine Simulator
BULK Reactor Property	The estimated or initial bulk species activities. This is required input for bulk species in bulk phases that are being etched. For example, BULK Ga(d) 1.0 assigns the estimated activity of 1.0 to the Ga(d) bulk phase species.
	Parameters	Optional/Reqd.	Units	Examples
	Bulk species name	Required	--	BULK Ga(d)1.0
	Bulk activity	Required	--	BULK Ga(d) 1.0
	Keyword Usage	Required keyword. The bulk activity should be specified for bulk species. By default, the initial or estimated bulk species activities are 0.0.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Cylindrical Shear Flow Reactor Honeycomb Reactor Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma Plug Flow Reactor Plasma PSR Plug Flow Reactor Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
	Notes	The sum of all estimated bulk phase activities for each bulk phase should equal one. If they do not sum to one, they will be normalized to one, and a warning message will be printed in the diagnostic output. See also: ETCH keyword. Formerly ACT keyword for some reactor models in previous Ansys Chemkin versions.
BULK_MASSFRAC Reactor Property	Mass fraction of a species within a bulk phase.
	Parameters	Optional/Reqd.	Units	Examples
	phase name	Required		BULK_MASSFRAC Gas 0.6
	mass fraction of a species within a bulk phase	Required		BULK_MASSFRAC jetFuel 0.4
	Keyword Usage	This keyword is used to specify the composition of the entire reactor. Bulk phase name follows the keyword. "Gas" indicates the gas phase. The composition is normalized to 1 at the start of simulation.
	Reactor Models	Closed Multiphase Reactor Open Multiphase PSR Reactor
BULK_MOLARITY Reactor Property	Molarity of a species within a liquid bulk phase. Used for dilute mixtures.
	Parameters	Optional/Reqd.	Units	Examples
	Molarity of a species within a liquid bulk	Optional	--	BULK_MOLARITY nc12h26(l) 1.0
	Keyword Usage	This keyword is used to specify the composition of a dilute liquid bulk. Species name must follow the keyword.
	Reactor Models	Closed Multiphase Reactor Multiphase PSR
BULK_MOLEFRAC Reactor Property	Mole fraction of a species within a bulk phase.
	Parameters	Optional/Reqd.	Units	Examples
	Mole fraction of a species within a liquid bulk	Required	--	BULK_MOLEFRAC Gas 0.6 BULK_MOLEFRAC jetFuel 0.4
	Keyword Usage	This keyword is used to specify the composition of the entire reactor. Bulk phase name follows the keyword. "Gas" indicates the gas phase. The composition is normalized to 1 at the start of simulation.
	Reactor Models	Closed Multiphase Reactor Multiphase PSR
BULK_SOLVENT Reactor Property	Solvent specification when molarity is used to specify composition of a liquid bulk phase. Used for dilute mixtures.
	Parameters	Optional/Reqd.	Units	Examples
	Solvent when molarity is used for composition of a liquid bulk	Optional	--	BULK_SOLVENT nc12h26(l)
	Keyword Usage	This keyword specifies the solvent when molarity is used to specify composition of a dilute liquid bulk. Species name must follow the keyword. The BULK_MOLARITY keyword must also be specified when this keyword is used.
	Reactor Models	Closed Multiphase Reactor Multiphase PSR
BURN Reactor Property	Indicates a burner-stabilized flame problem type, with specified inlet flow rates.
	Keyword Usage	Required keyword.
	Reactor Models	Premixed Laminar Burner-stabilized Flame
	Notes	The problem-type can be changed for a restart run. See also FREE.
CAAC Output	The crank angle at 50% mass burned and is also referred as the anchoring angle. This is one of the three crank angle parameters required to construct the Wiebe function profile that will pass these three crank angles at their corresponding burned mass fractions. By default, this angle marks when half of the original mass is burned. All three crank angles, CASC , CAAC , and CAEC must be provided.
	Parameters	Optional/Reqd.	Units	Examples
	Crankangle at 50% mass burned	Required	degree	CAAC 8.1
	Keyword Usage	Optional keyword.
	Reactor Models	SI Engine Zonal Simulator
CAADV Reactor Property	Additional CA shift.
	Parameters	Optional/Reqd.	Units	Examples
	Additional CA shift	Optional	degree	CAADV 1.5
	Keyword Usage	Optional keyword. Optional for use with OPMV or OPOC. Default value = 0.0.
	Reactor Models	Direct Injection Diesel Engine Simulator IC HCCI Engine Multi-Zone HCCI Engine SI Engine Zonal Simulator
CAATQ Output	Calculates the crank angle for the specified amount of total heat release. The crank angle for 10% and 50% of total heat release will be calculated by default.
	Parameters	Optional/Reqd.	Units	Examples
	Percentage of total heat release	Required	percent	CAATQ 90
	Keyword Usage	Optional keyword.
	Reactor Models	IC HCCI Engine Multi-Zone HCCI Engine Simulator SI Engine Zonal Simulator
CAEC Output	The crank angle at 90% mass burned. This is one of the three crank angle parameters required to construct the Wiebe function profile that will pass these three crank angles at their corresponding burned mass fractions. By default, this angle marks when 90% of the original mass is burned. All three crank angles, CASC , CAAC , and CAEC must be provided.
	Parameters	Optional/Reqd.	Units	Examples
	Crankangle at 90% mass burned	Required	degree	CAEC 23.0
	Keyword Usage	Optional keyword.
	Reactor Models	SI Engine Zonal Simulator
CAIR Reactor Property	Model coefficients for the air entrainment mass flow rate model. There are three parameters required for "before ignition", "after ignition", and "after reaching wall", respectively.
	Parameters	Optional/Reqd.	Units	Examples
	Coefficient before ignition	Required	--	CAIR 0.9 0.25 1.0
	Coefficient after ignition	Required	--	CAIR 0.9 0.25 1.0
	Coefficient after wall	Required	--	CAIR 0.9 0.25 1.0
	Keyword Usage	Required keyword. Default: before ignition: 1.0, after ignition: 0.58, after hitting wall: 1.2.
	Reactor Models	Direct Injection Diesel Engine Simulator
CARR Reactor Property	Specify the named species as the carrier gas. This keyword is used to identify the species in calculating binary diffusion coefficients for tables and for non-dimensionalizations that require a binary diffusion coefficient.
	Parameters	Optional/Reqd.	Units	Examples
	Species name	Optional	--	CARR H2
	Species number	Optional	--	CARR 3
	Keyword Usage	Optional keyword. The default is to use the gas species with the largest mole fraction (from the XBTH input) in the bath-gas composition. If the gas-phase bath-gas composition is not specified, the default is to use the first species in the mechanism.
	Reactor Models	Mechanism Analyzer
CASC Output	The crank angle at 10% mass burned. This is one of the three crank angle parameters required to construct the Wiebe function profile that will pass these three crank angles at their corresponding burned mass fractions. By default, this angle marks when 10% of the original mass is burned. All three crank angles, CASC , CAAC , and CAEC must be provided.
	Parameters	Optional/Reqd.	Units	Examples
	Crankangle at 10% mass burned	Required	degree	CASC -15.4
	Keyword Usage	Optional keyword.
	Reactor Models	SI Engine Zonal Simulator
CDCT Reactor Property	Include conduction through the substrate in the energy balance. Inclusion of this keyword requires specification of a substrate thickness ( CNDX). This value is used only if the disk temperature is being calculated from an energy balance by including keyword RADB . See Equation 15–18 of the Chemkin Theory Manual .
	Keyword Usage	Optional keyword. By default, conduction through the substrate is not included.
	Reactor Models	Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
CDIF Solver	Use central differencing on convective terms in the equations.
	Keyword Usage	Optional keyword. By default, windward differencing is used.
	Reactor Models	Diffusion or Premixed Opposed-flow Flame Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation
CFL Reactor Property	The Courant-Friedrichs-Lewy (CFL) number for the convective process; this parameter limits the fraction of particles whose properties can be set to the inlet conditions per time step.
	Parameters	Optional/Reqd.	Units	Examples
	CFL number	Required	--	CFL 1.0
	Keyword Usage	Optional keyword. By default, the CFL number is 0.5.
	Reactor Models	Closed Partially Stirred Reactor (PaSR) Partially Stirred Reactor (PaSR)
CHEM Reactor Property	Specifies that gas-phase chemistry will be included in the calculations.
	Keyword Usage	Optional keyword. This option is used to reactivate the chemical kinetics if the NOCH option was in effect for the previous calculation for CVD Reactors. For PaSRs, the default is to neglect chemistry and do a mixing calculation only.
	Reactor Models	Closed Partially Stirred Reactor (PaSR) Partially Stirred Reactor (PaSR) Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
CJ Problem Type	Chapman-Jouguet detonation. In this case, H, S, V, and T contain the unburned state and TEST gives the burned temperature estimate.
	Keyword Usage	Optional keyword. The user must include exactly one problem-type keyword
	Reactor Models	Chemical and Phase Equilibrium Calculations
CKTRN Reactor Property	An option to use the Chemkin mixture-averaged transport subroutines to evaluate any transport properties (for example, gas viscosity) needed by the reactor models. This option requires a valid transport linking file from pre-processing of the chemistry set, that is, the chemistry set must include the transport data of all gas species.
	Keyword Usage	Optional keyword.
	Reactor Models	IC HCCI Engine Multi-Zone HCCI Engine Simulator SI Engine Zonal Simulator
CLSC Reactor Property	Defines a critical particle class under which the oxidation process starts to affect (reduce) the particle number density. This parameter is only used by the particle burnout model and has no effect on particle formation and growth. The default value is the minimum particle class plus the maximum class change due to surface reaction.
	Parameters	Optional/Reqd.	Units	Examples
	Material name	Required	--	CLSC CARBON 40
	Critical particle class	Required	--	CLSC CARBON 40
	Keyword Usage	Optional keyword. The default value is the minimum particle class plus the maximum class change due to surface reaction.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Cylindrical Shear Flow Reactor Honeycomb Monolith Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma PSR Plasma Plug Flow Reactor Plug Flow Reactor SI Engine Zonal Simulator
CLSE Reactor Property	Flag indicating the reactor is a closed system, that is, mass flow rate is zero.
	Keyword Usage	Required Keyword.
	Reactor Models	Closed Partially Stirred Reactor (PaSR)
CLSM Reactor Property	Defines the smallest particle class that can exist in the system. This parameter is only used by the particle burnout model and has no effect on particle formation and growth. The default value is the smallest inception class defined by the nucleation reactions.
	Parameters	Optional/Reqd.	Units	Examples
	Material name	Required	--	CLSM CARBON 32
	Minimum particle class	Required	--	CLSM CARBON 32
	Keyword Usage	Optional keyword. The default value is the smallest inception class defined by the nucleation reactions.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Cylindrical Shear Flow Reactor Honeycomb Monolith Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma PSR Plasma Plug Flow Reactor Plug Flow Reactor SI Engine Zonal Simulator
CMIX Reactor Property	The controlling parameter for the modified Curl's and the IEM models for a PaSR.
	Parameters	Optional/Reqd.	Units	Examples
	Time ratio for scalar mixing ( Equation 10–1 of the Chemkin Theory Manual )	Required	--	CMIX 1.0
	Keyword Usage	Required keyword, unless WELL keyword is included.
	Reactor Models	Closed Partially Stirred Reactor (PaSR) Partially Stirred Reactor (PaSR)
CMPR Reactor Property	Engine compression ratio. The compression ratio is defined as the maximum total volume in the cylinder (clearance volume plus swept volume) divided by the clearance volume.
	Parameters	Optional/Reqd.	Units	Examples
	Engine compression ratio	Required	--	CMPR 10
	Keyword Usage	Optional keyword. By default, the ratio is 15.
	Reactor Models	IC HCCI Engine SI Engine Zonal Simulator
CNDT Reactor Property	The back-side temperature of the substrate for use in calculation of conduction losses. This value is used only if the disk temperature is being calculated from an energy balance by including keywords RADB and CDCT . See Equation 15–18 of the Chemkin Theory Manual .
	Parameters	Optional/Reqd.	Units	Examples
	Back-side temperature	Required	K	CNDT 350.
	Keyword Usage	Optional keyword. By default, the back-side temperature is 300.
	Reactor Models	Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
CNDX Reactor Property	The thickness of the substrate for calculation of conduction losses. This value is used only if the disk temperature is being calculated from an energy balance by including keywords RADB and CDCT . See Equation 15–18 of the Chemkin Theory Manual .
	Parameters	Optional/Reqd.	Units	Examples
	Substrate thickness	Required	cm	CNDX 0.03
	Keyword Usage	Optional keyword. By default, the substrate thickness is 0.0.
	Reactor Models	Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
CNTN Reactor Property	Inclusion of this keyword causes Ansys Chemkin to expect keywords for another problem to follow the END keyword. The following problem uses the solution of the previous problem as its initial guess. This capability is very similar to that provided by RSTR. However, in the case of CNTN , several related problems can be solved by one job submission, without having to manipulate the XML Solution File. The solutions resulting from CNTN keywords are written sequentially to one XML Solution File.
	Keyword Usage	Optional keyword. By default, no continuation is expected.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Cylindrical Shear Flow Reactor Honeycomb Reactor IC HCCI Engine Non-reactive Gas Mixer Normal Incident Shock Normal Reflected Shock Opposed-flow Flame Simulator Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma Plug Flow Reactor Plasma PSR Plug Flow Reactor Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation Rotating Disk CVD Reactor Using Steady-state Solver SI Engine Zonal Simulator Stagnation Flow CVD Reactor Using Steady-state Solver
CNTT Reactor Property	This will cause the starting time of the continuation calculation to be equal to the end time of the last solution.
	Keyword Usage	Optional keyword. By default, the starting time of a continuation is set to zero.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor IC HCCI Engine Non-reactive Gas Mixer Perfectly Stirred Reactor (PSR) Plasma PSR SI Engine Zonal Simulator
CNTX Reactor Property	This will cause the starting distance of the continuation calculation to be equal to the end distance of the last solution. This keyword is used for Plug Flow Reactors in place of CNTT.
	Keyword Usage	Optional keyword. By default, the starting distance of a continuation is set to zero.
	Reactor Models	Honeycomb Reactor Plasma Plug Flow Reactor Plug Flow Reactor
COLR Reactor Property	This flag indicates the collision formulation to be used to calculate the collision rate among particles. Three types of collision formulations are available: free molecular regime (=0), continuum regime (=1), and transition regime (=3). The collision rate in the transition regime is obtained as the harmonic mean of the collision rates of free-molecular regime and continuum regime. By default, formulation for free-molecular collision is used.
	Parameters	Optional/Reqd.	Units	Examples
	Material name	Required	--	COLR C(B)1
	Collision regime	Required	--	BETA C(B) 1
	Keyword Usage	Optional keyword. By default, the formulation for the free-molecular regime is used (0).
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Cylindrical Shear Flow Reactor Honeycomb Monolith Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma PSR Plasma Plug Flow Reactor Plug Flow Reactor SI Engine Zonal Simulator
COMP Reactor Property	The boundary condition used at the inlet boundary for the gas species equations will be that of a fixed gas composition, as specified by the REAC keywords.
	Keyword Usage	Optional keyword. By default, a flux balance is solved at the inlet (see keyword FLUX).
	Reactor Models	Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
CONC Output	If this keyword is used, the printed output will appear in molar concentration (mole/cc) rather than mole fraction.
	Keyword Usage	Optional keyword. By default, mole fractions are printed.
	Reactions	Normal Incident Shock Normal Reflected Shock
COND Reactor Property	The thermal conductivity of the substrate in SI units, for use in calculation of conduction losses. This value is used only if the disk temperature is being calculated from an energy balance by including keywords RADB and CDCT . See Equation 15–18 of the Chemkin Theory Manual .
	Parameters	Optional/Reqd.	Units	Examples
	Thermal conductivity	Required	W/cm K	COND 2.1
	Keyword Usage	Optional keyword. By default, the thermal conductivity is 1.38.
	Reactor Models	Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
CONP Problem Type	A transient solution will be obtained with the pressure held constant. The equations solved are those of a constant pressuresystem and the energy equation will be solved.
	Keyword Usage	Optional keyword. By default, a constant pressure problem is assumed.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor
CONV Problem Type	A transient solution will be obtained with the volume held constant. The equations solved are those of a constant volume system and the energy equation will be solved. In this case, the pressure is allowed to float.
	Keyword Usage	Optional keyword. By default, a constant pressure problem is assumed.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor
CONX Reactor Property	This keyword is used to specify a constant (constrained) mole fraction for a species. For example, CONX H2 0.1 will fix the fraction of hydrogen in the mixture to be 0.1.
	Parameters	Optional/Reqd.	Units	Examples
	Species name	Required	--	CONX H20.1
	Mole fraction of the species	Required	mole fraction	CONX H2 0.1
	Keyword Usage	Optional keyword. By default, composition equilibrium is determined for all species.
	Reactor Models	Chemical and Phase Equilibrium Calculations
COTV Problem Type	A transient solution will be obtained with the temperature and volume held constant at the initial values. In this case, the pressure is allowed to float.
	Keyword Usage	Optional keyword. By default, a constant pressure is assumed.
	Reactor Models	Closed Homogeneous Batch Reactor
CPROD Inlet or Reactor Property	One of these CPROD inputs must appear for each complete-combustion product species when the equivalence ratio option is used ( EQUI) for an inlet stream or for the initial conditions of a closed system.
	Parameters	Optional/Reqd.	Units	Examples
	Inlet stream name (PSRs only)	Optional If there is no stream name than the product species will be used for all defined inlet streams.	--	CPROD mixture1 CO2 CPROD mixture1 H2O
	Species name	Required	--	CPROD H2OCPROD CO2
	Keyword Usage	Required keyword when EQUI option is used for an inlet stream or for the initial conditions in a reactor. The specified group of complete-combustion product species must include all of the elements contained in the fuel and oxidizer species. The products must also be "saturated" species. See the Ansys Chemkin Tutorials Manual for more information.
	Reactor Models	Chemical and Phase Equilibrium Calculations Closed Homogeneous Batch Reactor Closed Plasma Reactor Cylindrical Shear Flow Reactor Diffusion or Premixed Opposed-flow Flame Honeycomb Reactor IC HCCI Engine Non-reactive Gas Mixer Partially Stirred Reactor (PaSR) Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma Plug Flow Reactor Plasma PSR Plug Flow Reactor Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
	Notes	The CPROD keywords must be changed as a set, not individually for a restart run. The CPROD keywords must be changed as a set, not individually for continuation run.
CRLN1 Reactor Property	Specify the intake-side connecting rod length.
	Parameters	Optional/Reqd.	Units	Examples
	Connecting rod length	Required	cm	CRLN1 9.2
	Keyword Usage	Optional keyword. Required for use with OPMV or OPOC.
	Reactor Models	Direct Injection Diesel Engine Simulator IC HCCI Engine Multi-Zone HCCI Engine SI Engine Zonal Simulator
CRLN2 Reactor Property	Specify the exhaust-side connecting rod length.
	Parameters	Optional/Reqd.	Units	Examples
	Connecting rod length	Required	cm	CRLN2 8.67
	Keyword Usage	Optional keyword. Required for use with OPMV or OPOC.
	Reactor Models	Direct Injection Diesel Engine Simulator IC HCCI Engine Multi-Zone HCCI Engine SI Engine Zonal Simulator
CRRD1 Reactor Property	Specify the intake-side crank radius.
	Parameters	Optional/Reqd.	Units	Examples
	Crank radius	Required	cm	CRRD1 3.1
	Keyword Usage	Optional keyword. Required for use with OPMV or OPOC.
	Reactor Models	Direct Injection Diesel Engine Simulator IC HCCI Engine Multi-Zone HCCI Engine SI Engine Zonal Simulator
CRRD2 Reactor Property	Specify the exhaust-side crank radius.
	Parameters	Optional/Reqd.	Units	Examples
	Crank radius	Required	cm	CRRD2 2.5
	Keyword Usage	Optional keyword. Required fo use with OPMV or OPOC.
	Reactor Models	Direct Injection Diesel Engine Simulator IC HCCI Engine Multi-Zone HCCI Engine SI Engine Zonal Simulator
CSVOUTPUT_FILENAME Output	Specify CSV output file name.
	Keyword Usage	Optional keyword.
	Parameters	Optional/Reqd.	Units	Examples
	CSV Output File Name	Optional. It is to be used along with CSVOUTPUT_WRITE. By default, the name of the file is Output.csv.	--	CSVOUTPUT_FILENAME modelOutput.csv
	Reactor Models	Closed Homogeneous Batch Reactor Multiphase PSR Honeycomb Reactor Internal Combustion Engine
CSVOUTPUT_KOUT Output	Write species mass-fraction to CSV output file.
	Parameters	Optional/Reqd.	Units	Examples
	Species for Mass Fraction	Optional It is to be used along with CSVOUTPUT_WRITE.	--	CSVOUTPUT_KOUT CH4
	Keyword Usage	Optional keyword. By default, a constant pressure is assumed.
	Parameters	Optional/Reqd.	Units	Examples
	CSV Output File Name	Optional. It is to be used along with CSVOUTPUT_WRITE. By default, the name of the file is Output.csv.	--	CSVOUTPUT_FILENAME modelOutput.csv
	Reactor Models	Closed Homogeneous Batch Reactor Honeycomb Reactor Internal Combustion Engine Multiphase PSR Plug Flow Reactor Diffusion or Premixed Opposed-flow Flame Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation Premixed Laminar Burner-stabilized Stagnation Flame
CSVOUTPUT_WRITE Output	Write output data to a CSV file.
	Keyword Usage	Optional keyword. By default, solution data is not written to a CSV file. Note that only a limited data is written to CSV file.
	Reactor Models	Closed Homogeneous Batch Reactor Honeycomb Reactor Internal Combustion Engine Plug Flow Reactor Multiphase PSR Diffusion or Premixed Opposed-flow Flame Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation Premixed Laminar Burner-stabilized Stagnation Flame
CTOL Reactor Property	Criterion for determining when steady state is reached using a transient solver for Partially Stirred Reactors. The required parameter sets the normalized slope of mean density change in time . The default number of time points used to determine the slope is 100; this value can be changed with the keyword NCFIT.
	Parameters	Optional/Reqd.	Units	Examples
	Normalized slope of mean density	Required	--	CTOL 1.0E-3
	Keyword Usage	Optional keyword. By default, the program does not check for the steady state.
	Reactor Models	Closed Partially Stirred Reactor (PaSR) Partially Stirred Reactor (PaSR)
CTOL Solver	Criterion for determining when steady-state is reached by a transient solver for CVD Reactors. The steady state is reached when the normalized absolute values of all time derivatives are less than CTOL.
	Parameters	Optional/Reqd.	Units	Examples
	Steady-state criterion	Required	--	CTOL 1.0E-2
	Keyword Usage	Optional keyword. By default, the criterion is 1.0E-4.
	Reactor Models	Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
CURL Reactor Property	Flag indicating that the modified Curl's model will be used to simulate the molecular mixing within the computational particle.
	Keyword Usage	Optional keyword. By default, a well mixed model is assumed.
	Reactor Models	Closed Partially Stirred Reactor (PaSR) Partially Stirred Reactor (PaSR)
CURV Solver	Parameter that controls the degree of mesh adaptation based on the second derivative, or curvature, in the solution. A reasonable value is usually between about 0.1 and 1.0, where no adaptation based on curvature is specified with 1.0.
	Parameters	Optional/Reqd.	Units	Examples
	Normalized curvature parameter	Required	--	CURV 0.7
	Keyword Usage	Optional keyword. By default, the curvature parameter is set to 0.5.
	Reactor Models	Diffusion or Premixed Opposed-flow Flame Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
	Notes	This keyword can be changed for a restart run. Steady-state 1-D Solution Methods of the Chemkin Theory Manual for more information.
CYBAR Reactor Property	The cylinder head area to bore-area ratio.
	Parameters	Optional/Reqd.	Units	Examples
	Ratio of cylinder head area to bore area.	Required	None	CYBAR 1.2
	Keyword Usage	Optional keyword. Default = 1.0.
	Reactor Models	IC HCCI Engine Multi-zone HCCI Engine SI Engine Zonal Simulator
	Notes	CYBAR should be > 1.0.
DASP Solver	Flag indicating the DASPK solver is used to integrate the transient equations.
	Keyword Usage	Optional keyword. By default, the DASPK solver will be used.
	Reactor Models	Closed Partially Stirred Reactor (PaSR) Partially Stirred Reactor (PaSR)
DEG0 Reactor Property	The starting crank angle for the transient IC HCCI Engine model, in degrees.
	Parameters	Optional/Reqd.	Units	Examples
	Crank angle	Required	degrees	DEG0 45
	Keyword Usage	Optional keyword. By default, this starting angle is 180 degrees.
	Reactor Models	IC HCCI Engine SI Engine Zonal Simulator
DEGE Output	The ending crank angle for the IC engine simulation. Normally, this is the same as the crank angle at Exhaust Valve Open (EVO).
	Parameters	Optional/Reqd.	Units	Examples
	Crankangle at end of simulation	Required	degree	CAAC 120.5
	Keyword Usage	Optional keyword.
	Reactor Models	IC HCCI Engine Multi-zone HCCI Engine SI Engine Zonal Simulator
DELT Solver	The time interval for solution printing to the diagnostic text output file, for the transient solver. Note that the number of time points written to the diagnostic output file is equal to the value given by TIME divided by DELT.
	Parameters	Optional/Reqd.	Units	Examples
	Time interval	Required	sec	DELT 1.0E-4
	Aurora Usage	Optional keyword. By default, the value of the maximum solver timestep ( STPT) is used.
	Spin Usage	Optional keyword. By default, this is a required keyword for a transient calculation.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor IC HCCI Engine Non-reactive Gas Mixer Normal Incident Shock Normal Reflected Shock Perfectly Stirred Reactor (PSR) Plasma PSR Multiphase PSR Rotating Disk CVD Reactor Stagnation Flow CVD Reactor SI Engine Zonal Simulator
	Notes	Backwards compatible with DT from previous versions.
DFAC Solver	Factor by which to divide the time step in the steady-state solver, Twopnt’s, time stepping procedure when necessary, that is, when the current time step does not converge.
	Parameters	Optional/Reqd.	Units	Examples
	Division factor	Required	--	DFAC 1.5
	Keyword Usage	Optional keyword. By default, the division factor is set to 2.2.
	Reactor Models	Closed Plasma Reactor Diffusion or Premixed Opposed-flow Flame Non-reactive Gas Mixer Perfectly Stirred Reactor (PSR) Plasma PSR Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
DIA Reactor Property	Shock-tube diameter, used for boundary layer corrections.
	Parameters	Optional/Reqd.	Units	Examples
	Tube diameter	Required	cm	DIA 2.0
	Keyword Usage	Optional keyword. By default, the tube diameter is set to 1.0.
	Reactor Models	Normal Incident Shock
DIAM Reactor Property	Tube diameter or hydraulic diameter, where the diameter is constant along the channel. See also DPRO, AREAF, AFLO and user subroutine GEOM.
	Parameters	Optional/Reqd.	Units	Examples
	Tube diameter	Required	cm	DIAM 5.3
	Keyword Usage	Optional keyword. The user must specify DIAM, DPRO, AREAF, or AFLO, unless the GEOM user routine is to be used.
	Reactor Models	Honeycomb Reactor Plasma Plug Flow Reactor Plug Flow Reactor
DIEN Problem Type	Specify that the spray-Combustion Direct Injection Engine Model is used. The Alphabetical Listing of Keywords [F-O] keyword must also be included in the same input file.
	Keyword Usage	Required keyword.
	Reactor Models	Direct Injection Diesel Engine Simulator
DINZL Inlet Property	Define the name of the injector.
	Parameters	Optional/Reqd.	Units	Examples
	Name of injector	Required	--	DINZL modelX
	Keyword Usage	Required keyword.
	Reactor Models	Direct Injection Diesel Engine Simulator
DIST XMLI	This keyword is valid with the XMLI option, when the XML Solution File that is used for initialization or restart contains data as a function of axial distance (e.g. from Shear-layer Flow or Plug Flow). In this case, select the values to use in initialization or restart as those corresponding to the distance that is closest to (greater than or equal to) the specified distance.
	Parameters	Optional/Reqd.	Units	Examples
	Axial distance	Required	cm	DIST 5.0
	Keyword Usage	Optional keyword. By default, uses the data from the last axial distance found in the XML Solution File.
	Reactor Models	Chemical and Phase Equilibrium Calculations Closed Homogeneous Batch Reactor Closed Plasma Reactor Cylindrical Shear Flow Reactor Diffusion or Premixed Opposed-flow Flame Honeycomb Reactor IC HCCI Engine Mechanism Analyzer Non-reactive Gas Mixer Normal Incident Shock Normal Reflected Shock Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma Plug Flow Reactor Plasma PSR Plug Flow Reactor Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation Rotating Disk CVD Reactor SI Engine Zonal Simulator Stagnation Flow CVD Reactor
DPRO Reactor Property Profiles	Hydraulic diameter or tube diameter as a function of distance. See also DIAM, AREAF, AFLO, and user subroutine GEOM.
	Parameters	Optional/Reqd.	Units	Examples
	Distance from inlet	Required	cm	DPRO 0.01.0
	Hydraulic diameter	Required	cm	DPRO 0.0 1.0
	Keyword Usage	Optional keyword. The user must enter DIAM, DPRO, AREAF, or AFLO, unless user subroutine GEOM is to be used.
	Reactor Models	Honeycomb Reactor Plasma Plug Flow Reactor Plug Flow Reactor
DT Reactor Property	The time step size of the Monte Carlo simulation.
	Parameters	Optional/Reqd.	Units	Examples
	Time step	Required	sec	DT 1.0E-4
	Keyword Usage	Required keyword.
	Reactor Models	Closed Partially Stirred Reactor (PaSR) Partially Stirred Reactor (PaSR)
DT0 Solver	The initial time step size used by the transient solver.
	Parameters	Optional/Reqd.	Units	Examples
	Initial time step size	Required	sec	DT0 1.0E-4
	Keyword Usage	Optional keyword. By default, the initial time step size is set to 1.0E-6.
	Reactor Models	Closed Partially Stirred Reactor (PaSR) Partially Stirred Reactor (PaSR) Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
	Notes	Backwards compatible with H0 keyword.
DTDEG Solver	The maximum time step in terms of crank angle that may be taken by the DASPK solver for the transient IC HCCI Engine model, in degrees. If DTDEG is specified, then it will overwrite the time step value specified by STPT.
	Parameters	Optional/Reqd.	Units	Examples
	Time step	Required	degrees	DTDEG 30
	Keyword Usage	Optional keyword. By default, this time step is value of STPT.
	Reactor Models	IC HCCI Engine SI Engine Zonal Simulator
	Notes	See also: STPT keyword.
DTIGN Output	Temperature threshold used to determine when ignition has occurred and allow printing of ignition delay times. The ignition temperature will be the initial temperature plus this value. Only applicable when you are solving the energy equation with the transient solver.
	Parameters	Optional/Reqd.	Units	Examples
	Ignition temperature delta	Required	K	DTIGN 200
	Keyword Usage	Optional keyword. See also TLIM .
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Honeycomb Monolith Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Plasma PSR Plasma Plug Flow Reactor Plug Flow Reactor SI Engine Zonal Simulator
DTMN Solver	Minimum time step tolerated in the steady-state solver, Twopnt ’s time stepping algorithm before flagging an error condition.
	Parameters	Optional/Reqd.	Units	Examples
	Minimum time step	Required	sec	DTMN 1.E-9
	Keyword Usage	Optional keyword. By default, the minimum time step is 1.E-10.
	Reactor Models	Cylindrical Shear Flow Reactor Diffusion or Premixed Opposed-flow Flame Non-reactive Gas Mixer Perfectly Stirred Reactor (PSR) Plasma PSR Rotating Disk CVD Reactor Stagnation Flow CVD Reactor Planar Shear Flow Reactor Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation
DTMX (steady-state) Solver	Maximum time step allowed in Twopnt ’s time-stepping algorithm. When this value is reached, the time step size will no longer be increased and time stepping will continue with a fixed time step.
	Parameters	Optional/Reqd.	Units	Examples
	Maximum time step	Required	sec	DTMX 1.E-3
	Keyword Usage	Optional keyword. By default, the maximum time step is 1.E-2.
	Reactor Models	Cylindrical Shear Flow Reactor Diffusion or Premixed Opposed-flow Flame Non-reactive Gas Mixer Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma PSR Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
DTMX (transient) Solver	Maximum time step used internally by the solver in transient calculations. DTMX determines the largest time-step the transient solver can take at one time and thereby controls the resolution for interpolation of specified time-profiles.
	Parameters	Optional/Reqd.	Units	Examples
	Maximum time step	Required	sec	DTMX 1.E-3
	Keyword Usage	Optional keyword. By default, the maximum time step is 1.E-4.
	Reactor Models	Closed Partially Stirred Reactor (PaSR) Partially Stirred Reactor (PaSR)
DTSV Output or Solver	Controls the time interval for data to be written to the XML Solution File (e.g., XMLdata.zip). Note that the number of time points written to the XML Solution File is equal to the value given by TIME divided by DTSV.
	Parameters	Optional/Reqd.	Units	Examples
	Time interval for solution saving	Required	sec	DTSV 1.0E-5
	Keyword Usage	Optional keyword. By default, the value of the STPT keyword is used.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor IC HCCI Engine Non-reactive Gas Mixer Perfectly Stirred Reactor (PSR) Plasma PSR Closed Partially Stirred Reactor (PaSR) Partially Stirred Reactor (PaSR) SI Engine Zonal Simulator
DX Output or Solver	Distance interval for printing the solution to the diagnostic output file.
	Parameters	Optional/Reqd.	Units	Examples
	Distance interval	Required	cm	DX 0.25.
	Keyword Usage	Optional keyword. By default, the distance interval is the value of the DXMX is used, or XEND divided by 100 if DXMX is not available.
	Reactor Models	Cylindrical Shear Flow Reactor Honeycomb Reactor Planar Shear Flow Reactor Plasma Plug Flow Reactor Plug Flow Reactor
DXMX Solver	The maximum distance step that can be used internally by the transient solver. DXMX determines the largest step that the solver can take at one time and thereby controls the resolution for interpolation of specified spatial-profiles. See also DX and DXSV.
	Parameters	Optional/Reqd.	Units	Examples
	Distance interval	Required	cm	DXMX 0.1
	Keyword Usage	Optional keyword. By default, If either DX or DXSV are specified, then DXMX is set to the smallest of these values. If neither DX nor DXSV are specified, then DXMX is set to the value of XEND divided by 100.
	Reactor Models	Cylindrical Shear Flow Reactor Honeycomb Reactor Planar Shear Flow Reactor Plasma Plug Flow Reactor Plug Flow Reactor
DXSV Solver	Controls the distance interval for data to be written to the XML Solution File (for example, XMLdata.zip). The number of points written to the XML Solution File is equal to the value given by XEND divided by DXSV.
	Parameters	Optional/Reqd.	Units	Examples
	Distance interval	Required	cm	DXSV 0.1
	Keyword Usage	Optional keyword. By default, the value of DXMX is used.
	Reactor Models	Cylindrical Shear Flow Reactor Honeycomb Reactor Planar Shear Flow Reactor Plasma Plug Flow Reactor Plug Flow Reactor
EGRR Reactor or Inlet Property	Specifies the EGR rate for an inlet stream or for the initial conditions in a closed reactor.
	Parameters	Optional/Reqd.	Units	Examples
	EGR ratio	Optional	None	EGRR 0.2
	Keyword Usage	Optional keyword. EGR rate can be used in any reactor model as a feature on input or initial composition panels. EGR specification can be activated when Equivalence ratio option is used to specify inlet or initial composition. Leaving the EGR Rate box empty will use no EGR, but use diluants if specified on the Added Species tab. When EGR Rate is specified, the composition on the Added Species tab is used as the EGR composition. The sum of all the fractions on the Added Species tab should be 1.0 when EGR Rate is specified. If the sum is less than 1, Chemkin will automatically normalize the EGR composition.
	Reactor Models	Closed Homogeneous Batch Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Honeycomb Reactor Plasma Plug Flow Reactor Plasma PSR Plug Flow Reactor
ELSH Reactor Property	Specified energy loss to ions in the sheath for each ion lost at a specified material. The energy that the ions gain in the sheath is typically assumed to be the sheath voltage, which can be described as a multiplier of . The value given here is the value of the multiplier. For example, "ELSH material1 5.0" would result in an ion energy gain of as it crossed the sheath near the material material1. This energy gain for the ions results in a reduced effective power deposition to the electrons, as described in Plasma Systems of the Chemkin Theory Manual .
	Parameters	Optional/Reqd.	Units	Examples
	Material name	Optional If there is no material name then the multiplier applies to all materials.	--	ELSH material15.0 1
	Multiplier value	Required	--	ELSH 5.0
	Reactor number (PSR clusters only)	Optional If no number is given, values are assumed to apply to all reactors in a cluster.	--	ELSH material1 5.0 1
	Keyword Usage	Optional keyword. By default, the multiplier is set to 0.0, when no ELSH keyword is included.
	Reactor Models	Closed Plasma Reactor Plasma Plug Flow Reactor Plasma PSR
EMIS Reactor Property	The emissivity of the disk. This value is used only if the disk temperature is being calculated from an energy balance by including keyword RADB . See Equation 15–18 of the Chemkin Theory Manual .
	Parameters	Optional/Reqd.	Units	Examples
	Emissivity	Required	--	EMIS 0.9
	Keyword Usage	Optional keyword. By default, the emissivity is 0.85.
	Reactor Models	Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
EMPAR Reactor Property	This keyword provides the value of the model parameter C _part for computing the overall emissivity of the named particle cloud as given in Equation 13–21 in the Chemkin Theory Manual .
	Parameters	Optional/Reqd.	Units	Examples
	Material name	Required	--	EMPAR soot 700
	Model coefficient	Required	m^-1K^-1	EMPAR soot 700
	Keyword Usage	Optional keyword. The default value is 700 (m^-1K^-1).
	Reactor Models	Diffusion or Premixed Opposed-flow Flame Burner-stabilized Pre-mixed Flame Premixed Laminar Flame-speed Calculation
EMSG Reactor Property Profiles	Approximation of the temperature-dependent emissivity of the gas-mixture, used to calculate a radiation-loss term in the gas energy equation. The radiation is calculated between the gas and the disk (using the gas temperature) and between the gas and the inlet (using the inlet temperature). The EMSG keyword provides temperature, emissivity pairs for the gas mixture.
	Parameters	Optional/Reqd.	Units	Examples
	Temperature	Required	K	EMSG 20000.03
	Emissivity	Required	--	EMSG 2000 0.03
	Keyword Usage	Optional keyword. By default, no gas radiation loss is included in the energy equation.
	Reactor Models	Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
END Reactor Property	This keyword signifies the end of the input data for a given reactor description. It must appear after each set of data when continuation jobs are indicated using the CNTN keyword.
	Keyword Usage	Required keyword.
	Reactor Models	Chemical and Phase Equilibrium Calculations Closed Homogeneous Batch Reactor Closed Partially Stirred Reactor (PaSR) Closed Plasma Reactor Cylindrical Shear Flow Reactor Diffusion or Premixed Opposed-flow Flame Honeycomb Reactor IC HCCI Engine Mechanism Analyzer Non-reactive Gas Mixer Normal Incident Shock Normal Reflected Shock Partially Stirred Reactor (PaSR) Perfectly Stirred Reactor (PSR) Planar Shear Flow Reactor Plasma Plug Flow Reactor Plasma PSR Multiphase PSR Plug Flow Reactor Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation Rotating Disk CVD Reactor SI Engine Zonal Simulator Stagnation Flow CVD Reactor
ENDTIMEMAX Reactor Property	Since the physical time required to reach steady-state normally increases with decreasing values of SSDR, the integration time is increased by the factor SSDR_nominal/currentSSDR for SSDR values smaller than the nominal. The maximum value for the end-time is limited to the value specified by this control.
	Parameters	Optional/Reqd.	Units	Examples
	Maximum value of end time	Optional	s	ENDTIMEMAX 1.0E+05
	Keyword Usage	Optional keyword. The default value for the Diffusion Flamelet Generator is 1.0E+05
	Reactor Models	Diffusion Flamelet Generator
ENGE Reactor Property	Solve the electron energy equation. The user must still specify a temperature (see ETMP), which provides the initial guess or initial value for the electron temperature.
	Parameters	Optional/Reqd.	Units	Examples
	Reactor number (PSR clusters only)	Optional If no number is given, values are assumed to apply to all reactors in a cluster.	--	ENGE 2
	Keyword Usage	Optional keyword. By default, the electron energy equation is not solved.
	Reactor Models	Closed Plasma Reactor Plasma PSR Plasma Plug Flow Reactor
	Notes	ENGE must be specified when electrons are present for all PSRs.
ENGY Reactor Property	Specifies the starting internal energy for the initial mixture.
	Parameters	Optional/Reqd.	Units	Examples
	Energy	Required	erg/g	ENGY 1.5E9
	Keyword Usage	Optional keyword. The user must specify two state variables and the composition to define the initial mixture.
	Reactor Models	Chemical and Phase Equilibrium Calculations
ENRG Problem Type	Solve the energy equation to determine the gas temperature.
	Parameters	Optional/Reqd.	Units	Examples
	Reactor number (PSR clusters only)	Optional If no number is given, the keyword is assumed to apply to all reactors in a cluster.	--	ENRG 2
	Bulk name	Optional	--	ENRG Gas
	Keyword Usage	Optional keyword. For the multiphase reactors, the keyword would be effective for the phase name following the keyword. The name of the bulk phase should be used. "Gas" indicates the gas phase. Either TGIV or ENRG must be specified in most cases. For closed homogeneous systems, ICEN, CONP, CONV, or COTV can be specified instead. For Premixed Flamespeed Calculations, ENRG is required.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Diffusion or Premixed Opposed-flow Flame Honeycomb Reactor Non-reactive Gas Mixer Perfectly Stirred Reactor (PSR) Plasma Plug Flow Reactor Plasma PSR Multiphase PSR Plug Flow Reactor Premixed Laminar Flame-speed Calculation Premixed Laminar Burner-stabilized Flame Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
	Notes	You must still specify an initial or initial estimate of the gas temperature or temperature profile. See also: TEMP or TPRO keyword. For steady-state reactor models, this initial temperature is used in solving the intermediate fixed-temperature problem and is an initial guess for the solution of the full problem including the energy equation. Inclusion of the keywords CONP, CONV, or ICEN, will also indicate that the energy equation should be solved.for closed homogeneous systems.
ENTH Reactor Property	Specifies the starting enthalpy for the initial mixture.
	Parameters	Optional/Reqd.	Units	Examples
	Enthalpy	Required	erg/g	ENTH 1.5E9
	Keyword Usage	Optional keyword. The user must specify two state variables and the composition to define the initial mixture.
	Reactor Models	Chemical and Phase Equilibrium Calculations
ENTH_DELTA_IN Reactor Property	Specifies the percentage with respect to the specified inlet enthalpy and is used to compute a new inlet temperature. For example, if the condition specified on the Inlet panel input is {T, Y_CH4} ={300, 1.0} and the input value for the enthalpy delta is -2%, then (a) the new enthalpy is Hnew = 0.98*H(T=300, Y_CH4=1), and (b) the new inlet temperature is Tnew = T(Hnew, Y_CH4). The typical intended usage is to facilitate flamelet generation at different enthalpy levels. Note that when there is more than one inlet (as in the opposed-flow-based reactor models), the enthalpy change is applied to all inlets the same and, depending on the specified composition, each inlet will have a corresponding temperature.
	Parameters	Optional/Reqd.	Units	Examples
	Percentage	Required	--	ENTH_DELTA_IN 5.0
	Keyword Usage	Optional keyword.
	Reactor Models	Diffusion Flamelet Generator Extinction of Diffusion or Premixed Opposed-flow Flame Opposed-flow Premixed-Burner-Stabilized_Stagnation Flame
ENTR Reactor Property	Specifies the starting entropy for the initial mixture.
	Parameters	Optional/Reqd.	Units	Examples
	Entropy	Required	erg/(g ⋅ K)	ENTR 7.0E7
	Keyword Usage	Optional keyword. The user must specify two state variables and the composition to define the initial mixture.
	Reactor Models	Chemical and Phase Equilibrium Calculations
EPSG Output	Threshold value for the first-order sensitivity coefficients for the growth rates of all bulk phases with respect to the rate constants. Coefficients below this value are neither printed to the diagnostic output file nor saved in the XML Solution File.
	Parameters	Optional/Reqd.	Units	Examples
	Threshold value	Required	--	EPSG .01
	Keyword Usage	Optional keyword. By default, the threshold value for bulk phases is set to 0.001.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Honeycomb Reactor Perfectly Stirred Reactor (PSR) Plasma Plug Flow Reactor Plasma PSR Plug Flow Reactor
	Notes	This keyword can be added but not removed from a continuation run.
EPSR Output	Threshold value for the rate-of-production coefficients. Coefficients below this value are neither printed to the diagnostic output file nor saved in the XML Solution File.
	Parameters	Optional/Reqd.	Units	Examples
	Threshold value	Required	--	EPSR .02
	Keyword Usage	Optional keyword. By default, the threshold value for rate-of-production coefficients is set to 0.01.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Honeycomb Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Plasma Plug Flow Reactor Plasma PSR Plug Flow Reactor SI Engine Zonal Simulator
	Notes	This keyword can be added but not removed from a continuation run.
EPSS Output	Threshold value for the first-order sensitivity coefficients for the species with respect to the rate constants. Coefficients below this value are neither printed to the diagnostic output file nor saved in the XML Solution File.
	Parameters	Optional/Reqd.	Units	Examples
	Threshold value	Required	--	EPSS .01
	Keyword Usage	Optional keyword. By default, the threshold value for species is set to 0.001.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Diffusion or Premixed Opposed-flow Flame Closed Multiphase Reactor Honeycomb Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Plasma Plug Flow Reactor Plasma PSR Multiphase PSR Plug Flow Reactor Premixed Laminar Burner-stabilized Flame Premixed Laminar Flame-speed Calculation Rotating Disk CVD Reactor SI Engine Zonal Simulator Stagnation Flow CVD Reactor
	Notes	This keyword can be added but not removed from a continuation run.
EPST Output	Threshold value for the first-order sensitivity coefficients for the gas temperature with respect to the rate constants. Coefficients below this value are neither printed to the diagnostic output file nor saved in the XML Solution File.
	Parameters	Optional/Reqd.	Units	Examples
	Threshold value	Required	--	EPST .01
	Keyword Usage	Optional keyword. By default, the threshold value for gas temperature is set to 0.001.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Closed Multiphase Reactor Honeycomb Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Plasma Plug Flow Reactor Plasma PSR Multiphase PSR Plug Flow Reactor SI Engine Zonal Simulator
	Notes	This keyword can be added but not removed from a continuation run.
EQRX Solver	Specifies that the products from the premixed flame will be estimated by equilibrium calculation with constant enthalpy and pressure in the 2-zone SI Engine simulation. By default, equilibrium calculation is used to obtain gas product composition from the premixed flame.
	Parameters	Optional/Reqd.	Units	Examples
	--	Optional	--	EQRX
	Keyword Usage	Optional keyword.
	Reactor Models	SI Engine Zonal Simulator
EQUI Reactor Property	Flag indicating that equilibrium composition will be calculated. The chemical state of the statistical event particles will be determined by the corresponding equilibrium states instead of by time integration of the chemical source terms.
	Keyword Usage	Optional keyword. By default, chemistry is neglected and a mixing-only calculation is performed. See also CHEM.
	Reactor Models	Closed Partially Stirred Reactor (PaSR) Partially Stirred Reactor (PaSR) SI Engine Zonal Simulator
EQUI Reactor or Inlet Property	Specifies the air/fuel equivalence ratio for an inlet stream or for the initial conditions in a closed reactor.
	Parameters	Optional/Reqd.	Units	Examples
	Inlet stream name (for open systems only)	Optional If there is no stream name than the air/fuel equivalence ratio applies to the default or all defined streams.	--	EQUI mixture1 1.1
	Air / fuel equivalence ratio	Required	--	EQUI 1.1
	Keyword Usage	Optional keyword. Either REAC or EQUI keywords are required for each inlet stream or to specify the initial conditions of a closed reactor. When EQUI is included, FUEL / OXID / CPROD keywords must also be supplied.
	Reactor Models	Closed Homogeneous Batch Reactor IC HCCI Engine Perfectly Stirred Reactor (PSR) Honeycomb Reactor Plasma Plug Flow Reactor Plasma PSR Plug Flow Reactor
ETCH Reactor Property	Inclusion of this keyword indicates that a given bulk phase is expected to be etched instead of grown or deposited. This option changes the form of the equations to be solved for the bulk phase composition, as described in Bulk Species Equations During Etch of the Chemkin Theory Manual .
	Parameters	Optional/Reqd.	Units	Examples
	Bulk phases	Optional Required if there is more than one bulk phase	--	ETCH BULK1
	Reactor number (PSR clusters only)	Optional If no number is given, the keyword is assumed to apply to all reactors in a cluster.	--	ETCH BULK1 2
	Keyword Usage	Optional keyword. By default, the names of the unnamed Surface Kinetics bulk phases is: BULK1, BULK2, etc.
	Reactor Models	Closed Homogeneous Batch Reactor Closed Plasma Reactor Honeycomb Reactor Perfectly Stirred Reactor (PSR) Plasma Plug Flow Reactor Plasma PSR Plug Flow Reactor Rotating Disk CVD Reactor Stagnation Flow CVD Reactor
	Notes	When the keyword ETCH is supplied for a bulk phase, it is required that bulk activities (see BULK) are also included for each bulk-phase species in that phase that is etched.
ETMP Reactor Property	The electron temperature in the reactor. This value is used as the initial estimate of the electron temperature for steady-state iteration (when ENGE is included), or as the initial electron temperature value for transient simulations.
	Parameters	Optional/Reqd.	Units	Examples
	Electron temperature	Required	K	ETMP 33000.
	Reactor number (PSR clusters only)	Optional If no number is given, values are assumed to apply to all reactors in a cluster.	--	ETMP 33000. 1
	Keyword Usage	Optional keyword. By default, the electron temperature is the same as the gas temperature.
	Reactor Models	Closed Plasma Reactor Plasma PSR Plasma Plug Flow Reactor
EXT_GETFLAMELETS Reactor Property	Compute extinguishing flamelets.
	Parameters	Optional/Reqd.	Units	Examples
	--	Required when computing the extinguishing flamelets	--	EXT_GETFLAMELETS
	Keyword Usage	Optional.
	Reactor Models	Diffusion Flamelet Generator
EXTINCTION Reactor Property	Indicates extinction problem type.
	Keyword Usage	Required keyword.
	Reactor Models	Extinction of Diffusion or Premixed Opposed-flow Flame
EXT_MAXTFRAC Reactor Property	The fraction multiplying the current T maximum that is used to constrain the flame toward extinction. The extinction simulator finds the location at which T = maximum temperature fraction * (Current maximum temperature — Inlet temperature). Temperature at this location is successively decreased by the user-specified temperature step size until it reaches T = minimum temperature fraction * (Current maximum temperature — Inlet temperature). A new location is then selected using the maximum temperature fraction. This process is repeated until the desired number of steps is reached or until the flame is effectively extinguished.
	Parameters	Optional/Reqd.	Units	Examples
	Maximum Temperature Fraction	Required	--	EXT_MAXTFRAC 0.8
	Keyword Usage	Required. The default value is 10.8.
	Reactor Models	Extinction of Diffusion or Premixed Opposed-flow Flame
	Notes	Also see keyword EXT_MINTFRAC .
EXT_METHOD Reactor Property	Specifies the type of control technique to be used in extinction simulation.
	Parameters	Optional/Reqd.	Units	Examples
	BOOLEAN	Required	--	EXT_METHOD 0
	Keyword Usage	Optional. By default, the value is 0 which indicates 1-point control. The other possible choice is 1 which indicates 2-point control.
	Reactor Models	Extinction of Diffusion or Premixed Opposed-flow Flame
EXT_MINTFLAME Reactor Property	If the maximum temperature in any solution obtained in the extinction simulation is below this value, the extinction simulator will stop assuming that there is no flame.
	Parameters	Optional/Reqd.	Units	Examples
	Minimum Flame Temperature	Required	K	EXT_MINTFLAME 1500
	Keyword Usage	Optional. The default value is 11500.
	Reactor Models	Extinction of Diffusion or Premixed Opposed-flow Flame
	Notes	This option is useful to avoid computing solutions beyond extinction point.
EXT_MINTFRAC Reactor Property	The fraction multiplying the current T maximum that is used to constrain the flame toward extinction. The extinction simulator finds the location at which T = maximum temperature fraction * (Current maximum temperature — Inlet temperature). Temperature at this location is successively decreased by the user-specified temperature step size until it reaches T = minimum temperature fraction * (Current maximum temperature — Inlet temperature). A new location is then selected using the maximum temperature fraction. This process is repeated until the desired number of steps is reached or until the flame is effectively extinguished
	Parameters	Optional/Reqd.	Units	Examples
	Minimum Temperature Fraction	Required	--	EXT_MINTFRAC 0.2
	Keyword Usage	Required. The default value is 10.2.
	Reactor Models	Extinction of Diffusion or Premixed Opposed-flow Flame
	Notes	Also see keyword EXT_MAXTFRAC .
EXT_NIGSTEPS Reactor Property	Number of (internal) integration steps after which a flamelet file is written when computing extinguishing flamelets.
	Parameters	Optional/Reqd.	Units	Examples
	Number of integration steps	Required when computing the extinguishing flamelets	--	EXT_NIGSTEPS 50
	Keyword Usage	Optional. The default value is 50.
	Reactor Models	Diffusion Flamelet Generator
EXT_SAVEINT Reactor Property	Frequency of saving solution in extinction simulation.
	Parameters	Optional/Reqd.	Units	Examples
	Saving frequency	Required	--	EXT_SAVEINT 10
	Keyword Usage	Optional. The default value is 10.
	Reactor Models	Extinction of Diffusion or Premixed Opposed-flow Flame
	Notes	Since extinction problems are numerically intensive, it may be prudent to save solutions frequently. The input value of this keyword indicates the number of solutions are found before an opposed-flow solution is saved in the process of marching towards the extinction point. (A new extinction simulation can be started by using the restart facility.).
EXT_STEPS Reactor Property	Number of times opposed flow solution is computed in search of the extinction point.
	Parameters	Optional/Reqd.	Units	Examples
	Solution steps	Required	--	EXT_STEPS 100
	Keyword Usage	Optional. The default value is 100.
	Reactor Models	Extinction of Diffusion or Premixed Opposed-flow Flame
EXT_TSTEP Reactor Property	Temperature step by which temperature at control point is decreased in extinction simulator.
	Parameters	Optional/Reqd.	Units	Examples
	Temperature step	Required	K	EXT_TSTEP 5
	Keyword Usage	Optional. Default value is 5.
	Reactor Models	Extinction of Diffusion or Premixed Opposed-flow Flame
EXT_VFCNTRL Reactor Property	Specifies how to constrain nozzle velocities in extinction simulation.
	Parameters	Optional/Reqd.	Units	Examples
	BOOLEAN	Required	--	EXT_VFCNTRL 1
	Keyword Usage	Required. The default value is 1 which indicates that momentum of the two jets should be balanced. This creates the stagnation plane in the middle. The other option is 0 which indicates that the magnitude of velocity from both nozzles is the same.
	Reactor Models	Extinction of Diffusion or Premixed Opposed-flow Flame
	Notes	This option can only be used for 1-point control. For a 2-point control, it is ignored if specified.