You can input specific heat effects using either the C (specific heat) or ENTH (enthalpy) property. Enthalpy has units of heat/volume and is the integral of C x DENS over temperature. If both C and ENTH are specified, the program uses ENTH. ENTH should be used only in a transient thermal analysis. For phase-change problems, you must input ENTH as a function of temperature using the MP family of commands (MP, MPTEMP, MPTGEN, and MPDATA).