absorbs energy first to raise the solid to its melting temperature then an amount of energy equivalent to its latent heat of fusion in melting and lastly additional sensible heat as the temperature of the now liquid pcm increases above the melting temperature the pcm maintains a near uniform temperature while solid and liquid co exist the uniform temperature over this range of thermal absorption is the basis for the use of pcms to moderate thermal variations in chemical reactions electronics packing and the like thus in many applications it is advantageous not to fully melt the pcm the molten pcm freezes upon removing the thermal body exposure and exposing the container with the pcm to an environment at a temperature less than the melting temperature of the pcm the energy absorbed in the process of the pcm melting is now reversibly radiated into the environment sensible heat storage within a pcm may be made comparable to that stored in the pcm as latent heat of fusion but at the cost of not being stored isothermally furthermore excessive heating of the molten pcm in order to store increasing amounts of sensible heat may degrade the pcm for these reasons it is a preferred embodiment that the maximal temperature of a pcm not be raised.