Accurate latent heat measurements of small liquid samples

Abstract

The sample is connected by a finite thermal resistance to a large capacity heat sink, suitably enclosed by an outside shield. Equivalent circuits of such a calorimeter system with a sample of high or low thermal diffusivity are analysed. In both cases relations are given for the accurate evaluation of the latent heat from the temperature difference measured between the sink and the sample during a phase transition. The analysis also helps to determine the optimum performance of the system which includes linear heating of the sink with the above difference constant away from the transition. The correct interpretation of superheating and supercooling effects is also included. This method has been used for latent heat measurements of liquid crystal phase transition.