Paraffin phase change emulsion is a new type of functional fluid that integrates heat storage and heat transfer

and has broad application prospects. However

the application of phase-change paraffin emulsion suffers from subcooling phenomenon

which weakens its ability to store and transfer heat remarkably. The degree of subcooling in phase-change paraffin emulsion is conventionally determined by differential scanning calorimetry (DSC)

the result of which is dependent on the heating / cooling rate. As the heating / cooling rate increases

the degree of subcooling is higher. Here an equilibrium volumetric method was presented to determine the degree of subcooling in phase-change paraffin emulsion by measuring its specific volume at different temperatures. The specific volume obtained was plotted against the temperature to identify the phase transition temperature of paraffin during heating / cooling process

then the degree of subcooling was deduced from the phase transition temperatures obtained. The results showed that the degree of subcooling in phase-change paraffin emulsion can be measured accurately using the equilibrium volumetric method presented in this work. The results also revealed the mechanism of subcooling in phase-change paraffin emulsion from the point of view of specific volume change.