Phase change dispersion properties, modeling apparent heat capacity

•Phase change dispersions allow for storing and releasing of heat.•PCD enable isothermal cooling at constant temperature.•An appropriate emulsifier results in low viscosity and high stability.•The phase content of the PCD has to be optimized with respect to viscosity. The authors present values and an application of a phase change dispersion (PCD). As the heat transfer during phase change takes place at constant temperature, the heat transfer fluid itself remains at nearly constant temperature while absorbing heat. Isothermal heating and cooling of devices with a fluid is possible. A quasi-homogenous model is used to characterize the PCD with emphasis on the calculation of the “apparent specific heat capacity”. The application of cooling a machine spindle with high thermal load at 24 °C ± 0.4 °C will be presented together with basic research work of calculating heat transfer within liquids practically not changing in temperature.