The application of a phase change dispersion (PCD) as heat transfer fluid allows one to cool a system at almost constant temperature by adding fine phase change material (PCM) particles to water. We present important aspects for the design of PCDs. An optimum between the increase of apparent heat capacity and resulting viscosity has to be found. Additionally, it is crucial to compare the melting time of PCM particles to the residence time of the PCD inside a heat exchanger. In this regard, we present a semi analytic expression for the heat capacity rate ratio which allows determining the ideal content of the dispersed phase assuming a laminar flow regime, as well as a quasi-stationary model describing the melting process of a PCM particle.

Numerical results indicate that in common cooling applications, the melting time is smaller than the residence time and should therefore not be a limiting factor. Certain cases, such as cooling by impinging jets, have to be treated specially.

heat transfer fluid, phase change dispersion (PCD), phase change material (PCM), melting, solidification, modelling.