Modelling of heat transfer in supercritical pressure recuperators

Abstract

Abstract In the paper presented is analysis of convective flow heat transfer at supercritical pressure in channels of heat exchanger working in the thermodynamic cycle. The modelling is based on the division of the flow into three regions, namely the heavy fluid, a two phase flow consisting of the heavy and light fluids and finally the light fluid flow. Modelling is concentrated on the region of simultaneous flow of two fluids divided into the zones with the light and heavy fluids. These agents are considered with averaged thermophysical properties in each region. The surface separating the two zones with respective fluids is assumed to feature the pseudocritical temperature. The problem is solved using a previously developed theoretical model based on considerations of energy dissipation in the flow. The fundamental hypothesis in the model is the fact that heat transfer is considered as being dependent on two contributions of energy dissipation, one stemming from the shearing pseudo two-phase flow of the heavy and light fluids, whereas the second contribution comes from the energy dissipation due to exchange of mass between the heavy and light fluids. The results of calculations have been compared with some experimental data from literature showing a good consistency.