Numerical Study on Phase Change Heat Transfer of Paraffin Filled in Aluminum Foams in Solar Flat-plate Collector

摘要

This paper is to study the phase change heat transfer process of paraffin filled in aluminum foams integrated in a solar fiat-plate collector. A two-temperature model is proposed to analyze conduction and convection between the aluminum foams and paraffin in solid or liquid phases. The momentum conservation of liquid paraffin is simulated with Darcy's model with the Brinkman-Forchheimer extension. The results indicate that the heat transfer performance is significantly improved by using the aluminum foams filled with paraffin. It is also shown that the assumption of the local thermal equilibrium between the foam and paraffin invoked in previous studies is inadequate in predicting the heat transfer behavior, whereas the two-temperature model proposed in this work without the local thermal equilibrium assumption can result in a more realistic prediction to the phase-change heat transfer process.