Heat Transfer Enhancement in Latent Heat Storage Units

Abstract

In the present work, latent heat thermal storage devices that use an array of fins are studied experimentally and theoretically. The thermal storage charging/discharging process is driven by a hot/cold heat transfer fluid (HTF) flowing inside the tube from which heat is conducted to the fins that are in contact with the bulk of the PCM inside a cylindrical shell, causing the PCM to melt/solidify. The present study focuses on a case in which the envelope of the unit is exposed to a heated environment and close-contact melting takes place on the upper surface of the fins. It is demonstrated that close-contact melting affects noticeably the melting rate and shortens the melting time considerably. Nomenclature= gravity acceleration S = momentum source term ħ = specific enthalpy k = thermal conductivity T = temperature ħref = reference enthalpy at the reference temperature Tref = reference temperature cp = specific heat L = specific enthalpy of melting (latent heat)  = liquid fraction A = porosity function C = mushy constant