Development of an innovative heat exchanger for sensible heat storage in agro-food industry

The present article deals with the numerical study of the thermal behaviour of three configurations of heat exchangers for sensible thermal energy storage. The objective is to compare their response to transient thermal conditions in order to characterize their kinetics of charge/discharge of heat/cold. One of these heat exchangers is commonly encountered in agro-food industry and used in this study as the reference against which the other two configurations are compared. The reference heat exchanger is made up of two fluid coils embedded in an aluminium cylindrical conducive element. The other two heat exchangers are derived from this reference exchanger by a partial substitution of the conducive element with a confined heat transfer fluid. The compactness and heat exchange surfaces of the coils are identical in all three cases. The thermal behaviour and the storage performance of these heat exchangers are analysed using a three dimensional numerical study with the CFD code Star CCM + V12.02. This study shows that a controlled substitution of the conducive material by a confined heat transfer fluid, at constant compactness and coils heat transfer surface does not only achieve material saving compared to the reference configuration, but also increase the energy reserve without significant decrease in the heat transfer kinetics.