Refrigerant charge reduction: On a new design optimization criterion for compact heat exchangers

With refrigerant charge reduction concern we introduce a new criterion, the so-called Ecological Cost (EC), and establish its relevance for HEXs design optimization. EC takes into account both entropy generation in the HEX and its refrigerant charge by the special environment cost values c and c’. EC minimization is conducted with given heat flux rate or given temperature difference. Results show that optimal design value depends on device life duration and on c/c’ Leakage effect can also be included in EC. We establish a link between EC and TEWI and show that optimal EC leads to optimal TEWI. We deal in the second part of this paper with volumes optimal allocation of cold and hot heat exchangers under given total volume or total refrigerant fluid mass constraint when assuming reversible cycle.