Efficient ecological function optimization for endoreversible Carnot heat pumps

Abstract

According to the definition of exergy-based efficient ecological-function (EBEEF) which is proposed as product of exergy-based ecological-function (EF) and coefficient of performance (COP) in previous literature, this paper applies the EBEEF to analyze and optimize performance of endoreversible Carnot heat-pumps (ECHPs). Via the ECHP cycle model established in previous literature, EBEEF expression for ECHP cycle model is deduced, relationships among the EBEEF and heating load (HTL) and COP are researched, and performance comparison for ECHP cycle working at the maximum EBEEF and the maximum EF conditions are performed. Results show that relationships among the EBEEF and the HTL and COP are parabolic like ones and the design points of the larger COP and HTL should be selected for designing heat pumps. When the maximum EBEEF is taken as primary objective, the optimized ECHP cycle can improve its COP and reduce its entropy-generation-rate by sacrificing a small amount of its HTL. The EBEEF not only considers the trade-off between the HTL and entropy-generation-rate, but also considers the trade-off between HTL and COP.