Title: Effect of heat transfer law on the ecological optimisation of a generalised irreversible Carnot heat pump

Authors: Xiaoqin Zhu, Lingen Chen, Fengrui Sun, Chih Wu

Addresses: Postgraduate School, Naval University of Engineering, Wuhan 430033, P.R. China and Jiangsu Technical Normal College, Changzhou 223001, P.R. China. ' Postgraduate School, Naval University of Engineering, Wuhan 430033, P.R. China. ' Postgraduate School, Naval University of Engineering, Wuhan 430033, P.R. China. ' Mechanical Engineering Department, US Naval Academy, Annapolis, MD 21402, USA

Abstract: The optimal exergy-based ecological performance of an irreversible Carnot heat pump with the losses of heat-resistance, heat leak and internal irreversibility, in which the transfer between the working fluid and the heat reservoirs obeys a generalised heat transfer law Q ∝ Δ (Tⁿ), is derived by taking into account an ecological optimisation criterion (E) as the objective function, which consists of maximising a function representing the best compromise between the exergy output rate and exergy loss rate of the heat pump. Numerical examples show that both the internal irreversibility and the heat leakage decrease the maximum E, the maximum COP, and the COP at maximum E point. In addition, the internal irreversibility does not change the curve shape between the optimal E and the COP, while the heat leakage changes the optimal E and the COP curve from a parabolic-like curve into a loop-shaped one.

Keywords: ecological optimisation; entropy generation rate; exergy output rate; finite time thermodynamics; heat transfer law; irreversible heat pumps; Carnot heat pumps.

DOI: 10.1504/IJEX.2005.007790

International Journal of Exergy, 2005 Vol.2 No.4, pp.423 - 436

Published online: 16 Sep 2005 *

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