Title: Exergy analysis of a thermostatic heat pump drying system with adjustable bypass air ratios

Authors: Qiuyuan Qin; Lan Tang

Addresses: Guangzhou University, Guangzhou Higher Education Mega Center, 230 Wai Huan Xi Road, Panyu District, Guangzhou 510006, China ' Guangzhou University, Guangzhou Higher Education Mega Center, 230 Wai Huan Xi Road, Panyu District, Guangzhou 510006, China

Abstract: Drying is the best method to preserve products, but it will consume large amounts of energy. In this paper, a new heat pump drying system is designed, the wet cotton cloth is selected as drying material and the exergy analyses for the main components and the whole system are carried out. The results show that the maximum exergy loss always occurs in the compressor. Both the drying air temperature (DAT) and bypass air ratio (BAR) affect the exergy efficiency of the whole system and components. For the whole system and main components, the optimal BAR at 35°C, 40°C, 45°C are always 40%, 0% and 60% respectively. Under a higher DAT, both the dehumidification ability of the evaporator and its exergy efficiency are reduced by the excess air mass flow rate. Through the exergy analysis, some improvement measures for the exergy efficiency are put forward.

Keywords: exergy analysis; heat pump drying; drying air temperature; DAT; bypass air ratio; BAR.

DOI: 10.1504/IJEX.2021.115092

International Journal of Exergy, 2021 Vol.35 No.1, pp.155 - 171

Received: 15 Mar 2020
Accepted: 13 Aug 2020

Published online: 06 May 2021 *

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