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International Journal of Photoenergy
Volume 2017, Article ID 3082740, 10 pages
Research Article

Effects of Ambient Parameters on the Performance of a Direct-Expansion Solar-Assisted Heat Pump with Bare Plate Evaporators for Space Heating

Department of Thermal Science and Energy Engineering, University of Science and Technology of China, No. 96 Jinzhai Road, Hefei City, Anhui Province, China

Correspondence should be addressed to Jie Ji; nc.ude.ctsu@eijij

Received 29 December 2016; Revised 3 June 2017; Accepted 4 July 2017; Published 1 October 2017

Academic Editor: Michel Feidt

Copyright © 2017 Wenzhu Huang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Research on the direct-expansion solar-assisted heat pump (DX-SAHP) system with bare plate evaporators for space heating is meaningful but insufficient. In this paper, experiments on a DX-SAHP system applying bare plate evaporators for space heating are conducted in the enthalpy difference lab with a solar simulator, with the ambient conditions stable. The independent effects of ambient temperature, solar irradiation, and relative humidity on the system performance are investigated. When ambient temperature changes as 5°C, 10°C, and 15°C, COP increases as 2.12, 2.18, and 2.26. When solar irradiance changes as 0 W m−2, 100 W m−2, 200 W m−2, 300 W m−2, and 500 W m−2, COP of the system changes as 2.07, 2.09, 2.14, 2.26, and 2.36. With ambient temperature of 5°C and solar irradiance of 0 W m−2, when relative humidity is 50%, no frost formed. Whereas with relative humidity of 70% and 90%, frost formed but not seriously frosted after 120 min of operating. Frost did not deteriorate but improved the heating performance of the DX-SAHP system. The change of relative humidity from 70% to 90% improves the evaporating heat exchange rate by 35.0% and increases COP by 16.3%, from 1.78 to 2.07.