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Analysis and Comparison of Some Low-Temperature Heat Sources for Heat Pumps

Department of Mechanical Engineering, Faculty of Engineering, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague-Suchdol, Czech Republic
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Energies 2019, 12(10), 1853; https://doi.org/10.3390/en12101853
Received: 12 April 2019 / Revised: 9 May 2019 / Accepted: 13 May 2019 / Published: 15 May 2019
(This article belongs to the Special Issue Sustainable Energy Reviews)
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Abstract

The efficiency of a heat pump energy system is significantly influenced by its low-temperature heat source. This paper presents the results of operational monitoring, analysis and comparison of heat transfer fluid temperatures, outputs and extracted energies at the most widely used low temperature heat sources within 218 days of a heating period. The monitoring involved horizontal ground heat exchangers (HGHEs) of linear and Slinky type, vertical ground heat exchangers (VGHEs) with single and double U-tube exchanger as well as the ambient air. The results of the verification indicated that it was not possible to specify clearly the most advantageous low-temperature heat source that meets the requirements of the efficiency of the heat pump operation. The highest average heat transfer fluid temperatures were achieved at linear HGHE (8.13 ± 4.50 °C) and double U-tube VGHE (8.13 ± 3.12 °C). The highest average specific heat output 59.97 ± 41.80 W/m2 and specific energy extracted from the ground mass 2723.40 ± 1785.58 kJ/m2·day were recorded at single U-tube VGHE. The lowest thermal resistance value of 0.07 K·m2/W, specifying the efficiency of the heat transfer process between the ground mass and the heat transfer fluid, was monitored at linear HGHE. The use of ambient air as a low-temperature heat pump source was considered to be the least advantageous in terms of its temperature parameters. View Full-Text
Keywords: heat pump; low-temperature power source; horizontal ground heat exchanger; vertical ground heat exchanger; heat transfer fluid; specific heat output; extracted energy heat pump; low-temperature power source; horizontal ground heat exchanger; vertical ground heat exchanger; heat transfer fluid; specific heat output; extracted energy
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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 (CC BY 4.0).
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Neuberger, P.; Adamovský, R. Analysis and Comparison of Some Low-Temperature Heat Sources for Heat Pumps. Energies 2019, 12, 1853.

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