THERMAL SCIENCE

International Scientific Journal

INFLUENCE OF WATER SUPPLY TEMPERATURE ON THE HEATING CHARACTERISTICS OF LOW TEMPERATURE AIR SOURCE HEAT PUMP WATER HEATERS

ABSTRACT
One of the inherent limitations of air source heat pump water heaters is their reduced performance when the external temperature is low. In order to investigate the impact of water supply temperature on system heating in low temperature conditions, a test bench for an air source heat pump water heater with a medium pressure air supply was constructed. The findings illustrate that within the two low temperature settings of -7°C and -15°C, the heating capacity of the system initially increases with the rise in water supply temperature, reaching a peak at 39°C. However, this effect is not sustained as the temperature of the water supply continues to rise. Concurrently, the system's heating capacity reaches its maximum at a water supply temperature of 39°C. At this temperature, the heating capacity is 45.8% lower than at -7°C, the compressor power is 42.1% lower, and the system coefficient of performance is 7.2% lower.
KEYWORDS
PAPER SUBMITTED: 2023-12-05
PAPER REVISED: 2024-05-10
PAPER ACCEPTED: 2024-05-10
PUBLISHED ONLINE: 2025-07-06
DOI REFERENCE: https://doi.org/10.2298/TSCI2503999C
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2025, VOLUME 29, ISSUE Issue 3, PAGES [1999 - 2006]
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2025 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International licence