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ISSN Online: 2379-1748

7th Thermal and Fluids Engineering Conference (TFEC)
SJR: 0.152 SNIP: 0.14 CiteScore™:: 0.5

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Clarivate CPCI (Proceedings) Scopus
May, 15-18, 2022 , Las Vegas, NV, USA


Get access (open in a dialog) pages 1227-1233
DOI: 10.1615/TFEC2022.sol.040678


Solar-Assisted-Heat-Pump Domestic-Hot-Water systems (SAHP-DHW) combine the use of solar-thermal collectors (STC) with Heat Pumps (HP) to heat water for use by the occupants of a building. This work implements a performance map of a custom variable-speed HP model described in Experimental Characterization of a Variable Refrigerant Flow Heat Pump for Solar-Domestic-Hot-Water Applications (Howarth and Collins, 2021). The custom HP simulated is able to modulate its heat transfer capacity by varying the speed of the compressor rotor by supplying electric power through a variable frequency drive. A comparison is made between the simulated performance of a VRF-SAHP system under a proportional control strategy with 3-stage control and a similar SAHP system with a simple on/off controller against the baseline operation of a typical Solar Domestic How Water (SDHW) system with no HP. All of the systems under comparison have the same collector configuration and installation location. Simulation work is performed using TRNSYS, a transient system simulation package. The results of this comparison show that the SAHP systems had an energy collection advantage of approximately 13400 kJ over the course of the day when compared with a traditional SDHW system. There was a slight energy collection benefit realized by including a modulating control system on the HP compressor of the SAHP system, but it was not significant. The inclusion of HP compressor speed modulation in an SAHP system, however, showed a benefit in terms of the resilience of the HP to short-cycling, which was reduced by one third for the system with proportion control as compared with the system with on/off control. This is significant because shortcycling of HPs is known to cause damage and shorten the lifespan of the equipment.