Performance investigation of a novel low-carbon solar-assisted multi-source heat pump heating system demonstrated in a public building in Hull

Global climate change has raised great attention from governments and prompted a wave of application of lowcarbon heating technologies. However, solar-assisted heat pump, as an attractive technology, has challenges of unstable performance and complex structure and control strategy in practical application. Following the carbonneutral strategy, a novel low-carbon solar-assisted multi-source heat pump heating system (LSMHS) is therefore proposed to improve the application potential of SAHP, which is demonstrated in Hull Central Library by replacing the library's original gas boiler heating system (GBHS). The LSMHS integrates eight novel multithroughout-flowing solar collector arrays with an innovative two-stage heat recovery heat pump which can automatically switch different operation modes according to weather conditions. The practical operation results revealed that the LSMHS maximized the advantages of each component and achieved a high monthly average system COPsys ranging from 2.12 to 2.68 in the three-month demonstration. Eventually, the LSMHS provided a bill saving of 0.73 % with a significant carbon reduction of 63.69 % when compared to the GBHS in practice, achieving an equivalent bill saving of 6.7 pound for every tone of carbon reduction. The remarkable demonstration results showcased the application potential of the novel LSMHS and gave valuable guidance for low-carbon building heating.