A review of heat pump research in China using bibliometric methods

The analysis of big data can reveal the macroscopic situation of a certain field from a relatively objective angle and indicate the potential development trends in the future. This study provides a novel approach to review the development of heat pump research from 1994 to 2020 in China using the bibliometric method which belongs to big data analysis. More than 15 000 references were selected, 2716 of which are from the Web of Science core collection and 13 183 of which are from China National Knowledge Infrastructure, including articles and reviews. Their knowledge maps and co-citation analysis were performed. Different major trends were identified for 15 clusters. Results showed that ground source heat pump (GSHP), air source heat pump (ASHP)-on frost, ASHP on heating, and solar-assisted heat pump are the most active research fronts. The studies on the GSHP account for the largest portion, reaching about 21%. Ground heat exchanger and thermal imbalance are the focus points. ASHP is the hottest research direction in recent years, mainly focusing on the technologies of frosting/defrosting and heating. The studies on defrosting experience a transition from the frosting/defrosting process and thermal energy storage for defrosting to frost-free ASHP. Besides, direct-expansion solar-assisted heat pump water heater was becoming more and more active. Finally, industrial heat pump showed great development potential.