Performance of a greenhouse heating system utilizing energy transfer between greenhouses based on the dual source heat pump

High energy consumption challenges the multi-span greenhouse industry in China. To address this, a greenhouse heating system utilizing energy transfer between greenhouses based on the dual source heat pump (ETGHP) was designed in our previous research. However, its performance in practical application remains largely unexplored. This study conducted a field test to comprehensively assess this system. Results showed stable heating effects, and the heat collection of the system in Chinese solar greenhouse (CSG) air source heating mode accounted for 2.1% to 28.2% of the total, validating the feasibility of energy transfer between greenhouses. The use of CSG air source increased heating capacity by 27% and coefficient of performance (COP) by 23% for air source heat pumps. Then the dual source configuration achieved a 10.8% increase in heat collection and a 7.9% improvement in COP compared with the single air source. During the test, the COP of the system achieved 2.8 during heat collection and 2.5 for heating the multi-span greenhouse. Outdoor weather, greenhouse structures and management were found to influence system operation. This study also conducted performance comparation and explored the economic and environmental benefits for the system, proving it to be an efficient solution for multispan greenhouse heating.