Testing of a multi-energy complementary absorption heat pump prototype for combined cooling and heating with large temperature range from − 20 to 90 °C

Abstract

In the process of carbon neutrality, the comprehensive utilization of clean and renewable energy, including solar, geothermal and biomass, is a potential solution to the low-carbon cooling and heating in distributed areas with weak power grids, such as countryside and suburban. In this paper, an absorption heat pump with multi-energy complementary was built to provide combined cooling and heating. Solar energy was collected through an evacuated tube collector using heat conduction oil, and a gas boiler was adopted to further heat the oil and balance the solar thermal fluctuations. Heat collected in the oil circulation was used to drive an ammonia-water absorption heat pump. A control strategy was proposed to achieve stable energy supply under different weather condition, and efficient operation in wide temperature zone. Environmental test of the prototype was performed in Jinan. The results showed that the prototype ran stably to provide 5-15 kW cooling at −20 to 10 °C, and 20-35 kW heating at 40 to 90 °C, with solar thermal ratio of 20–35 % in different weather conditions, and the renewable energy ratio in heating mode could exceed 55 % through further recovery of ambient heat. Furthermore, the COP for cooling reached 0.30–0.43 at −20 °C cold supply, and 0.70–0.78 at 7 °C cold supply, with cooling water temperatures varied from 30 to 20 °C; and the COP of heating reached 1.40–1.90 at 45 °C heat supply, and 1.35–1.56 at 80 °C heat supply, with evaporation temperature varied from −15 to 20 °C. Results demonstrated that the proposed prototype has significant energy and carbon reduction potential, and is a solution for combined cooling and heating in distributed areas.