Dynamic coupling method between air-source heat pumps and buildings in China’s hot-summer/cold-winter zone

Abstract

The existing selection methods for air-source heat pumps often result in insufficient heating effects and high electricity consumption in winter, in China's hot-summer/cold-winter zone. Because the existing basis for selection are diverse and difficult to convert for comparison, selection methods are not connected with actual dynamic load demand. This paper presents a dynamic coupling selection method for air-source heat pumps based on load balance. Dynamic output capacity models and energy efficiency models for air source heat pumps, dynamic load demand models for buildings, and dynamic coupling models are established to interpret the relationships between heat pumps and buildings. This paper puts forward the stable operation conditions, the output capacity, and the energy efficiency of heat pumps under the most unfavorable operation conditions, in order to select units. Our study finds that the lowest coefficient of performance is 1.12, which is only 43% of the rated value in the region. Heat pumps with higher performance generated excessive cooling capacity relative to load demands of buildings. Hence, the dynamic coupling method is a simple and engineering tool for optimizing entire air-source heat pump energy systems in buildings by matching the performance surfaces of heat pumps and buildings. It is a general method which can be applied by users to directly compare different units in buildings with higher energy efficiency and operation reliability, and also to guide manufacturers with a performance surface to complement existing indexes. This method has great significance for selection optimization and promotion of air-source heat pumps.