Operational mode study on an air-source heat pump assisted domestic solar water heating system in Xi'an

In this paper, the typical meteorological year of Xi'an is devided into three periods according to the different radiance-calculating periods and corresponding meteorological data, including daily average temperature and solar radiance are analyzed by statistical method. The hourly meteorological parameter of different periods and different weather regimes of a whole year are statisically analysed, and certain periods of time are determined based on similar solar irradiance. Furthermore, the optimal operational mode is proposed in accordance with the above division of working time for an air-source heat pump aissisted domestic solar water heating system (ASHP-SWHS). By means of analysis and determination of the optimal operational mode of such a system in Xi'an, a general method is proposed to determine the optimal operational mode of the ASHP-SWHS applied in different area, which would be a useful reference in design and operation of ASHP-SWHS for other areas in China.