| The Tibetan area of western Sichuan has complex climate characteristics,diverse topographic changes,and high traditional fossil fuel transportation costs.It is not appropriate to set up a central heating system.The air source heat pump has broad application prospects because of its energy-saving and efficient characteristics.However,due to the climate characteristics of low temperature and high humidity in this area,frosting has become the main factor restricting the application of air source heat pumps.In response to the problem of frost formation,the Tibetan area of western Sichuan is divided according to the climate characteristics.Different climate characteristics are formulated with different strategies for suppressing frost and controlling frost,so that the strategies for suppressing frost and controlling frost match the climate characteristics,and improve the unit performance.First,based on the regional frost maps,frost rate and heating season load as indicators,the climate of Tibetan area of western Sichuan was divided,and the climate characteristics of Tibetan area of western Sichuan were studied.The study found that the spatial distribution of frost rate is characterized by the gradual weakening of frost intensity from east to northeast to southwest,and the spatial distribution of load demand is gradually reduced from west to east to south.Combining the two indicators,under the premise of directional heating,the Tibetan area of western Sichuan is divided into areas I to IV,with heavy loads and weak frost areas(Type I),small loads and weak frost areas(Type II),and heavy loads and strong Frost area(Type III),small load strong frost area(Type IV).Secondly,using the principle of fuzzy control,a simplified controller for determining the degree of frost is designed,and the performance of the fuzzy controller is simulated.The controller has good performance,fast response,and can accurately determine the degree of frost in the air.Provide a basis for determining the starting point of frost suppression and frost control.Afterwards,a frost suppression strategy was devised for regular heating in different regions and rooms.Different counties and cities and different heating rooms were adjusted to different evaporation temperatures to delay frost formation,and a control flow was designed for the strategy.In order to avoid "mis-defrosting" and achieve efficient frost control,the frost map and fuzzy controller are combined.The frost map provides a basis for formulating control rules.At the same time,fuzzy control blurs the frost area.The frost rate is used to calculate the frost thickness to determine the starting point of the defrost.After the defrost is completed,the frost rate and the temperature of the evaporator coil surface are automatically adjusted to improve the control accuracy.Adjust the strategies of frost suppression and frost control within the four climate zones to match the strategy with the climate characteristics.Using the TRNSYS platform to simulate the performance of the unit before and after adjusting the evaporation temperature,it was found that the regular heating sub-area and room-by-room adjustment of the evaporation temperature increased the performance of the unit significantly.Compared with the unchanged evaporation temperature,the Xiangcheng,Jiuzhaigou,Luhuo and Kangding heat Seasonal performance coefficient(HSPF)increased by 8.94%,9.91%,12.10% and12.50%,higher than non-scheduled heating 4.02%,5.66%,8.05% and 9%. |
