Application analysis of the recovery fresh air heat pump units in the public building in the cold and serious cold regions

With the growth of economy and technology, the air source heat pump is more and more frequently used in the public buildings. The air-source heat pump is a convenience and with higher energy efficiency rating; it can make the best of low temperature energy sources of the atmosphere circumstance, and has less pollution to the region. The air source heat pump has energy conservation and environment protection effects; it is a kind of green air conditioning technique.But in northern, northwestern and northeastern of China,the air source heat pump can not work in the period of heating.When running in winter in the cold and serious cold regions,the fresh air units are often harmed by frostbite; it brings on the decline of Indoor Air Quality.Provided use the outdoor air as the low temperature heat source of air source heat pump,heat pump units can not available in the whole heating period,heating capacity substantially reduced,energy efficiency coefficient (COP) fell sharply,the outdoor heat exchanger became frosting, and it can't run.At the same time, in terms of balancing ventilation requirements, there had a large number of exhaust heating in the public buildings,which were discharged directly, it caused the waste of energy.In order to solve the above problems, we combinate the air source heat pump and fresh air system and exhaust system, recovery the exhaust heating of the public buildings to heating fresh air, when the outdoor air temperature is lower than a set value in winter, we start the heating pump to heating the fresh air, this method can increase the operation time of the heat pump unit and fresh air unit in the heating period effectively, it also can solve the running problem of the heat pump units and fresh air units in cold and serious cold regions, it can ensure good indoor air quality for a long time. II. THE RUNNING CONDITIONS AND EXISTING PROBLEMS OF AIR SOURCE HEAT PUMP IN THE EXISTING PUBLIC BUILDINGS