Research On Performance Characteristic And Simulation Of Double-Cold-Source Fresh Air Handling Unit

The indoor thermal and humid load are undertaken by single cold source in traditional air conditional system.That leads to several problems such as energy waste by combining handle temperature and humidity, miamatch of heat humidity ratio and poor indoor air quality. More and more temperature and humidity independent control systems are widely used in civil and industrial buildings. Fresh air system affords the whole indoor humid load in this air conditional system. So it is necessary to study on the double-cold-source fresh air handling unit.Firstly, this paper puts forward the fresh air operation strategy for temperature and humidity independent control system. Based on the general ventilation equation of industrial ventilation, the indoor humidity ratio dynamic model is analogically obtained. Without office staff in the office building which using the temperature and humidity independent control air conditioning system,the moisture load of infiltration fresh air is put forward as main source of indoor moisture load. In addition, the model is used for determination of new air dehumidification and pre-dehumidification time. This paper puts forward suitable fresh air volume per capita and pre-dehumidification time under different humidity ratio air supply, which can provide a reference basis for intermittent operation of radiation air conditioning system.Secondly,the simulation platform of double-cold-source fresh air handling unit is established. The main objects of double-cold-source fresh air handling unit model includes air source heat pump, pre-stage surface air cooler and centrifugal fan. Based on the simulation platform, surface air cooler and evaporator are respectively calculated to study the unit performance in variable condition. The whole unit’s energy consumption and COP of double-cold-source fresh air handling unit and single-cold-source are calculated and compared. The results show that the double-cold-source’s energy consumption is lower than single-cold-source and COP is higher than single-cold-source.The ratio of surface air cooler and evaporator cooling load proportion are studied. The calculating results show that,the ratio is 7:3 can achieve the lowest energy consumption and the highest COP.Lastly, air-to-air energy recovery condition of double-cold-source fresh air handling unit are studied experimentally. Effects of fresh air handling unit performance by fresh air temperatures and return air temperature are analyzed. The unit heating load and COP of air-to-air energy recovery condition and conventional condition are calculated and compared. Heat recovery efficiency of unit is also analyzed.