The Safety Study Of R290 Application In Household Air Conditioner And Heat Pump System

In recent years,the environmental problems such as global climate change have become increasingly serious,making the green and environmentally friendly R290(propane)refrigerant gradually become the research hotspot in the field of refrigeration and air conditioning.R290 has the excellent thermodynamic properties,but the shortcomings of flammability and explosiveness hindered its promotion,therefore it is urged to solve the safety issues in the replacement and application of R290.This paper based on the R290 replacement of Chinese household air conditioner and heat pump industry,analyzed and discussed the shortcomings of current relevant research,and systematically studied the performance and concentration distribution after a leakage of the 1-3HP split type household air conditioner and 5HP air-cooled heat pump system.The influence of temperature and pressure,shape area of the leakage and wind speed on the R290 concentration distribution after pipeline leakage was compared and analyzed in this paper,through the method of theoretical analysis and simulation calculation.The mass distribution of R290 in the components of the split type household air conditioner under different working conditions was measured by the new QLNM method.The results showed that about 62%~70% of the R290 refrigerant was distributed in the condenser when the air conditioner is turned on.After the air conditioner shutdown,the refrigerant will migrate to the evaporator,and the R290 mass distribution in the evaporator will account for 66%~73% of the whole charge quantity.Based on this,this paper studied the indoor R290 concentration distribution after a leakage of 1-3HP split type household air conditioner under actual conditions through the experiments.The experimental results indicated that the area where R290 concentration could excced the LFL will only appear directly under the indoor unit,the refrigerant charge quantity and diameter of the leak hole have a direct impact on the indoor R290 concentration distribution.According to the results of the refrigerant mass distribution experiment,a pratical method of installing the normally closed solenoid valve on the liquid connection pipe of indoor and outdoor unit was proposed,which hindered the R290 migration after the air conditioner shutdown,and effectively reduced the R290 leaking rate and fire hazard in the room.Through the structural optimization and performance measurement,the optimal charge quantity of the 5HP air-cooled heat pump system was reduced to 1.3 kg,which could meet the requirements of international standards such as EN 378.The R290 concentration distribution of the inside and outside area of the heat pump system was carried out after a 1.3 kg R290 leakage.The results indicated that in the surrounding area,the area where R290 concentration could exceed the LFL could only appear near the ground,and the position of the heat pump and the height of the leakage hole could affect the concentration distribution.While in the electric control cabinet inside the heat pump,the R290 concentration could exceed the LFL for a long time.