| Due to the destruction of the ozone layer and the effect of the global warming, the traditional refrigerants are gradually being eliminated. Many experts and scholars have proposed some new refrigerants, of which the refrigerant R32 is widely concerned because of the excellent thermodynamic properties and the friendliness of the environment. However, due to the refrigerant R32 has a certain degree of combustible, if it is used in the refrigeration equipment or air conditioner, leakage can cause certain risk. Therefore, based on the study of the subject group, the paper studied on the diffusion characteristics and ventilation of the combustible refrigerant R32 in the air conditioner.This paper was divided into two parts, experiment and numerical simulation. The diffusion characteristics of the combustible refrigerant R32, including the free diffusion and the influence of several ventilation modes on the R32 diffusion of refrigerant were studied. Meanwhile, the diffusion characteristics of refrigerant R32 under different leakage quantities and leakage directions were studied, too. Through the numerical simulation, some conditions of the experiment were studied, and the dilution effect of ventilation and the effect of temperature and humidity on the diffusion were studied, too.Research showed that: under the condition of no ventilation, leakage happened in front of leakage hole, refrigerant R32 had the free diffusion, the whole process was divided into two sections, concentration growth process and concentration slow down process, the concentration of the points in the final horizontal plane tended to be the same, that was, the distribution of the concentration of the plane was uniform; concentration increased at the highest speed of 3.16/min, and the rate of decline was only 0.14/min, the time of combustible range was 53min55 s, the maximum of combustible range was 66.5%, and the quantity of measuring point reached 6. From the simulation, the obvious stratification phenomenon was generated when the leakage was spread in the condition of no ventilation. At 7min, the height difference between 0.2m and 0.6m was small, when the height rose to 1m, the concentration difference was 8.8, and when the height rose to 1.4m, the concentration difference was 1.7. With the increase of time, the concentration difference between 1.4m and 1m was the maximum, which was 8.1, the concentration difference of 1m below(including 1m) and 1m above were small. After the opening the mechanical ventilation, we made the analysis of the maximum point of concentration measurement, several ways: no air vent, no air exhaust, send, send up, which had the concentration of the growth rate of 3.25/min, 2.46/min, 2.75/min, 2.3/min, the concentration of the rate of decline were 0.42/min, 2.06/min, 0.22/min, 1.81/min, average concentration of 0.2m height plane were the value of 16.17, 13.07, 16.38, 11.52, which showed that send down and separate exhaust effect were the best. Through the simulation result, compared send up on the plane of Z=0.3m with send, the highest difference of former was 9.33. When the leakage increased from 1kg to 0.65 kg, the concentration increased from 2.3/min to 2.66/min, the time of the detector’s combustible range was doubled, within the combustible range, the points were increased by three. When the leak direction was vertical downward, the hazardous area of combustible range of refrigerant R32 was the largest, next to the horizontal right, right, vertical upward, the concentration of the maximum point of the growth rate was 2.86/min, 1.95/min, 2.14/min, 0.83/min, all leakage directions had the characteristics of the subsidence. The effect of temperature and temperature on the R32 concentration of refrigerant was studied by simulation, the increase of the temperature can result in the concentration of R32 of refrigerant increasing, the average increase was within 3% to 6%, however, the effect of humidity change on the concentration was only about 1%.From the above conclusions can be drawn that, compared to the wall mounted air conditioner leak, after the leakage of floor air conditioner, the risk is much higher than the former, take the ventilation in the room, priority should be given to send down the ventilation mode, the possibility of reducing the harm caused by the time of the danger zone is reduced. Therefore, when residential chooses ventilation modes, if indoor air conditioning is filled with combustible refrigerant, we should not only consider the indoor air quality, but also to take into account the accident and ventilation, ventilation should be preferred to the bottom. |
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