CFD simulation of HC-290 leakage from a split type room air conditioner

Abstract

HC-290 is one of the alternatives to HCFC22 in room air-conditioners. With the phase-down schedules in Kigali Amendment, it is imperative to use HC-290. However, there are concerns about its flammability in the event of a leak from the AC indoor unit (IDU). IEC 60335-2-40 has been revised to extend the capacity ranges for A2L refrigerants and is being further revised with a focus on A2 and A3 refrigerants. In real-life situations, furniture and occupants are present inside the room and these may positively or negatively influence the dispersion of any leaked HC-290. CFD simulation of dispersion of leaked HC-290 has been carried out for a variety of scenarios. The variables include leakage rates, IDU installation heights, IDU blower ON or OFF and types of furniture. Furniture, in general, appears to promote mixing, thereby reducing HC-290 stratification. The maximum concentration occurs on the side where the leak is directed by the momentum of the jet from IDU. There is no significant effect on the concentration distribution by the type and size of furniture with legs, although solid furniture has some marginal effect due to reduction of room free volume. The average concentration of HC-290 in the room is slightly more when the solid furniture like cupboards are placed some distance away from the IDU. The highest concentration at 30 cm above floor level, is 44% of LFL when the blower is ON, while it is 62% when the blower is OFF.

An Improved Gas Leakage Model and Research on the Leakage Field Strength Characteristics of R290 in Limited Space

“…Cai et al [21] studied the diffusion process and concentration distribution of R290 after it leaked from a wall-mounted air conditioner into three rooms with different sizes; the results found that the larger space was more conducive to the dilution and uniform distribution of the leaked refrigerant. Prakash et al [22] analyzed the effects of leakage rate, indoor unit installation height, whether an indoor fan was on or off, and the type of furniture placed in the external space on the concentration distribution of leaked R290 in a wall-mounted air conditioner. Hu et al [23] studied the influence of the airflow rate and angle of the indoor unit on the diffusion process of R290 in a wall-mounted air conditioner, and the results showed that the airflow rate could dominate the diffusion of the leaked refrigerant, and the airflow angle only affected the dispersion when the velocity was small, and upward blowing was more conducive to uniform distribution of the refrigerant.…”