Application of Flammable Refrigerants in Rail Transit Vehicle Air-conditioners

Abstract

[Objective] To analyze the allowable charge quantity of flammable refrigerants in RTVAC (rail transit vehicle air-conditioners), it is necessary to explore the feasibility and solutions for the safe application of environmentally friendly flammable refrigerants in RTVAC. [Method] The installation site and access categories of AC are analyzed. Along with the thermophysical properties of various flammable refrigerants, the allowable charge quantity of refrigerants in current RTVAC is calculated. Further, by designing the indirect heat exchange system among AC units, the maximum allowable charge limit of flammable refrigerants in RTVAC is increased and the AC performance of different refrigerants is comparatively analyzed. [Result & Conclusion] Refrigerants with different flammability levels have varying allowable charge quantities in RTVAC. Due to the limitations imposed by the lower flammability limit of refrigerants, direct use of flammable refrigerants in RTVAC is challenging. However, through the design of indirect heat exchange, it is possible to effectively increase the allowable charge quantity of flammable refrigerants in AC, thereby addressing safety risks associated with the flammability of refrigerants and enabling the application of environmentally friendly refrigerants in RTVAC.

Keywords

• rail transit vehicle air-conditioner
• flammable refrigerant
• charge quantity limit
• indirect heat exchange