Design of Hybrid Air Conditioning System Using Phase Change Material for Commercial Sleeper Vehicles

Many road accident happens due to fatigue & deprive sleep of drivers. Many times driver use AC system for their quick thermal comfort during night with engine ON. This scenario is very critical from human's safety & vehicle functionality point of view. This also consumes additional 10-15% of fuel requirements in AC running condition. So, to address social problems of driver's sleep & pollution free environment by reducing the use of fossil there is a need of alternative techniques for air cooling which works during engine OFF condition. Various alternatives options for air cooling have been reviewed & extensive evaluations are mapped on the various performance parameters. Based on this the phase change material technology can be easily adopted due to its packaging flexibility. Phase change material (PCM) technology available in the market since decades for the use of storing the thermal energy. Perhaps the use of PCM material in controlled manner in not fully known for longer period of time in air conditioning application. This paper proposes a design of hybrid air conditioning system for sleeper commercial vehicle using combined conventional compression & phase change material. Latent heat of fusion & effective storage capacity is most desired factor in designing PCM based air conditioning system. The cold storage heat exchanger is designed for transacting heat between the three fluids-refrigerant, phase change material & air. Thermal energy is stored in PCM during vehicle running condition by extracting latent heat from refrigerant of conventional compression system & is reused during engine off condition by exchanging it to air for cooling. The designed cold storage heat exchanger is evaluated using CFD tool by varying various parameters & optimized for operation time. The use of hybrid air conditioning system found significantly useful for sleeper cabin for prolonged operation time reducing driver fatigue.