Cooling effect characteristic of the novel half-cycle refrigeration system on a liquefied petroleum gas (LPG) fueled vehicle

Abstract

• An experimental investigation of the harvested cooling effect in LPG-fueled vehicles was studied. • The cooling effect is calculated by considering the mixing ratio of water vapor in air. • Half-cycle refrigeration system contributes to the total engine efficiency of the vehicle. • EER of up to 21.06 was obtained by comparing the cooling effect ( q ̇ a ) and blower power ( w ̇ b ). This paper reports on the experimental investigation of the cooling effect harvested in liquefied petroleum gas (LPG)-fueled vehicles. The heat required to vaporize the LPG in a vaporizer, which was originally transferred by the engine coolant, was replaced by air flow. The fuel line was modified by adding an evaporator equipped with an expansion valve between the LPG tank and regulator. The no-load tests were carried out on a Daihatsu 1945 cc engine at 1000, 2000, and 3000 rpm with three different levels of air mass flow rate obtained through the setting of the electric blower switch. The LPG consumption was determined by the engine load instead of being regulated by an external valve. By considering the air temperature and humidity mixing ratio ( X ), a cooling effect of 0.89 kJ‧s −1 was achieved at an LPG mass flow rate of 0.407 g‧s −1 . This represents the fuel consumption of a 1495 cc engine at 3000 rpm and reduces the temperature to approximately 14 °C. The energy efficiency ratio of the half-cycle refrigeration system in LPG-fueled vehicles was also reported, which ranged from 6.77 to 21.06 for LPG mass flow rates of 0.139–0.407 g‧s −1 and air mass flow rates of 0.049–0.062 kg‧s −1 . Although the cooling effect produced is lower than that of the primary air conditioning (AC) system (vapor compression system) in passenger and pick-up vehicles, it has potential as a secondary AC system when combined with the primary AC system through a hybrid system.