Theoretical and experimental study on a self-refrigerating system for LNG-fueled refrigerated vehicles

LNG-fueled vehicle has been regarded as a promising substitute of the diesel vehicle owing to its clean burning characteristics. Especially for refrigerated vehicles, an additional advantage is that recovering of the LNG cold energy during vaporization will provide the refrigerating effect and therefore reduce the engine power used to drive the conventional vapor–compression system (VCS). This study focuses on analysis of the feasibility of a self-refrigerated vehicle by recovering the cold energy of LNG fuel. A prototype of a self-refrigerating system was constructed and its refrigeration performance has been investigated experimentally. The interrelations of the refrigerating temperature, the cooling capacity and the consumption rate of LNG fuel were studied. The temperature field uniformity and the temperature falling characteristics of the refrigerated compartment were discussed in this paper. The experiment results showed that the refrigerating temperature of the compartment could be kept lower −20 °C when the LNG consumption rate is larger than 5.607 kg/h. On the basis of the theoretical analysis, this value of LNG consumption rate could be achieved when the power output of the engine (CY4102CNG) for the LNG-fueled refrigerated vehicle is more than one third of its maximum output power (75 kW) under the full-load operating condition. The original mechanical refrigeration unit (Carrier Viento 200) could be totally substituted by the proposed self-refrigerating system under this condition. Furthermore, the study on the temperature dropping and temperature field uniformity characteristics of the refrigerated compartment showed that a satisfactory result can be achieved.