The Design Of LNG Truck Air Condition Control System With Cold Energy Utilization And Analysis Of LNG Vaporizer

The world energy and environment crises promote the development of Liquid Nature Gas (LNG) vehicle. LNG storage temperature is below -162℃, while the service temperature of Nature Gas in the engine is above 10℃. Huge amount of cold energy will be released during the gasification of LNG. The automotive air conditioning system involved in this paper utilizes LNG cold energy.LNG vaporizer is the key facility of the automotive air conditioning system, which not only affects the performance of automotive air conditioning but also influences the energy reliability. The paper is combined theoretical analysis with numerical calculation to do some studies of automotive air conditioning system and twisted spiral tube on the basis of others researches.The cold energy of LNG can’t be used in the air-conditioning system without refrigerant. The refrigerant involved in this paper is the choice of weighting the advantages and disadvantages based on theory and practice. The storage temperature of LNG is below -160℃ which can ice the pipe, and the LNG flow changes constantly. All of factors were be considered in the air-conditioning system to make sure the system reliability.LNG vaporizer is the key facility of the system.3-D calculation was been made on the vaporizer. Because of LNG phase transition, the phase transition function was added in the calculation to make sure the result real and reliable. Through a series of calculation the minimum refrigerant flow to avoid pipe freezing was been shown in this paper. The minimum refrigerant flow makes sure the system safety. However, the gasification performance of the second LNG vaporizer affects engine reliability. This paper also analyzed LNG vaporizer gasification performance. Heat transfer performance and pressure drop performance of twisted spiral tube vaporizers with different screw lead and different cross section were analyzed. Through the three-dimensional calculation, we get the optimization scheme which has better performance in heat transfer and pressure drop. The general correlations for calculating the heat transfer performance and pressure drop performance of twisted spiral tube were fitted.1-D software was uesd to calculate the air supply volume of air-conditioning system. At the same time, the relationship between refrigerant flow rate and refrigerant inlet temperature of air-conditioning hear exchange was analyzed. The whole system was built by Aspen to simulate the system operation. Based on the results of simulation some parameters in the system were optimized.