Fuel System Of LNG Vehicle And The Utilization Of LNG Cold Energy For Air Condition

In modern society, liquefied natural gas (LNG), as a kind of clean and efficient energy, is more and more favored, thus the related industry also develops rapidly. Due to the advantages of LNG vehicle (LNGV), such as large energy storage density, long running mileage, high security and light load etc, it was paid wide attention and had received many studies. As a kind of vehicle’s fuel, LNG needs to be gasified into gaseous natural gas when it is used for engine, and the gasification process will release a lot of cold energy. The recycled cold energy could be used in vehicle air conditioning, it will not only reduce the energy consumption of the engine, but also reduce pollution of the environment, which has the good economy and social value. A set of LNG vehicle fule system had been designed in this paper, and a set of recyclable cold energy system of LNG bus air condition had been designed based on LNG vehicle fule system. Then, the two systems had been simulated by the software of Aspen Plus. Comparing the theoretical calculation with the simulation result, the systems had been verified appropriate. In addition, the systems had also been optimized and improved.Taking the12metres YuTong(ZK6128HGM) bus as a research object, the relevant parameters of the LNG bus fule system were calculated. The specification of LNG vehicle cylinder was determined through the survey data. The calculation formula of LNG fuel flow was derived according to auto power balance equation. Considering that the decline of the liquid level in LNG vehicle cylinder will cause fluid power shortage and lead to unstable gas supply of the engine, the stable gas supply condition of LNG vehicle cylinder was put forward, and the relationship between the gasification quantity of air-heating vaporizer and the engine fuel flow was established in the process of stable gas supply. The results showed that the gasification quantities of air-heating vaporizer increases with the increase of temperature inside the cylinder, and decreases with the increase of pressure inside the cylinder and the decreasing trend gets more and more gentle. These results provides the basis for improving LNG bus fuel system, simultaneously, the calculation of LNG pipeline was also completed.The recyclable cold energy system of LNG vehicle air conditioning consists of LNG cold energy recovery system, refrigerating system, cold energy storage system and cold air distribution system, which was one of the important guarantee of LNG vehicle comfort. The air condition cold load of the12metres YuTong bus in summer was calculated by combining theoretical calculation and estimation. The relationships of cold recovery heat exchanger changed with LNG outlet temperature and vehicle speed, and the air supply volume changed with air supply temperature in cold air distribution system were analyzed, then reasonable air supply volume at low temperature and cold storage quantity were put forward. The cool load of air condition for LNG vehicle are varied with different vehicle running conditions, so the adjustment of refrigerating capacity for air conditionis significant. The influence factors of refrigerating capacity for air condition cold energy recovery system were simply analyzed, and the corresponding control scheme was also discussed.Finally, The fule system and recyclable cold energy system of LNG vehicle were simulated by the software of Aspen Plus. The self-pressurized system as a separate process was simulatedto get the air supply volume at low temperature and the fresh air volume which were verified by comparing with theoretical analysis results. The running situation of the automobile air condition system for LNG city vehicle under the condition of stable gas supply was simulated with optimization and sensitivity analysis module. The LNG fuel systems and air condition cold energy utilization system were suitable for LNGV, it not only can ensure the normal supply of engine fuel of LNGVand the recycling LNG gasification cold energy can be used for automobile air condition refrigeration, but also can realize rational utilization of energy of LNG vehicles and reduce the energy consumption of the engine, so ithas a good promotion value.