Performance Of The Radiant Cooling System On The Roof Of LNG-fueled Refrigerated Vehicles

Under the dual pressure of energy and environment,China is actively developing towards low-carbon energy,reducing the utilization rate of coal and oil,and improving the position of clean energy and new energy in the energy consumption structure.Liquefied Natural Gas(LNG),as the cleanest fossil energy,is widely favored and applied in many fields successfully.The LNG-fueled refrigerated vehicle is powered by LNG,and use the cooling capacity of the LNG gasification process to cool the refrigerated compartment.It not only reduces the consumption of power fuel,but also recycles LNG cold energy,which has obvious energy saving effect.At the same time,the use of clean energy reduces greatly the emission of pollutants such as automobile exhaust,and has significant environmental benefits.Therefore,the development of LNG cold energy utilization technology in the automotive field has attracted the attention of many scholars.At present,the research on the cold energy utilization system of the LNG-fueled refrigerated vehicle focuses on the design of heat exchanger and the overall structure of the system,but has not yet involved in the system dynamic control strategy and radiation refrigeration.This paper design the radiant cooling system on the roof of LNG-fueled refrigerated vehicles based on the no phase-change heat transfer of refrigerant carrier at low temperature.It establishes the insulation box model and the refrigeration system model by using TRNSYS simulation software,and analyzes the influence of various factors on the refrigeration performance of the system and its economic advantages,and provides a reliable basis for the dynamic control strategy of the system.The following are the main research contents:(1)This paper takes a 4000mm×1900mm×1900mm refrigerated vehicle as the research object,and calculates the refrigeration cooling load of the insulation box body,and analyzes the feasibility of LNG recyclable cooling capacity for refrigeration system of refrigerated vehicle.The result shows the cooling system can fully meet the demand of cooling load of the insulation compartment system of refrigerated vehicle.Based on this,this paper designs a set of the radiant cooling system on the roof of LNG-fueled refrigerated vehicles.The system mainly uses heat radiation and convection to heat exchange to achieve refrigeration purposes.The design of the bypass structure realizes the dynamic control of the system and ensures the stability of the temperature of the insulation box body.The paper selects KF-K1 brine for low temperature heat exchange and sleeve-type heat exchanger with simple structure.(2)This paper establishes the insulation box model and the refrigeration system model and simulates the operation of the system under different working conditions by using TRNSYS simulation software,and analyze the influence of various factors on the refrigeration performance of the system.The results show that when the refrigerated vehicle runs at an economical speed of 60-80km/h,the cooling capacity of the refrigeration system provided is 1.56~2.17 kW,which can meet the cooling capacity required for refrigerated vehicle to transport strawberries in Haikou.(3)By quantitatively analyzing the relationship between the LNG flow and the outdoor temperature,the dynamic control strategy of the radiant cooling system of the LNG refrigerated roof is obtained,which ensures the continuity and stability of the refrigerated compartment.(4)This paper compares the economics of a steam compression refrigeration unit with the same power and a roof radiant refrigeration unit using LNG cold energy,and proves that the LNG-fueled refrigerated vehicle and its refrigeration system save more than the mechanical refrigerated vehicle during its operation.The operating cost is 224,400 yuan and the payback period is 0.18 years,which has a significant economic advantage.In this paper,the theoretical and simulation analysis of the cooling capacity of LNG refrigerated roof radiant cooling system under different working conditions is carried out,and the influence law of various factors on the cooling capacity of the system is obtained,and the dynamic control strategy of the system and its economic advantages are determined.The research and development of this system conforms to the policy of sustainable development of low carbon in China,and has broad development prospects and strong promotion significance.