Preparation And Performance Study Of Energy Storage Adiabatic Foam For Refrigerated Vehicles

In the process of refrigerated vehicle transportation,the heat penetration through the insulation layer to the compartment will have a great impact on the energy consumption of the refrigeration system,accounting for 40%of the total energy consumption of the compartment refrigeration system,so the compartment envelope is critical to the insulation performance of refrigerated vehicles.Using the characteristic of phase change material to absorb or release a large amount of heat during phase change to keep the temperature constant,this paper prepares energy-storing adiabatic foam by compounding microencapsulated phase change material(Micro PCM)and rigid polyurethane foam(RPUF),and applies it to the enclosure of refrigerated vehicles to reduce the temperature fluctuation inside the vehicle and reduce the infiltration of external heat,so as to achieve the purpose of reducing the temperature inside the vehicle and saving energy.The purpose of this study is to reduce the temperature fluctuation inside the vehicle and reduce the amount of external heat penetration,so as to reduce the temperature inside the vehicle and save energy.Specific research includes.(1)According to the working environment of the refrigerated truck,phase change microcapsules with phase change temperature of 4.8℃,phase change enthalpy of 136.3J/g and n-tetradecane as core material were selected.Energy storage insulation foam was prepared by adding0～25wt%of phase change microcapsules into RPUF by one-step method,and the apparent morphology,chemical structure,apparent density,compression strength,thermal conductivity and thermal storage properties of the foam were characterized and analyzed.The surface morphology analysis shows that the addition of phase change microcapsules will lead to the enlargement of RPUF pores and the occurrence of bubble breakage,and the addition of phase change microcapsules should not exceed 20 wt%to ensure the foaming quality.The thermal conductivity analysis showed that the addition of phase change microcapsules would negatively affect the thermal insulation ability of RPUF,and the thermal conductivity increased from 0.0271W/(m·K)to 0.0295W/(m·K)at 25℃.The thermal storage performance analysis showed that the addition of phase change microcapsules gave RPUF the thermal storage capacity and the phase change enthalpy increased gradually with the increase of phase change microcapsules addition.By comparison,the ideal addition of phase change microcapsules for this foam is 15wt%,at which time the energy storage insulation foam has clear and complete bubble pores,the bubble pore size is 134.5μm,the density and compression strength are in line with the national standard requirements,the thermal conductivity is 0.029W/(m·K)at 25℃,the enthalpy of phase change is8.88J/g,which has better thermal insulation and thermal storage capacity.(2)On the basis of 15wt%phase change microcapsule addition,the catalyst and blowing agent types were changed to study the effect of additives on the foam performance.The overall performance of the samples prepared after the catalysts were replaced with PC-5 and PC-8 was excellent with a pore size of 296.1μm,density of 30.2kg/m~3 and thermal conductivity of0.0257W/(m·K)at 25℃.The density of the sample prepared by replacing the blowing agent with HCFC-141b is 33.8kg/m~3,the compression strength is 320.6k Pa,and the thermal conductivity is0.0261W/(m·K)at 25℃,but the ODP value of HCFC-141b is 0.11,which will damage the ozone layer.The samples prepared by all-water foaming agent showed the phenomenon of broken bubbles and the compression strength did not meet the requirements of the national standard,and it was initially thought that all-water foaming agent was not suitable for the preparation of energy storage adiabatic foam.The analysis concluded that the energy storage adiabatic foam prepared by using PC-5 and PC-8 as catalyst and HFC-356mfc as blowing agent under the condition of 15wt%of phase change microcapsule addition was the most ideal.(3)The temperature and heat flow density in the refrigerated car body and interior were simulated using FLUENT software,and the comparative analysis of the temperature and heat flow density in the refrigerated car using energy-storage insulation foam and RPUF was performed.Compared with RPUF as the enclosure,the cabin with energy-storage insulation foam has a lower temperature at 3.5h and a maximum temperature difference of 2.6°C at 2.1h.The results show that the addition of phase change microcapsules can delay the peak of heat flow density,reduce the heat load inside the carriage,slow down the temperature rise inside the carriage and prolong the insulation time,and the material is more suitable for short-distance transportation within 190km.