| Evaporative cooling air conditioner is a device that can directly use water evaporation for refrigeration.It embodies the national requirements for energy-saving,environmental protection and low-energy social development,so that the environment can be well protected.However,the air directly sent into the indoor air by the direct evaporative cooling air conditioner is directly discharged to the outside through the building exhaust vent after the indoor residual heat is absorbed,and the fresh air is not pre-cooled without effectively recovering the cold in the exhaust air.At the same time,the air supply and exhaust are independently designed,which is extremely inconvenient to use and install.According to this,this paper designs a new air-discharge integrated air-conditioner,which is a direct evaporative air-conditioner with exhaust air heat recovery device,which can use the part of the room containing part of the cooling air to the outdoor fresh air.After heat recovery and pre-cooling,direct evaporative cooling is performed to further cool down and then sent to the room.It can not only solve the problem of exhaust air in the evaporative cooling air conditioning system,but also effectively improve the energy utilization efficiency.It is a new type of evaporative air conditioner with remarkable energy saving effect.The heat treatment process of the exhaust air-integrated air conditioner is mainly performed in the heat recovery section and the direct evaporative cooling section.In this paper,five different combinations of heat recovery sections(heat exchanger heat recovery,indirect evaporative cooling heat recovery,direct evaporative cooling and plate heat exchanger combined heat recovery,heat exchanger and indirect evaporative combined heat recovery,fresh air return)The heat transfer mechanism of direct mixing and indirect evaporative cooling combined with heat recovery was carried out for comprehensive analysis and thermal calculation,and the suitable outdoor meteorological parameters for each scheme were analyzed,and combined with the annual meteorological parameters of Kuche City.The annual suitable running time and energy consumption of the whole year were obtained.After comparing the above factors,the most simple,efficient and economical air heat exchanger scheme was selected as the final calculation,design and system.Sample and experimental protocol.In order to further study and explain the improvement of regional applicability of evaporative cold air using heat exchanger for heat recovery,14 typical cities in different building climate regions of China were selected as research objects,and heat was obtained by heat exchanger.The recycled air conditioner is compared with the outdoor weather parameters of the ordinary direct evaporative air conditioner.Aiming at the structural characteristics of the evaporative air conditioner,this paper compares and analyzes the heat exchange process and advantages and disadvantages of several gas-type heat exchangers commonly used in the market.Finally,the plate heat exchanger is selected as the heat recovery device of this subject.However,the commonly used plate air heat exchanger has the same structure and the same secondary air passage,and is not suitable for use in the structure of the evaporative air conditioner.In order to solve the two contradictions of structural size and resistance balance,this paper designed a thin unequal-pitch plate heat exchanger,which has not yet seen similar product designs on the market.For the heat exchanger,detailed thermal calculation and resistance balance calculation were carried out,and the parameters such as the spacing between the primary air duct and the secondary air duct,the specific size of the heat exchanger and the theoretical heat exchange efficiency were determined.Finally,according to the design scheme,the plate heat exchanger and the direct evaporative cooling unit were combined and designed,and an air-sending integrated air-conditioner was designed.In order to further study the heat transfer performance and resistance characteristics ofthe thin unequal-pitch plate heat exchangers designed and the overall characteristics of the air-sending integrated air-conditioner,a complete machine and its heat exchanger were specially prepared.The experimental research on the heat exchanger under standard design conditions and under variable working conditions is carried out.The experimental results show that the error of the heat exchanger under the design conditions and the theoretical design is within the acceptable range,and the error is analyzed.Finally,performance experiments were carried out on the whole prototype of the experimental prototype.The parameters of the air supply temperature and the power of the whole machine under the design conditions were measured.After the calculation,the heat transfer efficiency and energy efficiency ratio of the unit were obtained.The results show that the unit can better meet the expected results in the design of the program.At the end of the paper,in order to better optimize the design of the thin unequal-pitch plate heat exchanger,the thermal and resistance characteristics of the heat exchanger under different structural conditions were numerically simulated by CFD software.The calculation was first carried out under the design structure conditions,and the agreement between the calculation results and the experimental results was verified.Finally,in order to improve the heat exchange capacity of the heat exchanger,the heat transfer performance of the heat exchanger is enhanced by setting the convex spoiler structure.The numerical simulation results show that the heat transfer performance of the heat exchanger with the convex spoiler structure is The plate heat exchanger has a heat transfer performance improvement of12%-19%,and the influence of the convex structure on the pressure drop of the heat exchanger is not obvious.The research done in this paper has certain reference significance for expanding the application field of evaporative cooling and developing this type of heat recovery evaporative air conditioner.The developed air conditioning unit will play a positive role in saving air-conditioning system fresh air energy consumption,improving indoor air quality and reducing ozone layer damage. |
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