Research On Theory And Application Of Dry Air Energy Central Air-conditioning Unit

With the development of air conditioning technology,traditional mechanical refrigeration is faced with transformation and upgrading.The evaporative cooling technology has the unique advantages of energy saving,low carbon,economy and health,while it is greatly influenced by meteorological conditions,and its own performance needs to be improved.Combining the evaporative cooling with the traditional mechanical refrigeration.The cooperative operation and mutual coupling of the two technologies can be realized to make up for the shortcomings of only one of them,which is beneficial to optimize the evaporative cooling equipment,broaden its use range,improve the performance of mechanical refrigeration,promote energy saving and emission reduction,and realize the complementary advantages of both.The research on composite technology of evaporative cooling and mechanical refrigeration is relatively scarce at home and abroad.Especially in combination with practical engineering applications,the matching,switching and cooperative operation strategies of evaporative cooling and mechanical refrigeration still need to overcome.According to the research status of relevant technology and equipment at home and abroad,A new type of co-coupled air conditioning unit with evaporative cooling and mechanical refrigeration is proposed.Through study of the theory and application of the unit,To realize the advantages of the natural cold source and the artificial cold source,the integration of the cold source and the end of the cold source of land saving,water saving,energy saving and environmental protection.(1)This paper introduces the research status at home and abroad,through the comparison of principle and structure.The air conditioning unit combined with evaporative cooling and mechanical refrigeration is analyzed and summarized.According to the meteorological parameters influence and characteristics,the applicability of different technical forms is analyzed and explained.(2)It is mainly about the introduction of design scheme and expatiation about air volume balance and heat balance of the unit.Meanwhile,it briefly introduced the methods to determine relative parameters.Thus,to except to provide some reference for the production and the subsequent experiment of similar proto.(3)The unit was tested and tested in the national enthalpy differencelaboratory.The matching,switching and cooperative operation mode and control strategy between the evaporative cooling and the mechanical refrigeration are discussed.Combined with similar engineering cases,the application and Prospect of compound energy saving air conditioning technology is prospected,which provides a reference for future equipment and structure optimization.Through the test:1)in drying condition: the first and second air drying ball temperature is 35?,the wet ball temperature is 21?.In the unit IDEC mode,the optimum water and gas ratio of the unit DEC section is 0.38.The optimum second air and first air volume ratio is 1.1,the drop of temperature is 7.6,and the efficiency up to 95%.The optimum water and gas ratio in the IEC section is 0.33,the best second air and first air volume ratio is 1.07,the temperature drop to 7.7,and the efficiency reaches57%.Meanwhile,the padding face velocity of first air and second air comes to 2.1m/s and1.3m/s respectively.2)In medium humidity conditions,the temperature of the first and second air dry ball is 38,and the wet ball temperature is 26.In the unit IEC+DX mode,the optimum water and gas ratio of the unit IEC section is 0.30.The optimum second air and first air volume ratio is 1.2,the temperature drop is 7.7,the efficiency up to 57%,and the mechanical refrigeration COP reaches 4.1.Meanwhile,the padding face velocity of first air and second air comes to 2.1m/s and1.51m/s respectively.3)In high humidity conditions,the temperature of the first and second air drying ball is 38,and the wet ball temperature is 28.In the unit IEC+DX mode,the optimum water and gas ratio of the unit IEC section is 0.25.The optimum second air and first air volume ratio is 1.4,the temperature drop is 7.7,the efficiency up to58.3%,and the mechanical refrigeration COP reaches 4.1.Meanwhile,the padding face velocity of first air and second air comes to 2.1m/s and1.76m/s respectively.The research shows that under the condition of standard high humidity,the direct evaporative cooling efficiency of the unit can reach more than 90%,and the indirect evaporative cooling efficiency can reach more than 60%,which is increased by 26%and 9% compared with the general efficiency parameter 75% and 55% in the high humidity area,respectively.The COP value of the mechanical refrigeration of the unit can reach more than 4,which up to 30%,compared with the traditional mechanical refrigeration system.The indirect evaporative cooling efficiency of the unit can reach 65%,which canplay a good role in precooling,and the outlet temperature of the IDEC mode can be reduced to below the rheumatic bulb temperature.In dry areas,the evaporative cooling mode can meet the basic requirements throughout the year,almost do not need to open the auxiliary mechanical refrigeration;as the humidity increases,the need to open the mechanical refrigeration time will be increased,while in moderate humidity in summer,the single-stage indirect evaporative cooling can bear 30% of the load,and in high humidity areas in summer,the proportion is still can reach about 20%,the annual energy-saving reaches about 40%-80%.