| The driving potential of general indirect evaporative cooling technology is the difference of dry-bulb temperature and wet-bulb temperature.The dew point indirect evaporative cooling technology, its driving potential is the difference of dry-bulb temperature and dew point temperature, in theory, the air can be lowed to below wet-bulb temperature and approach dew point temperature, this technology can be very cool range.Heat and mass transfer of dew point indirect evaporative cooler were first analyzed theoretically. A microunit was selected and the primary air and secondary air were analyzed, then a mathematical model and control equation were obtained.In order to analyze the actual performance of the dew point indirect evaporative cooler better,the test-bed was built and prototype performance test results showed that:(1) The outlet air dry-bulb temperature is mainly influenced by wet-bulb temperature, enthalpy value,dry-bulb temperature of inlet air. They are positive correlation.(2) The highest efficiency of the cooler is when the ratio of primary and secondary air at 1.48:1.(3) Under the same test conditions, wet-bulb efficiency of dew point indirect evaporative cooler is 10% higher than the tube type?s,is 20% higher than heat pipe?s. And its dew point efficiency is 5.4% higher than South Korea?s similar cooler. Dew Point indirect evaporative cooler itself also has enhancing space.(4) When the same amount air, resistance of dew point indirect evaporative cooler is higher than the heat pipe?s or tube type?s.According to the test data of prototype, the exergy calculation method and transforming relations in this cooler were researched, in order to analysis if dew point indirect evaporative cooler use exergy effectively. The results showed that: primary air export average thermal exergy by increasingΔexth1 is 0.142785 kJ / kg.a, average exergy efficiency ratio EERex is 4.375, average exergy efficiencyηis 58%. Compared with other coolers, we know dew point indirect evaporative cooler uses exergy adequately and has the value and significance for further study.Engineering example which use dew point indirect evaporative cooling complex mechanical refrigeration air-conditioning unit was tested and analyzed, test results showed that: Dew point indirect evaporative cooling segment can cool air 6-8℃, and maintain indoor relative humidity between 70% -85%. The use of new fresh air made workshop staff healthy and comfortable. However, compared with purely mechanical refrigeration, this complex air-conditioning units only save energy 12% and about 50,000 Yuan one summer(two monthes), from the target which popularize the unit must be at least save energy 20% is still far, and then some transformation measures if this unit used in future projects was proposed.To further enhance the dew point indirect evaporative cooler?s cooling performance and optimize its structure, various coolers which have the same principle both at home and abroad were introduced, and advantages and disadvantages were compared. Then on this basis, a new dew point plate type indirect evaporative cooler was presented, its structure are: (1) corrugated plate heat exchanger is used, corrugated inclination is between 70 to 80 ?; (2) Pre-cooling segment of the secondary air flow is the rectangular-shaped bend; (3) counter current of air and water are achieved; (4) change the tank and leaching water distribution uniformity. Finally, the optimization of the overall structure of the unit and its air flow were gave out.The observations in this work will provide a reference to comprehend dew point indirect evaporative cooling air-conditioning system and offer a theoretical gist for mastering system performance.
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