Study On The Air-conditioning Unit Of Evaporative Cooling Assisting To Mechanical Refrigeration

Energy-saving and emission reduction has been gradually into all areas of production and life.As a major of buildings energy consumption, traditional mechanical refrigeration air-conditioning is a high energy-consuming equipment, with the use of time, the cost of energy consumption, equipment damage and updates continued to rise, leading to the use of the cost increase every year, resulting in serious waste of energy.what'more, the use of mechanical refrigeration refrigerants CFC_s and HCFC, which has damaging effects on the ozone layer and greenhouse production, Therefore, mechanical refrigeration system is badly in need of an environmental protection and pollution-free energy-saving refrigeration as a co-ordinated manner to minimize environmental pollution. Evaporative cooling air-conditioning technology is a highly efficient and environmental friendly and economy way of cooling through the exchange of heat and moisture to get a cold between the air and water. It can potentially reduce the cost of mechanical refrigeration components and operating costs, to provide comfort at the same time can save a lot of power and reduce the compressor, condenser and cooling tower of wear and tear. When mechanical refrigeration system failure or maintenance, evaporative cooling can replace mechanical refrigeration for cooling and can offer a lot of ventilation. Evaporative cooling can reduce the cooling tower system in the water, according to the need to be able to provide low-cost wet winter. Consume very little power generated by fossil fuels ,and Contribute to protect the environment.Basised on this, the article put forward evaporative cooling assisting to mechanical refrigeration air-conditioning unit, for the majority of humidity in the outdoor area weather conditions. And made an in-depth theoretical and experimental research from the aspects of its theoretical basis, system architecture, system design and operation mode and energy-saving potential.First of all, Carried out energy-saving and economic analysis as well as the exergy analysis form the theory connection of unit. And through the example of calculated in the mid-humidity region, the application of evaporative cooling assisting to mechanical refrigeration air-conditioning system:1. Transition seasonal can give full play to the evaporative cooling "free cooling" ability to make mechanical refrigeration in a state of "hibernation" state; it consumes only fan and pump energy consumption, compared with the traditional mechanical refrigeration system have great energy-saving potential. 2. Pre-cooling the fresh air in the summer season , when the new wind ratio more than 50% , reduction mechanical refrigeration system of the run load to 26%, and can also make greater use of a year of free outdoor cooling time, play the advantages of evaporative cooling.3. Analyzed the air-conditioning energy consumption and operating costs, as well as energy efficiency ratio in the same cooling capacity of evaporative cooling assisting to mechanical refrigeration air-conditioning system compared with the traditional mechanical refrigeration system link up with the Specific projects. arrived at the former than the latter can save energy consumption 60% , SEER can increase 37%4. Through the use of exergy analysis, reveal the weak link of evaporative cooling technology and mechanical refrigeration is a complex unit, use the "free cooling" of evaporative cooling function and the new air pre-cooling at the same time, recycling the exhaust air of the indirect function and the condensate water. To optimize the design of the structure of the unit laid the foundation and for further guidance to the test-rig structures.In order to in-depth analysis the performance of evaporative cooling assisting to mechanical refrigeration air-conditioning unit, designed and build a 5000m~3 / h evaporative cooling assisting to mechanical refrigeration air-conditioning unit test-rig and made the experimental test dead against transition season and the summer season:1. Heat pipe heat side spilled water density unchanged, Secondary air flow and primary air volume ratio regulated by transducer, when the secondary / primary air ratio up to 0.9 ,and the highest value of the wet-bulb efficiency reaching 74%. an average temperature drop of about 4℃.2. Tube indirect evaporative cooling section spilled water density unchanged, when when the secondary / primary air ratio up to 0.85, its highest efficiency 80%; an average temperature drop of about 6℃.3. Through the switch of the different seasons function section, spring and autumn open the evaporative cooling section for "free cooling", the refrigeration unit of the total cooling capacity up to 15～18kW, the average EER as high as 16.3; in the summer to use indirect evaporative cooling function section for Pre-cooling the new wind ,when the new wind ratio more than 30%, a decrease of 15% of mechanical refrigeration cooling load,4. Cooling coil water temperature (10℃) unchanged, regulating the flow of frozen water, Compound air-conditioning unit than conventional mechanical refrigeration system to save frozen water 0.67kg / s, compressor energy consumption reduced by about 35% , EER increase 42.4% of the overall unit.5. Flow of cooling coil frozen water unchanged, regulating the water temperature ,when the supply water temperature increase 4℃, the compressor energy consumption to reduce by about 40% and the compound air-conditioning unit cooling capacity energy consumption in a unit fell 28.6 %, EER increase 39% of the overall unit. The content of this paper has a certain reference value for the development of evaporative cooling applications, familiarize the evaporative cooling assisting to mechanical refrigeration air-conditioning systems in the non-dry areas of application of the mode of operation and performance parameters, and development the energy-saving air-conditioning unit applicable to the non-dry areas.