Applied Research On Temperature And Humidity Independent Control Of Air-conditioning Systems In Changsha Area

Constructing energy-saving and comfortable air-conditioning system has beenthe pursuit of our air-conditioning field and it is more urgently desired to achieve thisgoal,especially in the present age of prominent issues about energy andenvironment.As the disadvantages of the traditional central air-conditioning systemhave been appearing gradually and attracting attentions,air-conditioning system ofindependently temperature-humidity control is being increasingly studied and relativeproducts are in an effort to research and develop,because it has the advantage toovercome these drawbacks.In the existing research work,there is little comparison andanalysis on temperature and humidity independent control of air-conditioning systemwith three different fresh-air-dehumidified methods.Therefore,this paper primarilystudys and optimizes temperature and humidity independent control ofair-conditioning system of different forms and it is very significant to spread andapply for this kind of systems.Firstly,this paper introduces the components and working principles of sometypical temperature-humidity independently control fresh air handling units andanalyses the performance,the advantages and disadvantages of every importantcomponent. Secondly,the energy consumption and the system efficiency calculationformula of typical independent temperature-humidity control air conditioning systemwith three common dehumidifying ways were listed.Thirdly,this paper works outparameters of a senior office building in Changsha’s summer conditions separatelyand then obtains the COPs of traditional air-conditioning system and theseair-conditioning system with three different dehumidification methods,and obtains theoptimum system form in a same dehumidification method and compares it withtraditional central air-conditioning system.Lastly, it optimizes the temperature-humidity independently control air-conditioning system,by adjusting the parametersof each important state,system structures and regenerative heat source modes.This paper firstly calculates COPs of one-stage and two-stage rotary desiccantcooling system using outdoor air heated by electricity in theoretical regenerationtemperature condition,demonstrating the superiority of two-stage system,and then bycomparing COPs of two-stage system with dehumidification rates of1:1,1:2,2:1,itdraws a conclusion that system with dehumidification rate of2:1is the optimum,also,high temperature cold water precooling system is better than exhaust airheat recovery mode system in this dehumidification rate,thus it provides a guide forchoosing system precooling modes. What’s more,by calculating the COP of rotarydesiccant cooling system based two-stage air source heat pump,a conclusion can bedrawn that its COP is the highest among the rotary desiccant coolingsystems.Secondly,it calculates COPs of one-stage and two-stage liquid desiccantcooling systems by heat pump,then by comparing COPs of two-stage system withdehumidification rates of1:1,1:2,2:1,a conclusion can be drawn that system withdehumidification rate1:2is the optimum.Finally,it confirms that the indoor exhaustreheat desiccant cooling system is the best air handling system of these desiccantmethods by analyzing and comparing COPs of the condensation desiccant coolingsystems. Through comparative analysises above,the optimal types oftemperature-humidity controlled independently air-conditioning systems’ COP arehigher than traditional central air-conditioning system’s,and the optimal temperatureand humidity independent control of air-conditioning system in Changsha’s summerconditions can be reached.