The Application Research Of Air Conditioning System Combined Evaporative Cooling And Mechanical Refrigeration In Data Center

Data center's huge air conditioning refrigeration energy consumption has been attracted wide attention,to create a green data center whose PUE closes to 1 has become the public.Evaporative air conditioning has the characteristics of big airflow,small enthalpy difference and wet filtration,and these can meet the requirements of cooling,humidifying and purifying of the computer room at the same time.More importantly,it can prolong the effective time of the natural cold source and reduce the PUE.However,the meteorological conditions in China are large,evaporative cooling alone can not meet the demand of uninterrupted cooling of the data center for 356 days throughout the year subjected to meteorological conditions,especially in areas with high humidity and hot weather,it is important to ensure the normal cooling of the computer room by mechanical refrigeration.At present,the combined equipments of evaporative cooling and mechanical refrigeration have been common,but in data center applications are still less,and mainly are energy-saving renovation project,have not formed a complete air-conditioning system.So this article from the existing wind-side combined air conditioning equipments of evaporative cooling and mechanical refrigeration to start research for data center air conditioning system.Firstly,the key problems of the data center air conditioning system are analyzed.Proposed the influence of architectural form to the air conditioning system selection.And the complex,storage plant type and container type modular data center suited for air conditioning system is discussed.The air distribution forms in the non high heat computer room which is built or building are summarized.And the advantages and disadvantages of each air flow organization in the aspects of building form,power density,energy saving and so on are summarized.Secondly,the three types combined air conditioning systems of evaporative cooling and mechanical refrigeration are studied.Including:linkage air conditioning system,unit form type combined air conditioning system and combined air conditioning system in theform of fan wall.And according to each kind of systems one by one introduced the corresponding air conditioning equipment,the combined way,the plan layout,the air flow organization and the annual operation pattern.It is concluded that the air conditioning system should be combined with the architectural form and the functional requirements for the preferred choice.Propose 1)evaporation type air conditioner supply air under the frame high floor air conditioning system;2)composite dew point indirect evaporative cooling and mechanical refrigeration linkage air conditioning system;3)the integrated air conditioning system combined with evaporative cooling and mechanical refrigeration used in data center;4)dry air energy central air conditioning system used in data center.Finally,the test and analysis of air conditioning equipment proposed in the above 2)and 4)respectively were carried out.From August to April 2016,the optimum operating conditions of 3 kinds of cooling modes(DEC,IDEC and IEC+DX)for the dry air energy central air conditioning used in data center were determined.At the same time,the influence of the secondary exhaust air on the condensation pressure and the cooling rate between the evaporative cooling and mechanical refrigeration were studied in the IEC+DX mode.Results show:1)in the entrance conditions for tg=35±1?and ts=21.5±1?,when primary air volume is 5000m~3/h,the best secondary air volume in the IDEC operation mode is that indirect evaporative cooler section is 5329m~3/h,the best leaching water is 2100L/h,the indirect evaporative cooling efficiency gets to 57.3%,the corresponding temperature is7.8?;direct evaporation's best leaching water is 2300L/h,direct evaporative cooling efficiency is 95%,the corresponding temperature dropped to 7.6?;a whole air temperature drop get to 15.4?,wet bulb efficiency is 113%.2)in the entrance conditions for tg=26±0.5?and ts=18.3±0.5?,when primary air volume is 5000m3/h,the best secondary air volume in the IEC+DX operation mode is that indirect evaporative cooler section is 5500m~3/h,the best leaching water is 2300L/h,the indirect evaporative cooling efficiency is 56.6%,corresponding to the temperature drop to4.3?;evaporator the temperature is kept at 11?,the condenser pressure is basically stable in 1.6MPa.Finally at the established optimum operating condition,simulation standard high wet condition obtained cooling parameters,cooling efficiency of each function unit of 3operating modes and the correctness of the best operating conditions have been certified.In August 2015,the composite dew point indirect evaporative cooling air conditioning system was tested in a simulated heat room in Fuzhou.The results show that:1)the ratio of secondary and primary air volume of the unit was 0.85,the corresponding average wet bulb efficiency was 97.4%;2)to open the 2kW heat source and at the same time unit are respectively opened 10 files and 8 files,the indoor temperature is maintained at31.5~32.1?,relative humidity is maintained at 69~71.4%,close to the actual engineering closed hot aisle temperature,surface temperature of the heat source in the 33.4~34.7?,relative humidity is 57.9~61.6%,basically meeting the requirements of 2?3 electronic equipment environment.Then theoretically calculated the air conditioning supply and exhaust air parameters using in northwest region,obtained the feasibility according to room environment standard,finally calculated effective hours of supply air temperature is less than or equal to 20?.the result showed that the selected typical cities about80%~100%time need not to open the mechanical refrigeration,just open the evaporative cooling to cooling,energy saving potential great.