| In order to vigorously promote the construction of ecological civilization and further implement the strategy of sustainable development,China regards clean,safe and efficient utilization of energy as an important part of accelerating green and low-carbon development.As a big energy user in HVAC field,it is more necessary to build a clean,low-carbon,safe and efficient energy system architecture.In order to make full use of natural clean energy such as solar energy and dry air energy,this paper proposes a compound refrigeration system of solar energy injection and indirect dew point evaporation,and explores its applicability and economy in Xi ’an,a typical city in moderate humidity area.The main research contents are as follows:1.A composite refrigeration system of solar energy injection and indirect dew point evaporation was constructed.The system consists of a solar jet cooling subsystem and a dew point indirect evaporative cooling subsystem.Combination principle of two subsystems of their respective advantages and outdoor climate conditions,determine the corresponding operation strategy: morning session by dew point evaporative cooling subsystem separately provide cold quantity for air conditioning room,noon time open the solar ejector refrigeration subsystem,run jointly with dew point evaporative cooling subsystem for cooling of air conditioning room,in order to realize the continuous composite system run efficiently.2.Establish the energy analysis model of the composite refrigeration system,and write the calculation program with FORTRAN language.Firstly,the effects of solar radiation intensity,heat collecting area,generation temperature and condensation temperature on the thermal and mechanical properties of the solar jet refrigeration subsystem were calculated and analyzed.The results show that the stronger the solar radiation intensity and the larger the heat collecting area,the greater the cooling capacity of the solar jet refrigeration subsystem is.The overall performance coefficient of the system COP increases with the increase of temperature and decreases with the increase of condensation temperature.Secondly,the influences of air dry bulb temperature,relative humidity,air velocity and air volume ratio on the evaporative cooling efficiency and produced air temperature of the dew point evaporative cooling subsystem are calculated and analyzed.The results show that:The higher the inlet dry bulb temperature is,the higher the relative humidity is,the smaller the proportion of produced air is,and the higher the air velocity is,the lower the produced air temperature of the dew point evaporative cooling subsystem is,while the wet bulb efficiency and dew point efficiency of the system increase with the increase of the inlet dry bulb temperature and the proportion of working air,and decrease with the increase of the inlet wind speed.Finally,the influence of solar radiation intensity and outdoor air dry-wet bulb temperature difference on the mechanical performance coefficient of the composite refrigeration system COP,is comprehensively analyzed.The results show that the lower the solar radiation intensity,the greater the outdoor air dry-wet bulb temperature difference,and the greater the mechanical performance coefficient of the composite refrigeration system.3.Combined with meteorological conditions,the structure size of the two parts of the integrated cooler,namely,the dew point evaporative cooling and evaporative condensation,is calculated,mainly including the heat exchange area,coil structure,arrangement and channel size,etc.In addition,the effects of structural parameters and outdoor air conditions on the performance and size of the cooler are also analyzed.The results show that the heat transfer area of the evaporative condensing part increases with the increase of the wet bulb temperature and enthalpy of the inlet air,and decreases with the increase of the air distribution volume,water distribution volume and the face wind speed,but has little effect on the dry bulb temperature of the inlet air.4.TRNSYS is used to simulate the change of meteorological parameters in the cooling season of Xi ’an City,calculate the cooling load of an energy-saving building in the cooling season,and analyze the refrigeration performance and economy of the composite refrigeration system in typical days and the cooling season.The results show that:For three consecutive days days typical composite cooling refrigeration system can completely meet the hourly cooling load of buildings,typical consecutive days of dew point evaporative cooling refrigeration mode,the system of mechanical performance coefficient up to 12.08,and solar injection with compound dew point indirect evaporative cooling mode,the system of mechanical performance coefficient increase with the decrease of the first,a minimum of7.35.In the whole cooling season,the cooling capacity of the composite cooling system can basically meet the hourly cooling load of the building.The total cooling capacity of the composite system is 3858.92 k Wh,among which the cooling capacity of the dew point evaporative cooling subsystem is 2149.19 k Wh,and the cooling capacity of the solar jet cooling subsystem is 1709.73 k Wh.The cooling capacity of the dew-point evaporative cooling subsystem accounted for 55.7% of the total cooling capacity of the composite system,while the cooling capacity of the solar jet cooling subsystem was 44.3%.The average daily mechanical property coefficient of the combined cooling system of the solar jet and indirect evaporation was basically maintained in the range of 8 to 10.The typical intraday cooling time of the composite refrigeration system is 36 hours,and the total power consumption is13.37 k Wh.In the cooling season,the maximum daily power consumption is 5.01 k Wh,the minimum daily power consumption is 2.98 k Wh,and the total power consumption is404.49 k Wh.Under the same total cooling capacity,the total power consumption of the traditional compression refrigeration system in the cooling season is 948.64 k Wh in the total cooling time of 1104 hours.Compared with the traditional compression refrigeration system,the compound refrigeration system can save 57.4% of the electric energy in the cooling season and has good economy. |
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