Research On High Effective Utilizations Of Water Evaporative Cooling Technology Based On Exergy Analysis Of Virtual Cycles

Energy efficiency in HVAC system which energy consumption is a large part in building energy consumption is very important for energy efficiency work. Water Evaporative Cooling (WEC) is one of the energy efficiency technologies urgently needed because of the "high efficiency" and "replacement". Supported by the National "11th Five-Year Plan" to support science and technology project of China (NO.2006BAJ04B04), this paper stress exergy analysis of virtual cycles of WEC technology and finding out the effect forηDEC by different temperature of spray water. The principle of Direct Water Evaporative Cooling (DWEC) and the heat and mass transfer process are analyzed based on other people'research production in this paper. The calculation model of WDWEC process is built and the system of equations is derived and simplified; the theoretical analysis and a series of experiments are put into practice to find the effect forηDEC by different temperature of spray water. The main contents are shown as following:In chapter 1, the basic principle of Engineering Thermodynamics and Heat Transfer Theory about WEC were introduced briefly, the extreme temperature of DWEC and IWEC were under discussion, especially the essence of two forms of extreme temperature.In chapter 2, the virtual cycle of DWEC was set up, and exergy analysis of working substance at each stage in virtual cycles was completed. By the way, the direction and amount of energy transfer were clearly indicated in the text. Optimization analysis of equipments and systerms'energy transfer process was done, and two criteria were built up to improve equipments and systerms'performance, in order to provide the theoretical basis for the later chapters.In chapter 3, the common process which use of recycled water for DWEC has been to expand, the effect forηDEC by different temperature of spray water is considered during the theoretical analysis of DWEC process. And the equation what give a scientific description of heat and mass transfer process is built up, the effect forηDEC by some different influence factors were discussed according to theoretical analysis based on the criteria of improving equipments and systerms'performance. Then the system of equations of heat and mass transfer process is derived, simplified and solved in the case of isenthalpic and cooling process to show the validity and rationality of calculation model. Focus on finding out the effect for performance of DWEC by different temperature of spray water according to theoretical analysis.In chapter 4, the main work is analyzing the effect forηDEC by different temperature of spray water according to experimental method. A series of experiments are done with pipes enthalpy potential method test bench to find the effect forηDEC by different air velocity, different water-gas ratio and different temperature of spray water. Based on fitted result of these experiments, we can get two fitted formulas aboutηDEC,Δp. All of this can provide supports to standard of Water Evaporative Cooling Air Conditioning Unit.In chapter 5, the adaptability of loop nests which called Multistage Evaporative Cooling was discussed according to theoretical analysis based on the criteria of improving the scale of temperature reductions. Both exergy conversion form and characteristic of exergy efficiency of six basic structures were sumed up, and the method of exergy efficiency calculate was given..