| With China's rapid economic development, as well as the persuit of the high-qualitywork and life, the relative shortage of energy is becoming increasingly serious. Buildingenergy consumption is an important component part in the national economy energyconsumption, and air conditioning and refrigeration system's energy consumption is one ofthe main energy consumption of building energy consumption. As one of the refrigerationsystems, the evaporative condensed refrigeration system has the features of high efficiencyenergy-conservation and water-conservation. But the research is still rare, related researchinformation and data are very lack. Based on the above reasons, the evaporative condensedrefrigeration system had been in-depth research and analysis in the issue, and the mainresearch contents are as follows:Based on CFD (computational fluid dynamics) on gas-liquid two-phase approach, usingthe VOF(volume of fluid) multiphase flow model, and the gas-liquid two-phase flow andheat and mass transfer computational model outside horizontal heat exchanged tube wasestablished, the fluid flow characteristics and heat and mass transfer phenomena wassimulated by numerical simulation. Simulation results show that: in the gas-liquid two-phaseprocess of counter current flow, the heat transfer of latent heat percentage ratio is more than90%in the total heat transfer rate on gas-liquid interface, and the latent heat transfer rate ofgas-liquid two-phase counter current flow is higher than that of the gas-liquid two-phaseconcurrent flow. The form of heat and mass transfer in the gas-liquid interface is caused bywater evaporation's latent heat exchange based, supplemented by sensible heat exchange, heatexchange is more conducive to counter current flow than that of concurrent flow.The evaporative condensed refrigeration system's experimental device was introduceddetailedly. The experimental device mainly was used to provide experimental data for thevalidation of evaporative condensed refrigeration system models, and also used to provide theexperimental research platform for evaporative condensed refrigeration system performanceoptimization. the cooling water spray density, outdoor air dry (wet) bulb temperature, air flow,intake air relative humidity etc key parameters were Tested for the enhanced heat transferperformance and refrigeration performance of the evaporative condensed refrigeration system,and tested to get the energy efficiency of the experimental system energy efficieny ratio(EER) of3.78nearly in the nominal operation conditions, it is much higher than the relevantnational standards for evaporative condensed (system) chiller's energy efficieny ratio (EER) (GB requirement of not less than2.4) values.The steady-state model of scroll compressors was established by the usage of efficientmethod, the steady-state distribution parameters' models of the evaporator and evaporativecondenser were established by the usage of the distribution parameters method, theevaporative condensed refrigeration system model was established by the Usage of sequentialmodular approach. the comparison of the system model through simulation and experimentalvalues shows that: the system cooled capacity simulation error is less than10%, the systemcondensed heat simulation error is within10%error, and energy efficiency ratio (EER)simulation error is about10%; thus, the result shows the high accuracy of the model of theevaporative condenser refrigeration system, and it can accurately simulate the thermalperformance of the system.Based on the above study, combined simulation and experimental means, the choice ofevaporative condensed refrigeration system's compressor, refrigerant, evaporator andenhanced heat transfer research of evaporative condenser was analyzed. The followingconclusions are obtained:(1) R134a is adapted to evaporative condensed refrigeration system;as an alternative to R22refrigerant, R-407C is suitable for dry-type evaporator's evaporativecondensed refrigeration system; R-410A is suitable for flooded evaporator design ofevaporative condensed refrigeration system.(2) The energy efficiency ratio (EER) of floodedevaporator's chiller system (R22refrigerant is used) is higher than that of the dry-typeevaporator for about8.6%-14%.(3) in a certain experimental range, for the effect to theevaporative condensed refrigeration system performance, the gradation from much more toless is air wet bulb temperature, air velocity, relative humidity of the air, the cooling waterspray density orderly; in the same experimental conditions, the energy efficiency ofevaporative condensed refrigeration system with which evaporative condenser's heatexchange coil is tube, oval tube and twisted respectively in turn increases, and the increase issignificantly.The rapid selection software for evaporative condensed plant was developed by usingVisual Basic language, it can achieve the following functions:(1) according to building type,building size, predicted EER values, the main design parameters of an evaporativecondensed refrigeration plant can be selected rapidly for the manufacturer to provide specificdesign requirements basis.(2) When the detailed cooled capacity for building requirements isconfirmed, the main design parameters of an evaporative condensed refrigeration plant can beselected rapidly to check the manufacturer's specific product, which is produced to meet theactual requirement or not. Moreover, the actual condition of an energy-conservation demonstration project used evaporative condensed refrigeration plant was introduced. Thefield-tested results showed that: compared to the original water-cooled refrigeration plantresource system, the evaporative condensd refrigeration plant resource system'senergy-conservation rate was16.3%, and its energy-conservation rate was39.7%.The results of this issue can provide reliable theoretical and experimental data for theevaporative condensed refrigeration system's applications in the field of comforted airconditioning in buildings, and have important reference values. |
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