| Summary: | 碩士 === 國立臺北科技大學 === 冷凍空調工程系所 === 93 === The vapor-compression liquid chiller is the main energy consuming equipment in the air-conditioner system, so studying on energy saving has been an important issue. The coefficient of performance (COP) used to express the whole energy efficiency for liquid chillers performance is based on the conservation of energy of thermodynamics, which is not able to indicate the exergy destruction or irreversibility of each component. Therefore, focusing on the irreversibilities of chiller components becomes the most direct way to improve energy efficiency of liquid chiller. In addition, the research on thermodynamic optimization as well as thermoeconomic of liquid chiller is urgent for equipment designer.
Therefore, the main research purposes of this study are: (1) developing an irreversibility analysis method for liquid chiller to indicate the direction of performance improvement; (2) parametric studing the influence of design parameters, such as condensing and evaporating temperature, on the component irreversibilities and the system performance, and to estimate the improvement potention of each component on the system energy efficiency; (3) developing a thermodynamic optimization method together with the consideration of thermoeconomic to study the optimium allocation proportion of thermal conductance of heat exchangers. Three experimental data are comparied with the prediction results obtained herein.
The results show that the compressor possesses the largest potential to improve energy efficiency with the ranges of 37.4 to 46.6%, followed in order by the condenser (about 22.1-26.7 %), and then the evaporator (about 16.7-24.2 %). Reducing 1℃of the condensation temperature will results the change of irreversibilities of - 4.7 % and the COP of 3.4 %. In addition, increasing 1℃of the evaporation temperature will results the change of irreversibility of -4.6% and the COP of 3.9%. Under the same total thermal conductance of heat exchanger and cooling capacity, the optimum allocation ratio of thermal conductance of the condenser and evaporator is 0.5.
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