|Abstract: ||冷媒是冷凍空調系統中之工作流體, 藉著相變化可帶走大量的熱能.由於新的環保冷媒一直陸續被研發出來, 但卻又未必適合舊的冷凍系統.本計畫以目前最常用的環保冷媒R-134a為例, 擬建立一套能快速計算冷凍系統性能之電腦模擬程式.針對熱力性質之觀點, 調整冷媒在冷凍空調系統之冷凝壓力與蒸發壓力比、蒸發溫度、冷凝溫度、蒸發的過熱度, 以及冷凝之過冷度, 來探討其對冷凍系統性能的影響.除此之外, 藉著冷凍能力、耗電量, 及蒸發器與冷凝器尺寸等數據之評估, 並嘗試找出系統運作時最省能源之最佳操作點.本計畫主要的工作項目如下: ( 一 )完成一冷凍系統之電腦計算模擬程式, 可分析各種冷媒在冷凍空調系統中之熱傳性能.( 二 )針對目前使用最廣泛之冷媒: R-22及R-134a, 計算其冷凍能力、耗電量等數值, 分析該系統冷凍性能之優劣, 並作比較.( 三 )改變系統之操作壓力、溫度、過冷度及過熱度, 進一步找出冷媒在冷凍系統中之最佳操作狀態( 最省能源 ).( 四 )由系統模擬程式計算的結果, 找出影響冷凍系統的主要參數, 並設計一實驗裝置以及規劃實驗方法與流程.預期效益則為: ( 一 )經由本研究對於冷空調系統之模擬計算, 可對目前市面上使用之冷凍及空調系統在一般之操作條件下進行性能之計算評估.( 二 )隨著國內用電量的增加, 尤其到了夏天, 用於空調的耗電量相當驚人.本模擬程式可運用, 在初步設計時評估系統之耗電量、冷凍能力、冷凍性能及最佳的工作條件.( 三 )國際間對臭氧層遭受破壞日益關切, 因此新一代的環保冷相繼被研發出來, 因此需要一套系統評估方法.本電腦程式可快速計算該冷媒運用於冷凍空調系統中之整體性能.|
Refrigerant is used for energy exchanges in a heating, ventilating and air-conditioning system.It usually absorbs a large amount of heat while undergoing a phase change in the evaporator.More and more refrigerants, which are proved to have less effect on environment, have been developed recently.These refrigerants, however, may not be applied to traditional refrigerating system.In this project, a system with refrigerant R-134a is investigated.Parameters of ratio of condensing pressure to evaporating pressure, evaporating temperature, condensing temperature, superheating and subcooling of the refrigerating system are varied to compute the coefficient of performance ( COP )and power consumption of compressor.An optimum operating condition is investigated with the effects of condenser's as well as evaporator's sizes are considered.The main working items are listed as follows: ( A )A computer program, which can evaluate COP of a refrigerating system using different refrigerants immediately, is developed.( B )A refrigerating system with refrigerant of R-22or R-134a is analyzed and the calculated refrigerating capacities and power consumptions are compared.( C )An optimum ( most energy-saving )condition is investigated by varying the operating pressures and temperatures, subcooling and superheating of the refrigerant and the sizes of condenser and evaporator.( D )The parameter that affects COP a lot may be obtained from the calculated results.The experimental apparatus and method can be set up referring to the results of computer simulation.The expected benefits of this project are ( A )The computer program developed can be used to evaluate all the heating, ventilating and air-conditioning system.The results are obtained immediately and straightforward.( B )The electric power consumed vastly for the uses of air-conditioning and refrigerating systems especially in summer.The proposed simulating program facilitates the prospective design of an energy-saving refrigerating system.( C )Increasing concerns have been attended for the depletion of Ozone layer.Refrigerants having less impact on environment have been developed lately.The proposed program can predict the COP of the refrigerating system with new refrigerant immediately.