R-404A雙溫冷凍機提升系統性能之研究

Research of Improving the Performance of R-404A Dual-temperature Refrigerator

林謙育(Chien-Yu Lin)

指導教授 ： 卓清松

國立臺北科技大學/機電學院/能源與冷凍空調工程系碩士班/碩士(2010年)

摘要

本論文係以電腦理論模擬與實驗兩種方式，探討非共沸冷媒R-404A、 R-407C、R-410A等多種冷媒進行電腦理論模擬研究探討，分析不同冷媒在系統不同過冷卻與過熱狀態下其性能係數(Coefficient of performance，以下簡稱COP)為何，期能以分析結果來推論冷媒系統安裝「液氣熱交換器」之可行性。藉此瞭解雙溫冷凍系統在本研究所設計不同模式下，實際運轉情形與系統性能各方面之表現，並從所得之相關數據來探討冷媒選用及本研究所開發之「儲冷式液氣熱交換器」之可行性。
本研究開發設計一台商用雙溫冷凍系統，利用一組單壓縮機及兩組蒸發器來提供系統之製冷，且系統提供兩種蒸發溫度，藉以達到冷凍及冷藏工作溫度；本研究設計四種不同實驗模組分別為：Model-A雙溫冷凍系統(對照組)；Model-B電子膨脹閥取代機械蒸發壓力調節閥；Model-C雙溫冷凍系統裝設「傳統液器熱交換器」；Model-D雙溫冷凍系統裝設本研究創新開發「儲冷式液氣熱交換器」等實驗模組進行研究分析探討。
由本實驗數據分析可得知，在Model-B運轉模式下可有效控制中溫蒸發器之回流管過熱度，進而提升冷凍速率，且可改善傳統式蒸發壓力調節閥會積存冷凍油及泵集停機不穩定等問題；在Model-C運轉模式下分析比較，雙溫冷凍機之COP可提升約21.73％；當Model-D運轉模式下實驗分析比較發現，儲冷式液器熱交換器可有效在負載變動下，亦可提供較佳之過冷卻度，且此裝置可改善壓縮機排氣及機殼溫度過高情況，在於整體COP方面可有效提升約29.53％。

關鍵字

冷凍機 ； 過冷卻 ； 性能係數 ； 溫室效應

並列摘要

Using the two ways of computer simulation and experimental research, the paper explores the natures of azeotropic refrigerants, including R-404A, R407C and R-410A, and analyzes the coefficient of performance (COP) of different refrigerants when the system is under various overcooling and overheating situations. It is hoped that the analytical results can be used to infer the feasibility of installing “liquid-gas heat exchanger” at refrigeration system. Through the research, we are able to understand the actual operation of dual-temperature refrigeration system under the various models designed by the study, and the performance of different functions of the system. From the acquired data, the paper discusses about the selection of refrigerant and the feasibility of installing the “air-cooled liquid-gas heat exchanger” developed by the study.
The study develops and designs a dual-temperature refrigerator system for business use. The system is composed of a single compressor and two evaporators to provide cool air for the system. And the system provides two different evaporation temperatures so as to achieve the expected freezing and cooling temperatures. The study designs four different experimental models for making analytical discussion, and these models include: Model-A, dual-temperature refrigerator system (comparative group); Model-B, electronic expansion valve, which replaces mechanical evaporation pressure adjustment valve; Model-C, dual-temperature refrigerator system equipped with a “traditional liquid heat exchanger”; and Model-D, dual-temperature refrigerator system equipped with an “air-cooled liquid-gas heat exchanger” developed by the study.
As known from analysis of the experimental data, under the operation of Model-B, the overheating situation at the return conduit of medium-temperature evaporator can be effectively controlled. Furthermore, the model can enhance the refrigeration speed, and improve the problems of accumulation of refrigerator oil as well as the shutdown and instability of pump appeared in traditional evaporation pressure adjustment valve. After making analysis and comparison under the operation of Model-C, the COP of dual-temperature refrigerator is found improved by around 21.73%. When experimental analysis and comparison are made under the operation of Model-D, it is found that air-cooled liquid-gas heat exchanger can effectively provide better overcooling degree, and this device can improve the exhaust of compressor and excessively high temperature of machine shell. Eventually, the overall COP can be effectively improved by around 29.53%.

並列關鍵字

refrigerator ； subcooling ； Coefficient of performance(COP) ； global warming

參考文獻

[4]行政院環境保護署“溫室效應之影響與因應對策”

[9]鄭喬鴻 ，「儲能元件應用於空調機過冷卻之性能研究」，國立臺灣大學機械工程學研究所博士論文。

[21]林振源、顏貽乙，HC冷媒特性與應用情形，中國冷凍空調雜誌，1998，第77-81頁。

[22]王偉儒，家用冰箱系統換裝碳氫冷媒之性能研究，國立台北科技大學冷凍空調工程研究所，碩士論文，台北，2005。

[7]J. R. Khan and S. M. Zubair, 2000, “Design and Rating of an Integrated Mechanical-subcooling Vapor-compression Refrigeration System”, Energy Conversion and Management, vol. 41, pp. 1201-1222.