二元冷凍系統之性能改善分析

本論文係以實驗比較方式，探討常見冷媒R-134a與非共沸冷媒R-404A、兩種冷媒進行二元冷凍系統，增設儲液預冷器裝置與減熱器研究探討，分析二元冷凍系統加裝冷媒過冷卻前後之比較與差異。由系統變化過冷卻與過熱狀態下其性能係數(Coefficient of performance，以下簡稱COP)能力，以實驗數據分析來推論冷媒系統安裝「儲液預冷器」之可行性。藉此瞭解二元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。由本實驗數據分析可得知，以低溫側壓縮機吐出口加裝減熱器有效控制冷凝器之液管過冷度低於38℃以下；而加裝儲液預冷器改善低溫側蒸發器泵集停機後冷媒溫升等不穩定等問題，進而提升製冷速率；在將上述兩種加裝元件同時運轉模式下與基礎模式作比較分析，結果發現，以原二元冷凍系統耗能為基準，加裝減熱器、預冷裝置與減熱器加預冷裝置等三種模式下其節能效益，依序分別為24%、54.3%以及57.8%。因此，對於二元冷凍系統加裝減熱器及預冷裝置將能有效提升整體性能，降低碳排放量。

關鍵字

降溫減熱器；儲液預冷器；性能係數；二元冷凍系統

並列摘要

This paper examines how the common refrigerant R-134a and the non-azeotropic refrigerant R-404A perform in a binary refrigeration with the addition of a refrigerant precooler and a desuperheater and the changes in the system with the added refrigerants before and after subcooling through experiments and comparison. Inferences are made on the viability of installing a ‘refrigerant precooler’ in the refrigerant system through theoretical analysis of changes in the coefficient of performance (COP) of the system in the subcooled and superheated states. The purpose is to understand how the binary refrigeration system performs in terms of actual operation and system performance in the different models designed for this study and examine the possibility to optimize the ‘refrigerant precooler and desuperheater combination’ developed in this study based on the data obtained. Analysis of the data obtained from this experiment reveals that the addition of a heat receiver at the outlet of the compressor in a refrigerated vehicle can effectively control the degree of subcooling of the drainage pipe in the condenser at below 38℃ and the addition of a refrigerant precooler improves problems such as unstable refrigerant temperature rise in the refrigerated vehicle after evaporator pump-down and shutdown, thereby increasing the refrigeration speed. An analysis that compares the model in which both additional components are synchronized with the basic model shows that with the power consumption of the binary refrigeration system as the baseline, adding only the desuperheater, only the precooler, and the desuperheater and precooler combination achieves energy efficiency of 24%, 54.3% and 57.8%, respectively. Therefore, the addition of the desuperheater and precooler combination to the binary refrigeration system can effectively improve overall performance and reduce carbon emissions.

並列關鍵字

Refrigerant Precooler ； Desuperheater ； Cascade Refrigeration System ； Coefficient of Performance(COP)

參考文獻

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[5] 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.

[6] 鄧敦平，「蒸氣壓縮機械過冷卻系統提升冷凍機性能之研究」，國立台灣師範大學工業教育學系碩士論文

[9] W. F. Stoecker and J. W. Jones, 2001, Refrigeration and Air Conditioning, McGraw-Hill.

[13] Souvik Bhattacharyya,Anirban Garai , J.Sarkar, “Thermodynamic analysis and optimization of a novel N2O-CO2 cascade system for refrigeration and heating”, International Journal of Refrigeration 32(2009) 1077-1084

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二元冷凍系統之性能改善分析

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