- 學位論文
R600a碳氫冷媒在Sub型兩段式蒸氣壓縮冷凍系統COP特性解析
Performance Analysis of Sub Type Two stage Vapor Compression Refrigeration System with R600a Hydrocarbon Refrigerant
摘要
低溫冷凍系統於人類生活中扮演著相當重要的角色，可廣泛地應用於民生、高科技、國防及能源等多領域中。低溫兩段式蒸氣壓縮冷凍系統最早可追溯至19世紀，因為單段蒸氣壓縮冷凍系統於低溫時呈現低效率性能表現，故因而發展出使用於中低溫蒸發器溫度需求之兩段式蒸氣壓縮冷凍系統，以提升能源使用效率。隨著環境永續發展觀點下，傳統CFCs、HCFCs和HFCs冷媒已漸不採用，所以開發次世代潔淨冷媒為重要課題。碳氫類 (HC)冷媒具有零ODP、低/零GWP、優異熱物化特性和高效率等優點，故可成為次世代冷凍系統冷媒。 故本文研究(1)R134a (HFC類)、R404A(HFC類)、R600a(HC類)和R717(自然冷媒)等多種冷媒應用於低溫過冷卻型兩段式蒸氣壓縮冷凍系統中，探討各系統參數與系統COP值之變化關係，(2)比較低溫過冷卻型兩段式蒸氣壓縮冷凍系統和cascade低溫冷凍系統於相同蒸發器溫度之COP值變化關係，(3)相較R600a和R717冷媒於相同蒸發器溫度之高壓/低壓壓縮機入口比容及其變化關係。以期得知R600a冷媒系統特性，作為設計改善次世代低溫冷凍系統之參考依據。
並列摘要
Low-temperature storage refrigeration system is vital for much industry range. The traditional single-stage vapor compressor system is not suitable for low-temperature system; therefore, it should be used cascade refrigeration system. For many years, as a result of environmental protection issue related global warning and depletion of ozone layer caused by the use of synthetic refrigerants (CFC’s, HCFC’s and HFC’s), the return to the use of harmless natural substances as alternative refrigerants in refrigeration systems. Ammonia (R717) and hydrocarbon refrigerant have excellent thermodynamic and thermo-physical properties; they can be used in much range of refrigeration system. In this paper, a cascade refrigeration system with Ammonia (R717) and Hydrocarbon refrigerant (HC) as working fluids in the low and high temperature stages, respectively, has been analysed and compared with R22 and R134a of traditional refrigerant. Further to research and analysis the relation of COP and mass flow ratio versus operating and design parameters of 6 group’s refrigerant in order to get optimization of parameter and analysed refrigerant in cascade low-temperature refrigeration system.