換裝環保新冷媒之油冷卻器系統性能研究

STUDY OF REFRIGERATION SYSTEM PERFORMANCE USING NON-CFC REFRIGERANT FOR INDUSTRIAL OIL COOLERS

隨著產業機械走向精密化、高速化及對加工精度要求不斷提升，為防止精密加工機產生熱變位而影響精度，因此須適當地冷卻來控制精密加工所產生之溫升，而油冷卻器（oil cooler）即是提供工具機械之冷卻切削油之最佳溫度控制方案。然而，為因應世界各先進國對氫氟氯碳（HCFC）冷媒管制之趨勢，全面使用氫氟碳(HFC)新環保冷媒於工業冷卻器勢在必行。然而，環保新冷媒如R-407C與R-410A屬非共沸冷媒，具溫度滑移與成分變動之特性，在系統運轉性能、系統充填冷媒或組裝維修階段洩漏等問題上皆與純冷媒（如R-22）有所不同。因此，本文擬以性能實驗探討有關非共沸冷媒之溫度滑移現象對冷凝器與蒸發器之影響，同時也將針對換裝環保新冷媒後之相關運轉參數對系統性能及熱交換性能之差異變化作研究分析，使系統不僅與新非共沸混合冷媒相容外，亦將提供精密加工機械冷卻時之最佳溫度控制。

Accurate, stable and precise machinery can not exist without good temperature control. Temperature control depends, largely, on efficient refrigerants. Oil coolers are the best managers of oil temperature for the industrial machinery. However, following the successful termination of CFC (chloro-floro-carbon) production in 1996, machine cooler makers are facing a compressed schedule to phase out HCFC (hydro-chloro-floro-carbon) refrigerants. Among several ODP (ozone depletion potential) free refrigerants, R-407C and R-410A are considered to be the best candidates to replace R-22 refrigerant (an HCFC), which is currently used in machine coolers. The non-azeotropic characteristic of R-407C and R-410A provide a temperature glide during phase change and composition shift during leakage. When a non-azeotropic refrigerant is used, the performance during operation and considerations of refrigerant charging and leakage during assembling and maintenance stages present difficulties which are quite different from the problems when a pure refrigerant, like R-22, is used. In this study, the effect due to temperature glide during phase change, and its associated effects on heat exchanger performance as well as system overall performance will be investigated. Proper components and system designs for refrigeration systems will be proposed. The purpose of this study is to complete a brand new system form design through an actual performance field test. The refrigeration system is not only directly compatible with new non-CFC refrigerants, but can also maintain a permanent temperature control, specific for industrial machines.