Experimental investigation of a process cooling system retrofitted with HFC-404A refrigerant for precise manufacturing application

摘要

Precise-manufacturing facilities, which emphasize accurate and stable machining of the working components to be used in semiconductor industry, cannot function properly without appropriate and precise cooling. HCFC (hydro-chloro-floro-carbon) has been commonly used as the coolant for precise manufacturing facilities; but it is facing the pressing schedule to be phased out. Additionally, the dramatic variation of heat load during high-accuracy and high-speed applications need a critical control of coolant (brine or water) temperature. Use of eco-friendly HFC 404A to replace HFC has been suggested as an effective alternative to alleviate the problems. In this study, the performance of a process cooling system retrofitted with HFC-404A refrigerant was evaluated; the energy efficiency ratio and accuracy of temperature control specific to −15°C precise manufacturing application were examined. Effects of using thermostatic expansion valve associated with hot-gas by-pass control scheme under different loading conditions have been investigated extensively. The energy efficiency ratio and accuracy of temperature control for the cooling system were measured and analyzed for comparing and evaluating HCFC-22 and HFC-404A using different throttling devices under specific coolant temperatures. The comprehensive studies on improving the accuracy of temperature control and energy-saving efficiencies through different temperature control strategies are presented in this paper.