An analytic model for working fluids flowing through capillary tubes has been established with the approximate integral method. All the possible flow regimes in the capillary tubes,including subcooled, two-phase and s...An analytic model for working fluids flowing through capillary tubes has been established with the approximate integral method. All the possible flow regimes in the capillary tubes,including subcooled, two-phase and superheated regimes, are covered in the model, and different analytic solutions are given respectively for each flow regime. As examples, the mass flow rates of refrigerants R12, R134a and R600a through capillary tubes are predicted by the model,and compared with those evaluated by a general distributed-parameter model. The mean bias falls into 1% and the maximum bias is 2.2%, while the computation speed of the new model is more than one order of magnitude higher than that of the distributed-parameter one.展开更多
The machine tool coolers are the best managers of coolant temperature in avoiding the deviation of spindle centerline for machine tools. However, the machine coolers are facing the compressed schedule to phase out the...The machine tool coolers are the best managers of coolant temperature in avoiding the deviation of spindle centerline for machine tools. However, the machine coolers are facing the compressed schedule to phase out the HCFC （hydro-chloro-floro-carbon） refrigerant and little attention has been paid to comparative study on sizing capillary tube for retrofitted HFC （hydro-floro-carbon） refrigerant. In this paper, the adiabatic flow in capillary tube is analyzed and modeled for retrofitting of HFC-407C refrigerant in a machine tool cooler system. A computer code including determining the length of sub-cooled flow region and the two phase region of capillary tube is developed. Comparative study of HCFC-22 and HFC-407C in a capillary tube is derived and conducted to simplify the traditional trial-and-error method of predicting the length of capillary tubes. Besides, experimental investigation is carried out by field tests to verify the simulation model and cooling performance of the machine tool cooler system. The results from the experiments reveal that the numerical model provides an effective approach to determine the performance data of capillary tube specific for retrofitting a HFC-407C machine tool cooler. The developed machine tool cooler system is not only directly compatible with new HFC-407C refrigerant, but can also perform a cost-effective temperature control specific for industrial machines.展开更多
文摘An analytic model for working fluids flowing through capillary tubes has been established with the approximate integral method. All the possible flow regimes in the capillary tubes,including subcooled, two-phase and superheated regimes, are covered in the model, and different analytic solutions are given respectively for each flow regime. As examples, the mass flow rates of refrigerants R12, R134a and R600a through capillary tubes are predicted by the model,and compared with those evaluated by a general distributed-parameter model. The mean bias falls into 1% and the maximum bias is 2.2%, while the computation speed of the new model is more than one order of magnitude higher than that of the distributed-parameter one.
基金supported by Science Council of Taiwan, China (Grant No. NSC 98-2622-E-167-029-CC3)Industrial Technology Research Institute of Taiwan, China
文摘The machine tool coolers are the best managers of coolant temperature in avoiding the deviation of spindle centerline for machine tools. However, the machine coolers are facing the compressed schedule to phase out the HCFC （hydro-chloro-floro-carbon） refrigerant and little attention has been paid to comparative study on sizing capillary tube for retrofitted HFC （hydro-floro-carbon） refrigerant. In this paper, the adiabatic flow in capillary tube is analyzed and modeled for retrofitting of HFC-407C refrigerant in a machine tool cooler system. A computer code including determining the length of sub-cooled flow region and the two phase region of capillary tube is developed. Comparative study of HCFC-22 and HFC-407C in a capillary tube is derived and conducted to simplify the traditional trial-and-error method of predicting the length of capillary tubes. Besides, experimental investigation is carried out by field tests to verify the simulation model and cooling performance of the machine tool cooler system. The results from the experiments reveal that the numerical model provides an effective approach to determine the performance data of capillary tube specific for retrofitting a HFC-407C machine tool cooler. The developed machine tool cooler system is not only directly compatible with new HFC-407C refrigerant, but can also perform a cost-effective temperature control specific for industrial machines.
