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정동수,김종보,Jung, D.S.,Kim, C.B. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.3
In this paper, pressure drop through a capillary tube is modeled to determine the length of a capillary tube for a given set of conditions. HCFC-22 and its alternatives, HFC-134a, R407B, and R410A are used as working fluids. The conditions on which the model is tested are as follows : condensing temperature; 40.0, 45.0, 50.0, $55.0^{\circ}C$, degree of subcooling;0.0, 2.5, $5.0^{\circ}C$, capillary tube exit condition;choked flow, capillary tube diameter;1.2~2.4mm, mass flow rate;5.0~50.0g/sec. The results justify the use of Stoecker's model which yields the results very close to the values in ASHRAE handbook. While McAdams' method yields much better results than Duckler's in calculating the viscosity of the fluid in 2-phase, the friction factor suggested by Stoecker seems to be the best for capillary tubes of large diameter used in residential air conditioners. For each refrigerant, 372 data with various variables are calculated by the model. The results show that capillary tube length varies very uniformly with changes in condensing temperature and degree of subcooling. Based on this fact, regression analysis is performed to determine the dependence of mass flow rate on the length and diameter of a capillary tube, condensing temperature, and degree of subcooling. Thus determined correlation yields a mean deviation of 2.36% for 1,488 data, showing an excellent agreement.
정동수(D. S. Jung),이용범(Y. B. Lee),김홍욱(H. W. Kim),이종직(J. J. Lee) 유공압건설기계학회 2022 유공압건설기계학회 학술대회논문집 Vol.2022 No.12
The electronically controlled main pump applied to the excavator is an important part that supplies hydraulic power to the excavator, and high reliability is required to enhance the reliability of mechanical equipment. Reliability is proven through test evaluation on test equipment reflecting the working environment because it maintains the performance and function of the product without failure occurring at the work site during the warranty life required by the mechanical equipment. Reliability evaluation consists of test items that affect performance degradation and loss of function, and is largely classifies into performance tests, life tests, and environment tests.