조도를 고려한 R-22용 모세관 선정 선도

김창년,황의필,박영무,Kim, C.N.,Hwang, U.P.,Park, Y.M. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.4

A new set of capillary tube selection charts for R-22 is proposed. The set of charts takes into account of the roughness effect on the mass flow rate. For this purpose, a set of numerical model is developed and a series of experiments is conducted to verify the numerical model. A numerical model is used to calculated the mass flow rate for several sets of tube diameter, length, inlet pressures and degree of subcooling. The outlet of the tube is controlled to be at critical condition. The experimental flow rate is compared with calculated values. The calculated values are consistently less than the experimental ones except for the flow rate range below 40kg/hr. The deviation is within 10---. Based on the nunmerical model and results of experiments, the set of capillary tube selection charts for R-22 is constructed. The set of charts consists of standard capillary tube chart(L=2030mm, d=1.63mm, ${\varepsilon}=2.5{\mu}m$), non -standard flow factor(${\phi}_1$) chart, and non-standard roughness factor(${\phi}_2$) chart. The mass flow rate, flow factor, and the roughness factor are defined respectively as; $\dot{m}={\phi}_1{\phi}_2\dot{m}_{standard}\\{\phi}_1=\frac{\dot{m}(L,\;d,\;\varepsilon_{standard})}{\dot{m}_{standard}(L_{standard},\;d_{standard},\;{\varepsilon}_{standard})}\\{\phi}_2=\frac{\dot{m}(L_{standard},\;d_{standard},\;{\varepsilon})}{\dot{m}_{standard}(L_{standard},\;d_{standard},\;{\varepsilon}_{standard})}$.

HFC32/134a 계의 기-액상평형에 관한 연구

김창년,박영무,이병권,안병성,Kim, C.N.,Park, Y.M.,Lee, B.K.,An, B.S. 대한설비공학회 1997 설비공학 논문집 Vol.9 No.4

Vapor-liquid equilibrium apparatus is designed and set up. The vapor-liquid equilibrium data of the binary system HFC32/134a are measured in the range between 258.15 and 283.15K at compositions of 0.2, 0.4, 0.6 and 0.8 mole fraction of HFC32. Twenty-two equilibrium data are obtained. Based upon the present data, the binary interaction parameter for Carnahan-Starling-De Santis equation of state is calculated. Temperature range of data is extended to 313.04K using the data in the open literatures. Interaction parameters are determined at nine isotherms.

HFC-32/143a와 HFC-143a/134a계의 기-액상평형 실험에 관한 연구

김창년,박영무,Kim, C.N.,Park, Y.M. 대한설비공학회 1999 설비공학 논문집 Vol.11 No.1

Vapor-liquid equilibrium apparatus is designed and set up. The equilibrium data of two binary systems, HFC-32/143a and HFC-143a/134a, are measured. Fifteen equilibrium data for HFC-32/143a and HFC-143a/134a systems are measured over the temperature range 263.15~283.15K at 10K interval and the composition range 0.10~0.80, respectively. And vapor-liquid equilibrium data are calculated using equation of state and correlation of activity coefficient and compared with the present data. Equation of state is used CSD and RKS equations and correlation of activity coefficient is used Margules' and Van Ness and Abbott's correlations. Real behavior of HFC-32/143a system has very large deviation with Raoult's rule which is ideal behavior. But real behavior of HFC-143a/134a system is similar to ideal behavior. The calculated data from CSD equation are compared with the data in the open literatures and the calculated data from REFPROP. In the results for REFPROP, the relative deviations of bubble point pressure for HFC-32/143a system are within -2.16~0.84% for CSD equation and within -0.20~1.10% for RKS equation. And the relative deviations of bubble point pressure for HFC-143a/134a system are within -0.45~0.12% and -0.20~2.8% for CSD and RKS equations, respectively.

대체냉매 HFC-134a의 모세관 성능에 관한 수치해석적 연구

김창년,박영무,Kim, C.N.,Park, Y.M. 대한설비공학회 1993 설비공학 논문집 Vol.5 No.3

Performance charts of capillary tubes for R-134a are presented. The calculation is based on the one-dimensional, adiabatic flow through capillary tube. The length of capillary tube changes with inlet pressure, mass flux, inlet quality(or subcooling), and inside diameter. The length for R-134a is shorter by 12.5~23% than that for R-12 as mass flux varies, by 13~18.5% as inlet pressure changes, by 15~15.2% as inside diameter changes, and by 3.6~20% as subcooling(or quality) changes. In general, the length for R-134a is shorter than that for R-12 by 10~20%. Pressure drop per unit length for R-134a is greater than that for R-12 since specific volume of R-134a is larger that of R-12 and vapor pressure of R-134a is greater than that of R-12. Flash point of R-134a is ahead of that of R-12.

HFC32 / 143a와 HFC143a / 134a 계의 기-액상평형 실험

김창년(C.N. Kim),박영무(Y.M. Park) 대한설비공학회 1998 대한설비공학회 학술발표대회논문집 Vol.1998 No.6-2

조도를 고려한 모세관 성능 연구

김창년(C. N. Kim),황의필(U. P. Hwang),박영무(Y. M. Park) 대한설비공학회 1995 대한설비공학회 학술발표대회논문집 Vol.1995 No.6

밀도계를 이용한 비추출식 냉동기유농도 측정에 관한 연구

김상현,김창년,박영무,Kim, S.H.,Kim, C.N.,Park, Y.M. 대한설비공학회 1999 설비공학 논문집 Vol.11 No.1

In order to predict thermodynamic performance of refrigeration system, it is required to know the oil concentration of the refrigerant/oil mixture. The current method to measure the oil concentration is to extract the working mixture and then to measure the oil weight. However, it is Quite necessary to estimate oil concentration without any extraction of the working fluid. In this study a new method and working equation is presented as follows. It is based on the measurement of spedific gravity and temperature : $$C=a+b{\times}t+c{\times}t^2+(d+e{\times}t+f{\times}t^2){\times}SG$$ C is oil concentration, t is temperature($^{\circ}C$), SG is specific gravity of mixture and a~f is coefficients. The oil concentration ranges over 0~12 wt% and the temperature ranges over $20{\sim}50^{\circ}C$. The specific gravity and temperature are measured using the on-line densimeter and thermometer. This working equation enables to predict the oil concentration without any extraction of the mixture. This equation can be applied for R-12/Naphthenic oil and R-134a/POE oil oiquid mixtures.

대체냉매 R-407c의 모세관 선정에 관한 연구

김용환(Y. H. Kim),김창년(C. N. Kim),박영무(Y. M. Park) 대한설비공학회 1997 대한설비공학회 학술발표대회논문집 Vol.1997 No.6-1

R-22 대체용 혼합냉매의 Drop-In 열역학적 성능 계산

주종문,김창년,박영무,Ju, J.M.,Kim, C.N.,Park, Y.M. 대한설비공학회 1996 설비공학 논문집 Vol.8 No.3

Thermodynamic performance of eight zeotropic R-22 alternative refrigerant mixtures selected by AREP(R-22 Alternative Refrigerants Evaluation Program) and R-32/R-125/R-134a(23%/25%/52%), namely R-407C were evaluated by the "drop-in" simulation method. An existing air conditioner was selected and its design data were used for the simulation. "ARI Test A" air conditions were applied. The degree of vapor superheat at the compressor inlet fixed at $5^{\circ}C$ for all the mixtures. The results of the simulation were compared with those of R-22. COPs of all mixtures except for R-32/R-227ea(35%/65%) and R-32/R-125/R-134a(10%/70%/20%), were higher than that of R-22 by 2%~8%, while the capacities were all lower than that of R-22 by 13%~27%. COP of R-32/R-134a(40%/60%) was 2.4% higher but the capacity was 15% lower than those of R-22. In the case of R-32/R-134a(30%/70%), COP and capacity were 5.5% higher and 15% lower than those of R-22, respectively. Among the ternary mixtures, R-407C and R-32/R-125/R-134a(30%/10%/60%) showed the best performance. COP of R-407C was 2.4% higher than those of R-22 but the capacity was 15% lower.

R-22 대체용 혼합냉매의 열역학적 성능에 대한 실험연구

황의필,김창년,박영무,Hwang, E.P.,Kim, C.N.,Park, Y.M. 대한설비공학회 1997 설비공학 논문집 Vol.9 No.1

R-410a and R-407c witch have the best potential among the substances being considered as R-22 alternatives were tested as "drop in" refrigerants against a set R-22 baseline tests for comparison. The performance evaluations were carried out in a psychrometric calorimeter test facility using the residential split-type air conditioner under the ARI rating conditions. Other than the use of different lubricant and a hand-operated expansion valve, one of the commercial systems was selected for the experiment. Performance characteristics were measured; compressor power, capacity, VCR, mass flow rate and COP. The tests showed that R-407c can be directly applied to the existing refrigeration system because of its similar vapor pressure and other thermopysical properties with those of R-22. However, it required change to the volume flow rate of compressor in order to achieve the similar performance with R-22 because of its relatively small VCR and capacity. Meanwhile, R-410a has too high a vapor pressure to be applied to the existing system and this feature results in relatively low COP of the system compared to that of R-22. But this could be improved by changing compressor design considering R-410a's relatively high VCR and capacity compared to those of R-22.