• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.8
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• pp.710-719
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• 2001

Pool boiling heat transfer coefficients (HTCs) of HCFC123, HFC134a, HCFC22, HFC407C, HFC410A and HFC32 wre measured on a horizontal smooth tube, 26 fpi low fin tube, Turbo-B and Thermoexcel-E enhanced tubes. AN experimental apparatus was designed such that all tubes heated by cartridge heaters could be installed at the same time to save the refrigerant. Data were taken in the pool of $7^{\circ}C$ with the heat flux decreasing from 80 kW/$m^2\;to\;5kW/m^2$. Test results showed that HTCs of pure refrigerants and those of a azeotrope were greatly influenced by reduced pressure. HTCs of HFC407C were 21~25% lower than those of HCFC22 due to mass transfer resistance. For all refrigerants, enhanced tubes with sub-surface and sub-tunnels showed the largest heat transfer enhancement. Especially the largest heat enhancement was obtained for HCFC123 whose reduced pressure is the lowest among al the refrigerants tested. This indicates that either Turbo-B or Thermoexcel-E enhanced tube would be the best choice when used with a low vapor pressure refrigerant.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.776-781
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• 2001

To enhance thermal efficiency of thermal facility through recovery of low and medium temperature waste heat, 1MW organic Rankine cycle system was designed and developed. The exhaust gases of $175^{\circ}C$ at two 100MW power plants in pohang steel works were selected as the representative of low and medium temperature waste heat in industrial process for the heat source of the organic Rankine cycle system. HCFC-123, a kind of harmless refrigerant, was chosen as the working fluid for Rankine cycle. The organic Rankine cycle system with selected exhaust gases and working fluid was designed and constructed. From the operation, it was confirmed that the organic Rankine cycle system is available for low and medium temperature waste heat recovery in industrial process. The optimum operating manuals, such as heat-up of hot water, turbine start-up, and the process of electric power generation, were derived. However, electric power generated was not 1MW as designed but only 670kW. It is due to deficiency of pump capacity for supply of HCFC-123. So it is necessary to increase the pump capacity or to decrease the pressure loss in pipe for more improved HCFC-123 supply.

• 월간산업보건
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• s.357
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• pp.23-34
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• 2018

• International Journal of Air-Conditioning and Refrigeration
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• v.9 no.3
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• pp.1-9
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• 2001

In this study, condensation heat transfer coefficients (HTCs) of nonazeotropic refrigerant mixtures of HFC32/HFC 134a and HCFC123 at various compositions were measured on a horizontal smooth tube. All data were taken at the vapor temperature of 39$^{\circ}C$ with a wall subcooling of 3~8K. Test results showed that HTCs of tested mixtures were 11.0~85.0% lowed than the ideal values calculated by the mass fraction weighting of the HTCs of the pure components. Thermal resistance due to the diffusion vapor film was partly responsible for the significant reduction of HTCs with these nonazeotropic mixtures. The measured data were compared against thc predicted ones by Colburn and Drew's film model and a good agreement was observed within a deviation of 15%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.12
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• pp.1049-1056
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• 2000

In this study, condensation heat transfer coefficients(HTCs) of 2 nonazeotropic refrigerant mixtures of HFC32/HFC134a and HFC134a/HCFC123 at various compositions were measured on a horizontal smooth tube. All data were taken at the vapor temperature of 39$^{\circ}C$ with a wall subcooling of 3~8K. Test results showed that HTCs of tested mixtures were 11.0~85.0% lower than the ideal values calculated by the mass fraction weighting of the pure components HTCs. Thermal resistance due to the diffusion vapor film was partly responsible for the significant reduction of HTCs with these nonazeotropic mixtures. The measured data were compared against the predicted ones by Colburn and Drew\`s film model and a good agreement was observed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.5
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• pp.569-580
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• 1998

In this study, condensation heat transfer coefficients(HTCs) of a plain tube, low fin tube, and Turbo-C enhanced tube for CFC-11, HCFC-123, CFC-12, HFC-l34a are measured and compared against each other. All data are taken at the vapor temperature of 39$^{\circ}C$ with a wall subcooling temperature 3~8$^{\circ}C$. Test results show that HTCs of a low vapor pressure refrigerant, HFC-123, for a plain, low fin, and Turbo-C tubes are 10.5~20.5%, 8.2~12.2%, 16.5~19.2% lower than those of CFC-11, respectively. On the other hand, HTCs of a medium vapor refrigerant, HFC-l34a, for a plain, low fin, and Turbo-C tubes are 20.6~31.8%, 0.0~8.0%, 13.2~20.9% higher than those of CFC-12, respectively. For all refrigerants tested, HTCs of Turbo-C tube are the highest among the three tubes showing almost 8 times increase in HTCs as compared to those of a plain tube. Nusselt's prediction equation for a plain tube yielded 12% deviation for all plain tube data while Realty and Katz's prediction equation for a low fin tube yielded 20% deviation for all low tube data.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.28 no.5
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• pp.368-374
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• 1999

최근 세계적으로 환경보호에 대한 관심이 고조됨에 따라 기술개발 방향이 환경을 고려한 규정 및 장치에 제한을 받고 있다. 따라서 냉동 공조 기기에 사용되는 기존의 CFC계열 냉매가 오존층 파괴의 주 원임이 판명됨에 따라 환경 문제가 없는 HCFC계열인 R123와 HFC R134a로의 대체가 불가피하게 되었다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.10
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• pp.941-949
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• 2000

Pool boiling heat transfer coefficients (HTCs) of HCFC123, CFC11, HCFC142b, HFC134a, CFC12, HFC22, HFC125 and HFC32 on a horizontal smooth tube have been measured. The experimental apparatus is specially designed to simulate the real heat transfer tube with the use of the secondary fluid of water as a heat source rather than a conventional electric heat source. Data were taken in the order of decreasing heat flux starting at $80 ㎾/m^2\; and \;ending\; at\; 5㎾/m^2\;in\; the\; poo\;l temperature\; at\; 7^{\circ}C$, Test results showed that HTCs of HFC125, and HFC32 are 50~67% higher than those of HCFC22. It is also found that some of the popular pool boiling heat transfer correlations in the literature are not good to predict the HTCs of newly developed alternative refrigerants. A new correlation was developed by a regression analysis which is based upon the consistent data obtained in this study and it showed an excellent agreement with all experimental data having an absolute mean deviation of less than 10%.

• Journal of Korean Society of Disaster and Security
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• v.10 no.2
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• pp.35-41
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• 2017

Recently chemical intoxication related with the use of chemical extinguishing agents occurs frequently. With the industrialization, high-rising of building and increase of fire risk, we use the various extinguishing agents and the safe use become important. In this study I carried out the risk assessment of representative chemical extinguishing agents (HCFC-123, HFC-125) using the CHARM and got the meaningful qualitative outcome. This study is significant in that the risk assessment of chemicals was conducted using CHARM, chemical risk assessment tool. It is expected that the results will be utilized as the basic data for the national chemical safety management.

• Journal of the Korean Chemical Society
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• v.38 no.9
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• pp.695-700
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• 1994

Hydrogenolysis reactions of CFC-113a catalyzed by various heterogeneous catalysts $(Rh/Al_2O_3,\;Pd/C,\;Ni,\;Al_2O_3,\;Active\;carbon)$ were investigated in the liquid and gas phases. In the liquid phase reaction, different catalysts showed different activities, but all catalysts used gave high selectivities toward HCFC-123 over 95%. It was noticeable that the neutral $Al_2O_3$ showed both a high activity and a selectivity in the liquid phase reaction. In the gas phase reaction, transition metals on carbon(Pd/C, Pt/C) were so active for hydrogenolysis of CFC-113a that they even catalyzed the production reaction of overhydrogenated compounds such as $HCFC-133a(CF_3CH_2Cl)\;and\;HFC-143a(CF_3CH_3)$. $Al_2O_3$, which showed the high activity in the liquid phase reaction, did not show a remarkable activity. When $Al_2O_3$ was used in the liquid phase reaction, the hydrogenolysis of CFC-113a proceeded without any side products in THF. However, the same reaction in MeOH produced side products, such as $CH_3OCH_3\;and\;CH_3CH_2OCH_3$ from solvent. Based on this result, including heterogeneous catalysts, it was concluded that the solvent played an important role in the liquid phase reaction.