• 설비공학논문집
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• 제20권9호
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• pp.590-598
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• 2008

In this study, performance of R170/R290 mixtures is measured on a heat pump bench tester in an attempt to substitute R22. The bench tester is equipped with a commercial hermetic rotary compressor providing a nominal capacity of 3.5kW. All tests are conducted under the summer cooling and winter heating conditions of $7/45^{\circ}C$ and $-7/41^{\circ}C$ in the evaporator and condenser respectively. During the tests, the composition of R170 is varied from 0 to 10% with an interval of 2%. Test results show that the coefficient of performance (COP) and capacity of R290 are up to 15.4% higher and 7.5% lower than those of R22 for both conditions respectively. For R170/R290 mixture, the COP decreases and the capacity increases with an increase in the amount of R170. The mixture of 4%R170/96%R290 shows the similar capacity and COP as those of R22. For the mixture, the compressor discharge temperature is $16{\sim}30^{\circ}C$ lower than that of R22. There is no problem with mineral oil since the mixture is mainly composed of hydrocarbons. The amount of charge is reduced up to 58% as compared to R22. Overall, R170/R290 mixture is a good long term 'drop-in' candidate to replace R22 in residential air-conditioners and heat pumps.

• 설비공학논문집
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• 제12권3호
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• pp.315-324
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• 2000

R-410A, R-407C, and four refrigerant mixtures composed of R-32, R-l34a, R-l43a, R-l52a, R-600(butane), and R-600a(isobutane) were tested in an attempt to replace R-22 used in most of the residential air conditioners. The performance evaluation was carried out in a psychrometric calorimeter test facility using a residential spilt type air conditioner under the KS rating conditions. Except for the lubricant and hand-operated expansion valve, the other parts of the air conditioner were the same with the commercial system. Performance characteristics were measured; COP, capacity, compressor power, and VCR. R-410A was shown to have 5.5% higher COP and 3.5% lower capacity than R-22. R-32/134a/600a (42.8/ 46.0/11.2 wt%) mixture have the best performance among the four refrigerant mixtures composed of hydrofluorocarbon and hydrocarbon. This inixture have 3.0% lower COP and 1.6% lower capacity than R-22.

• 설비공학논문집
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• 제13권4호
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• pp.242-251
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• 2001

Flow boiling heat transfer coefficients (HTCs) of R22, R134a, R407C, and R410A were measured for a horizontal plain tube. The test section was made of a copper tube of 8.8mm inner diameter and 1000mm length respectively. The refrigerant was heated by passing hot water through an annulus surrounding the test section. All tests were performed at a fixed refrigerant saturation temperature of $5^{\circ}C$ with mass fluxes of 100~300 kg/$m^2$,/TEX>s. HTCs were measured by two methods: the direct wall temperature measurement method and the indirect Wilson plot method. Experimental results showed that the Wilson plot method was affected greatly by the external test conditions and yielded inconsistent results. For the mass flux of 100kg/$m^2$,/TEX>s, HTCs were almost constant regardless of the quality for a given refrigerant HTCs of R134a and R407C were similar to those of R22 while those of R410A were 60% higher than those of R22. For the mass fluxes of 200 and 300kg/$m^2$,/TEX>s, HTCs of R407C were almost the same as those of R22, while HTCs of R134a and R410A were 12-13% and 20~23% higher than those of R22 respectively. For pure refrigerant, Shah\`s correlation yielded a good agreement with the measured data both qualitatively and quantitatively.

• 대한기계학회논문집
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• 제17권9호
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• pp.2131-2137
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• 1993

This study, examines the performance and the heat pump cycle systematizing characteristics for non-azeotropic refrigerant systems. In order to conduct such an examination, the cycle characteristics of heat pumps for pure R-22, R-114, and their mixtures were experimentally investigated. The results show that cooling/heating capacities for the mixtures was more suited at the evaporating temperature of $5^{\circ}C$ than that of $0^{\circ}C$, $-5^{\circ}C$, and $-10^{\circ}C$. The C.O.P of the 50 wt% mixtures was considerably higher than for pure R-22, and the compression power of the 25 wt% was as much as 60% lower than that of pure R-22. Even small fractional mixture variations can lead to significant changes in the characteristics of the heat pump cycle. This experiment verified the importance of accurate weight fractions of refrigerant mixtures.

• Bulletin of the Korean Chemical Society
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• 제22권2호
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• pp.237-240
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• 2001

• 설비공학논문집
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• 제11권4호
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• pp.537-541
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• 1999

The system performance of a room air conditioner using R410A was experimentally evaluated and compared with that of R22 system. The results indicated that the cooling EER(energy efficiency ratio) of R410A was 1% higher than that of R22 at the outdoor temperature of $35^{\circ}C$. As outdoor temperature increases above $35^{\circ}C$ ambient, EER of the R410A system decreased more substantially compared with R22 system. R410A showed higher compressor discharge temperature than that of R22 system at the outdoor temperature of higher than $50^{\circ}C$.

• 동력기계공학회지
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• 제18권5호
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• pp.55-59
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• 2014

This study performed experimental research to visualize the moisture content absorbed in R-22, refrigerant of refrigerator. Sulfuric acids were mixed with bromothylmol blue solution to make indicating solutions, and humidity papers were prepared by impregnation of the indicating solutions into solid supporters. Prior to the impregnation, small amount of lithium chloride was added into indicating solution. Moisture measuring cell was composed to test sensitivity of the humidity papers. Color changing characteristics of the humidity papers were also examined at various moisture contents in R-22. Color of the humidity paper varied linearly with the moisture content in R-22 in the range from 150 ppm to 300 ppm. The humidity papers showed complete color change to yellow at the moisture content of 300 ppm within 8 hours.

• 설비공학논문집
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• 제7권2호
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• pp.225-233
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• 1995

Experiments were performed to investigate the heat transfer characteristics of nonazeotropic mixture R-22+R-114 in a heat pump system. The ranges of parameter, such as heat flux, mass flow rate, and quality were $8,141{\sim}32,564W/m^2$, 24~58kg/h, and 0~1, respectively. The overall compositions of the mixtures were 50 and 100 per-cent of R-22 by weight for R-22+R-114 mixture. The results indicated that there were distinct different heat transfer phenomena between the pure substance and the mixture. In case of pure refrigerant the heat transfer rates for cooling were strongly dependent upon quality of the refrigerant. Overall evaporating heat transfer coefficients for the mixture were somewhat lower than pure R-22 values in the forced convective boiling region. For a given flow rate, the heat transfer coefficient at the circumferential tube wall(top, side, and bottom of the test tube) for R-22/R-114(50/50wt%)mixture, however, was higher than for pure R-22 at side and bottom of the tube. Furthermore, a prediction for the evaporating heat transfer coefficient of the mixtures was developed based on the method of Yoshida et.al.'s. The resulting correlation yielded a good agreement with the data for the refrigerant mixtures.

• 대한기계학회논문집B
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• 제25권6호
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• pp.860-867
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• 2001

In this study, condensation heat transfer experiments were conducted with plate and shell heat exchangers(P&SHE) using R-22. An experimental refrigerant loop has been established to measure the condensation heat transfer coefficient of R-22 in a vertical P&SHE. Two vertical counter flow channels were formed in the P&SHE by three plates of geometry with a corrugated trapezoid shape of a chevron angle of 45°. Downflow of the condensing R-22 in one channel releases heat to the cold upflow of water in the other channel. The effect of the refrigerant mass flux, average heat flux, system pressure and vapor quality of R-22 on the measured data were explored in detail. The results indicate that at a higher vapor quality the condensation heat transfer coefficients are significantly higher. A rise in the refrigerant mass flux causes an increase in the h(sub)r. Also, a rise in the average heat flux causes an increase in the h(sub)r. Finally, at a higher system pressure the h(sub)r is found to be slightly lower. Correlation is also provided for the measured heat transfer coefficients in terms of the Nusselt number.

• 설비공학논문집
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• 제18권3호
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• pp.218-224
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• 2006

The performance of an air to water vapor compression heat pump has been investigated experimentally. The main purpose of this study was to study the possibilities of using hydrocarbon refrigerants as a working fluid to replace R-22 for vapor compression heat pumps. Pure R-22 and R-290, R-600a, R-1270 were considered as working fluids. The performance of the system was characterized by compression shaft work, refrigeration capacity, pressure ratio, discharge temperature and COP. The experimental apparatus has basic parts of cycle that uses the air as a heat source. The experimental results show that refrigeration capacity of HC refrigerants is same or higher than that of R-22. On the other hand, compression shaft work of HC refrigerants is lower than that of R-22. Compression shaft work is lower than that of R-22. Come to the conclusion that, it is possible that hydrocarbon refrigerants could be drop-in alternatives for R-22.