• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.2
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• pp.87-96
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• 2008

Flow condensation heat transfer coefficients(HTCs) of R123 and R245fa are measured in a horizontal plain tube. The main test section in the experimental flow loop is made of a plain copper tube of 9.52 mm outside diameter and 530 mm length. The refrigerant is cooled by passing cold water through an annulus surrounding the test section. Tests are performed at a fixed saturation temperature of $50\;{\pm}\;0.2\;^{\circ}C$ with mass fluxes of 50, 100, $150\;kg/m^2s$ and heat flux of $7.3{\sim}7.7\;kW/m^2$. Heat transfer data are obtained in the vapor quality range of $10{\sim}90%$. Test results show that the flow condensation HTCs of R245fa are overall 7.9% higher than those of R123 at all mass fluxes. The pressure drop of R245fa is smaller than that of R123 at the same heat flux. In conclusion, R245fa is a good candidate to replace ozone depleting R123 currently used in chillers from the view point heat transfer and environmental properties.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.293-299
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• 2012

The thermodynamic efficiency characteristics of R245fa and water as working fluids have been analyzed for the electricity generation system applying the Rankine cycle to recover the waste heat of the exhaust gas from a diesel engine for the propulsion of a large ship. The theoretical calculation results showed that the cycle, system, and total efficiencies were improved as the turbine inlet pressure was increased for R245fa at a fixed mass flow rate. In addition, the net work rate generated by the Rankine cycle was elevated with increasing turbine inlet pressure. In the case of water, however, the maximum system efficiencies were demonstrated at relatively small ratios of mass flow rate and turbine inlet pressure, respectively, compared to those of R245fa. The optimized values of the net power of the cycle, system efficiency, and total efficiency for water had relatively large values compared to those of R245fa.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.8
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• pp.555-562
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• 2007

In this study, condensation heat transfer coefficients (HTCs) of R22, R134a, R245fa and R123 are measured on a horizontal plain tube. All data are taken at the vapor temperature of $39^{\circ}C$ with a wall subcooling temperature $3-8^{\circ}C$. Test results show the HTCs of newly developed alternative low vapor pressure refrigerant, R245fa, on a plain tube are 9.5% higher than those of R123 while they are 3.3% and 5.6% lower than those of R134a and R22 respectively. Nusselt's prediction equation for a plain tube underpredicts the data by 13.7% for all refrigerants while a modified equation yielded 5.9% deviation against all data. From the view point of environmental safety and condensation heat transfer, R245fa is a long term good candidate to replace R123 used in centrifugal chillers.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.6
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• pp.593-600
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• 2012

The exergy characteristics for R245fa and water working fluids have been analyzed for an electric generation system utilizing the Rankine cycle to recover heat from the wasted exhaust gas from a diesel engine used for the propulsion of a large ship. The theoretical calculation results showed that the efficiencies of exergy and system exergy improved as the turbine inlet pressure increased for R245fa at a fixed mass flow rate. Furthermore, the exergy destruction rates of the condenser and evaporator were relatively larger than those in other components. The exergy efficiency of the system increased with increasing mass flow rate. For a water working fluid, although the exergy destruction rate of the evaporator was similar to that for R245fa, the exergy loss rate varied significantly in response to variations in the pressure and mass flow rates at the turbine inlet.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.3
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• pp.167-175
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• 2009

In this study, condensation heat transfer coefficients(HTCs) of R22, R123, R134a and R245fa are measured on both 26fpi low fin and Turbo-C tubes. All data are taken at the vapor temperature of $39^{\circ}C$ with a wall subcooling of $3{\sim}8^{\circ}C$. Test results show that HTCs of the newly developed low vapor pressure alternative refrigerant, R245fa, are $7.8{\sim}9.2%$ and $10.3{\sim}18.6%$ higher than those of R123 for 26fpi low fin tube and Turbo-C tube respectively. For all refrigerants tested, HTCs of Turbo-C enhanced tube are higher than those of 26fpi low fin tube. For the low fin tube, Beatty and Katz's prediction equation yielded 20% deviation for all fluids. The heat transfer enhancement ratio of R245fa on the Turbo-C tube is $5.9{\sim}6.4$ while that of R123 is $5.7{\sim}5.9$. From the view point of environmental safety and condensation heat transfer, R245fa is a long term candidate to replace R123 currently used in centrifugal chillers.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.12 no.3
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• pp.17-23
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• 2016

A test unit for Organic Rankine Cycle (ORC) power generation system was developed and experimentally reviewed the performance of the ORC system. Two different organic fluids (R-245fa & Novec 649) were tested as working fluids for the system. System behavior was measured and analyzed along with the variables, such as temperature, pressure, rpm and shaft power. It is one of the findings that Novec 649 fluid is to be less pressurized than R-245fa in order to up to the heat source (boiler) capacity, that limits the experiment as high as 2 kW in shaft power.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.3
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• pp.208-215
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• 2011

In this work, pool boiling heat transfer coefficients(HTCs) of R22, R123, R134a, and R245fa are measured on both horizontal plain and 26 fpi low fin tubes. The pool boiling temperature is maintained at $7^{\circ}C$ and heat flux is varied from 80 $kW/m^2$ to 10 $kW/m^2$ with an interval of 10 $kW/m^2$. Wall temperatures are measured directly by thermocouples inserted through holes of 0.5 mm diameter. Test results show that HTCs of high vapor pressure refrigerants are usually higher than those of low pressure fluids in both plain and low fin tubes. On a plain tube, HTCs of R245fa are 23.3% higher than those of R123 while on a 26 fpi low fin tube, HTCs of R245fa are 46.3% higher than those of R123. The fin effect is more prominent with low vapor pressure refrigerants than with high vapor pressure ones due to a sweeping effect.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.7
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• pp.413-417
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• 2013

The organic Rankine Cycle (ORC) uses a kind of refrigerant as a working fluid that evaporates at relatively low temperature, as the Rankine Cycle uses superheated steam as the working fluid. A small scale ORC test bench was installed, and two different working fluids (R245fa and R134a) were injected into the test bench. The test bench was in operation with the two different working fluids under the same conditions. The effects against the system performance from the different working fluids were analysed, and root causes were identified. Other factors reflecting the power generation efficiency were also found. A conclusion was drawn, that R245fa makes the system perform better, than R134a.

• Proceedings of the SAREK Conference
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• 2007.06a
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• pp.116-116
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• 2007

• Journal of Power System Engineering
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• v.20 no.2
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• pp.73-78
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• 2016

In this study, the performance characteristics of a high temperature heat pump dryer that is able to raise the air temperature up to $80^{\circ}C$ by using waste heat as heat source were investigated numerically. The main components of the heat pump dryer were modeling as a compressor, condenser, evaporator and expansion device, and R245fa was selected as refrigerant. Experiments were also conducted to validate the numerical data. As a result, when the evaporator air inlet temperature increased from $50^{\circ}C$ to $65^{\circ}C$, the numerical results of the hot air temperature at outlet and heat pump COP were about 8~11% and 5~8% higher than that of experimental ones, respectively.