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Showing 1 to 13 of 13 for “"R245fa"”.
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Design and performance characterization of high power density air-cooled compact condenser heat exchangers
… liquid flow of dielectric refrigerant R245fa at 80 °C and high-speed flow of air at ~25 °C to demonstrate a power density performance of nearly 70 W/cm3. The heat exchangers are operated using two-phase condensation of R245fa at 80 °C and high-speed flow of air at ~25 °C to achieve …
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A study of organic Rankine cycle systems with the expansion process performed by twin screw machines
… was estimated as approximately 6% using R245fa. This and the power output are highly dependent on the ambient air temperature when using air-cooled condensers. Allowing for a small degree of subcooling at the condenser exit, it is shown that the heat recovery should be maximised.
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Periodic reverse flow in microchannel evaporators
… presented. Four refrigerants (R134a, R1234yf, R245fa and R32) are tested in the same system. Heat flux and superheat are maintained the same. It has been found experimentally that R245fa which has similar heat of vaporization with R134a but much larger specific volume difference between vapor …
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Modeling and design of a power boosted turbo-compression cooling system
… five working fluids (R134a, R1234ze(E), R1234yf, R245fa, R515a) were evaluated over the range of case study conditions using a fixed heat exchanger effectiveness thermodynamic model. The hybrid thermally and electricity driven "power boosted" TCCS reduced electricity consumption for cooling by …
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The coupled effect of surface roughness and nanoparticle size on the heat transfer enhancement of nanofluids for pool boiling
… based nanofluids. However, at SPIP: 16, R245FA based nanofluid achieves higher heat flux than water based nanofluid at higher wall superheat temperatures.
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A new experimental approach of characterizing two-phase flow and heat transfer in plate heat exchangers
… under adiabatic and diabatic conditions by using R245fa as the working fluid. The effects of mass flux, heat flux, vapor quality, inlet flow regime and gravity are separately investigated. The tested mass flux ranges from 5 to 50 kg m^{-2}s^{-1} and heat flux ranges from 2 to 21 kW m^{-2}, with …
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Contribution to the Characterization of Piston Expanders for Their Use in Small-scale Power Production Systems
… expander integrated into an ORC using R245fa is also investigated in a wide range of operating conditions. Performance maps in terms of pressure ratio and rotational speed are given. Maximal reached isentropic efficiency is 54% at 2500 RPM for a pressure ratio of 10.5. Experimental …
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Numerical investigation into the effects of multiple bubbles in microchannel flow boiling
… bubbles during flow boiling of refrigerant R245fa. The two-dimensional numerical domain had a length of 36 mm, consisting of three sections, and a height of 0.5 mm. The first section was adiabatic to allow the patched bubbles to develop in shape before phase change was present. The middle …
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Evaporation from nanoporous membranes for high heat flux thermal management
… chamber for comparison to the model using R245fa, methanol, pentane, water and isopropyl alcohol as working fluids. A comparison of the results with different working fluids demonstrates that transport at the liquid-vapor interface is the dominant thermal resistance in the system, …
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Charge-sensitive methods for the off-design performance characterization of organic Rankine cycle (ORC) power systems
… system). In a first step, a miscibility model of R245fa/POE oil is developed to account for the presence of the lubricant in the ORC operation. Afterwards, the modelling of each system component is conducted, with a particular focus on the heat exchangers and their charge estimation. Then a global …
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Refrigerant flow distribution in vertical headers of reversible microchannel heat exchangers
… For pure refrigerants, the churn flow region of R245fa is larger than that of R134a, R410A, and R32, mainly due to its low vapor density and high liquid-to-vapor density ratio. For refrigerant-oil mixture, the distribution is better at high oil circulation rate (OCR) because enough amount of oil …
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Experimental study and modeling of liquid-vapor flow in the second header of microchannel condensers with separation circuitry
… at same condensing temperature is: R32 > R134a > R245fa. 3-D CFD simulation is also conducted for the separation phenomenon. Results are validated against the experimental data. It is found from the CFD results that vortices exist between each two adjacent MC tube intrusions, making the other half …
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Instability of flow boiling in parallel microchannels
… channel sizes 2 mm and 1 mm using refrigerant R245fa at T_sat=24.5oC. The theoretical model consistently predicted the trends in the data very well, and it predicted pressure drop within 19.3% for the 2 mm tube and within 32.5% for the 1 mm tube. Furthermore, the effect of fluid properties, …