Flow Boiling of R134a and R245fa in a 1.1 mm Diameter Tube

Emily A. Pike-Wilson, Mohamed M. Mahmoud, Tassos G. Karayiannis

Research output: Chapter in Book/Conference proceeding with ISSN or ISBNConference contribution with ISSN or ISBN

Abstract

New refrigerants are required for cooling systems due to the fact that refrigerants like R134a are about to be phased out. This paper presents a comparison between the flow boiling heat transfer and pressure drop results of refrigerants R245fa and R134a. The experiments with R245fa were conducted in a vertical cold drawn stainless steel tube with an inner diameter of 1.1 mm and heated length of 150 mm. Experimental conditions include: mass flux range 100–400 kg/m2s, heat flux range 10–60 kW/m2, pressures of 8 and 10 bar and 1.9 and 2.5 bar for R134a and R245fa corresponding to saturated temperatures 31 °C and 39 °C and exit vapour quality range 0–0.95. The data for R134a were obtained earlier using the same experimental facility at the same experimental conditions and with the same test tube. The results demonstrated that refrigerant properties have a significant effect on heat transfer and pressure drop. The pressure drop of R245fa is higher by up to 300% compared to that of R134a at similar conditions. In addition, the effect of mass flux and heat flux on the local flow boiling heat transfer coefficient was different. Heat transfer coefficients of R245fa showed a greater dependence on vapour quality. The agreement with past heat transfer correlations is better with R134a than with R245fa.
Original languageEnglish
Title of host publicationASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels
PublisherASME
ISBN (Print)9780791855591
DOIs
Publication statusPublished - 2013

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Refrigerants
Boiling liquids
Pressure drop
Heat transfer
Heat transfer coefficients
Heat flux
Mass transfer
Vapors
Cooling systems
Stainless steel
Experiments
Temperature

Cite this

Pike-Wilson, E. A., Mahmoud, M. M., & Karayiannis, T. G. (2013). Flow Boiling of R134a and R245fa in a 1.1 mm Diameter Tube. In ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels [ICNMM2013-73090] ASME. https://doi.org/10.1115/ICNMM2013-73090
Pike-Wilson, Emily A. ; Mahmoud, Mohamed M. ; Karayiannis, Tassos G. / Flow Boiling of R134a and R245fa in a 1.1 mm Diameter Tube. ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels. ASME, 2013.
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Pike-Wilson, EA, Mahmoud, MM & Karayiannis, TG 2013, Flow Boiling of R134a and R245fa in a 1.1 mm Diameter Tube. in ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels., ICNMM2013-73090, ASME. https://doi.org/10.1115/ICNMM2013-73090

Flow Boiling of R134a and R245fa in a 1.1 mm Diameter Tube. / Pike-Wilson, Emily A.; Mahmoud, Mohamed M.; Karayiannis, Tassos G.

ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels. ASME, 2013. ICNMM2013-73090.

Research output: Chapter in Book/Conference proceeding with ISSN or ISBNConference contribution with ISSN or ISBN

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N2 - New refrigerants are required for cooling systems due to the fact that refrigerants like R134a are about to be phased out. This paper presents a comparison between the flow boiling heat transfer and pressure drop results of refrigerants R245fa and R134a. The experiments with R245fa were conducted in a vertical cold drawn stainless steel tube with an inner diameter of 1.1 mm and heated length of 150 mm. Experimental conditions include: mass flux range 100–400 kg/m2s, heat flux range 10–60 kW/m2, pressures of 8 and 10 bar and 1.9 and 2.5 bar for R134a and R245fa corresponding to saturated temperatures 31 °C and 39 °C and exit vapour quality range 0–0.95. The data for R134a were obtained earlier using the same experimental facility at the same experimental conditions and with the same test tube. The results demonstrated that refrigerant properties have a significant effect on heat transfer and pressure drop. The pressure drop of R245fa is higher by up to 300% compared to that of R134a at similar conditions. In addition, the effect of mass flux and heat flux on the local flow boiling heat transfer coefficient was different. Heat transfer coefficients of R245fa showed a greater dependence on vapour quality. The agreement with past heat transfer correlations is better with R134a than with R245fa.

AB - New refrigerants are required for cooling systems due to the fact that refrigerants like R134a are about to be phased out. This paper presents a comparison between the flow boiling heat transfer and pressure drop results of refrigerants R245fa and R134a. The experiments with R245fa were conducted in a vertical cold drawn stainless steel tube with an inner diameter of 1.1 mm and heated length of 150 mm. Experimental conditions include: mass flux range 100–400 kg/m2s, heat flux range 10–60 kW/m2, pressures of 8 and 10 bar and 1.9 and 2.5 bar for R134a and R245fa corresponding to saturated temperatures 31 °C and 39 °C and exit vapour quality range 0–0.95. The data for R134a were obtained earlier using the same experimental facility at the same experimental conditions and with the same test tube. The results demonstrated that refrigerant properties have a significant effect on heat transfer and pressure drop. The pressure drop of R245fa is higher by up to 300% compared to that of R134a at similar conditions. In addition, the effect of mass flux and heat flux on the local flow boiling heat transfer coefficient was different. Heat transfer coefficients of R245fa showed a greater dependence on vapour quality. The agreement with past heat transfer correlations is better with R134a than with R245fa.

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DO - 10.1115/ICNMM2013-73090

M3 - Conference contribution with ISSN or ISBN

SN - 9780791855591

BT - ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels

PB - ASME

ER -

Pike-Wilson EA, Mahmoud MM, Karayiannis TG. Flow Boiling of R134a and R245fa in a 1.1 mm Diameter Tube. In ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels. ASME. 2013. ICNMM2013-73090 https://doi.org/10.1115/ICNMM2013-73090