Condensation of R-134a on horizontal integral-fin titanium tubes

Fernández-Seara, José; Uhía, Francisco J.; Diz, Rubén; Dopazo, Alberto

doi:10.1016/j.applthermaleng.2009.09.007

Cited by 22 publications

(4 citation statements)

References 15 publications

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“…This is due to the augmentation in the condensate layer on, the tube as mentioned earlier. This result agrees with previous studies for finned tubes [16,17,18,19,22]. However, a wide range of experimental data has to be provided to confirm the effect of condensing temperature on the condensation HTC.…”

Section: Effect Of Condensing Temperature On the Htcsupporting

confidence: 92%

“…At each conFigure 11a , figure 11b , figure 11c and figure 11d show a comparison between the SFT and smooth tube with R134a and R1234yf at constant condensing temperature 37 and 40°C respectively, figure 11 show the change of U with LMTD for the SFT and smooth tube at condensing temperatures 37 and 40°C respectively. These figures show densing temperature, the cooling water inlet temperature was set to be 16,18,20,22,24,26, and 28 °C. It means that the tube side thermal resistance, in terms of varying the cooling water inlet temperature, is extremely significant in the overall heat transfer process.…”

Section: Comparison Between Smooth and Finned Tubes For Condensation ...mentioning

confidence: 99%

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FILM –WISE CONDENSATION OF R1234yf AND R134a REFRIGERANTS ON FINNED TUBE WITH 32 FINS PER INCH

Khalid

Al-Badry²

2022

ejuow

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Researchers have been motivating by the global warming challenge to develop alternatives substances to compounds that contribute to this problem. The refrigerant R134a (HFC134a) has been identified as one of the most environmentally damaging gases. As a result, the refrigerant R1234yf has been employed in air conditioning systems as a substitute to the refrigerant R134a. The condensation heat transfer coefficient (HTC) of the refrigerants R1234yf and R134a was measured on smooth and standard finned tubes in this study. The finned tube is characterized by 32 Fins per inch (FPI) and 1 mm fin height. The condensation process was investigated at 37°C and 40°C condensing temperatures and 16°C to 28°C water inlet temperatures. The Nusselt theory accurately predicted the condensation HTCs on the smooth tube within mean absolute percentage deviation (MAPD) of 5.3% for R134a and 4.7% for R1234yf. As the wall sub-cooling increases, the condensation HTC decreases. With a drop in LMTD, the overall heat transfer coefficient (HTC) rises. For finned tube, the refrigerant R134a showed a greater HTC than R1234yf. In comparison to smooth tube, the enhancement ratio in HTC was 78% at 37 and 82% at 40°C for R134a. The enhancement ratio with R1234yf was 65% and 81% at 37 and 40 ° C, respectively. The experimental data was compared with predictions of two previous analytical models for film condensation on finned tubes.

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Section: Effect Of Condensing Temperature On the Htcsupporting

confidence: 92%

Section: Comparison Between Smooth and Finned Tubes For Condensation ...mentioning

confidence: 99%

FILM –WISE CONDENSATION OF R1234yf AND R134a REFRIGERANTS ON FINNED TUBE WITH 32 FINS PER INCH

Khalid

Al-Badry²

2022

ejuow

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“…Yun [50] as well found a small deviation between experimental and theoretical values in case of Honda and Nozu model [69] among all models when he performed an experimental study regarding integral-fin tubes against R134a. In additional study where titanium made integral-fin tube against R134a and ammonia were used as working fluids, it was found out that the condensate flooded fraction decreased with the increase in saturation temperature [53,54].…”

Section: Experimental Investigationsmentioning

confidence: 99%

“…Moreover, the weight of the heat exchanger reduces as well for the same heat transfer by using titanium tubes as its weight is lower by 55% and 50% than stainless steel and copper alloys respectively. Therefore, to analyze the condensation behavior of R134a and ammonia using titanium tubes initially experiments are conducted [53,54 ]over plain and integral low-fin titanium tubes. Against R134a and a fin density of 32 fpi, these enhanced fin tubes provide the enhancement factors ranging from 3 -4 for different condensing temperatures of 30˚C, 40˚C and 50˚C and there is a reduction in condensation HTC with increasing the wall sub cooling.…”

Section: Experimental Heat Transfer Measurementsmentioning

confidence: 99%

An Overview of Recent Progress in Condensation Heat Transfer Enhancement Across Horizontal Tubes and the Tube Bundle

Bano

2021

Journal of Thermal Engineering

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The present paper presents a review of condensation heat transfer across smooth and enhanced horizontal surfaces due to its significance in refrigeration, air conditioning and heat pump applications. The emphasizes is on the recent understanding of experimental as well as the semi-empirical correlations to investigate the heat transfer phenomena during condensation associated with enhanced geometries. An effort has been made to submit freeconvection condensation effects outside of single tubes and the tube bundle with the influence of tube geometries, condensate retention and gravity on film condensation; however, comparison of forced convection is also presented. Alternative of conventional refrigerants in condensation process by low-global warming potential (GWP) refrigerants is addressed as well due to increase in atmospheric burden affected by hydro-fluoro-carbons (HFCs). Although many researchers have reviewed the condensation impact across enhanced surfaces, a few of them revised its behavior across pin-fin tubes. The effects of geometry, surface wettability, and operating conditions on the location, amount and form of condensate film are discussed. Various theoretical models prediction with the new experimental data across pin-fin tubes is also revealed. This review is distributed into two main sections: the first section focuses on condensation across enhanced tubes, sub dividing the study into integral-fin and pin-fin tubes based on theoretical and experimental investigations. It covers the geometrical effects concerning three dimensional (3D) surfaces, fin density, fin spacing and fin thickness. The later part of the paper concentrates on condensation behavior across the tube bundle incorporating the effects of fin density and refrigerant mixtures highlighting both theoretical and experimental knowledge. Recent research shows an agreement between theoretical and experimental models in the defined area; though, a considerable amount of work on semi-empirical correlation formulation is visible in the literature. The strength of this paper is the latest findings on condensation against different geometrical parameters of extended surfaces specifically across pin-fin tubes and the tube bundle. Finally, theoretical enhancement factors along with many heat transfer correlations are presented and recommendations are suggested for the future work.

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Modeling the Condensation Heat Transfer on Horizontal Low‐Finned Tubes

Losher,

Klein,

Rehfeldt

2024

Chemie Ingenieur Technik

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Most studies regarding heat transfer on low‐finned tubes address the condensation of refrigerants and water on copper tubes. Existing models are mainly validated for this use case since studies regarding different substances or tube materials are scarce in the literature. This paper presents measurement data on the condensation of n‐propanol, isopropanol, isobutanol, and acetone on low‐finned stainless‐steel tubes. Together with experimental data from the literature, the measurements are used to test the performance of models from the literature. As the investigated models fail to describe all measurement data, a new model based on a set of dimensionless numbers is derived and fitted to the experimental data.

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Condensation of R-134a on horizontal integral-fin titanium tubes

Abstract: ABSTRACT

Cited by 22 publications

References 15 publications

FILM –WISE CONDENSATION OF R1234yf AND R134a REFRIGERANTS ON FINNED TUBE WITH 32 FINS PER INCH

FILM –WISE CONDENSATION OF R1234yf AND R134a REFRIGERANTS ON FINNED TUBE WITH 32 FINS PER INCH

An Overview of Recent Progress in Condensation Heat Transfer Enhancement Across Horizontal Tubes and the Tube Bundle

Modeling the Condensation Heat Transfer on Horizontal Low‐Finned Tubes

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