scholarly journals Condensation Heat Transfer and Pressure Drop of R245fa inside a Horizontal Smooth Tube - Effect of Saturation Temperature on Condensation Characteristics

2016 ◽  
Vol 51 (6) ◽  
pp. 871-878
Author(s):  
Kazuhide Watanabe ◽  
Daisuke Jige ◽  
Norihiro Inoue
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Saturation Temperature ◽  
Condensation Heat Transfer ◽  
Smooth Tube

scholarly journals Correlation for Condensation Heat Transfer in a 4.0 mm Smooth Tube and Relationship with R1234ze(E), R404A, and R290

2018 ◽  
Vol 8 (11) ◽  
pp. 2267 ◽  
Author(s):  
Norihiro Inoue ◽  
Masataka Hirose ◽  
Daisuke Jige ◽  
Junya Ichinose
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Small Diameter ◽  
Saturation Temperature ◽  
Condensation Heat Transfer ◽  
Smooth Tube ◽  
General Correlation ◽  
Condensation Heat Transfer Coefficient

In this study, the condensation heat transfer coefficient and pressure drop characteristics of a 4 mm outside diameter smooth tube, using R32, R152a, R410A, and R1234ze(E) refrigerants, were examined. Condensation heat transfer coefficients and pressure drops were measured at a saturation temperature of 35 °C, in the region of mass velocities from 100 to 400 kg m−2s−1. The frictional pressure drop, and the condensation heat transfer from the new measurements, using R1234ze(E) as a refrigerant, were compared with those of R32, R152a, and R410A, in the smooth tube. Experimental values of condensation heat transfer coefficient of smooth tube were also compared to the predicted values obtained using the previously established correlations. The previous correlation from Cavallini et al., for the condensation heat transfer coefficient of small-diameter smooth tube, was estimated to be within ±30%. However, the general correlation, which can be easily predicted, for condensation heat transfer inside small-diameter smooth tubes, was suggested, and the relationship of the general correlation was compared with data for R1234ze(E) obtained by us, and R404A and R290 obtained by other researchers.

Experimental Investigation of Condensation Heat Transfer and Adiabatic Pressure Drop Characteristics Inside a Microfin and Smooth Tube

2017 ◽  
Vol 25 (03) ◽  
pp. 1750027 ◽  
Author(s):  
M. Mostaqur Rahman ◽  
Keishi Kariya ◽  
Akio Miyara
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Saturation Temperature ◽  
Condensation Heat Transfer ◽  
Vapor Quality ◽  
Transfer Coefficients ◽  
Frictional Pressure Drop

Experiments on condensation heat transfer and adiabatic pressure drop characteristics of R134a were performed inside smooth and microfin horizontal tubes. The tests were conducted in the mass flux range of 50[Formula: see text]kg/m2s to 200[Formula: see text]kg/m2s, vapor quality range of 0 to 1 and saturation temperature range of 20[Formula: see text]C to 35[Formula: see text]C. The effects of mass velocity, vapor quality, saturation temperature, and microfin on the condensation heat transfer and frictional pressure drop were analyzed. It was discovered that the local heat transfer coefficients and frictional pressure drop increases with increasing mass flux and vapor quality and decreasing with increasing saturation temperature. Higher heat transfer coefficient and frictional pressure drop in microfin tube were observed. The present experimental data were compared with the existing well-known condensation heat transfer and frictional pressure drop models available in the open literature. The condensation heat transfer coefficient and frictional pressure drop of R134a in horizontal microfin tube was predicted within an acceptable range by the existing correlation.

Condensation Heat Transfer and Pressure Drop of R-134a Flowing in Annular Helical Pipes at Different Orientations

2003 ◽  
Author(s):  
B. Yu ◽  
C. X. Lin ◽  
M. A. Ebadian ◽  
R. C. Prattipati
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Cooling Water ◽  
Saturation Temperature ◽  
Condensation Heat Transfer ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
Cooling Water Temperature ◽  
Helical Pipe ◽  
R 134A

This paper presents an experimental investigation of condensation heat transfer and pressure drop characteristics of refrigerant R-134a flowing through an annular helicoidal passage with the hydraulic diameter of 8.5 mm. The angles of helix axis are oriented at 0, 45, 90 degrees to gravity. The overall and refrigerant-side heat transfer coefficients and pressure drops are experimentally determined at saturation temperature 35°C, refrigerant mass flux 35–180 kg/s·m2, and cooling water temperature 27°C. The results show that orientation has significant influence on the thermal and hydraulic behaviors of the helical pipe. The results can be employed for reference in the effective design of annular helicoidal heat exchangers with R-134a as the working fluid.

Condensation Heat Transfer Characteristics on the Outside of Horizontal Smooth, Herringbone and Enhanced Surface 1EHT Tubes

2015 ◽  
Author(s):  
Xiao-peng Zhou ◽  
David J. Kukulka ◽  
Jing Li ◽  
Jian-Jun Sun ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Mass Flux ◽  
Saturation Temperature ◽  
Condensation Heat Transfer ◽  
Smooth Tube ◽  
Outer Diameter ◽  
Thermal Systems ◽  
Low Mass ◽  
Enhanced Surface

Heat transfer enhancement plays an important role in improving energy efficiency and developing high performance thermal systems. Phase-change heat transfer processes take place in thermal systems; typically heat transfer enhanced tubes are used in these systems and they are designed to increase heat transfer coefficients in evaporation and condensation. Enhanced heat transfer tubes are widely used in refrigeration and air-conditioning applications in order to reduce cost and create a smaller footprint of the application. Microfins, roughness and dimples are often incorporated into the inner surface of tubes in order to enhance heat transfer performance. Under many conditions, enhanced surface tubes can recover more energy and provide the opportunity to advance the design of many heat transfer products. Convective condensation heat transfer and pressure loss characteristics were investigated for R410A on the outside of: (i) a smooth tube (outer diameter 12.7 mm); (ii) an external herringbone tube (fin root diameter 12.7 mm); and (iii) the 1EHT tube (outer diameter 12.7 mm) for very low mass fluxes. Data was obtained for values of mass flux ranging from 8 to 50 kg/(m2 s); at a saturation temperature of 318 K; with an inlet quality of 0.8 (±0.05) and an outlet quality of 0.1 (±0.05). In a comparison of heat transfer at a low mass flux, both the 1EHT tube and the herringbone tube did not perform as well as the smooth tube. And it’s difficult to analyze the reason for this strange phenomenon.

Effects of Pitch and Depth on the Condensation Heat Transfer of R-134a Flowing Through Corrugated Tubes

2011 ◽  
Author(s):  
Suriyan Laohalertdecha ◽  
Somchai Wongwises
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Condensation Heat Transfer ◽  
Smooth Tube ◽  
Maximum Heat ◽  
Frictional Pressure Drop ◽  
R 134A

The effects of pitch and depth on the condensation heat transfer of R-134a flowing inside corrugated tubes are experimentally investigated. The test section is a horizontal tube-in-tube heat exchanger. The refrigerant flows in the inner tube and the water flows in the annulus. The length of heat exchanger is 2 m. A smooth tube and corrugated tubes having inner diameters of 8.7 mm are used as an inner tube. The corrugation pitches used in this study are 5.08, 6.35, and 8.46 mm. Similarly, the corrugation depths are 1, 1.25, and 1.5 mm. The effects of corrugation pitch and depth on tube wall temperature, heat transfer coefficient and frictional pressure drop are discussed. The results illustrate that the maximum heat transfer coefficient and frictional pressure drop obtained from the corrugated tube are up to 50% and 70% higher than those obtained from the smooth tube, respectively.

Experimental Investigation of Evaporation and Condensation in Herringbone, Smooth and EHT Tubes

2015 ◽  
Author(s):  
Xiao-peng Zhou ◽  
Jian-jun Sun ◽  
Si-pu Guo ◽  
Sun Zhichuan ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Saturation Temperature ◽  
Condensation Heat Transfer ◽  
Smooth Tube ◽  
Evaporation And Condensation ◽  
Condensation Heat Transfer Coefficient

An experimental investigation was performed for evaporation and condensation characteristics inside smooth tube, herringbone tube and EHT tube with the same outer diameter 12.7 mm, refrigerant are R22 and R410a. Mass flux are 60–140 kg/m2s, 81–178.5 kg/m2s, for evaporation and condensation respectively. The evaporation saturation temperature is 6°C, with inlet and outlet vapor qualities of 0.1 and 0.9, respectively. The condensation saturation temperature is 47°C, with inlet and outlet vapor qualities of 0.8 and 0.2, respectively. EHT tube has best evaporating performance for both R22 and R410a. Herringbone tube is also batter than smooth tube. Evaporation heat transfer coefficient increases with mass flux increasing obviously. Pressure drop of R22 evaporation in EHT tube is the highest, herringbone tube is a little higher than in smooth tube. Herringbone tube has highest condensation heat transfer coefficient, about 3 and 2.3 times that of smooth tube for R22 and R410a respectively. EHT tube has heat transfer coefficient about 2 and 1.8 times that of smooth tube for R22 and R410a respectively. Condensation heat transfer coefficient increases with increasing of mass flux, but very slowly, R410a flow in micro-fin tube even decreases with mass flux increasing.

The Characteristics of Flow Boiling Heat Transfer and Pressure Drop in Small Tube with the Pipe Sections Having Increased Diameters

2013 ◽  
Vol 651 ◽  
pp. 525-529
Author(s):  
Mao Yu Wen ◽  
Kang Jang Jang
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Small Diameter ◽  
Saturation Temperature ◽  
Smooth Tube ◽  
Flow Boiling Heat Transfer ◽  
Small Tube

This study presents an experimental investigation of the characteristics of the flow boiling heat transfer and pressure drop for refrigerant of R134a flowing in a small - diameter evaporative tube with the pipe sections having increased diameters. The experiments were performed at the saturation temperature of 5°C , heat flux of 5.12 ~ 10.96 ( KW/m2), mass flux of 200~600 ( kg/m2s), different length-to-diameter ratios of the test tubes and refrigerant quality of 0.07~0.78, and based on the same surface area of heat transfer. The enhancement performance ratios, θa/s for the tubes with the pipe sections having increased diameters relative to the smooth tube are higher than 1 (about 1.01~1.10). It means that the augmented tubes show the better overall performance than the smooth tube under study.

A General Correlation for Condensation Heat Transfer in Micro-Fin for Herringbone and Dimple-Texture Tubes

2015 ◽  
Author(s):  
Wei Li ◽  
Si-pu Guo ◽  
Xiao-peng Zhou ◽  
David J. Kukulka ◽  
Jin-liang Xu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Saturation Temperature ◽  
Condensation Heat Transfer ◽  
Smooth Tube ◽  
Outer Diameter ◽  
Coefficient Multiplier ◽  
The Heat Transfer Coefficient

An experimental investigation was performed to evaluate the condensation characteristics inside smooth, herringbone and dimple-textured (Vipertex 1EHT) tubes; with the same outer diameter (12.7 mm); using R22 and R410a refrigerants; for a mass flux that ranges from 81 to 178.5 kg/m 2 s. The condensation saturation temperature is 47°C; with an inlet quality of 0.8 and an outlet vapor quality of 0.2. Results indicate that the condensation heat transfer coefficient of the herringbone tube was approximately 3 times that of the smooth tube for R22; and has an enhancement heat transfer factor of 2.3 for R410a. The enhancement heat transfer coefficient multiplier for the textured dimple tube is approximately 2 times that of a smooth tube for R22; and 1.8 for R410a. Severalpreviously reported correlations are used to compare the heat transfer coefficient measurements in the plain tube; while a new equation is proposed to predict the heat transfer coefficient in the herringbone tube.

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