Experimental results on boiling heat transfer coefficient, frictional pressure drop and flow patterns for R134a at a saturation temperature of 34 °C

2014 ◽  
Vol 40 ◽  
pp. 317-327 ◽  
Author(s):  
E. Manavela Chiapero ◽  
M. Fernandino ◽  
C.A. Dorao
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Saturation Temperature ◽  
Flow Patterns ◽  
Experimental Results ◽  
Frictional Pressure Drop ◽  
Boiling Heat Transfer Coefficient

Heat Transfer Enhancement in Pool Boiling of Distilled Water Using Gridded Metal Surface With Protrusions Over Microporous-Coated Surface

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Vidushi Chauhan ◽  
Manoj Kumar ◽  
Anil Kumar Patil
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Metal Surface ◽  
Boiling Heat Transfer ◽  
Particle Diameter ◽  
Saturation Temperature ◽  
Grid Size ◽  
Boiling Heat Transfer Coefficient ◽  
Coated Surface

Abstract The nucleate pool is a useful technique of heat dissipation in a variety of thermal applications. This study investigates the effect of the gridded metal surface (GMS) with and without protrusions on the heat transfer from a surface maintained at a temperature above the saturation temperature of water. The experimental data have been collected pertaining to boiling heat transfer at atmospheric pressure by varying the grid size of gridded metal surface with protrusions from 6 mm to 22.5 mm placed over a boiling surface having microporous coating. The mean particle diameter of coating is varied as 11, 24, and 66 μm during the experimentation. It is observed that the increase in the boiling heat transfer coefficient of the aluminum disk with GMS with protrusions of grid size 11.5 mm compared to that of the smooth boiling surface is found to be 10.7%. Furthermore, the effect of GMS having protrusions with coated surface on the heat transfer is studied. The results showed that by using GMS having protrusions and with coated surface, the heat transfer is further enhanced. The boiling heat transfer coefficient obtained in case of GMS with protrusions (grid size = 11.5 mm) and microporous-coated surface (dm = 66 μm) shows the maximum enhancement of 39.93% in comparison to the smooth surface.

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.

Boiling heat transfer coefficient and pressure drop of R1234yf flow inside smooth flattened tubes: An experimental study

2020 ◽  
Vol 165 ◽  
pp. 114595 ◽  
Author(s):  
Soorena Azarhazin ◽  
Behrang Sajadi ◽  
Hamidreza Fazelnia ◽  
Mohammad Ali Akhavan Behabadi ◽  
Sajjad Zakeralhoseini
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Boiling Heat Transfer Coefficient

Heat Transfer Characteristics for a Single Fin in a Boiling Liquid

2000 ◽  
Author(s):  
Yingzong Bu ◽  
Allan D. Kraus ◽  
Benjamin T. F. Chung
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Saturation Temperature ◽  
Base Temperature ◽  
Heat Transfer Characteristics ◽  
Boiling Liquid ◽  
Transfer Characteristics ◽  
Boiling Heat Transfer Coefficient

Abstract This work utilizes the cascade algorithm to predict the heat transfer characteristics of a one-dimensional longitudinal fin of rectangular profile in a boiling liquid. In this analysis, the geometric parameters of the fin, the temperature at the fin base and the saturation temperature of the boiling liquid are assumed. With the utilization of experimental boiling heat transfer coefficient curves, the heat flux, temperature profile, and boiling heat transfer coefficient of each point on the fin are obtained. The effectiveness of the fin in a boiling liquid is plotted for different fin thicknesses. It is found that the fin conductivity, boiling liquid, fin geometry and fin base temperature all affect the effectiveness of the fin in boiling. The effectiveness curves clearly indicate whether a fin should be used or when it is advantageous to use a fin in boiling liquid.

Experiment and CFD Simulation of Boiling Heat Transfer Coefficient of R410A in Minichannels

2015 ◽  
Vol 23 (04) ◽  
pp. 1550032 ◽  
Author(s):  
Nguyen Ba Chien ◽  
Kwang-Il Choi ◽  
Jong-Taek Oh
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Boiling Heat Transfer ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Saturation Temperature ◽  
Boiling Heat Transfer Coefficient

This study performed a comparison between experimental and computational fluid dynamic (CFD) simulation results of boiling heat transfer coefficient of R410A in a small tube. The experimental data were obtained in the horizontal circular tubes of 3.0[Formula: see text]mm inner diameter, the length of 3000[Formula: see text]mm including: mass flux and heat flux in a range from 300[Formula: see text]kg/m2s to 600[Formula: see text]kg/m2s and from 5[Formula: see text]kW/m2 to 10[Formula: see text]kW/m2, respectively, and the saturation temperature constantly kept at 20[Formula: see text]C. In the simulation procedure, the Eulerian multiphase with wall boiling were obtained. The effects of mass flux and heat flux on the heat transfer coefficient of R410A were analyzed. The comparative data between CFD and experiment was also illustrated.

Evaporation Heat Transfer and Pressure Drop Characteristics of R32 Inside a Multiport Tube with Microfins

2018 ◽  
Vol 26 (02) ◽  
pp. 1850017 ◽  
Author(s):  
Daisuke Jige ◽  
Shogo Kikuchi ◽  
Hikaru Eda ◽  
Norihiro Inoue ◽  
Shigeru Koyama
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Mass Velocity ◽  
Saturation Temperature ◽  
High Quality ◽  
Frictional Pressure Drop ◽  
Evaporation Heat ◽  
The Heat Transfer Coefficient

This study investigated the evaporation heat transfer and pressure drop characteristics of R32 in a horizontal multiport tube consisting of rectangular minichannels with straight microfins. The heat transfer coefficient and pressure drop were measured for a mass velocity range of 50–400[Formula: see text]kgm[Formula: see text]s[Formula: see text] and heat flux range of 5–20[Formula: see text]kWm[Formula: see text] at a saturation temperature of 15[Formula: see text]C. The frictional pressure drop during an adiabatic two-phase flow was also measured for a mass velocity range of 50–400[Formula: see text]kgm[Formula: see text]s[Formula: see text] and quality range of 0.1–0.9 at the same saturation temperature. The heat transfer coefficient increased with an increasing quality owing to the increase in forced convection. The dryout inception quality increased with the increase in mass velocity. The effects of heat flux on the heat transfer coefficient were small, except in a high-quality region. The heat transfer coefficient in a multiport tube with microfins was higher than that in a multiport tube without microfins in a high-quality region at a mass velocity of 200[Formula: see text]kgm[Formula: see text]s[Formula: see text] and in a low-quality region at a mass velocity of 400[Formula: see text]kgm[Formula: see text]s[Formula: see text]. The effects of mass velocity and microfins on the frictional pressure drop were clarified. It is suspected that the effects of a microfin on the frictional pressured drop can be considered using the hydraulic diameter. The frictional pressure drop was shown to be in good agreement with previous correlations.

Enhanced Heat Transfer for Boiling of a Refrigerant on a Micro-Structured Cylindrical Surface and Effect of Saturation Temperature

2010 ◽  
Author(s):  
Tailian Chen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Smooth Surface ◽  
Saturation Temperature ◽  
Structured Surface ◽  
Cylindrical Tubes ◽  
Boiling Heat Transfer Coefficient ◽  
Micro Structures

Boiling on the outside surface of cylindrical tubes is an important heat transfer process widely used in industry applications. It is known that boiling heat transfer coefficient increases with increasing saturation temperature. However, a quantitative measure of saturation temperature effect on boiling heat transfer is not readily available, especially for boiling on surfaces of microstructures. This work was motivated by the need to predict evaporator performance in a chiller while taking into account the effect of saturation temperature on boiling heat transfer coefficient. Experiments of boiling of refrigerant R123 on the micro-structured outside surface of an evaporator tube have been performed at three saturation temperatures in the range of 4.4 to 17.8°C. Water flows inside the test tubes and provides heat to the refrigerant for boiling. In addition, experiments of R123 boiling on smooth cylindrical tubes have been performed at the saturation temperature 4.4°C to provide a baseline to quantify the enhancement in boiling heat transfer due to microstructures on the test tubes. For boiling on the micro-structured surface, the boiling heat transfer coefficient increases by nearly 15% for the temperature range considered in this work. Measurements also showed that heat transfer coefficient for boiling on the test tubes of micro-structures is 12.3 times higher than boiling on the smooth surface. The Cooper correlation over-predicted by 40% the boiling heat transfer coefficient on the smooth cylindrical surface, but significantly under-predicted the performance for boiling on the tubes of micro-structures. It is found that the prediction of Cooper correlation multiplied by an enhancement factor 7.9 has a good agreement with measured heat transfer coefficient for boiling on the tubes of micro-structures at all the three saturation temperatures. Visual observations indicated that bubble departure characteristics on the micro-structured surface are different from those on the smooth surface. In addition to promoted bubble nucleation by re-entrant cavities on the micro-structured surface, the different bubble departure characteristics also contribute to the enhancement of boiling performance.

Two Phase Pressure Drop and Boiling Heat Transfer in Micro Pin Fin Channel

2016 ◽  
Author(s):  
Ki Moon Jung ◽  
Hee Joon Lee
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Boiling Heat Transfer ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Pin Fin ◽  
Boiling Heat Transfer Coefficient

In this paper, boiling experiments were conducted to study two-phase pressure drop and the heat transfer coefficient in a staggered array micro pin fin channel of degassed water at a mass flux range of 9.3 to 46.6 kg/m2s and a heat flux of 0.5 to 0.9 W/cm2. Copper was used for the pin fin array microchannel heat sink, which was 31 mm in width and 82 mm in length. Micro pin fins, of 400 μm in diameter and 700 μm in height, were manufactured using a micro milling machine on the channel block. The distance between two pin fin surfaces is 300 μm. A thin film heater, which supplies a maximum constant heat flux of 1.55 W/cm2, was attached underneath the heat sink. From the experimental results, at a vapor quality of up to 0.04, the boiling heat transfer coefficient decreased as the quality increased. Results show that the heat transfer coefficient is dependent on the mass flux. The data also showed that the pressure drop increased with increasing mass flux. The data obtained in this study were compared to the existing correlations of boiling pressure drop and heat transfer coefficients. Results showed that the correlation with boiling pressure drop of Qu and Siu-Ho[22] yielded a prediction of 21.3% average error Additionally, as a result of comparison with the four existing correlations of boiling heat transfer coefficient, all correlations had a lower prediction for the heat transfer coefficients obtained in this study. Through visualization, it was found that the bubbles generated between the fins began to grow and moved downstream. We observed a stationary vapor pocket in which bubbles did not flow.

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