Two-Phase Heat Transfer Performance of Dielectric Fluid HFE-7100 Within Multiport Microchannel

2008 ◽  
Author(s):  
Lung-Yi Lin ◽  
Yeau-Ren Jeng ◽  
Chi-Chuan Wang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Single Phase ◽  
Heat Transfer Performance ◽  
Convective Heat Transfer Coefficient ◽  
Dielectric Fluid ◽  
Transfer Performance ◽  
Two Phase ◽  
Two Phase Heat Transfer

This study presents convective single-phase and boiling two-phase heat transfer performance of HFE-7100 coolant within multi-port microchannel heat sinks. The corresponding hydraulic diameters are 450 and 237 μm, respectively. For single-phase results, the presence of inlet/outlet locations inevitably gives rise to considerable increase of total pressure drop of a multi-port microchannel heat sink whereas has virtually no detectable influence on overall heat transfer performance provided that the effect of entrance has been accounted for. The convective boiling heat transfer coefficient for the HFE-7100 coolant shows a tremendous drop when vapor quality is above 0.6. For Dh = 450 μm, it is found that the mass flux effect on the convective heat transfer coefficient is rather small.

Impingement Heat Transfer of Various Lobe-Shaped Nozzles

2019 ◽  
Author(s):  
Sanskar S. Panse ◽  
Srivatsan Madhavan ◽  
Prashant Singh ◽  
Srinath V. Ekkad
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Convective Heat Transfer Coefficient ◽  
Transfer Performance ◽  
Impingement Heat Transfer ◽  
Circular Jets ◽  
Contour Plots ◽  
Drastic Effect

Abstract This paper presents heat transfer characteristics of lobed nozzles, three different lobe configurations viz. three-, four- and six-lobe jets have been tested over a range of Reynolds numbers (based on the effective jet diameter, de) between 8000 and 16000 and normalized jet-to-target spacings (z/de) of 1.6, 3.2 and 4.8. The heat transfer results of lobed configurations were compared to the baseline configuration of circular jets. Steady-state infrared thermography (IRT) experiments were carried out for convective heat transfer coefficient calculations. Experimental results show that the three lobe configuration has a superior heat transfer performance compared to other configurations. Jet-to-target plate standoff distance had drastic effect on the heat transfer performance and contour plots for the lobed nozzles, as heat transfer performance diminished with increase in z/de. For the lobe configurations, with increase in jet-to-target spacing (z/de), the heat transfer coefficient maps tend towards a more circular profile due to the effect of jet diffusion.

Experimental Investigation and Empirical Analysis of Non-Boiling Gas-Liquid Two Phase Heat Transfer in Vertical Downward Pipe Orientation

2012 ◽  
Author(s):  
Swanand M. Bhagwat ◽  
Mehmet Mollamahmutoglu ◽  
Afshin J. Ghajar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Annular Flow ◽  
Single Phase ◽  
Phase Flow ◽  
Upward Flow ◽  
Two Phase ◽  
Reynolds Analogy ◽  
Two Phase Heat Transfer

The non-boiling gas-liquid two phase flow is pertinent to industrial applications like the reduction of paraffin wax depositions in petroleum transport lines, air lift systems and the chemical processes such as ethanol-water fractionation seeking enhanced heat and mass transfer. The non-boiling two phase heat transfer mechanism in horizontal and vertical orientations has been investigated by many researchers. However, till date very little experimental work and investigation has been performed for vertical downward flow. In order to contribute more to this research and have a better understanding of the non-boiling two phase heat transfer phenomenon for this pipe orientation, experimental investigation is undertaken for a vertical downward oriented 0.01252 m I.D. schedule 10 S stainless steel pipe using air-water as fluid combination. The influence of different flow patterns on the two phase convective heat transfer coefficient is studied using experimental measurements of 165 data points for bubbly, slug, froth, falling film and annular flow patterns spanned over the entire range of the void fraction. In general the two phase heat transfer coefficients are found to be consistently higher than that of the single phase flow. This tendency is observed to increase with increase in the gas flow rate as the flow regime migrates from bubbly to the annular flow. The concept of Reynolds analogy as implemented by Tang and Ghajar [1] for horizontal and vertical upward flow is analyzed against the vertical downward flow data collected in the present study. Due to lack of correlations available for predicting the two phase heat transfer coefficient in vertical downward orientation it was decided to perform the quantitative analysis of the seventeen two phase heat transfer correlations available for vertical upward flow. This analysis is concluded by the recommendation of the top performing correlations in the literature for each flow pattern. Based on the pressure drop data and using Reynolds analogy, a simple equation is proposed to correlate the two phase heat transfer coefficient with the single phase heat transfer coefficient.

Experimental Study of Nature-Inspired Enhanced Microscale Heat Transfer

2016 ◽  
Author(s):  
A. L. Goh ◽  
B. Han ◽  
K. T. Ooi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Convective Heat Transfer Coefficient ◽  
Fish Scale ◽  
Transfer Performance ◽  
Cylindrical Pipe ◽  
Microscale Heat Transfer ◽  
Scale Profile

Microscale heat transfer in macro geometry has been proven to yield comparable heat transfer performance to that of typical microchannels. This paper takes it a step further by looking at three passive heat transfer enhancement techniques to improve the heat transfer performance of the newly proposed system for single-phase liquid flow. The novelty of the study lies in that the enhancement features are designed based on inspiration from nature. Fish scale, Durian (a thorny tropical fruit), and Inverted Fish Scale enhancement profiles are considered. In this study, an annular microchannel is formed by securing a cylindrical insert of mean diameter 19.4 mm within a cylindrical pipe of internal diameter 20 mm. The enhancement features are introduced on the surface profile of the insert, while the heat is supplied to the flow via the cylindrical pipe of fixed surface area. Therefore, heat transfer is improved by increasing convective heat transfer coefficient, for a constant heat transfer area. The enhancement features serve to increase heat transfer coefficient by disturbing the flow and thermal boundary layers. Experiments were carried out to investigate the effect of the three enhancement profiles on the heat transfer and flow characteristics of the microscale flow. The extent of enhancement is computed with the Plain profile as benchmark. The constant parameters include microchannel length of 30 mm, mean hydraulic diameter of 600 μm, and heat input of 1000 W. Reynolds number range is 1,300 to 4,600, with water as working fluid. Results show that the Inverted Fish Scale profile doubles the Nusselt number as compared to the Plain profile. However, when friction factor increment is considered, Durian profile yields the best overall thermal performance, nearly 1.4 times better than the Plain profile. In the whole study, the maximum convective heat transfer coefficient achieved is 45.0 kW/m2·K, using Inverted Fish Scale profile at Reynolds number of 4,300. The pressure drop values of the system are all less than 3 bars, which may easily be achieved by a commercially available pump.

Production Process and Heat Transfer Performance of 10/316 Clad Tube

2014 ◽  
Vol 1081 ◽  
pp. 270-274
Author(s):  
Zui Xian Yu ◽  
Xue Sheng Wang ◽  
Qin Zhu Chen
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Heat Transfer Coefficient ◽  
Carbon Steel ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Steel Tube ◽  
Stainless Steel Tube ◽  
Transfer Performance ◽  
Clad Tube

A new preparation technique of carbon steel/stainless steel clad tube was introduced, and the contact surface was well combined. Meanwhile, with the using of tube heat exchanger, the experiment on the heat transfer performance of the clad tube was done. Comparing the 10/316 clad tube and the 316 stainless steel tube, the effects on the heat transfer performance of 316 stainless steel tube attached to carbon steel was evaluated. It is showed that overall heat transfer coefficient of 10/316 clad tubes is higher than that of stainless steel tube. The average heat transfer coefficient of 10/316 clad tubes is about 18.7%~34.4% higher than that of stainless steel tube. Experimental investigation indicates that, by brazing and cold drawing, the 10/316 clad tube was well combined and the thermal conductivity was better than that of stainless steel tube.

Heat Transfer Performance of Different Nanofluids Flows in a Helically Coiled Heat Exchanger

2013 ◽  
Vol 832 ◽  
pp. 160-165 ◽  
Author(s):  
Mohammad Alam Khairul ◽  
Rahman Saidur ◽  
Altab Hossain ◽  
Mohammad Abdul Alim ◽  
Islam Mohammed Mahbubul
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Transfer Performance

Helically coiled heat exchangers are globally used in various industrial applications for their high heat transfer performance and compact size. Nanofluids can provide excellent thermal performance of this type of heat exchangers. In the present study, the effect of different nanofluids on the heat transfer performance in a helically coiled heat exchanger is examined. Four different types of nanofluids CuO/water, Al2O3/water, SiO2/water, and ZnO/water with volume fractions 1 vol.% to 4 vol.% was used throughout this analysis and volume flow rate was remained constant at 3 LPM. Results show that the heat transfer coefficient is high for higher particle volume concentration of CuO/water, Al2O3/water and ZnO/water nanofluids, while the values of the friction factor and pressure drop significantly increase with the increase of nanoparticle volume concentration. On the contrary, low heat transfer coefficient was found in higher concentration of SiO2/water nanofluids. The highest enhancement of heat transfer coefficient and lowest friction factor occurred for CuO/water nanofluids among the four nanofluids. However, highest friction factor and lowest heat transfer coefficient were found for SiO2/water nanofluids. The results reveal that, CuO/water nanofluids indicate significant heat transfer performance for helically coiled heat exchanger systems though this nanofluids exhibits higher pressure drop.

Research on Heat Transfer Performance of Water Film for Outside the Tubes of the Microscale Evaporative Condenser

2009 ◽  
Author(s):  
Minghui Hu ◽  
Dongsheng Zhu ◽  
Jialong Shen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Water Film ◽  
Transfer Performance ◽  
Air Velocity ◽  
Microscale Heat Transfer ◽  
High Heat Transfer ◽  
Spray Density

It is requested to develop a microscale and high performance heat exchanger for small size energy equipments. The heat transfer performance of the water film on the condensing coils of the microscale evaporative condenser was studied for a single-stage compressed refrigeration cycle system. Under various operation conditions, the effects of the spray density and the head-on air velocity on the heat transfer performance of the water film were investigated. The results show that the microscale heat transfer coefficient of the water film αw increases with the increase of spray density and decreases with the increase of head-on air velocity. The results indicate that the key factor affecting the microscale heat transfer of the water film is the spray density. As the results, it is measured that the present device attained high heat transfer quantity despite the weight is light. In addition, via regression analysis of the experimental data, the correlation equation for calculating the microscale heat transfer coefficient of the water film was obtained, its regression correlation coefficient R is 0.98 and the standard deviation is 7.5%. Finally, the correlations from other works were compared. The results presented that the experimental correlation had better consistency with the correlations from other works. In general, the obtained experimental results of the water film heat transfer are helpful to the design and practical operation of the microscale evaporative condensers.

On the Application of Macro-Pipe Two-Phase Heat Transfer Correlations and Flow Regime Maps to Mini-Channels

2006 ◽  
Author(s):  
Avram Bar-Cohen ◽  
Ilai Sher ◽  
Emil Rahim
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Regime ◽  
Annular Flow ◽  
Negative Slope ◽  
Two Phase ◽  
Heat Transfer Correlations ◽  
Two Phase Heat Transfer ◽  
Flow Regime Maps

The present study is aimed at evaluating the ability of conventional “macro-pipe” correlations and regime transitions to predict the two-phase thermofluid characteristics of mini-channel cold plates. Use is made of the Taitel-Dukler flow regime maps, seven classical heat transfer coefficient correlations and two dryout predictions. The vast majority of the mini-channel two-phase heat-transfer data, taken from the literature, is predicted to fall in the annular regime, in agreement with the reported observations. A characteristic heat transfer coefficient locus has been identified, with a positive slope following the transition from Intermittent to Annular flow and a negative slope following the onset of partial dryout at higher qualities. While the classical two-phase heat transfer correlations are generally capable of providing good agreement with the low-quality annular flow data the quality at which partial dryout occurs and the ensuing heat transfer rates are not predictable by the available macro-pipe correlations.

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