scholarly journals AN EXPERIMENTAL STUDY OF THE EFFECT OF SURFACTANT AND TI02 NANOPARTICLES ADDITIVES IN R141B ON THE NUCLEATE POOL BOILING PROCESS

2017 ◽  
Vol 39 (5) ◽  
pp. 37-40
Author(s):  
O. Khliyeva ◽  
T. Gordeychuk ◽  
A. Nikulin ◽  
N. Lukianov ◽  
V. Zhelezny
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Tio2 Nanoparticles ◽  
Pool Boiling ◽  
Nucleate Pool Boiling ◽  
Boiling Process ◽  
The Heat Transfer Coefficient

The results of experimental study of effect of TiO2 nanoparticles (0.1 % mass.) and surfactant Span80 (0.1 % mass.) additives in refrigerant R141b on the heat transfer coefficient of nucleate pool boiling process at three values of pressure 0.2, 0.3 and 0.4 MPa and range of heat flux from 5 to 70 kWm-2 are presented in paper.  

scholarly journals Pool Boiling of Water on Surfaces with Open Microchannels

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3062
Author(s):  
Robert Kaniowski ◽  
Robert Pastuszko
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Computational Models ◽  
Pool Boiling ◽  
Experimental Investigations ◽  
Maximum Heat ◽  
Area Of Interest ◽  
The Heat Transfer Coefficient

Boiling, as the most efficient type of convective heat transfer, is an area of interest in many fields of industry and science. Many works have focused on improving the heat transfer efficiency of boiling by altering the physical and chemical properties of surfaces by using different technological processes in their fabrication. This paper presents experimental investigations into pool boiling on enhanced surfaces with open microchannels. The material of the fabricated surface was copper. Parallel microchannels made by machining were about 0.2, 0.3, and 0.4 mm wide, 0.2 to 0.5 mm deep, and spaced with a pitch equal to twice the width of the microchannel. The experiments were carried out in water at atmospheric pressure. The experimental results obtained showed an increase in the heat flux and the heat transfer coefficient for surfaces with microchannels. The maximum (critical) heat flux was 2188 kW/m2, and the heat transfer coefficient was 392 kW/m2K. An improvement in the maximum heat flux of more than 245% and 2.5–4.9 times higher heat transfer coefficient was obtained for the heat flux range of 992–2188 kW/m2 compared to the smooth surface. Bubble formation and growth cycle in the microchannel were presented. Two static computational models were proposed to determine the bubble departure diameter.

Evolution of Heat Transfer in Pool Boiling in Contaminated Water

2020 ◽  
Author(s):  
Jacob Graham ◽  
Angelo Hawa ◽  
Patricia Weisensee
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Calcium Sulfate ◽  
Pool Boiling ◽  
Surface Orientation ◽  
Aluminum Surface ◽  
The Heat Transfer Coefficient

Abstract Boiling heat transfer serves as an efficient mechanism to dissipate large amounts of thermal energy due to the latent heat of phase change. In academic studies, typically ultra-pure deionized (DI) water is used to avoid contamination. However, in industrial and commercial settings, the working fluid might be contaminated with sediments, dust, salts, or organic matter. Long-term boiling processes in non-DI water cause substantial build-up of a stable layer of deposit that dramatically reduces the heat transfer coefficient. Therefore, heating applications in a contaminated medium demand strategies to prevent such fouling. Here, we studied the use of lubricant infused surfaces (LIS) and their ability to possibly minimize the deposition of calcium sulfate. Aluminum samples were infused with Krytox 102 oil and the heat transfer coefficient was investigated at a vertical and horizontal surface orientation. Fouling effects were introduced by pool boiling for 7.5 hours in a 6.97 mM calcium sulfate solution at constant heat flux. Heat flux curves for both plain aluminum and LIS were calibrated before contamination. Initially, the LIS was unable to support a nucleate phase and transitioned directly from liquid convection to film boiling heat transfer. Upon partial degradation of the lubricant layer during long-run experiments, nucleate boiling ensued. Over 7.5 hours, the heat transfer coefficient of each sample (Al and LIS) degraded between 5.4% and 7.9% with no significant correlation with either lubricant treatment or surface orientation. Post boiling profilometry was conducted on each sample to characterize the thickness and distribution of the calcium sulfate layer. In these experiments, the plain aluminum surface outperformed the LIS at both orientations in minimizing calcium layer thickness. The LIS oriented vertically outperformed the LIS oriented horizontally.

Nanoparticle aggregation kinematics on the quadratic convective magnetohydrodynamic flow of nanomaterial past an inclined flat plate with sensitivity analysis

2021 ◽  
pp. 095440892110562
Author(s):  
AS Sabu ◽  
Joby Mackolil ◽  
B Mahanthesh ◽  
Alphonsa Mathew
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Sensitivity Analysis ◽  
Heat Transfer Coefficient ◽  
Heat Source ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Inclined Plate ◽  
The Impact ◽  
The Heat Transfer Coefficient

The study focuses on the aggregation kinematics in the quadratic convective magneto-hydrodynamics of ethylene glycol-titania ([Formula: see text]) nanofluid flowing through an inclined flat plate. The modified Krieger-Dougherty and Maxwell-Bruggeman models are used for the effective viscosity and thermal conductivity to account for the aggregation aspect. The effects of an exponential space-dependent heat source and thermal radiation are incorporated. The impact of pertinent parameters on the heat transfer coefficient is explored by using the Response Surface Methodology and Sensitivity Analysis. The effects of several parameters on the skin friction and heat transfer coefficient at the plate are displayed via surface graphs. The velocity and thermal profiles are compared for two physical scenarios: flow over a vertical plate and flow over an inclined plate. The nonlinear problem is solved using the Runge–Kutta-based shooting technique. It was found that the velocity profile significantly decreased as the inclination of the plate increased on the other hand the temperature profile improved. The heat transfer coefficient decreased due to the increase in the Hartmann number. The exponential heat source has a decreasing effect on the heat flux and the angle of inclination is more sensitive to the heat transfer coefficient than other variables. Further, when radiation is incremented, the sensitivity of the heat flux toward the inclination angle augments at the rate 0.5094% and the sensitivity toward the exponential heat source augments at the rate 0.0925%. In addition, 41.1388% decrement in wall shear stress is observed when the plate inclination is incremented from [Formula: see text] to [Formula: see text].

scholarly journals Enhancement of Nucleate Pool Boiling Heat Transfer with Sodium Oleate

2017 ◽  
Vol 29 (1) ◽  
pp. 44-48
Author(s):  
KM Tanvir Ahmmed ◽  
Sultana Razia Syeda
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Sodium Oleate ◽  
Surfactant Concentration ◽  
Chemical Engineering ◽  
Pool Boiling ◽  
Nucleate Pool Boiling ◽  
Maximum Heat ◽  
Maximum Heat Transfer

In this study saturated nucleate pool boiling of water with sodium oleate surfactant on a horizontal cylindrical heater surface has been investigated experimentally and compared with that of demineralized water. The concentration of sodium oleate in water was 100-300 ppm. The experimental results show that a small amount of surfactant enhances the heat transfer coefficient significantly. At low surfactant concentrations, heat transfer coefficient increases with increasing surfactant concentration in water. The maximum heat transfer enhancement is found to be at 250 ppm of sodium oleate solution. By adding more surfactant to water, heat transfer coefficient is found to be lowered. Surface tension of different concentration of sodium oleate solutions is measured. It is observed that the maximum heat transfer coefficient is obtained at a surfactant concentration that corresponds to the critical micelle concentration (cmc) of the sodium oleate solution.Journal of Chemical Engineering, Vol. 29, No. 1, 2017: 44-48

Experimental Study on Integrated Performance for Flower Baffle Heat Exchanger’s Distance between Two Flower Baffles

2010 ◽  
Vol 29-32 ◽  
pp. 132-137 ◽  
Author(s):  
Xue Jiang Lai ◽  
Rui Li ◽  
Yong Dai ◽  
Su Yi Huang
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
The One ◽  
Integrated Performance ◽  
Quantity Of Heat ◽  
Side Flow ◽  
The Heat Transfer Coefficient

Flower baffle heat exchanger’s structure and design idea is introduced. Flower baffle heat exchanger has unique support structure. It can both enhance the efficiency of the heat transfer and reduce the pressure drop. Through the experimental study, under the same shell side flow, the heat transfer coefficient K which the distance between two flower baffles is 134mm is higher 3%~9% than the one of which the distances between two flower baffles are 163mm,123mm. The heat transfer coefficient K which the distance between two flower baffles is 147mm is close to the one of which the distances between two flower baffles is 134mm. The shell volume flow V is higher, the incremental quantity of heat transfer coefficient K is more. The integrated performance K/Δp of flower baffle heat exchanger which the distance between two flower baffles is 134mm is higher 3%~9% than the one of which the distances between two flower baffles are 163mm,123mm. Therefore, the best distance between two flower baffles exists between 134mm~147mm this experiment.

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