scholarly journals Effect of Low Volume Concentration on Heat Transfer Enhancement of EG-Water Based Fe3O4 Nanofluid

2020 ◽  
Vol 9 (4) ◽  
pp. 1796-1802
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Enhancement ◽  
Friction Factor ◽  
Base Fluid ◽  
Volume Concentration ◽  
Transfer Enhancement ◽  
Water Based ◽  
The Heat Transfer Coefficient

Customization of thermophysical properties of the working fluids has tremendous potential in heat transfer enhancement. In the present paper, experimentation is conducted to determine the heat transfer coefficient and friction factor of 20:80 Ethylene Glycol-Water(20:80 EG-Water) based Fe3O4 nanofluid in a Double Pipe Heat Exchanger with U Bend (DPHE). Experiments are performed in the turbulent flow regime at an operating temperature of 47.5°C. Fe3O4 nanoparticles of size less than 50 nm are mixed with 20:80 EG-Water solution in the volume concentration range of 0.02% to 0.08%. Results indicate that as the concentration of nanoparticles increase, the heat transfer coefficient of the nanofluid increases up to 0.04% concentration and then decreases, while the friction factor is observed to increase with the increase of volume concentration. Within the Reynolds number range considered in the analysis, the average enhancement in the heat transfer coefficient is 24.1% at 0.04% concentration compared to that of the base fluid. The average enhancement in the friction factor is observed to be 25.58% at 0.08% concentration of Fe3O4 / 20:80 EG-Water nanofluid compared to that of base fluid.

An Experimental Investigation of Structured Roughness Effect on Heat Transfer During Single-Phase Liquid Flow at Microscale

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Ting-Yu Lin ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Enhancement ◽  
Enhancement Factor ◽  
Roughness Element ◽  
Hydraulic Diameter ◽  
Transfer Enhancement ◽  
Roughness Elements ◽  
The Heat Transfer Coefficient

The effect of structured roughness on the heat transfer of water flowing through minichannels was experimentally investigated in this study. The test channels were formed by two 12.7 mm wide × 94.6 mm long stainless steel strips. Eight structured roughness elements were generated using a wire electrical discharge machining (EDM) process as lateral grooves of sinusoidal profile on the channel walls. The height of the roughness structures ranged from 18 μm to 96 μm, and the pitch was varied from 250 μm to 400 μm. The hydraulic diameter of the rectangular flow channels ranged from 0.71 mm to 1.87 mm, while the constricted hydraulic diameter (obtained by using the narrowest flow gap) ranged from 0.68 mm to 1.76 mm. After accounting for heat losses from the edges and end sections, the heat transfer coefficient for smooth channels was found to be in good agreement with the conventional correlations in the laminar entry region as well as in the laminar fully developed region. All roughness elements were found to enhance the heat transfer. In the ranges of parameters tested, the roughness element pitch was found to have almost no effect, while the heat transfer coefficient was significantly enhanced by increasing the roughness element height. An earlier transition from laminar to turbulent flow was observed with increasing relative roughness (ratio of roughness height to hydraulic diameter). For the roughness element designated as B-1 with a pitch of 250 μm, roughness height of 96 μm and a constricted hydraulic diameter of 690 μm, a maximum heat transfer enhancement of 377% was obtained, while the corresponding friction factor increase was 371% in the laminar fully developed region. Comparing different enhancement techniques reported in the literature, the highest roughness element tested in the present work resulted in the highest thermal performance factor, defined as the ratio of heat transfer enhancement factor (over smooth channels) and the corresponding friction enhancement factor to the power 1/3.

scholarly journals Numerical analysis of heat transfer enhancement with the use of γ-Al2O3/water nanofluid and longitudinal ribs in a curved duct

2012 ◽  
Vol 16 (2) ◽  
pp. 469-480 ◽  
Author(s):  
Hosseinali Soltanipour ◽  
Parisa Choupani ◽  
Iraj Mirzaee
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Base Fluid ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Transfer Enhancement ◽  
Dean Number ◽  
Particle Volume ◽  
The Heat Transfer Coefficient

This paper presents a numerical investigation of heat transfer augmentation using internal longitudinal ribs and ?-Al2O3/ water nanofluid in a stationary curved square duct. The flow is assumed 3D, steady, laminar, and incompressible with constant properties. Computations have been done by solving Navier-Stokes and energy equations utilizing finite volume method. Water has been selected as the base fluid and thermo- physical properties of ?- Al2o3/ water nanofluid have been calculated using available correlations in the literature. The effects of Dean number, rib size and particle volume fraction on the heat transfer coefficient and pressure drop have been examined. Results show that nanoparticles can increase the heat transfer coefficient considerably. For any fixed Dean number, relative heat transfer rate (The ratio of the heat transfer coefficient in case the of ?- Al2o3/ water nanofluid to the base fluid) increases as the particle volume fraction increases; however, the addition of nanoparticle to the base fluid is more useful for low Dean numbers. In the case of water flow, results indicate that the ratio of heat transfer rate of ribbed duct to smooth duct is nearly independent of Dean number. Noticeable heat transfer enhancement, compared to water flow in smooth duct, can be achieved when ?-Al2O3/ water nanofluid is used as the working fluid in ribbed duct.

Applied Pulsed Flow for Single-Phase Convective Heat Transfer Enhancement in a Laminar Flow Cooling System

2008 ◽  
Author(s):  
Bolaji O. Olayiwola ◽  
Gerhard Schaldach ◽  
Peter Walzel
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Cooling System ◽  
Transfer Enhancement ◽  
Flow Rates ◽  
The Heat Transfer Coefficient

Experimental and CFD studies were performed to investigate the enhancement of convective heat transfer in a laminar cooling system using flow pulsation in a flat channel with series of regular spaced fins. Glycerol-water mixtures with dynamic viscosities in the range of 0.001 kg/ms–0.01 kg/ms were used. A steady flow Reynolds number in the laminar range of 10 < Re < 1200 was studied. The amplitudes of the applied pulsations are in the range of 0.25 < A < 0.55 mm and the frequency range is 10 < f < 60 Hz. Two different cooling devices with active length L = 450 mm and 900 mm were investigated. CFD simulations were performed on a parallel-computer (Linux-cluster) using the software suit CFX11 from ANSYS GmbH, Germany. The rate of cooling was found to be significant at moderate low net flow rates. In general, no significant heat transfer enhancement at very low and high flow rates was obtained in compliance with the experimental data. The heat transfer coefficient was found to increase with increasing Prandtl number Pr at constant oscillation Reynolds number Reosc whereas the ratio of the hydraulic diameter to the length of the channel dh/L has insignificant effect on the heat transfer coefficient. This is due to enhanced fluid mixing. CFD results allow for performance predictions of different geometries and flow conditions.

Experimental and Numerical Investigations on the Heat Transfer of Film Cooling With Cylindrical Holes Fed With Internal Coolant Cross Flows

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Lin Ye ◽  
Cun-Liang Liu ◽  
Dao-En Zhou ◽  
Hui-Ren Zhu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Enhancement ◽  
Cross Flow ◽  
Skewed Distribution ◽  
Transfer Enhancement ◽  
High Heat Transfer ◽  
Cylindrical Holes ◽  
The Heat Transfer Coefficient

Abstract The heat transfer coefficient of cylindrical holes fed by varying internal cross-flow channels with different cross-flow Reynolds numbers Rec is experimentally studied on a low-speed flat-plate facility. Three coolant cross flow cases, including a smooth case and two ribbed cases with 45/135-deg ribs, are studied at Rec = 50,000, and 100,000 with varying blowing ratios M of 0.5, 1.0, and 2.0. A transient liquid-crystal (LC) measurement technique is used to determine the heat transfer coefficient. At lower M, the heat transfer enhancement regions are asymmetrical for the smooth and 45-deg cases. The asymmetrical vortex is more pronounced with increasing cross-flow direction velocity, resulting in a more skewed distribution at Rec = 100,000. Conversely, the contours are laterally symmetric in the 135-deg case at varying Rec. A fork-shaped trend with a relatively high heat transfer coefficient appears upstream, and the increases in the heat transfer in the 135-deg cases are lower than those in the 45-deg cases. As M increases to 2.0, the vortex intensity increases, resulting in a stronger scouring effect upstream, especially at large Rec. The range and degree are affected by Rec at M = 2.0. The core of the heat transfer enhancement is skewed to the −Y side for both cases.

scholarly journals Experimental Comparative Analysis of Overall Heat Transfer Coefficient in Counter-Flow Heat Exchanger by using Helical Ribs

2021 ◽  
pp. 42-53
Author(s):  
Ankesh Kumar ◽  
Ajay Singh ◽  
Parag Mishra
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Heat Transfer Enhancement ◽  
Cold Water ◽  
Hot Water ◽  
Transfer Enhancement ◽  
Enhancement Technique ◽  
The Heat Transfer Coefficient

More performance or reduced the size of heat exchanger can be achieved by heat transfer enhancement technique. Tube helical ribs have been used as one of the passive heat transfer enhancement technique and are most widely used tube in a several heat transfer process. The results of the heat transfer characteristics in horizontal double pipe with helical ribs are presented. Six test section with different characteristics parameters of helical rib depth 1.0mm, 1.25mm, 1.5mm and helical rib pitch 4mm, 6mm, 8mm, are tested. Cold water and hot water are used as the working fluids in the shell side and tube side respectively. Experiments are performed under the condition of mass flow rate varying from 0.030 to 0.130kg/s for cold water and 0.040 to 0.140kg/s for hot water respectively. The inlet cold and hot water temperature are between 28- 300C and between 68-710C respectively. The results obtained from the tubes with helical ribs are compared with those without helical ribs. It is found that the helical ribs have a significant effect on the heat transfer coefficient and the heat transfer increases with the helical rib pitches and depth. Based on fitting the experimental data, on- isothermal correlations of the heat transfer coefficient and friction factor are proposed.

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.

Heat Transfer Enhancement in a Horizontal Channel by the Addition of Curved Baffles

2006 ◽  
Author(s):  
J. L. Luviano ◽  
A. Hernandez ◽  
C. Rubio ◽  
D. Banerjee
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Transfer Rate ◽  
Fluid Motion ◽  
Horizontal Channel ◽  
Parallel Plates ◽  
Energy Transfer Rate ◽  
Transfer Enhancement ◽  
The Heat Transfer Coefficient

This paper presents the heat transfer and fluid dynamics analysis of a horizontal channel formed by parallel plates with periodic insertions of heated blocks, having curved deflectors to direct the flow. The heat transfer coefficient investigated is compared with that of the horizontal channel without deflectors. The aim of the deflectors is to lead the fluid to the space between the heated blocks increasing the dynamics in this area. This zone will normally, without deflectors, become a stagnant fluid zone in which low energy transfer rate occurs. The results show that the heat transfer coefficient is larger as compared to that of the case without deflectors. The increment in the heat transfer coefficient is due primarily to the fluid motion stirred in the area between the heated block due to the deflectors. However, it must be pointed out. This implementation also increases the pressure drop in the channel.

scholarly journals Comparison of heat transfer performance of ZnO-PG, α-Al2O3-PG, and γ-Al2O3-PG nanofluids in car radiator

2019 ◽  
Vol 9 ◽  
pp. 184798041987646 ◽  
Author(s):  
XiaoRong Zhou ◽  
Yi Wang ◽  
Kai Zheng ◽  
Haozhong Huang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Propylene Glycol ◽  
Flow Rate ◽  
Volume Concentration ◽  
Maximum Heat ◽  
Cooling Performance ◽  
Maximum Heat Transfer ◽  
The Heat Transfer Coefficient

In this study, the cooling performance of nanofluids in car radiators was investigated. A car radiator, temperature measuring instrument, and other components were used to set up the experimental device, and the temperature of nanofluids passing through the radiator was measured by this device. Three kinds of nanoparticles, γ-Al2O3, α-Al2O3, and ZnO, were added to propylene glycol to prepared nanofluids, and the effects of nanoparticle size and type, volume concentration, initial temperature, and flow rate were tested. The results indicated that the heat transfer coefficients of all nanofluids first increased and then decreased with an increase in volume concentration. The ZnO-propylene glycol nanofluid reached a maximum heat transfer coefficient at 0.3 vol%, and the coefficient decreased by 25.6% with an increase in volume concentration from 0.3 vol% to 0.5 vol%. Smaller particles provided a better cooling performance, and the 0.1 vol% γ-Al2O3-propylene glycol nanofluid had a 19.9% increase in heat transfer coefficient compared with that of α-Al2O3-propylene glycol. An increase in flow rate resulted in a 10.5% increase in the heat transfer coefficient of the 0.5 vol% α-Al2O3-propylene glycol nanofluid. In addition, the experimental temperature range of 40–60°C improved the heat transfer coefficient of the 0.2 vol% ZnO-propylene glycol nanofluid by 46.4%.

Phase Change Material Particulate Flow Through a Rectangular Channel: Effect of Parachute-Shaped Particles on the Heat Transfer

2011 ◽  
Author(s):  
Laura Small ◽  
Fatemeh Hassanipour
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Phase Change ◽  
Transfer Coefficient ◽  
Heat Transfer Enhancement ◽  
Phase Change Material ◽  
Volume Fraction ◽  
Particulate Flow ◽  
Transfer Enhancement ◽  
Change Material

This study presents numerical simulations of forced convection with parachute-shaped encapsulated phase-change material particles in water, flowing through a square cross-section duct with top and bottom iso-flux surfaces. The system is inspired by the gas exchange process in the alveolar capillaries between the red blood cells (RBC) and the lung tissue. The numerical model was developed for the motion of elongated encapsulated phase change particles along a channel in a particulate flow where particle diameters are comparable with the channel height. Results of the heat transfer enhancement for the parachute-shaped particles are compared with the circular particles. Results reveal that the key role in heat transfer enhancement is the snugness movement of the particles and the parachute-shaped geometry yields small changes in heat transfer coefficient when compared to the circular ones. The effects of various parameters including particle diameter and volume-fraction, as well as fluid speed, on the heat transfer coefficient is investigated and reported in this paper.

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