Experimental Investigation of Rewetting During Quenching of Hot Surface by Round Jet Impingement Using Al2O3–Water Nanofluids

2016 ◽  
Author(s):  
Avadhesh K. Sharma ◽  
Mayank Modak ◽  
Santosh K. Sahu
Keyword(s):  
Experimental Investigation ◽  
Cooling System ◽  
Removal Rate ◽  
Pure Water ◽  
Heat Removal ◽  
Jet Impingement ◽  
Dimensionless Number ◽  
Surface Cooling ◽  
Fuel Rods ◽  
Hot Surface

Impinging jet surface cooling is being used in many industrial and engineering applications due to their higher heat removal rate. Jet impingement is one of the methods to cool hot surfaces, especially in textile, metal and electronic industries. Due to high heat removal rate the jet impingement cooling of the hot surfaces is being used in nuclear industries. During the loss of coolant accidents (LOCA) in nuclear power plant, an emergency core cooling system (ECCS) cool the cluster of clad tubes using consisting of fuel rods. The usual water flow within a reactor core is bottom to top, parallel to the fuel rods. When a hot surface quenched at very high temperature using a jet of cold fluid, during the quenching the initial heat transfer is limited by film boiling. The effective cooling takes place only after the surface temperature is below the leidenfrost temperature. In the present work an experimental investigation has been carried out to analyze the rewetting phenomenon of a hot vertical stainless steel foil by circular impinging jets of pure water and Al2O3–water nanofluids. The rewetting time and rewetting velocity in the form of dimensionless number (Peclet number) obtained from the thermal images obtained from infrared thermal imaging camera (A655sc, FLIR System). Experiments are performed for different Reynolds number (Re = 5000, 8000), and Al2O3–water nanofluids concentration (Φ = 0.15%, 0.6%)

Experimental Investigation of Submerged Impinging Jet Using Cu-Water Nanofluid

2010 ◽  
Author(s):  
Qiang Li ◽  
Yimin Xuan ◽  
Feng Yu ◽  
Junjie Tan
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Volume Fraction ◽  
Cooling System ◽  
Heated Surface ◽  
Particle Volume Fraction ◽  
Jet Impingement ◽  
Particle Volume ◽  
Impingement Cooling ◽  
System Pressure

An experimental investigation was performed to study the heat transfer and flow features of Cu-water nanofluids (Cu particles with 26 nm diameter) in a submerged jet impingement cooling system. Three particular nozzle-to-heated surface distances (2, 4 and 6 mm) and four particle volume fractions (1.5%, 2.0%, 2.5% and 3.0%) are involved in the experiment. The experimental results reveal that the suspended nanoparticles increase the heat transfer performance of the base liquid in the jet impingement cooling system. Within the range of experimental parameters considered, it has been found that highest surface heat transfer coefficients can be achieved using a nozzle-to-surface distance of 4 mm and the nanofluid with 3.0% particle volume fraction. In addition, the experiments show that the system pressure drop of the dilute nanofluids is almost equal to that of water under the same entrance velocity.

Design of the Controller Cooling System of an Electric Vehicle

2014 ◽  
Vol 663 ◽  
pp. 213-217 ◽  
Author(s):  
M.M. Rahman ◽  
T.J. Hua ◽  
H.Y. Rahman
Keyword(s):  
Heat Transfer ◽  
Electric Vehicle ◽  
Cooling System ◽  
Removal Rate ◽  
Heat Removal ◽  
Developed Countries ◽  
Internal Resistance ◽  
Heat Transfer Fluids ◽  
Computational Fluid Dynamics Cfd ◽  
Forced Air

As an effort in reducing the dependency on fossil fuel, efforts have been gathered to develop electric vehicle (EV) for the past decades. Technology of electric vehicles (EV) has been initialized in developed countries. However, the latter have different geographical and environmental conditions. Therefore, the system of EV cannot be utilized directly in this country. The controller of an EV functions by utilizing a potentiometer; supplying a certain amount of voltage from the batteries to the motor by driver’s force applied to the acceleration pedal. This action generates a huge amount of heat due to the internal resistance of the controller (e.g. potentiometer). In order for an EV to operate at optimum condition, temperature of the controller has to be maintained at a certain limit. Hence an effective cooling system is required to be designed to fulfill the above condition. The objective of this paper is to present the design of the cooling system for the controller of an electric vehicle (EV). Two types of cooling system namely liquid cooled plate heat exchanger and forced air cooled finned structure are designed and evaluated to assess the behavior of heat transfer as well as effects of heat transfer fluids and cooling system material towards the heat removal rate. Simulation using Computational Fluid Dynamics (CFD) for both cooling systems has been carried out to have better understanding. CFD results are compared with some of the analytical results. The findings revealed that both systems are suitable to be implemented as EV controller cooling system in Malaysian Environment.

Multiphase Submerged Jet Impingement Cooling Utilizing Nanostructured Plates

2012 ◽  
Author(s):  
Ebru Demir ◽  
Ali Kosar ◽  
Turker Izci ◽  
Osman Yavuz Perk ◽  
Muhsincan Sesen ◽  
...  
Keyword(s):  
Cooling System ◽  
Electronic Devices ◽  
Control Sample ◽  
Heat Removal ◽  
Jet Impingement ◽  
Impinging Jets ◽  
Copper Plate ◽  
Impingement Cooling ◽  
Surface Morphologies ◽  
Aluminum Base

An experimental setup is designed to simulate the heat dissipated by electronic devices and to test the effects of nanostructured plates in enhancing the heat removal performance of jet impingement systems in such cooling applications under boiling conditions. Prior experiments conducted in single phase have shown that such different surface morphologies are effective in enhancing the heat transfer performance of jet impingement cooling applications. In this paper, results of the most recent experiments conducted using multiphase jet impingement cooling system will be presented. Distilled water is propelled into four microtubes of diameter 500 μm that provide the impinging jets to the surface. Simulation of the heat generated by miniature electronic devices is simulated through four aluminum cartridge heaters of 6.25 mm in diameter and 31.75 mm in length placed inside an aluminum base. Nanostructured plates of size 35mm×30mm and different surface morphologies are placed on the surface of the base and two thermocouples are placed to the surface of the heating base and the base is submerged into deionized water. Water jets generated using microtubes as nozzles are targeted to the surface of the nanostructured plate from a nozzle to surface distance of 1.5 mm and heat removal characteristics of the system is studied for a range of flow rates and heat flux, varying between 107.5–181.5 ml/min and 1–400000 W/m2, respectively. The results obtained using nanostructured plates are compared to the ones obtained using a plain surface copper plate as control sample and reported in this paper.

An Experimental Investigation on Heat Transfer Characteristics of Hot Surface by Using CuO–Water Nanofluids in Circular Jet Impingement Cooling

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Mayank Modak ◽  
Sandesh S. Chougule ◽  
Santosh K. Sahu
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Jet Impingement ◽  
Test Surface ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Hot Surface ◽  
Plate Distance

In the present study, an experimental investigation has been carried out to analyze the heat transfer characteristics of CuO–water nanofluids jet on a hot surface. A rectangular stainless steel foil (AISI-304, 0.15 mm thick) used as the test surface is electrically heated to obtain the required initial temperature (500 °C). The distribution of surface heat flux on the target surface is evaluated from the recorded thermal images during transient cooling. The effect of nanoparticle concentration and Reynolds number of the nanofluids on the heat transfer characteristics is studied. Tests are performed for varied range of Reynolds number (5000 ≤ Re ≤ 12,000), two different CuO–water nanofluids concentration (Ф = 0.15%, 0.6%) and two different nozzle to plate distance (l/d = 6, 12). The enhancement in Nusselt number for CuO–water nanofluids was found to be 14% and 90%, for nanofluids concentration of Ф = 0.15% and Ф = 0.60%, respectively, compared to pure water. The test surface characteristics after nanofluids jet impingement are studied using scanning electron microscope (SEM). Based on the investigation, a correlation among various parameters, namely, Reynolds number (Re), Prandtl number (Pr), nozzle to plate distance (l/d), and Nusselt number (Nu), is presented.

scholarly journals Numerical Investigations on Magnetohydrodynamic Pump Based Microchannel Cooling System for Heat Dissipating Element

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1713
Author(s):  
Jae-Hyeong Seo ◽  
Mahesh Suresh Patil ◽  
Satyam Panchal ◽  
Moo-Yeon Lee
Keyword(s):  
Shear Stress ◽  
Nusselt Number ◽  
Applied Voltage ◽  
Hartmann Number ◽  
Cooling System ◽  
Removal Rate ◽  
Heat Removal ◽  
Magnetic Flux Density ◽  
Numerical Investigations ◽  
Microchannel Cooling

Numerical investigations are performed on the magnetohydrodynamic (MHD) pump-based microchannel cooling system for heat dissipating element. In the present study, the MHD pump performance is evaluated considering normal current density, magnetic flux density, volumetric Lorentz force, shear stress and pump flow velocity by varying applied voltage and Hartmann number. It is found that for a low Hartmann number, the Lorentz force increases with an increase in applied voltage and Hartmann number. The velocity distribution along dimensionless width, the shear stress distribution along dimensionless width, the magnetic flux density along the dimensionless width and radial magnetic field distribution showed symmetrical behavior. The MHD pump-based microchannel cooling system performance is evaluated by considering the maximum temperature of the heat dissipating element, heat removal rate, efficiency, thermal field, flow field and Nusselt number. In addition, the influence of various nanofluids including Cu-water, TiO2-water and Al2O3-water nanofluids on heat transfer performance of MHD pump-based microchannel is evaluated. As the applied voltage increased from 0.05 V to 0.35 V at Hartmann number 1.41, the heat removal rate increased by 39.5%. The results reveal that for low Hartmann number, average Nusselt number is increasing function of applied voltage and Hartmann number. At the Hartmann number value of 3.74 and applied voltage value of 0.35 V, average Nusselt numbers were 12.3% and 15.1% higher for Cu-water nanofluid compared to TiO2-water and Al2O3-water nanofluids, respectively. The proposed magnetohydrodynamic microcooling system is effective without any moving part.

Analysis and Performance Comparison of Competing Desktop Cooling Technologies

2007 ◽  
Author(s):  
Niru Kumari ◽  
Shankar Krishnan ◽  
Suresh V. Garimella
Keyword(s):  
Heat Sink ◽  
Single Phase ◽  
Heat Dissipation ◽  
Removal Rate ◽  
Heat Removal ◽  
Jet Impingement ◽  
Ambient Air ◽  
Pumping Power ◽  
Maximum Heat ◽  
Phase Liquid

The present work compares the performance of various competing thermal management technologies for the desktop sector. An air-cooled heat sink used for the Intel Pentium 4 Processor is used as the baseline for comparison. Heat sinks based on metal foams, microchannels (with single-phase liquid) and jet impingement (with air and single-phase liquid) are compared based on total heat sink system thermal resistance and heat dissipation capacity. The analysis is carried out under the constraints of a fixed heat sink volume available in a typical desktop, and a fixed ambient air temperature. The comparison of thermal resistances is made under the constraint of the same pumping power as in the baseline heat sink. The maximum heat dissipation possible using a particular heat sink technology is estimated and this can be used to select technologies to meet future thermal challenges as outlined in the International Technology Roadmap for Semiconductors (ITRS). The results show that microchannel and liquid jet impingement cooling provide the greatest heat removal rates under the given constraints. The maximum power dissipation for these cases is almost double that of the baseline air-cooled heat sink. Under the chosen constant value of the junction to heat sink resistance, only modest improvements in heat removal rate are obtained with the microchannel and jet impingement technologies even if the pumping power constraint is relaxed, and a specific pump curve is used instead. The junction to heat sink resistance is significantly higher than the heat sink to ambient resistance, and is the key determinant in the comparisons.

Optimal Ratio of Heat Removal Rate to Pumping Power for PCM Emulsion Fluids: Low Reynolds Number Limits

2006 ◽  
Author(s):  
P. Maloji ◽  
Y.-X. Tao
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Phase Change ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Removal Rate ◽  
Pure Water ◽  
Heat Removal ◽  
Pumping Power ◽  
Optimal Ratio

There are many applications where high heat transfer removal rate in a limited tight space are required. The applications include mini and micro-scale channels flows in compact heat exchangers. The increase in heat transfer rate often requires the significant increase in fluid velocity and therefore the increase in the pumping power. One option is to utilize Phase Change Materials (PCM). This study contributes to the further understanding of performance enhancement of an improved heat transfer fluid by studying the optimal ratio of heat removal rate to the fluid pumping power. PCMs have the unique characteristics that can increase the thermal capacity of heat transfer fluids by providing latent heat capacity at a temperature different than the melting point of the carrier fluid. The ratio of heat transfer rate (Q) to fluid pumping power (P) is about twice as that for using pure water without PCM particles. The effectiveness factor (compared to water without PCM) is also doubled. It has been observed that as Re decreases the effective factor increases and Q/P ratio increases, which is also true if the concentration of PCM increases. In this experimental study focuses are on the heat transfer enhancement effects for very low Reynolds number (Re < 180 of pure water velocity) and PCM concentration slurry flow of 10% to 20%. Experimental investigations relevant to PCM slurry flows are carried out. Experimental results indicate that PCM slurry's heat transfer coefficient and apparent specific heat are affected significantly by the phase change process and the slurry mass fraction. It is found that the Q/P ratio primarily is a function of Reynolds number.

Experimental investigation on thermal characteristics of hot surface by synthetic jet impingement

2020 ◽  
Vol 165 ◽  
pp. 114596
Author(s):  
Pushpanjay K. Singh ◽  
Santosh K. Sahu ◽  
Prabhat K. Upadhyay ◽  
Akash K. Jain
Keyword(s):  
Experimental Investigation ◽  
Thermal Characteristics ◽  
Jet Impingement ◽  
Synthetic Jet ◽  
Hot Surface

Thermal Nanofluid Property Model With Application to Nanofluid Flow in a Parallel Disk System—Part II: Nanofluid Flow Between Parallel Disks

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Yu Feng ◽  
Clement Kleinstreuer
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Cooling System ◽  
Pure Water ◽  
Jet Impingement ◽  
Velocity Profiles ◽  
Entropy Generation Rate ◽  
Nanofluid Flow ◽  
Parallel Disks ◽  
Simulation Results

This is the second part of a two-part paper which proposes a new theory explaining the experimentally observed enhancement of the thermal conductivity, knf, of nanofluids (Part I) and discusses simulation results of nanofluid flow in an axisymmetric jet-impingement cooling system using different knf-models (Part II). Specifically, Part II provides numerical simulations of convective nanofluid heat transfer in terms of velocity profiles, friction factor, temperature distributions, and Nusselt numbers, employing the new knf-model. Flow structures and the effects of nanoparticle addition on heat transfer and entropy generation are discussed as well. Analytical expressions for velocity profiles and friction factors, assuming quasi-fully-developed flow between parallel disks, have been derived and validated for nanofluids as well. Based on the numerical simulation results for both alumina-water nanofluids and pure water, it can be concluded that nanofluids show better heat transfer performance than convectional coolants with no great penalty in pumping power. Furthermore, the system’s entropy generation rate is lower for nanofluids than for pure water.

NUMERICAL AND EXPERIMENTAL INVESTIGATION OF PASSIVE HEAT REMOVAL FROM POROUS BED IN PATH FACILITY

2018 ◽  
Author(s):  
Anil Kumar Sharma ◽  
Venkateswarlu S ◽  
E Hemanth Rao ◽  
B Malarvizhi ◽  
S S Murthy ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Heat Removal ◽  
Porous Bed
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