Numerical Investigation of a Confined Laminar Jet Impingement Cooling of Heat Sources Using Nanofluids

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Orkodip Mookherjee ◽  
Shantanu Pramanik ◽  
Uttam Kumar Kar
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Base Fluid ◽  
Strong Dependence ◽  
Jet Impingement ◽  
Effective Density ◽  
Eckert Number ◽  
Maximum Temperature ◽  
Pumping Power

Abstract The thermal and fluid dynamic behavior of a confined two-dimensional steady laminar nanofluid jet impinging on a horizontal plate embedded with five discrete heating elements subjected to a constant surface heat flux has been studied for a range of Reynolds number (Re) from 100 to 400 with Prandtl number, Pr = 6.96, of the base fluid. Variation of inlet Reynolds number produces a significant change of the flow and heat transfer characteristics in the domain. Increasing the nanoparticle concentration (ϕ) from 0% to 4% exhibits discernible change in equivalent Re and Pr caused by the modification of dynamic viscosity, effective density, thermal conductivity, and specific heat of the base fluid. Considerable improvement in heat transfer from the heaters is observed as the maximum temperature of the impingement wall is diminished from 0.95 to 0.55 by increasing Re from 100 to 400; however, the result of increasing ϕ on cooling of the heaters is less appreciable. Self-similar behavior has been depicted by cross-stream variation of temperature and streamwise heat flux in the developed region along the impingement wall up to Re = 300 for ϕ=0% to 4%. But the spread of the respective quantities shows strong dependence on ϕ at Re = 300 with sudden attenuation in magnitude in the developed region of flow. Substantial influence of Re is evident on Eckert number and pumping power. Eckert number decreases, whereas pumping power increases with an increase in Re, and the respective variations exhibit correspondence with power fit correlations.

CFD study of slot jet impingement heat transfer with nanofluids

2015 ◽  
Vol 230 (2) ◽  
pp. 206-220 ◽  
Author(s):  
Rabijit Dutta ◽  
Anupam Dewan ◽  
Balaji Srinivasan
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Base Fluid ◽  
Volume Fraction ◽  
Jet Impingement ◽  
Pumping Power ◽  
Inlet Velocity ◽  
Impingement Heat Transfer

We present a numerical investigation of hydrodynamic and heat transfer behaviors for Al2O3–water nanofluids for laminar and turbulent confined slot jets impingement heat transfer at nanoparticle volume fractions of 3% and 6%. A comparison of the nanofluid with the base fluid has been performed for the same Reynolds number and same jet inlet velocity. A single-phase fluid approach was used to model the nanofluid. Further, the thermo-physical properties of nanofluid were calculated using a recent approach. For the same value of Reynolds number, maximum increase in the average heat transfer coefficient at the impingement plate was found to be approximately 27% and 22% for laminar and turbulent slot impingements, respectively, for 6% volume fraction of nanofluid as compared to that of water. However, the pumping power curve showed a steep increase with the volume fraction with nearly five times increase in the pumping power observed for 6% volume fraction nanofluid. Further, the energy-based performance was assessed with the help of the performance evaluation criterion (PEC). PEC values indicate that nanofluids do not necessarily represent the most efficient coolants for this type of application. Moreover, at the same jet inlet velocity, a reduction in the heat transfer coefficient of 7% and 20% was observed for nanofluid as compared to base fluid for laminar and turbulent flows, respectively.

Submerged Jet Impingement Boiling of Water Under Subatmospheric Conditions

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Ruander Cardenas ◽  
Vinod Narayanan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Roughness ◽  
Reynolds Number ◽  
Strong Dependence ◽  
Jet Impingement ◽  
Nucleate Boiling ◽  
Pressure Surface ◽  
Wall Superheat ◽  
Jet Impingement Boiling

An experimental study of jet impingement boiling is presented for water under saturated and subcooled conditions. Unique to this study is the documentation of boiling curves of a submerged water jet under subatmospheric conditions. Data are reported at a fixed nondimensional nozzle-to-surface distance of H/dj = 6 and for a fixed surface-to-nozzle diameter ratio, dsurf/dj, of 23.8. Saturated jet impingement experiments are performed at three subatmospheric pool pressures of 0.176 bar, 0.276 bar, and 0.478 bar with corresponding saturation temperatures of 57.3 °C, 67.2 °C, and 80.2 °C. At each pressure, jet impingement boiling at varying Reynolds numbers are characterized and compared with pool boiling heat transfer. The effect of surface roughness and fluid subcooling is studied at the lowest pressure of 0.176 bar. Boiling curves indicate a strong dependence of heat flux on jet Reynolds number in the partially developed nucleate boiling region but only a weak dependence in the fully developed nucleate boiling region. At a fixed wall superheat, fluid subcooling is found to shift the boiling curve to the left thereby enhancing heat transfer performance. Critical heat flux is found to increase with increases in pressure, surface roughness, and Reynolds number.

Submerged Jet Impingement Boiling on a Polished Silicon Surface

2011 ◽  
Author(s):  
Preeti Mani ◽  
Ruander Cardenas ◽  
Vinod Narayanan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Silicon Surface ◽  
High Speed ◽  
Jet Impingement ◽  
Working Fluid ◽  
Uniform Heat Flux ◽  
Submerged Jet ◽  
Jet Impingement Boiling

Submerged jet impingement boiling has the potential to enhance pool boiling heat transfer rates. In most practical situations, the surface could consist of multiple heat sources that dissipate heat at different rates resulting in a surface heat flux that is non-uniform. This paper discusses the effect of submerged jet impingement on the wall temperature characteristics and heat transfer for a non-uniform heat flux. A mini-jet is caused to impinge on a polished silicon surface from a nozzle having an inner diameter of 1.16 mm. A 25.4 mm diameter thin-film circular serpentine heater, deposited on the bottom of the silicon wafer, is used to heat the surface. Deionized degassed water is used as the working fluid and the jet and pool are subcooled by 20°C. Voltage drop between sensors leads drawn from the serpentine heater are used to identify boiling events. Heater surface temperatures are determined using infrared thermography. High-speed movies of the boiling front are recorded and used to interpret the surface temperature contours. Local heat transfer coefficients indicate significant enhancement upto radial locations of 2.6 jet diameters for a Reynolds number of 2580 and upto 6 jet diameters for a Reynolds number of 5161.

scholarly journals Non-stationary convective heat transfer in an air synthetic impinging jet. Experiment and numerical simulation

2021 ◽  
Vol 2119 (1) ◽  
pp. 012024
Author(s):  
V.V. Lemanov ◽  
M.A. Pakhomov ◽  
V.I. Terekhov ◽  
Z. Travnicek
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Target Surface ◽  
Local Heat ◽  
Reynolds Stress Model ◽  
Heat Flux Sensor ◽  
Flux Sensor

Abstract An unsteady local heat transfer in an air synthetic non-steady-state jet impingement onto a flat plate with a variation of the Reynolds number, nozzle-to-plate distance and pulses frequency is experimentally and numerically studied. Measurements of the averaged and pulsating heat transfer at the stagnation point are conducted using a heat flux sensor. The axisymmetric URANS method and the Reynolds stress model are used for numerical simulations. For local values of heat transfer, zones with the maximum instantaneous value of heat flux and heat transfer coefficient are identified. The heat transfer increases at relatively low nozzle-to-plate distances (H/d ≤ 4). The heat transfer decreases at high distance from the orifice and target surface. An increase in the Reynolds number causes reduction of heat transfer.

Heat Transfer Investigation with Multiple Jet Impingement

2020 ◽  
Vol 12 (3) ◽  
Author(s):  
Niranjan Murthy ◽  
B.K. Naveenkumar
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Research Work ◽  
Jet Impingement ◽  
Test Surface ◽  
Simple Relationship ◽  
Flux Flow ◽  
Air Jets ◽  
Air Jet

An experimental study was carried out to study the effect of multiple jet impingement on a virtual electronic component using water and air as working fluids. It consists of an electrically heated test plate of size 20mm×20mm. Heat flux is varied between 25 to 250W/cm2 was dissipated using 0.25 and 0.5mm diameter jets placed in a 7×7 array with a pitch of 3mm. The difference in temperature between test surface and fluid inlet is within 30 degC for water jets and within 75 degC for air jet experiments. Experiments were conducted by changing the heat flux, flow rate and distance between the test surface and jet exit and [iv] horizontal and vertical positioning of the jets. It was found that heat flux, jet diameter and Reynolds number are important factors in determining the heat transfer. The effects of distance between test surface and jet exit [Z] and positioning of the jets were insignificant. Though the multiple jet impingement heat transfer problem is complex, the heat transfer results could be correlated using a simple relationship in the form of Nu = AqmRen. The constant (m) which indicates the effect of heat flux has the value of 0.8 and 0.9 depending upon the jet diameter and the coolant. The constant (n) which indicates the influence of Reynolds number has the value of 0.25 for both water and air jets. The value of constant (A) is different for water and air jets. The correlation developed in this research work can be effectively used to design multiple water and air jet cooling system for electronic components.

Laminar Forced Convection of Nanofluids in a Circular Tube: A New Nonhomogeneous Flow Model

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Saptarshi Mandal ◽  
P. S. Ghoshdastidar
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Base Fluid ◽  
Flow Model ◽  
Circular Tube ◽  
Average Heat Transfer Coefficient ◽  
Pumping Power ◽  
Average Heat ◽  
Nonhomogeneous Flow ◽  
Agglomeration Of Nanoparticles

Abstract In this paper, the local and average heat transfer coefficient enhancement or deterioration, and rise in pumping power in steady, laminar alumina–water, titania–water, and carbon nanotube (CNT)–water nanofluids flow in a horizontal circular tube subjected to constant heat flux at the outer wall have been investigated numerically based on a new variable property nonhomogeneous flow model which takes into account agglomeration of nanoparticles. The results have been compared with the published experimental results of Utomo et al. (Utomo, A. T. et al., 2014, “The Effect of Nanoparticles on Laminar Heat Transfer in a Horizontal Tube,” Int. J. Heat Mass Transfer, 69, pp. 77–91.) using various property models of thermal conductivity and viscosity, and for equal Reynolds number, equal inlet velocity, equal mass flowrate, and equal pumping power of nanofluid and base fluid. Stream function–vorticity–temperature formulation and finite difference method have been used. Using the same Reynolds number of nanofluid and base fluid gives much higher enhancement in average heat transfer coefficient as compared to other modes of comparison. Interestingly, the criterion of equal pumping power gives negative percent enhancement in the case of CNT–water nanofluid. The pumping power is found to rise for all three nanofluids. It is found that consideration of agglomeration of nanoparticles has produced improved accuracy in the numerical solution.

scholarly journals Thermal and Fluid Dynamic Performance Comparison of Three Nanofluids in Microchannels Using Analytical and Computational Models

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 754
Author(s):  
Dustin R. Ray ◽  
Roy Strandberg ◽  
Debendra K. Das
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Aluminum Oxide ◽  
Copper Oxide ◽  
Wall Temperature ◽  
Base Fluid ◽  
Fluid Dynamic ◽  
Convective Heat Transfer Coefficient ◽  
Pumping Power ◽  
Flux Boundary Condition

The fluid dynamic and thermal performance of three nanofluids containing aluminum oxide, copper oxide, and silicon dioxide nanoparticles dispersed in 60:40 ethylene glycol and water base fluid as a coolant in a microchannel heatsink are compared here by two methods. The first is a simple analytical analysis, which is acceptable for very low nanoparticle volumetric concentration (1–2%). The second method is a rigorous three-dimensional finite volume conjugate heat transfer and fluid dynamic model based upon a constant heat flux boundary condition, which is applicable for cooling electronic chips. The fluids’ thermophysical properties employed in the modeling are based on empirically derived, temperature dependent correlations from the literature. The analytical and computational results for pressure drop and Nusselt number were in good agreement with the nanofluids showing a maximum difference of 4.1% and 2.9%, respectively. Computations cover the practical range of Reynolds number from 20 to 200 in the laminar regime. Based on equal Reynolds number, all of the nanofluids examined generate a higher convective heat transfer coefficient in the microchannel than the base fluid, while copper oxide provided the most significant increase by 21%. Based on the analyses performed for this study, nanofluids can enhance the cooling performance of the heatsink by requiring a lower pumping power to maintain the same maximum wall temperature. Aluminum oxide and copper oxide nanofluids of 2% concentration reduce the pumping power by 23% and 22%, respectively, while maintaining the same maximum wall temperature as the base fluid.

Numerical Heat Transfer and Pressure Drop Studies of Turbulent Al2O3 - Ethylene Glycol/Water Nanofluid Flow in an Automotive Radiator Tube

2015 ◽  
Vol 787 ◽  
pp. 152-156 ◽  
Author(s):  
N. Mohanrajhu ◽  
K. Purushothaman ◽  
N. Kulasekharan
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Ethylene Glycol ◽  
Base Fluid ◽  
Unit Length ◽  
Thermal Characteristics ◽  
Turbulent Regime ◽  
Pumping Power ◽  
Numerical Heat Transfer ◽  
Nano Fluid

Automotive radiators use flattened tubes within which Ethylene Glycol (EG) and Water (W) based nanofluids flow to enhance the heat transfer. Computations were carried out to understand the flow and thermal characteristics of the Aluminium oxide based nanofluids, with EG:W ratio of 60:40 as the base fluid, flowing inside a flattened tube. The flow was maintained in the turbulent regime with the Reynolds number (Re) ranging from 5,000 to 14,000.Investigations were carried out for nano particle concentrations (φ) varying from 1% to 5% of the base fluid by volume. Computations were also carried out for a circular tube to study the influence of tube shape. The nanofluid with φ = 5% increased the Nusselt number values by 40% for the flattened tubes compared to the base fluid at Re =14,000. These estimates are done at constant flow Reynolds number in-line with literature, which necessitated increased inlet velocity, which meant increased pumping power. Pumping power increased with increase in φ and Re. For a constant pumping power per unit length (Pp) of 5W/m the values of average heat transfer coefficient () decreases with increase in φ. The values of for the 2% and 5% nano fluid were lower than the base fluid by 6% and 23.8% respectively. Nanofluid with φ = 1% alone showed a 1.2% higher value than the base fluid indicating the need of further exploration of φ in a closer range.

Effect of Jet Position on Cooling an Array of Heated Obstacles

2017 ◽  
Vol 10 (1) ◽  
Author(s):  
Hussein M. Maghrabie ◽  
M. Attalla ◽  
H. E. Fawaz ◽  
M. Khalil
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Flow Structure ◽  
Numerical Study ◽  
Cross Flow ◽  
Jet Impingement ◽  
Pumping Power ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Number Ratio

Numerical study of the effect of jet position (JP) on cooling process of an array of heated obstacles simulating electronic components has been investigated based on realizable k–ε model. Jet positions have been changed to impinge each row of obstacles consecutively. The experiments have been achieved at three different values of jet-to-channel Reynolds number ratio, Rej/Rec = 1, 2, and 4. In this study, a comparison between two different cooling processes, cross flow only (CF) and jet impingement with cross flow (JICF), has been achieved. The flow structure, heat transfer characteristics, and the pumping power have been investigated for different jet positions. The results show that the jet position affects significantly the flow structure, as well as the heat transfer characteristics. According to the results of average heat transfer coefficient and the pumping power, the more effective jet position for all values of jet-to-channel Reynolds number ratio (1, 2, and 4) is achieved when the jets impinge the third row of obstacles (JP3).

A Novel Cooling Enhancement in Microelectronic Devices and Systems Using Oscillatory Impinging Air Jets

2001 ◽  
Author(s):  
Victor Adrian Chiriac ◽  
Tien -Yu Tom Lee ◽  
Jorge Luis Rosales
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Channel Flow ◽  
High Temperatures ◽  
Local Heat Transfer ◽  
Impinging Jet ◽  
Maximum Temperature ◽  
Pumping Power ◽  
Cooling Enhancement ◽  
Unsteady Jet

Abstract A new cooling technique is proposed to simultaneously enhance the heat transfer and significantly reduce the prohibitive high temperatures usually reached by high-powered chips embedded in the last generation of packages. A comparison between flow and heat transfer characteristics for several types of microelectronic cooling arrangements was conducted using a numerical investigation. The maximum temperature and local heat transfer coefficient were determined on a single heated chip cooled by a channel flow, a steady impinging jet, and an oscillatory impinging jet at a Reynolds number of 600. A uniform inlet velocity was used for the channel flow calculation, and the upper and lower channel walls confined the jets. The calculation domain for the three simulations was identical; the steady jet configuration had an inlet jet width twice that of the unsteady jet. The results indicate that the unsteady nature of the confined impinging jet greatly enhances the removal of heat transfer and reduces the high temperatures on the heated chip. The jet core becomes distorted and buckles beyond a critical Reynolds number of 600, which leads to a sweeping motion of its tip (stagnation point). As a result of the combined buckling/sweeping jet motion, the cooled area is significantly enhanced. A comparison between the unsteady impinging jet and the stationary impinging jet reveals that the heat transfer enhancement provided by the unsteady jet is at least two times better. A 25% cooling enhancement is observed when compared with the channel flow technique, yet the jet uses a flow rate 6.3 times lower, therefore a smaller pumping power. The new cooling method does not require the incorporation of costly heat sinks and heat spreaders, or the unnecessary increase of pumping power/blower work, yet provides effective cooling at significantly reduced manufacturing/operating costs.

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