scholarly journals Mat Lab Coding and Experimental Analysis of Heat Transfer Rate In Multi Air Jet Impingement

2019 ◽  
Vol 8 (3) ◽  
pp. 1068-1077
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Jet Impingement ◽  
Heat Sinks ◽  
Pin Fin ◽  
Air Jets ◽  
Air Jet ◽  
Existence Time ◽  
Plate Distance

The Electronic equipment’s have turned out to be practically unavoidable. This electronic gadget assumes a key job in numerous basic zones of innovation and brought about high thickness of segments in little volume. In this manner, there has been a consistent increment in heat squandered rate from electronic segments. Advancement likewise prompted more prominent power in the segments and there is an extensive increment in the heat dissemination of electronic segments. Analysts for the most part utilized the idea of constrained convection air to evacuate heat at the outside of the segments. Increment the existence time of parts. In this present paper impinging air jets is examined tentatively. Heat transfer attributes are analyzed. Analysis have been directed at (Z/D =5, 10 and 15) and Velocity of air (V (m/sec) = 5.6,5.2,4.8,3.9,3.5,2.6) and (V(m/sec)= 6.1,5.8,5.3,3.7,3.3,2.9) for flat plate and pin fin heat sinks are respectively and Heat input (Q=32watts). Empirical correlations are developed from results and Mat lab coding was developed at different conditions and the results show that the relation between heat transfer coefficient Vs velocity and Reynolds number Vs Nusselt number and Nu(theoretical) Vs Nu(experimental) and heat transfer coefficient Vs nozzle to plate distance(z/d)

Experimental Investigation of Air–Water Mist Jet Impingement Cooling Over a Heated Cylinder

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Chunkyraj Khangembam ◽  
Dushyant Singh
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Stagnation Point ◽  
Jet Impingement ◽  
Water Mist ◽  
Heated Cylinder ◽  
Air Jet ◽  
The Heat Transfer Coefficient

Experimental investigation on heat transfer mechanism of air–water mist jet impingement cooling on a heated cylinder is presented. The target cylinder was electrically heated and was maintained under the boiling temperature of water. Parametric studies were carried out for four different values of mist loading fractions, Reynolds numbers, and nozzle-to-surface spacings. Reynolds number, Rehyd, defined based on the hydraulic diameter, was varied from 8820 to 17,106; mist loading fraction, f ranges from 0.25% to 1.0%; and nozzle-to-surface spacing, H/d was varied from 30 to 60. The increment in the heat transfer coefficient with respect to air-jet impingement is presented along with variation in the heat transfer coefficient along the axial and circumferential direction. It is observed that the increase in mist loading greatly increases the heat transfer rate. Increment in the heat transfer coefficient at the stagnation point is found to be 185%, 234%, 272%, and 312% for mist loading fraction 0.25%, 0.50%, 0.75%, and 1.0%, respectively. Experimental study shows identical increment in stagnation point heat transfer coefficient with increasing Reynolds number, with lowest Reynolds number yielding highest increment. Stagnation point heat transfer coefficient increased 263%, 259%, 241%, and 241% as compared to air-jet impingement for Reynolds number 8820, 11,493, 14,166, and 17,106, respectively. The increment in the heat transfer coefficient is observed with a decrease in nozzle-to-surface spacing. Stagnation point heat transfer coefficient increased 282%, 248%, 239%, and 232% as compared to air-jet impingement for nozzle-to-surface spacing of 30, 40, 50, and 60, respectively, is obtained from the experimental analysis. Based on the experimental results, a correlation for stagnation point heat transfer coefficient increment is also proposed.

scholarly journals Experimental investigation of heat transfer of flowing liquid film with inserted metal foam layer subjected to air jet impingement

2019 ◽  
Vol 23 (5 Part B) ◽  
pp. 3093-3104
Author(s):  
Yunsong Zhang ◽  
Wei Chen ◽  
Wei Li ◽  
Xiao Zhu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Liquid Film ◽  
Transfer Coefficient ◽  
Porous Layer ◽  
Metal Foam ◽  
Jet Impingement ◽  
Heated Wall ◽  
Flowing Liquid ◽  
Air Jet

In this paper, coupling the air jet impingement and the copper metal foam above flowing liquid film were employed to enhance the heat transfer. The thickness of flowing liquid film can be controlled owing to the application of the metal foam above the film, and its solid matrix extends the air-liquid-solid interface of heating surface. The evaporated water can be supplied by the capillary force in the porous layer. The experiments were conducted to investigate the performances of the flowing liquid film with inserted porous layer subjected to impinging jet air. The air jet velocity, the flow rate and thicknesses of the liquid film as well as the porosity of metal foam influence the surface temperature of heated wall and the corresponding local heat transfer coefficient greatly. The change ratios of heat transfer coefficient due to the above factors were presented. More cooling can be obtained on the heated wall in the flowing liquid film with inserted porous layer subjected to impinging jet air while the higher liquid film velocity and air jet velocity, the thinner liquid film and the lower porosity of metal foam occur.

scholarly journals Experimental analysis of parallel plate and crosscut pin fin heat sinks for electronic cooling applications

2010 ◽  
Vol 14 (1) ◽  
pp. 147-156 ◽  
Author(s):  
Harish Sivasankaran ◽  
Godson Asirvatham ◽  
Jefferson Bose ◽  
Bensely Albert
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Parallel Plate ◽  
Electronic Cooling ◽  
Heat Sinks ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Pin Fin ◽  
Pin Fins

Experimental investigation of parallel plate fin and the crosscut pin fin heat sinks where the heating element placed asymmetrically is performed. Theoretical calculations were done and compared with the experimental results. A comparative study was made based on their efficiencies, heat transfer coefficient, and the thermal performance. From the experimental results it was found that the average heat transfer coefficient of parallel plate fins is higher than that of crosscut pin fins with many perforations. However the performance efficiency of both the crosscut pin fins and parallel plate fins is similar. A hybrid approach was employed to significantly optimize the distance between the fan and heat sink for parallel plate and crosscut pin fins. Parallel plate heat sink with an average heat transfer coefficient of 46 W/m?K placed at an optimum fan distance of 40-60 mm is selected as the suitable choice for the micro-electronic cooling when the heating element is placed asymmetrically.

The Thermal Resistance of Pin Fin Heat Sinks in Transverse Flow

2003 ◽  
Author(s):  
Sukhvinder Kang ◽  
Maurice Holahan
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Building Blocks ◽  
Heat Sinks ◽  
Cfd Simulations ◽  
Pin Fin ◽  
Thermal Wake

This paper presents a physics based analytical model to predict the thermal behavior of pin fin heat sinks in transverse forced flow. The key feature of the model is the recognition that unlike plate fins, streamwise conduction does not occur in pin fin heat sinks. Thus, the heat transfer from each fin depends on its local air temperature or adiabatic temperature and the local adiabatic heat transfer coefficient. Both experimental data and simplified CFD simulations are used to develop the two building blocks of the model, the thermal wake function and the adiabatic heat transfer coefficient. These building blocks are then used to include the effect of the thermal wake from upstream fins on the adiabatic temperature of downstream fins in determining the fin-by-fin heat transfer within the pin fin array. This approach captures the essential physics of the flow and heat transport within the fin array and yields an accurate model for predicting the thermal resistance of pin fin heat sinks. Model predictions are compared with existing experimental data and CFD simulations. The model is expected to provide a sound basis for a consistent performance comparison with plate fin heat sinks.

Supersonic Two-Phase Impinging Jet Heat Transfer

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Richard R. Parker ◽  
James F. Klausner ◽  
Renwei Mei
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Removal ◽  
Jet Impingement ◽  
Impinging Jet ◽  
High Heat Flux ◽  
Two Phase ◽  
Air Jet

The experimental heat transfer rates from a supersonic two-phase impinging air jet with disperse droplets are presented. The experimental configuration consists of an expanding disperse mixture of air and water through a converging–diverging nozzle, designed for Mach 3.26 with a liquid to air mass flow ratio ranging from 1.28% to 3.83%, impinging upon a thin film heater constructed of nichrome. The spatially varying heat transfer coefficient is measured, and peak values are on the order of 200,000 W/m2K. Two distinct regions of heat transfer are identified, one dominated by the jet impingement flow and another dominated by thin film heat transfer. The heat transfer coefficient of an impinging jet with dry air and no droplets is measured during the investigation as well. The heat transfer results are compared, and it is demonstrated that the addition of disperse water droplets to the jet significantly increases the heat removal capability of the jet as well as smoothing the spatial temperature distribution of the heater surface. As much as an order of magnitude increase in heat transfer coefficient is observed near the centerline of the jet and a factor of 3–5 increase is seen at a distance of approximately 4 nozzle diameters from the jet. The fundamental heat transfer coefficient measurements should benefit applications involving supersonic two-phase jets for high heat flux thermal management.

Experimental Measurements of the Flow and Heat Transfer of a Square Jet Impinging on an Array of Square Pin Fins

2005 ◽  
Vol 128 (1) ◽  
pp. 61-70 ◽  
Author(s):  
Johnny S. Issa ◽  
Alfonso Ortega
Keyword(s):  
Heat Transfer ◽  
Flow Behavior ◽  
Jet Impingement ◽  
Tip Clearance ◽  
Heat Sinks ◽  
Clearance Ratio ◽  
Pressure Loss Coefficient ◽  
Pin Fin ◽  
Air Jet ◽  
Pin Fins

The flow behavior and heat transfer due to free air jet impingement on pin fin heat sinks was experimentally studied. Flow velocities and tip clearance ratios were varied from 2to20m∕s and 0 to 1, respectively. The stagnation pressure recovered at the center of the heat sink was higher for tall pins than for short pins. The pressure loss coefficient showed little dependence on Re, increased with increasing pin density and pin diameter, and decreased with increasing pin height and clearance ratio. The overall base-to-ambient thermal resistance decreased with increasing Re number, pin density, and pin diameter.

Experimental Thermal Characterization of Pin Fin Heat Sinks With Top and Side Bypass

2005 ◽  
Author(s):  
Ning Lei ◽  
Alfonso Ortega
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Cross Section ◽  
Heat Sinks ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Pin Fin

Extensive tests were conducted to obtain thermal characteristics of pin fin heat sinks with pins of square cross-section under different top and side bypass conditions. A consistent set of aluminum heat sinks with constant planform area and variable pitch were utilized. The heat sinks were tested in an adjustable cross-section wind tunnel, which provides 0 to 1 top and 0 to 10 side clearance ratios. The base temperature of the heat sinks was measured under constant heat flux. The overall thermal resistance and average heat transfer coefficient of the heat sinks were calculated and the influence of top and side bypass was explored. The thermal experimental data were consistent with the previous hydraulic experimental data. With the increase of flow velocity, flow transition from laminar to turbulent flow was revealed by the thermal resistance data. It was found that the average heat transfer coefficient depends strongly on the flow velocity through the heat sinks. Heat sinks with side clearance only result in smaller overall thermal resistance compared to top clearance only at the same clearance ratio. In some cases, the heat sinks with a small side clearance had better thermal performance than the same heat sinks without clearance. The empirical equation for infinitely long tube bundles of circular cross-section was used to correlate the thermal experimental data.

Experimental and Numerical Investigation of Thermal Performance of Synthetic Jet Impingement

2020 ◽  
Author(s):  
Pushpanjay K. Singh ◽  
Rohit Kothari ◽  
Santosh K. Sahu ◽  
Prabhat K. Upadhyay ◽  
Shashwat Singh
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Test Specimen ◽  
Electronics Cooling ◽  
Jet Impingement ◽  
Synthetic Jet ◽  
Geometrical Parameters ◽  
The Heat Transfer Coefficient ◽  
Plate Distance

Abstract Synthetic jet potentially useful in electronics cooling is investigated both numerically and experimentally. In the present study, a confined three dimensional synthetic jet with sinusoidal moving wall is considered. Computations are carried out using the FLUENT software with the coupled user defined function describing the diaphragm movement. In this study the effect of various geometrical parameters influencing the flow field and heat transfer are investigated. The effects of change in orifice geometry (circular, square and rectangular), orifice aspect ratio, and jet-to-plate distance are studied for a given hydraulic diameter. The heat transfer results obtained from the synthetic jet is compared with the continuous jet. An electromagnetic actuator is used as an oscillating diaphragm for the generation of synthetic jet. A stainless steel foil with 0.05 mm thickness is used as the test specimen. The surface temperature of the test specimen is measured by using a thermal imaging technique during synthetic jet impingement and a constant temperature anemometer has been employed for velocity measurement. Tests are carried out for Reynolds number of 5448, varied range of jet-to-plate distance (1–18). The maximum value of the heat transfer coefficient is found to be 16 times more than the heat transfer coefficient for natural convection.

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