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

2002 ◽  
Author(s):  
Johnny S. Issa ◽  
Alfonso Ortega
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Flow Behavior ◽  
Jet Impingement ◽  
Tip Clearance ◽  
Heat Sinks ◽  
Clearance Ratio ◽  
Cross Sectional ◽  
Pressure Loss Coefficient ◽  
Air Jet

An experimental investigation was conducted to explore the flow behavior, pressure drop, and heat transfer due to free air jet impingement on square in-line pin fin heat sinks (PFHS) mounted on a plane horizontal surface. A parametrically consistent set of aluminum heat sinks with fixed base dimension of 25 × 25 mm was used, with pin heights varying between 12.5 mm and 22.5 mm, and fin thickness between 1.5 mm and 2.5 mm. A 6:1 contracting nozzle having a square outlet cross sectional area of 25 × 25 mm was used to blow air at ambient temperature on the top of the heat sinks with velocities varying from 2 to 20 m/s. The ratio of the gap between the jet exit and the pin tips to the pin height, the so-called tip clearance ratio, was varied from 0 (no tip clearance) to 1. The stagnation pressure recovered at the center of the heat sink was higher for tall pins than short pins. The pressure loss coefficient showed a 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. Surprisingly, the dependence of the thermal resistance on the pin height and clearance ratio was shown to be mild at low Re, and to vanish at high Re number.

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)

scholarly journals Experimental and Numerical Examinations of Temperature Distributions along SSF Pin Fins Cast through Semisolid Materials Processing

2019 ◽  
Vol 8 (12) ◽  
pp. 500-503
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Stainless Steel ◽  
Heat Sinks ◽  
Materials Processing ◽  
Length Scale ◽  
Pin Fin ◽  
Temperature Distributions ◽  
Pin Fins ◽  
Enhancing Heat Transfer

Heat sinks or fins stand deployed for enhancing heat transfer. That’s why, planned experiments remain fortified for examining the impacts of SSF pin fin on thermal dispersal concerning constant thermal value 6 W/cm2 . For that five chromel-alumel thermocouples are preferred, above and beyond, SSF pin fins materials of stainless steel and aluminum. As anticipated, for both the stated SSF pin fins, temperature declines for increasing length scale. Besides, both results are comparable with each other. However, temperature distributions over SSF aluminum pin fin declines relatively at faster rate comparable to that over SSF stainless steel pin fin. Obviously, it may be owing to higher thermal conductivity of SSF aluminum pin fin. Therefore, it carries superior, pleasant and momentous thermal performances.

Effect of Pin Density on Heat-Mass Transfer and Fluid Flow at Low Reynolds Numbers in Minichannels

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
N. K. C. Selvarasu ◽  
Danesh K. Tafti ◽  
Neal E. Blackwell
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Entropy Generation ◽  
Plane Channel ◽  
Performance Measure ◽  
Tip Clearance ◽  
Turbulent Regime ◽  
Pin Fin ◽  
Pin Fins ◽  
Optimal Spacing

Previous investigations on the performance of straight pins, pins with tip clearance, and profiled fins showed that closely packed cylindrical pin fins are very competitive with the modified pins. Therefore, the objective of this paper is to investigate the effect of pin density on performance. Steady/time-dependent calculations are performed to investigate the effect of pin density on friction and heat transfer. Pins packed at distances of SD=1.1, 1.2, 1.3, 1.4, 1.5, 2.0, 2.5, and 3 pin diameters (D) are investigated for 10≤ReD≤600. Two performance measures are used to compare the different pin fin densities. The first measure is to maximize heat transfer capacity for a given pumping power compared with a plane channel. The second measure used is based on entropy generation minimization (EGM), where the objective is to reduce the total irreversibility of the pin fin array to obtain an optimal spacing. Based on the performance measure of maximizing heat capacity, it is shown that for plain channels operating in the laminar range using denser pin packing has distinct advantages with SD=1.1 providing the best augmentation. However, the augmentation in heat capacity becomes relatively independent of the pin density for a channel operating in the turbulent regime. Based on the EGM method, at ReD>200, SD=1.3, 1.4, and 1.5 are the most suitable, with the least entropy generation observed at SD=1.4. At ReD<200, SD=1.1, 1.2, and 1.3 are also suitable for keeping entropy generation low.

scholarly journals Heat Transfer From a Finned Surface in Ducted Air Jet Suction and Impingement

1999 ◽  
Vol 122 (3) ◽  
pp. 282-285 ◽  
Author(s):  
Luis A. Brignoni ◽  
Suresh V. Garimella
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Jet Impingement ◽  
Target Distance ◽  
Transfer Coefficients ◽  
Pin Fin ◽  
Heat Transfer Coefficients ◽  
Air Jet ◽  
Finned Surface ◽  
Different Diameters

Experimental measurements were obtained to characterize the thermal performance of ducted air suction in conjunction with a pin-fin heat sink. Four single nozzles of different diameters and two multiple-nozzle arrays were studied at a fixed nozzle-to-target distance, for different turbulent Reynolds numbers 5000⩽Re⩽20,000. Variations of nozzle-to-target distance, i.e., open area, in ducted suction were found to have a strong effect on heat transfer especially with the larger diameter single nozzle and both multiple-nozzle arrays. Enhancement factors were computed with the heat sink in suction flow, relative to a bare surface, and were in the range of 8.3 to 17.7, with the largest value being obtained for the nine-nozzle array. Results from the present study on air jet suction are compared with previous experiments with air jet impingement on the pin-fin heat sink. Average heat transfer coefficients and thermal resistance values are reported for the heat sink as a function of Reynolds number, air flow rate, and pumping power. [S1043-7398(00)00903-8]

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.

Effect of Pin-fins On Jet Impingement Heat Transfer Over a Rotating Disk

2021 ◽  
Author(s):  
Pratik S. Bhansali ◽  
Kishore Ranganath Ramakrishnan ◽  
Srinath V. Ekkad
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Jet Impingement ◽  
Reynolds Numbers ◽  
High Heat ◽  
Maximum Enhancement ◽  
Pin Fin ◽  
Smooth Disk ◽  
Pin Fins

Abstract Many engineering applications consist of rotating components which experience high heat load. For instance, applications like the gas turbine engine consist of rotating disks and the study of heat transfer over such rotating surfaces is of particular interest. In the case of gas turbines, the disk also needs to be protected from the ingress of hot turbine gases caused by the low pressure region created due to the radially outward pumping of fluid close to the rotating surface. Present experimental study investigates the effects of introducing pin-fins on heat transfer over surface of a rotating gas turbine disk. Experiments were conducted at rotational Reynolds numbers (ReR) of 5487 - 12803 and jet Reynolds numbers (Re) of 5000 - 18000, nozzle to target spacing (z/d = 2 - 6), impingement eccentricities (e = 0 -0.67), angles of impingement (0°-20°), and the pin fin height (Hf = 3.05mm - 19.05mm). Steady state temperature measurements were taken using thermocouples embedded in the disk, and area average Nusselt number (Nu) was calculated. The results have been compared with those for a smooth aluminum disk. Nu was significantly enhanced by the presence of pin-fins. The enhancement was higher for lower Re and the maximum enhancement was found to be 3.9 times that of a smooth disk for Re = 5000. Qualitative visualization of flow field has been performed for smooth and the pin-fin case using the commercial simulation package Ansys Fluent to further understand the flow features that result in the enhancement.

Sign in / Sign up

Export Citation Format

Share Document