EXPERIMENTAL INVESTIGATIONS ON THE COOLING PERFORMANCE OF MICROCHANNELS USING ALUMINA NANOFLUIDS WITH DIFFERENT BASE FLUIDS

2018 ◽  
Vol 25 (3) ◽  
pp. 283-291 ◽  
Author(s):  
Harkirat Sandhu ◽  
D. Gangacharyulu ◽  
Mani Kanwar Singh
Keyword(s):  
Experimental Investigations ◽  
Cooling Performance

scholarly journals Experimental investigations of thermal performance improvement of aluminum ceiling panel for heating and cooling by covering its surface with paint

2018 ◽  
Vol 44 ◽  
pp. 00002 ◽  
Author(s):  
Łukasz Amanowicz ◽  
Janusz Wojtkowiak
Keyword(s):  
Heat Exchange ◽  
Performance Improvement ◽  
Aluminum Surface ◽  
Experimental Investigations ◽  
Cooling Performance ◽  
Heating Performance ◽  
Heating And Cooling ◽  
Heat Exchange Surface ◽  
Low Energy Buildings ◽  
Exchange Surface

Due to the low emissivity of raw metal surface (i.e. aluminum), the specific heating or cooling performance of non-painted surfaces is powered mainly on the natural convection and is relatively small. It can be sufficient for low energy buildings but not for the traditional ones. To increase the heat exchange through the radiation one can cover the raw surface with paint to increase its emissivity. To investigate the influence of paint cover on the heating and cooling performance of the ceiling-oriented flat aluminum surface the experimental investigations were done. The experiment was conducted on the aluminum ceiling panel with heat exchange surface of the dimensions 0.32 ⨯ 3.0 m. Heating performance of painted surface increased from 2.3 to 2.8 times and cooling performance increased from 1.5 to 1.7 times in the comparison to the non-painted one.

Numerical and experimental investigations of electronic evaporative cooling performance with a coiled channel

2016 ◽  
Vol 94 ◽  
pp. 256-265 ◽  
Author(s):  
Xiang Yin ◽  
Feng Cao ◽  
Lei Jin ◽  
Bin Hu ◽  
Pengcheng Shu ◽  
...  
Keyword(s):  
Evaporative Cooling ◽  
Experimental Investigations ◽  
Cooling Performance

Experimental Investigations of the Film Cooling Performance of a Micro-Tangential-Jet Scheme on a Gas Turbine Vane: Part 1 — Effectiveness

2012 ◽  
Author(s):  
O. Hassan ◽  
I. Hassan
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Density Ratio ◽  
Suction Side ◽  
Experimental Investigations ◽  
Stream Velocity ◽  
Pressure Side ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Turbine Vane

This paper presents experimental investigations of the film cooling effectiveness performance of a Micro-Tangential-Jet (MTJ) Film cooling scheme on a gas turbine vane using transient Thermochromic Liquid Crystal (TLC) technique. The MTJ scheme is a micro-shaped scheme designed so that the secondary jet is supplied tangentially to the vane surface. The scheme combines the benefits of micro jets and tangential injection. The film cooling performance of one row of holes on both pressure and suction sides were investigated at a blowing ratio ranging from 0.5 to 1.5 on the pressure side and 0.25 to 0.625 on the suction side. The average density ratio during the investigations was 0.93, and the Reynolds Number was 1.4E+5, based on the free stream velocity and the main duct hydraulic diameter. The pitch to diameter ratio of the cooling holes is 5 on the pressure side and 6.5 on the suction side. The turbulence intensity during all investigations was 8.5%. Minor changes in the Mach number distribution around the airfoil surface were observed due to the presence of the MTJ scheme, compared with the case with no MTJ scheme. The investigations showed great film cooling performance for the MTJ scheme, high effectiveness values, and excellent lateral jet spreading. A 2-D coolant film was observed in the results, which is a characteristic of the continuous slot schemes only. The presence of this 2-D film layer helps minimize the rate of mixing between the main and coolant streams and provides uniform thermal loads on the surface. Furthermore, it was noticed that the rate of effectiveness decay on the suction side was less than that on the pressure side, while the lateral jet spreading on the pressure side was better than that of the suction side. The main disadvantage of the MTJ scheme is the increased pressure drop.

Experimental Investigations of the Effect of Scheme Exit Height and Double Row Injection on the Film Cooling Performance of a Micro Tangential Jet Scheme: Part I — Pressure Side

2015 ◽  
Author(s):  
O. Hassan ◽  
I. Hassan
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Suction Side ◽  
Average Density ◽  
Hole Diameter ◽  
Experimental Investigations ◽  
Pressure Side ◽  
Thermochromic Liquid Crystal ◽  
Double Row ◽  
Cooling Performance

This paper presents experimental investigations of the effect of scheme exit height and double jet injection on the film cooling performance of a Micro-Tangential-Jet (MTJ) scheme. The investigations were conducted over a gas turbine vane pressure side using the transient Thermochromic Liquid Crystal technique. The suction side investigations are presented in Part II of the present paper. The MTJ scheme is a micro-shaped scheme designed so that the micro-sized secondary jet is supplied tangentially to the vane surface. The scheme combines the benefits of micro jets and tangential injection. In order to investigate the effect of scheme exit height, one row of the MTJ scheme with 1.0 hole diameter exit height and another row with 1.5 hole diameter exit height were investigated. Meanwhile, to investigate the effect of double injection, one row of the MTJ scheme in staggered arrangement with one row of fan-shaped scheme was investigated. The investigations were conducted at various blowing ratios, calculated based on the scheme exit area. The average density ratio, turbulence intensity and Reynolds number were 0.93, 8.5, and 1.4E+5, respectively. The investigations showed that the smaller the exit height, the better the film cooling performance. Meanwhile, double injecting the secondary stream from MTJ and shaped schemes did not result in significant film cooling enhancement due to the enhanced turbulence over the vane surface.

Studies on Cooling Performance of Round Cooling Holes With Various Configurations on a High-Pressure Turbine Vane

2018 ◽  
Author(s):  
Ken-ichi Funazaki ◽  
Fumiya Kikuchi ◽  
Issei Tashiro ◽  
Takeomi Ideta ◽  
Yuhi Tanaka
Keyword(s):  
High Pressure ◽  
Gas Turbines ◽  
Large Scale ◽  
Experimental Investigations ◽  
Test Model ◽  
High Pressure Turbine ◽  
Blow Down ◽  
Ir Camera ◽  
Cooling Performance ◽  
Turbine Vane

This study deals with detailed experimental investigations on cooling performance of round cooling holes with three hole configurations on the pressure surface of a large-scale test model of a high-pressure turbine vane for gas turbines, where one configuration is a conventional one and the other two are newly designed through a GA (Generic Algorithm) optimization. The purpose of this study is to see how those new hole configurations perform under realistic flow conditions. A blow-down type wind tunnel is used in this study, where IR camera-based transient method is applied to the measurement of film effectiveness and heat transfer distributions on the test model. Numerical simulations using a commercial software are also carried out to enhance the understanding of the cooling performance of each of the hole configurations.

Cooling Performance of Using a Confined Slot Jet Impinging onto Heated Heat Sinks

2005 ◽  
Vol 128 (1) ◽  
pp. 82-91 ◽  
Author(s):  
Ta-Wei Lin ◽  
Ming-Chang Wu ◽  
Li-Kang Liu ◽  
Chun-Jen Fang ◽  
Ying-Huei Hung
Keyword(s):  
Steady State ◽  
Jet Impingement ◽  
Separation Distance ◽  
Heat Sinks ◽  
Experimental Investigations ◽  
Width Ratio ◽  
Cooling Performance ◽  
Nusselt Numbers ◽  
Data Regression ◽  
Good Agreement

A series of experimental investigations on the studies related to transient- and steady-state cooling performance from the horizontally heated heat sinks with a confined slot jet impingement have been conducted. The relevant parameters influencing the transient convective cooling performance include the steady-state Grashof number, ratio of jet separation distance to nozzle width, ratio of heat sink height to nozzle width, and jet Reynolds number. The transient heat transfer behaviors such as the temperature distribution, local and average Nusselt numbers on the heated heat sinks have been systematically explored. Two empirical correlations of steady-state local and average Nusselt numbers are presented. Furthermore, a complete composite correlation of steady-state average Nusselt number for mixed convection due to jet impingement and buoyancy is proposed. This empirical correlation obtained by data regression is in good agreement with the experimental data. The maximum and average regression errors are 7.46% and 2.87%, respectively.

scholarly journals Vibration and cooling performances of piezoelectric cooling fan: numerical and experimental investigations

2020 ◽  
Vol 306 ◽  
pp. 04002
Author(s):  
Thomas Jin-Chee Liu ◽  
Yu-Shen Chen ◽  
Hsi-Yang Ho ◽  
Jyun-Ting Liu
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Experimental Methods ◽  
Experimental Investigations ◽  
Experimental Measurements ◽  
Cooling Performance ◽  
Optimal Geometry ◽  
Cooling Fan ◽  
Fan Blade ◽  
Good Agreement

In this paper, the vibration and cooling performances of the piezoelectric cooling fan are studied. The finite element and experimental methods are adopted for the analyses. The natural frequency, mode shape, flapping amplitude, and cooling performance are discussed for the primary design. The numerical results have good agreement with the experimental measurements. For the cooling purpose, the piezoelectric cooling fan has to work under the natural frequency. The aspect ratio 2:3 is the optimal geometry of the fan blade.

Experimental Investigations of the Effect of Scheme Exit Height and Double Row Injection on the Film Cooling Performance of a Micro Tangential Jet Scheme: Part II — Suction Side

2015 ◽  
Author(s):  
O. Hassan ◽  
I. Hassan
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Suction Side ◽  
Average Density ◽  
Experimental Investigations ◽  
Stream Velocity ◽  
Thermochromic Liquid Crystal ◽  
Double Row ◽  
Cooling Performance ◽  
Staggered Arrangement

This paper presents experimental investigations of the effect of scheme exit height and double jet injection on the film cooling performance of a Micro-Tangential-Jet (MTJ) scheme on the suction side of a gas turbine vane using the transient Thermochromic Liquid Crystal (TLC) technique. In part I of the present paper the investigations over the pressure side are presented. The MTJ scheme is a micro-shaped scheme designed so that the micro-sized secondary jet is supplied tangentially to the vane surface. In order to investigate the effect of scheme exit height, one row of the MTJ scheme with exit height of 1.5 hole diameters was investigated and compared with the case of 1.0 hole diameter scheme exit height. Meanwhile, to investigate the effect of double injection, one row of the MTJ scheme in staggered arrangement with one row of fan-shaped scheme was investigated. The investigations were conducted at a blowing ratio, calculated based on the scheme exit area, ranging from 0.25 to 0.625. The average density ratio during the investigations was 0.93, and the Reynolds Number was 1.4E+5, based on the free stream velocity and the main duct hydraulic diameter. The pitch to diameter ratio of the cooling holes is 6.5, and the turbulence intensity during all investigations was 8.5%. The increase in the MTJ scheme exit height did not result in significant change in the Mach number distribution. Moreover, increasing the scheme exit height resulted in enhanced effectiveness performance. The enhanced effectiveness was accompanied with Heat Transfer Coefficient (HTC) ratio augmentation as well. As a result, a reduction in the Net Heat Flux Reduction (NHFR) accompanied increasing the scheme exit height from 1.0 to 1.5 hole diameters. Besides, adding a row of shaped schemes in front of the MTJ scheme result in significant effectiveness reduction, compared to the case of single row injection. The latter was attributed to the presence of the shaped scheme inclination angle that result in enhanced secondary stream loss due to the perpendicular momentum component to the vane surface accompanying the shaped scheme secondary jet.

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