Experimental Study on Heat Transfer Characteristics of Circular Jet Impingement Boiling on the Variety of Structured Copper Surfaces in Stagnation Zone

2016 ◽  
Author(s):  
Mayank Modak ◽  
Vishal Nirgude ◽  
Avadhesh K. Sharma ◽  
Santosh K. Sahu
Keyword(s):  
Heat Transfer ◽  
Jet Impingement ◽  
Copper Surface ◽  
Heat Transfer Characteristics ◽  
Two Phase ◽  
Copper Surfaces ◽  
Transfer Rates ◽  
Copper Target ◽  
Pin Fin ◽  
Transfer Characteristics

In the present work an attempt has been made to study the heat transfer characteristics of single circular jet on a variety of enhanced surfaces. In the present investigation three different copper target surfaces of various surface modifications: bare copper surface, pin fin enhancement surface and a flat surface coated with alumina porous layer. The heat transfer performance of each surface is studied in two phase boiling operation at different flow rates (3959 < Re < 7900). The comparison indicates that both the surface modification have enhanced the boiling heat transfer rates.

Numerical Investigation of an Integrated Impingement and Pin-Fin Cooling Configuration in a Wedge Duct

2014 ◽  
Author(s):  
Xiaoxing Feng ◽  
Shuqing Tian ◽  
Jiangtao Bai ◽  
Hong Zhang ◽  
Kefei Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Jet Impingement ◽  
Heat Transfer Characteristics ◽  
Convergence Angle ◽  
Turbine Blade Cooling ◽  
Pin Fin ◽  
Transfer Characteristics ◽  
Nusselt Numbers ◽  
Pin Fins ◽  
Cooling Design

In the gas turbine blade cooling design, impingement insert and pin-fins arranged as an array in the trailing region are usually used to enhance the heat transfer. To investigate the heat transfer characteristics of the integrated impingement and the pin-fin cooling configuration in wedge channels, the numerical simulations with k-ε turbulence model and scalable wall function algorithm are carried out using a commercial CFD code. To reveal the factors that enhance the heat transfer in the blade internal trailing channel, heat transfer characteristics of pin-fins with impingement slot are compared with that without impingement slot. The effect of the ratio of jet impingement distance to pin-fin diameter on the heat transfer is analyzed. The convergence angle of the channel is studied. The heat transfer characteristics of the integrated impingement and pin-fin cooling configuration in the wedge channels are evaluated. The results reveal that the impinging jet enhances largely the heat transfer in the first two rows. In the studied range of L/D = 0.5∼2.0, the heat transfer of the pin-fins with impingement is about 20%∼25% higher than that without impingement. The averaged Nusselt numbers on the endwall surface, the pin surface, and the overall surfaces respectively in the wedge duct increase linearly with the increase of Reynolds number, decrease gradually with the increase of the impingement distance and increase with the increase of the convergence angle.

Local Heat Transfer Characteristics in Channels With Pin Fin and Pin Fin-Dimple Arrays

2011 ◽  
Author(s):  
Yu Rao ◽  
Chaoyi Wan ◽  
Yamin Xu ◽  
Shusheng Zang
Keyword(s):  
Heat Transfer ◽  
Local Heat Transfer ◽  
Flow Region ◽  
Local Heat ◽  
Main Flow ◽  
Heat Transfer Characteristics ◽  
Transfer Rates ◽  
Pin Fin ◽  
Transfer Characteristics ◽  
Spatially Resolved

A comparative study was conducted to investigate the spatially-resolved local heat transfer characteristics of air turbulent flow in rectangular channels with pin fin and pin fin-dimple arrays. The spatially-resolved Nusselt numbers on the endwall surface of the pin fin and pin fin-dimple channels have been obtained and compared with each other. Compared with the pin fin channel, the pin fin-dimple channel shows distinguishing heat transfer characteristics on the wall beneath the main flow and the wake flow region. Due to the presence of the dimples in the pin fin arrays, additional strong vortex flows are generated near the wall beneath the main flow region, which distinctively increase the heat transfer rates there; however the turbulent mixing in the wake of the pin fins is reduced appreciably, which leads to decreased heat transfer rates in the wake.

Heat Transfer Characteristics of Downward Facing Hot Horizontal Surfaces Using Mist Jet Impingement

2017 ◽  
Author(s):  
Ashutosh Kumar Yadav ◽  
Parantak Sharma ◽  
Avadhesh Kumar Sharma ◽  
Mayank Modak ◽  
Vishal Nirgude ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Cooling System ◽  
Water Pressure ◽  
Jet Impingement ◽  
Surface Heat ◽  
Heat Transfer Characteristics ◽  
Impingement Cooling ◽  
Transfer Characteristics

Impinging jet cooling technique has been widely used extensively in various industrial processes, namely, cooling and drying of films and papers, processing of metals and glasses, cooling of gas turbine blades and most recently cooling of various components of electronic devices. 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. Controlled cooling, as an important procedure of thermal-mechanical control processing technology, is helpful to improve the microstructure and mechanical properties of steel. In industries for heat transfer efficiency and homogeneous cooling performance which usually requires a jet impingement with improved heat transfer capacity and controllability. It provides better cooling in comparison to air. Rapid quenching by water jet, sometimes, may lead to formation of cracks and poor ductility to the quenched surface. Spray and mist jet impingement offers an alternative method to uncontrolled rapid cooling, particularly in steel and electronics industries. Mist jet impingement cooling of downward facing hot surface has not been extensively studied in the literature. The present experimental study analyzes the heat transfer characteristics a 0.15mm thick hot horizontal stainless steel (SS-304) foil using Internal mixing full cone (spray angle 20 deg) mist nozzle from the bottom side. Experiments have been performed for the varied range of water pressure (0.7–4.0 bar) and air pressure (0.4–5.8 bar). The effect of water and air inlet pressures, on the surface heat flux has been examined in this study. The maximum surface heat flux is achieved at stagnation point and is not affected by the change in nozzle to plate distance, Air and Water flow rates.

Evaporation of Single Drops of n-Pentane/n-Hexane Mixtures in Water

1992 ◽  
Vol 114 (4) ◽  
pp. 965-971 ◽  
Author(s):  
H. Shimaoka ◽  
Y. H. Mori
Keyword(s):  
Heat Transfer ◽  
Temperature Difference ◽  
Vapor Bubble ◽  
Experimental Results ◽  
Rise Velocity ◽  
Heat Transfer Characteristics ◽  
Two Phase ◽  
Transfer Characteristics ◽  
Preceding Work ◽  
Liquid Vapor

The evaporation of isolated drops (2.1−3.0 mm diameter) of nonazeotropic n-pentane/n-hexane mixtures in the medium of water was observed under pressures of 0.11−0.46 MPa and temperature differences up to 27 K. The mole fractions of n-pentane, x, in the mixtures were set at 0.9, 0.5, 0.1, and 0, to be completed by the condition x = 1 set in a preceding work (Shimaoka and Mori, 1990). Experimental results are presented in terms of the instantaneous rise velocity of, and an expression of instantaneous heat transfer to, each drop evaporating and thereby transforming into a liquid/vapor two-phase bubble and finally into a vapor bubble. The dependencies of the heat transfer characteristics on the pressure, the temperature difference, and x are discussed.

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