Heat Transfer Characteristics of a Liquid-Metal Filled Closed Thermosyphon

1972 ◽  
Vol 94 (3) ◽  
pp. 202-206 ◽  
Author(s):  
P. F. Pucci ◽  
J. C. R. Gerretsen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Metal ◽  
Uniform Heat Flux ◽  
Heat Transfer Characteristics ◽  
Constant Wall Temperature ◽  
Sodium Potassium ◽  
Transfer Characteristics ◽  
Wall Boundary Conditions ◽  
Existing Data

Experimentally determined heat transfer characteristics are presented for two geometrically similar, closed thermosyphons. Results using water, mercury, and the sodium-potassium eutectic, NaK 56/44, were obtained for two hot wall boundary conditions, namely, constant wall temperature and uniform heat flux. The water filled thermosyphon data were correlated over a range of td = GrdPr (d/Lh) from 5 × 104 to 1.3 × 107, which agrees with and extends existing data. The liquid-metal filled thermosyphon data were correlated over a range of GrdPr2 from 3. × 102 to 2. × 105.

Effect of Swirl Intensity on Heat Transfer Characteristics of Swirling Flame Impinging on a Flat Surface

2013 ◽  
Author(s):  
Gurpreet Singh ◽  
Subhash Chander
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Stagnation Point ◽  
Flat Surface ◽  
Operating Conditions ◽  
Uniform Heat Flux ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Swirl Intensity ◽  
Swirling Flame

An experimental investigation has been carried out to determine the effect of swirl intensity on heat transfer characteristics of swirling flame impinging on a flat surface. The swirl intensity was varied by using helical vane swirlers having angles of 15°, 30° and 60° (low, medium and high swirl). Qualitative flame structures were studied by taking direct photographs of impinging flames. Experiments were conducted for different helical vane swirlers at different dimensionless separation distances (H/d = 1–6) for fixed value of Reynolds number (Re = 5000) and equivalence ratio (ϕ = 1.0). A dip in heat flux was observed at stagnation point for all levels of swirl. Peak heat flux was observed slightly away from the stagnation point due to centrifugal effect. A comparison of stagnation point heat flux has been done for different swirl intensities and for fixed operating conditions. Most uniform heat flux distribution was obtained corresponds to 30° helical vane swirler (medium swirl) at all separation distances.

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.

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