Heat Transfer Characteristics of a Pair of Impinging Rectangular Flame Jets

2003 ◽  
Vol 125 (6) ◽  
pp. 1140-1146 ◽  
Author(s):  
L. L. Dong ◽  
C. W. Leung ◽  
C. S. Cheung
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Reynolds Number ◽  
Flat Plate ◽  
Effective Diameter ◽  
Heat Transfer Characteristics ◽  
Average Heat ◽  
Transfer Characteristics ◽  
Premixed Laminar ◽  
Plate Distance

Experiments were carried out to study the heat transfer characteristics of a pair of premixed, laminar, rectangular, butane/air flame jets impinging vertically upon a water-cooled flat plate. The effects of jet-to-jet spacing and the nozzle-to-plate distance on heat transfer were examined. The Reynolds number of the exit flow was 800. The non-dimensional jet-to-jet spacing ranged from 0.9 to 4.1, while the non-dimensional nozzle-to-plate distance varied from 1 to 6. The between-jet interference decreased with increasing jet-to-jet spacing and nozzle-to-plate distance. Both the maximum local and average heat flux occurred at a moderate jet-to-jet spacing of twice effective nozzle diameter, and when the nozzle-to-plate distance was equal to the effective diameter of the nozzle. The heat flux decreased faster along the shorter sides of the slot jets than the longer sides.

Heat Transfer Characteristics of Impinging Two-Dimensional Air Jets

1966 ◽  
Vol 88 (1) ◽  
pp. 101-107 ◽  
Author(s):  
Robert Gardon ◽  
J. Cahit Akfirat
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Two Dimensional ◽  
Heat Transfer Characteristics ◽  
Transfer Coefficients ◽  
Average Heat ◽  
Heat Transfer Coefficients ◽  
Transfer Characteristics ◽  
Air Jets

Local as well as average heat transfer coefficients between an isothermal flat plate and impinging two-dimensional jets were measured for both single jets and arrays of jets. For a large and technologically important range of variables the results have been correlated in relatively simple terms, and their application to design is briefly considered.

Heat Transfer Characteristics of an Inclined Impinging Jet on a Curved Surface in Crossflow

2014 ◽  
Vol 136 (8) ◽  
Author(s):  
X. L. Wang ◽  
H. B. Yan ◽  
T. J. Lu ◽  
S. J. Song ◽  
T. Kim
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Flat Plate ◽  
Local Heat Transfer ◽  
Impinging Jet ◽  
Local Heat ◽  
Curved Surface ◽  
Heat Transfer Characteristics ◽  
Potential Core ◽  
Transfer Characteristics

This study reports on heat transfer characteristics on a curved surface subject to an inclined circular impinging jet whose impinging angle varies from a normal position θ = 0 deg to θ = 45 deg at a fixed jet Reynolds number of Rej = 20,000. Three curved surfaces having a diameter ratio (D/Dj) of 5.0, 10.0, and infinity (i.e., a flat plate) were selected, each positioned systematically inside and outside the potential core of jet flow where Dj is the circular jet diameter. Present results clarify similar and dissimilar local heat transfer characteristics on a target surface due to the convexity. The role of the potential core is identified to cause the transitional response of the stagnation heat transfer to the inclination of the circular jet. The inclination and convexity are demonstrated to thicken the boundary layer, reducing the local heat transfer (second peaks) as opposed to the enhanced local heat transfer on a flat plate resulting from the increased local Reynolds number.

scholarly journals Heat Transfer Characteristics of a Coaxial Inverse Diffusion Flame Jet Impingement with an Induced Swirl

2020 ◽  
Vol 38 (4) ◽  
pp. 887-894
Author(s):  
Shankar Badiger ◽  
Vadiraj V. Katti ◽  
Anil R. Tumkur
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Diffusion Flame ◽  
Twisted Tape ◽  
Heat Transfer Characteristics ◽  
Average Heat ◽  
Impingement Plate ◽  
Inverse Diffusion ◽  
Inverse Diffusion Flame ◽  
Plate Distance

Flame jet has a wide range of applications in the industries and also in domestics field. The efforts have been put to enhance the heat transfer and to reduce the emissions from the premixed and inverse diffusion flame burners. Especially, the IDF burner suffers from lack of proper air and fuel mixing, the swirl generated motion from twisted tape would improve the combustion efficiency. Therefore, an aim of experiment is to study the heat transfer characteristics of an inverse diffusion flame (IDF) jet impinging on a flat surface in a coaxial tube burner with swirl. The twisted tape of 15mm pitch creates the swirl in the flame jet (Corresponding to the twist ratio of 3 and swirl number of 0.52). An effect of swirl at air jet Reynolds number of 1000 to 2500 and surface of the burner-to-impingement plate distance (H/da) varying from 2 to 20 is studied at fixed equivalence ratio (ϕ) of 1.1. An average heat flux and peak heat flux are studied for the region of 0<r/da<3 on an impingement plate. From an investigation, it is found that the swirling in the flame jet enhances the average heat flux by up to 179.2%. The maximum average heat flux is found at the optimal burner-to-target plate distance of 8.

An Experimental Investigation on Heat Transfer Characteristics of Hot Surface by Using CuO–Water Nanofluids in Circular Jet Impingement Cooling

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Mayank Modak ◽  
Sandesh S. Chougule ◽  
Santosh K. Sahu
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Jet Impingement ◽  
Test Surface ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Hot Surface ◽  
Plate Distance

In the present study, an experimental investigation has been carried out to analyze the heat transfer characteristics of CuO–water nanofluids jet on a hot surface. A rectangular stainless steel foil (AISI-304, 0.15 mm thick) used as the test surface is electrically heated to obtain the required initial temperature (500 °C). The distribution of surface heat flux on the target surface is evaluated from the recorded thermal images during transient cooling. The effect of nanoparticle concentration and Reynolds number of the nanofluids on the heat transfer characteristics is studied. Tests are performed for varied range of Reynolds number (5000 ≤ Re ≤ 12,000), two different CuO–water nanofluids concentration (Ф = 0.15%, 0.6%) and two different nozzle to plate distance (l/d = 6, 12). The enhancement in Nusselt number for CuO–water nanofluids was found to be 14% and 90%, for nanofluids concentration of Ф = 0.15% and Ф = 0.60%, respectively, compared to pure water. The test surface characteristics after nanofluids jet impingement are studied using scanning electron microscope (SEM). Based on the investigation, a correlation among various parameters, namely, Reynolds number (Re), Prandtl number (Pr), nozzle to plate distance (l/d), and Nusselt number (Nu), is presented.

A visualization study on flat plate heat pipe (FPHP)

2021 ◽  
pp. 095765092199022
Author(s):  
Wan Yu ◽  
Dan Gao ◽  
Gang Wang ◽  
Tao Hu ◽  
Qichao Gong ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Film ◽  
Flat Plate ◽  
Heat Pipe ◽  
Heat Transfer Characteristics ◽  
Plate Heat ◽  
Transfer Characteristics ◽  
Flat Plate Heat Pipe ◽  
Vapor Liquid

With the aim to analyze the flow pattern and heat transfer characteristics of the working fluid in a flat plate heat pipe (FPHP) which was sealed by a transparent tempered glass plate, ethanol, acetone, and R141b were taken as the working medium, and visual experiments were performed at different heat flux when the inclination angle was 90°. The vapor-liquid distribution and the heat transfer characteristics of the FPHP were investigated at different liquid filling ratios. According to the experimental results and the recording of high-speed cameras, some important conclusions had been drawn as follows: (i) As the power increases, the vapor-liquid interface in the FPHP declines and the effects of dryout is significantly intnsified, leading to a sharp increase in temperature. The FPHP with a filling ratios of 25.7% owns better thermal performance than that with the filling ratios of 11.8% and 66% at different heating power; (ii) the bubble generation inside the FPHP became more intense with increasing heat flux, and various bubble movement patterns were found at different the liquid filling ratios; (iii) As the liquid film flowed downward, the thickness of the liquid film increased at first and then decreases. The condensation of steam was reduced due to the thickening of the liquid film on the wall. The liquid film became thinner when it was entrapped and evaporated in the downward flow.

scholarly journals Effect of Pulsating Flame Jet on Flow and Heat Transfer Characteristics

2020 ◽  
Vol 77 (1) ◽  
pp. 11-23
Author(s):  
Wongsathon Boonyopas ◽  
Nuttamas Uppatam ◽  
Chattawat Aroonrujiphan ◽  
Natthaporn Kaewchoothong ◽  
Somchai Sae-ung ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flame Structure ◽  
Cooling Water ◽  
Digital Camera ◽  
Heat Transfer Characteristics ◽  
Distance Ratio ◽  
Average Heat ◽  
Transfer Characteristics ◽  
Impingement Surface

This research aims to study the effect of pulsating frequency on flame structure and heat transfer characteristics of premixed flame from a pipe nozzle. The LPG and air were used as gas fuel and oxidizer. The equivalence ratios ( ) were evaluated at 0.8, 1.0, and 1.2 under a constant Reynolds number Re = 500. The effect of nozzle-to-impingement surface distance ratio was investigated at H = 2D to 10D, here D is the nozzle diameter at 12 mm. The frequency of pulsating (f) was varied from f = 0 to 10 Hz using a solenoid valve. The flame structures of free flame jet and the impinging flame jet were recorded with a digital camera. The average heat flux on impingement surface was measured with water cooling plate and evaluated from the heat balance of the cooling water. The results show that the pulsating of flame jet become having gap on flame and the mushroom appear at the end of flame. The size of mushroom structure becomes larger when increasing the frequency. While the non-pulsating jet did not appear in this structure. Pulsating flame jet can increase the overall average heat flux on the impingement surface up to about 12% for case of = 1.2 and H = 2D and f = 10 Hz. when compared to case of f = 0 Hz.

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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