Effects of geometric parameters on confined impinging jet heat transfer

Lou, Zhipeng; Mujumdar, Arun S.; Yap, Cheng‐Hon

doi:10.1016/j.applthermaleng.2004.10.014

Cited by 35 publications

(13 citation statements)

References 7 publications

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“…Polat [11] has provided an excellent review of impinging jet heat transfer. Several recent papers also deal with impinging jet heat transfer with a variety of jet designs and include important effects such as those of jet multiplicity, [12] complex geometries such as noncircular nozzles, [13] effects of cross-flow, [14] effect of large temperature differences, [15] etc. The jet configuration used in this study cannot be considered optimal but is a reasonable design based on literature recommendation.…”

Section: Baking Of Flat Bread In An Impingement Oven: An Experimentalmentioning

confidence: 99%

Baking of Flat Bread in an Impingement Oven: An Experimental Study of Heat Transfer and Quality Aspects

et al. 2008

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A new impingement oven was designed and tested for its thermal and quality performance for baking of thin flat bread. The test facility was instrumented to monitor and record during the baking process. Bread temperature and weight loss were recorded on-line during baking at oven temperatures of 150, 175, 200, 225, and 250 C and 1, 2.5, 5, 7.5, and 10 m/s jet velocities, respectively. Image processing was used for monitoring the bread volume and surface color changes during baking. Better baking conditions were obtained with the impingement oven in comparison with the conventional direct fired ovens. Experiments showed that a higher jet velocity can be used for flat bread baking at lower oven temperatures and yield shorter baking times for the same quality product. For very thin breads (such as the Iranian breads), results show that conduction heat transfer from the bottom surface of the tray must also be considered along with the convective heat transfer from the jets in selection of optimal operating parameters. It is noted that desirable baking conditions, e.g., good browning, uniform color, high volume increase, etc., can be achieved in a well-designed and operated impingement oven in shorter baking times compared to the conventional ovens.

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Section: Baking Of Flat Bread In An Impingement Oven: An Experimentalmentioning

confidence: 99%

Baking of Flat Bread in an Impingement Oven: An Experimental Study of Heat Transfer and Quality Aspects

et al. 2008

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“…Many studies have investigated single circular impinging jets for both submerged and free-surface jet configurations and have provided information regarding the heat transfer for fluids such as air, FC-77 and water [5,[8][9][10][11][12][13][14][15][16][17]. The local heat transfer coefficient distribution has generally been found to be bell-shaped in nature.…”

Section: Introductionmentioning

confidence: 99%

Nozzle geometry effects in liquid jet array impingement

Whelan

Robinson

2009

Applied Thermal Engineering

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The use of impinging liquid jets in electronics thermal management is attracting some consideration due to their very high heat transfer coefficients, hot spot targeting capabilities and moderate hydraulic power requirements. In this investigation an experimental study of the cooling capabilities of impinging water jet arrays is presented. Of particular interest here is the influence that the inlet and outlet geometries have on the thermal-hydraulics of jet impingement heat transfer with the aim of determining practical configurations in which heat transfer to the impinging jets is increased and/or the hydraulic pumping power is decreased. For a square array of 45 jets of fixed 1.0 mm diameter and fixed interjet spacing of 5 mm, six different nozzle geometries were investigated. The arrays impinged normally upon a heated circular copper surface of 31.5 mm diameter for a nominal heat flux of 25.66 W/cm2. Each array was tested under confined-submerged flow conditions with a constant jet-to-target spacing of 2.0 mm as well as free-surface conditions with a constant jet-to-target spacing of 20 mm. All nozzles were tested for a Reynolds number range of approximately 800 ≤ Redn ≤ 10000. It has been found that the confined-submerged tests yield greater heat transfer coefficients compared with their free jet counterparts. Chamfering and contouring the nozzle inlets showed significant decrease in the pressure drop across the nozzle plate whilst chamfering and contouring the exit showed moderate gains in the surface averaged heat transfer coefficient. Nozzles that provide the highest heat transfer for a given hydraulic pumping power are identified for each free-surface and confined-submerged scenarios. Chamfering and contouring the nozzle inlets showed significant decrease in the pressure drop across the nozzle plate whilst chamfering and contouring the exit showed moderate gains in the surface averaged heat transfer coefficient. Nozzles that provide the highest heat transfer for a given hydraulic pumping power are identified for each free-surface and confined-submerged scenarios. Nozzle Geometry Effects in Liquid Jet

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“…The key parameters for effective heat transfer in jet impingement are nozzle geometry, nozzle to surface distance, velocity and temperature of jet (Garimella and Nenaydykh 1996). Some of the studies carried out by various researchers focused primarily on the effect of nozzle geometry on heat transfer (Garimella andNenaydykh 1996, Zhao et al 2004), the effects of single and multiplicity jets on heat transfer (Lou et al 2005), the effects of pulsating jets on heat transfer (Zulkifli et al 2009;Kurnia et al 2012), etc. However, there is less understanding about the flow pattern of a jet.…”

Section: Cfd Modeling For Jet Impingement Ovenmentioning

confidence: 99%

Computational Fluid Dynamics Applications in Food Processing

Anandharamakrishnan

2013

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Effects of geometric parameters on confined impinging jet heat transfer

Cited by 35 publications

References 7 publications

Baking of Flat Bread in an Impingement Oven: An Experimental Study of Heat Transfer and Quality Aspects

Baking of Flat Bread in an Impingement Oven: An Experimental Study of Heat Transfer and Quality Aspects

Nozzle geometry effects in liquid jet array impingement

Computational Fluid Dynamics Applications in Food Processing

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