The Effects of duct height on heat transfer enhancement of a co-rotating type rectangular finned surface in duct

Islam, M.D.; Oyakawa, Kenyu; Yaga, Minoru; Kubo, I.

doi:10.1016/j.expthermflusci.2008.10.005

Cited by 16 publications

(3 citation statements)

References 18 publications

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“…Their findings revealed that, under constant pressure loss and mass flow rate per unit collector area, an SAH‐duct with a shorter length yielded the maximum value of overall heat transfer coefficient. A duct height of 35 mm was chosen, and a duct height of less than 50 mm had been suggested by Islam et al [ 52 ] The study had been performed to study the effect of duct height (20–50 mm) on the performance of SAH. A comparative study revealed that small duct height (<50 mm) offered maximum thermal performance.…”

Section: Methodsmentioning

confidence: 99%

Experimental Study of Reverse Flow Solar Air Heater Having Perforation and Delta Wing on Absorber Plate

Sharma,

Debbarma

2024

Energy Tech

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fThe traditional solar air heater (SAH) has poor thermal performance due to low heat transfer coefficient. Artificial roughness, flow passage alteration, absorber modification, etc. can enhance it. Thus, an experimental investigation is performed to study the thermohydraulic characteristics of a reverse flow SAH with perforated absorber and delta wing (DW) structure. The present study investigates the effect of attack angle (15°–75°) at constant streamwise pitch (35 mm), transverse pitch (70 mm), height (h), and width (w) of DW 20 mm, under Reynolds number (Re) ranging from 4000 to 20 000. The perforation index (PI = ADW/Aap) for inline and staggered arrangements are 9.52 and 4.76, respectively. The results indicate that the concept of perforated absorber and DW leads to enhanced heat transfer, reduced pressure drops, and enhanced utilization of solar energy. The Nusselt number (Nu), friction factor (f), and thermohydraulic performance enhance about 6.6, 9.4, and 3.06 times, respectively, at attack angle 75o for inline arrangement of DW over the smooth duct. Thermohydraulic performance of reversed‐flow SAH is compared with previously published works, and it highlights that the full‐length inline and staggered arrangement of the DW offers the most significant improvements in heat transfer and friction factor.

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Section: Methodsmentioning

confidence: 99%

Experimental Study of Reverse Flow Solar Air Heater Having Perforation and Delta Wing on Absorber Plate

Sharma,

Debbarma

2024

Energy Tech

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“…Geometry is checked in a small-scale model in non-rotation rotation. The study [7] presented that experimental procedure to investigate the effect of air duct circulation height on heat transfer enhancement. Deck affixed to arrays (7*7) of rectangular and short fin-type co-rotation in the channel.To measure heat transfer in the inner wall with fin base.…”

Section: Introductionmentioning

confidence: 99%

Flow Disturbing to Enhance Heat Transfer Inside a Duct: an Experimental Study

Ibadi

Diabil

2022

IOP Conf. Ser.: Earth Environ. Sci.

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In the present experimental work, the effect of air circulation on increasing heat transfer rates within the duct was studied. Three air circulation speeds are implemented: 2400, 1800, and 1200 rpm. In addition, the effect of the distance between the heat source and the location of the circulating fan on heat transfer rates was investigated using three different distances: 20, 40, and 60 cm. The Exhaust fan, placed at the outlet of the duct, changed its speed to three values: 2850, 2140, and 1425 revolutions per minute. The Reynolds range ranged from 65,000 to 175,000. The results showed that the best thermal performance is achieved when the exhaust fan speed, air circulation speed, and the distance between the heat source are 1425 rpm, 2400 rpm, and 60 cm, respectively.

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“…Using delta winglet VGs in tube heat exchangers, therefore, is a promising technique to augment the thermo-hydraulic performance of heat exchangers. Author's previously conducted research with rectangular VGs [41][42][43][44][45][46] in rectangular channel. Researchers have typically studied the winglets, wing, V-baffles, twisted tapes in the rectangular duct, flat plate or finned tube heat exchangers, and observed that the delta winglets are one of the most effective VG.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of heat transfer and flow of delta winglets inline arrays in a tube heat exchanger for enhanced heat transfer

et al. 2020

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This experiment was carried out using delta winglet arrays of vortex generators (VG) with inline arrangement in a tube heat exchanger to study enhanced heat transfer and flow behaviour. The experiment was conducted for the turbulent flow (Re = 6000 to 27000). In this experiment, different parameters, pitch ratios (PR = 1.6, 2.4, and 4.8), lengths (L = 10, 15, and 20 mm), and attack angles (B = 0°, 10°, 20°, 30°, and 45°) were studied and then their effect on thermal performance was observed. Results indicate that the PR affected f and Nu significantly. For PR = 1.6, VGs showed the highest f and Nu for all of the cases. Vortex generators with L10 B45 PR4.8 achieved the best TPE with 1.23 at Re = 6000. Attack angle B indicated a significant impact on thermal performance and 45 degree showed the TPE of 1.23 at lower Re. Oil film flow and smoke flow visualization were employed to identify the flow vortices and understand flow mechanism. The oil film flow and smoke flow visualization clearly traced longitudinal vortex, and induced vortex, which induced impingement flow and recirculation zone that lead to significant heat transfer enhancement.

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The Effects of duct height on heat transfer enhancement of a co-rotating type rectangular finned surface in duct

Cited by 16 publications

References 18 publications

Experimental Study of Reverse Flow Solar Air Heater Having Perforation and Delta Wing on Absorber Plate

Experimental Study of Reverse Flow Solar Air Heater Having Perforation and Delta Wing on Absorber Plate

Flow Disturbing to Enhance Heat Transfer Inside a Duct: an Experimental Study

Experimental study of heat transfer and flow of delta winglets inline arrays in a tube heat exchanger for enhanced heat transfer

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