Thianpong, Chinaruk
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Preferred name
Thianpong, Chinaruk
Alternative Name
Thianpong, C.
Main Affiliation
Email
chinaruk.th@kmitl.ac.th
6 results
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Item type:Publication, Heat transfer behaviors in a solar air heater channel with multiple V-baffle vortex generators(2014-12-01); The article presents a study on heat transfer augmentation in a solar air heater channel fitted with multiple V-baffle vortex generators (BVG). During the test air was passed through the test channel under a uniform wall heat-flux of the absorber plate. The fluid flow and heat transfer characteristics are presented for Reynolds numbers based on the channel hydraulic diameter ranging from 4000 to 21,000. The V-baffles are applied at a relative baffle height (in terms of blockage ratio, BR. =. b/. H=. 0.25) and attack angle of 45° with respect to the main flow direction. The use of BVG in the channel is to generate multiple longitudinal vortex flows through the test channel to increase turbulence intensity and stronger mixing of fluid between the core and the near-wall flow. Influences of three different baffle-pitch to channel-height ratios (PR. =. P/. H=. 0.5, 1 and 2) on heat transfer and pressure drop in terms of respective Nusselt number and friction factor (or energy loss for propelling air through the channel) are examined. Three BVG arrangements, namely, one BVG wall (or single BVG), in-line and staggered BVGs on two opposite walls are also investigated. The experimental result reveals that the smaller PR provides the highest heat transfer and friction factor for all BVGs. The in-line BVG yields higher heat transfer and friction loss than the staggered and the single BVG. However, the single BVG with PR. =. 0.5 yields the highest thermal performance. To shed light of heat transfer mechanism, a numerical work is also conducted to investigate heat transfer and flow friction characteristics in the channel fitted with 45° BVGs and in comparison, the numerical results are in good agreement with experimental data. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Thermal performance in solar air heater with perforated-winglet-type vortex generator(2018-08-01); ; An experimental and numerical study of turbulent convective heat transfer in a solar air heater duct with winglet-type vortex generators (WVGs) placed on the absorber plate is presented. Air as the test fluid enters the duct having a uniform wall heat-flux applied on the upper wall or the absorber plate with Reynolds number from 4100 to 25,500. Two types of WVGs are introduced: rectangular (RWVG) and trapezoidal (TWVG) WVGs, in order to create multiple vortex flows along the duct. The WVG parameters in the present study include two relative height (B<inf>R</inf> = e/H = 0.2 and 0.48), three longitudinal pitch ratios (P<inf>R</inf> = P<inf>l</inf>/H = 1, 1.5 and 2) and a single attack angle, α = 30°. The experimental result reveals that the RWVG with B<inf>R</inf> = 0.48 and P<inf>R</inf> = 1 provides the highest heat transfer and friction factor at about 7.1 and 109.5 times above the flat duct, respectively while the TWVG with B<inf>R</inf> = 0.2 and P<inf>R</inf> = 1.5 yields the maximum thermal performance around 1.84. Then, to improve the performance by reducing the substantial pressure loss, both the WVGs with B<inf>R</inf> = 0.48 and P<inf>R</inf> = 1.5 are modified to be perforated rectangular and trapezoidal winglet-type vortex generators (P-RWVG and P-TWVG) with four different punched hole/pore diameters (d = 1, 3, 5 and 7 mm) on their central area. The investigation indicates that among the perforated WVGs, the P-RWVG at d = 1 mm yields the highest heat transfer and friction factor up to 6.78 and 84.32 times higher than the smooth duct but the best thermal performance of about 2.01 is found for the P-TWVG with d = 5 mm. To explore the flow and heat transfer pattern, a 3D numerical flow simulation is performed and validated with available measurements where both the numerical and measured results are in good agreement. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Experimental and numerical heat transfer investigation in a tubular heat exchanger with delta-wing tape inserts(2016-11-01); ; Effects of insertion of a straight tape with double-sided delta wing pairs (called “delta-wing tape”, DWT) used as a longitudinal vortex generator (LVG) on forced convective heat transfer and flow friction characteristics in a uniform heat-flux heat exchanger tube are investigated experimentally and numerically in the present work. The experiment is conducted for turbulent airflow with the Reynolds number (Re) from 4200 to 25,500. The delta wings are in a forward-wing arrangement with three wing inclination angles (α = 30°, 45° and 60°) and with five ratios of wing-pitch to tube-diameter (P/D = PR = 0.5, 1.0, 1.5, 2.0 and 2.5). Influences of the DWT insert on heat transfer in terms of Nusselt number (Nu) and pressure drop in the form of friction factor (f) are examined. The results indicate that the DWT provides the increases in Nu and f up to 505% and 69 times above the plain tube, respectively and the maximum thermal enhancement factor (TEF) is at 1.49. The 60° DWT with PR = 0.5 yields the highest Nu and f but the 30° one with PR = 1.0 gives the best TEF. To understand the flow structure and heat transfer mechanism, a three dimensional CFD simulation of the inserted tube is also performed. The simulated results are validated and are in good agreement with the current measurements. A simulated heat transfer and fluid flow structure is also reported. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Thermal performance in solar air heater channel with combined wavy-groove and perforated-delta wing vortex generators(2016-05-05); ; An experimental investigation on thermal performance improvement in a solar air heater channel with combined wavy-groove and delta-wing vortex generator (WVG) placed on the absorber plate having a uniform wall heat-flux is carried out. The Reynolds number based on the hydraulic diameter of the channel ranges from 4800 to 23,000. The effect of the combined groove and WVG on the heat transfer and pressure drop in the channel in terms of respective Nusselt number and friction factor is examined. Investigated parameters of the WVG mounted on the grooved absorber are three wing porosity area ratios (called porosity ratio, A<inf>h</inf>/A<inf>w</inf> = 0.031, 0.085 and 0.167) and four groove-wing distance to channel-height ratios (g/H = 0.4, 0.5, 0.75 and 1) at a single attack angle (α = 45°). The experimental result reveals that at g/H = 0.5, the smaller A<inf>h</inf>/A<inf>w</inf> provides the highest Nusselt number and friction factor around 6 and 30 times over the smooth channel, respectively, but the optimum thermal performance is at A<inf>h</inf>/A<inf>w</inf> = 0.085 and g/H = 0.5. The combined devices give the thermal performance augmentation at about 37.7-46.3% higher than the groove alone and also at about 1.5-12.5% above the combined groove and non-perforated WVG (without hole). - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Experimental and numerical heat transfer investigation in turbulent square-duct flow through oblique horseshoe baffles(2016-01-01); ; An experimental and numerical work has been carried out to study the heat transfer enhancement in a heat exchanger square-duct fitted with 30° oblique horseshoe baffles (HB). In the current work, air is passed through the HB-inserted duct having a constant surface heat-flux. The air flow and heat transfer behaviors are presented for turbulent flow region, Reynolds number ranging from 4000 to 25,000. The pertinent parameters of the 30° HB elements include three relative baffle-pitches (P<inf>R</inf>=P/H=0.5, 1 and 2) and five relative baffle heights (B<inf>R</inf>=b/H=0.05, 0.1, 0.15, 0.2 and 0.25). Influences of those parameters on heat transfer and energy loss due to friction in terms of Nusselt number and friction factor, respectively are studied. The experimental result shows that at a given B<inf>R</inf>, the smallest pitch spacing (P<inf>R</inf>=0.5) provides the highest heat transfer and friction factor. The HB at B<inf>R</inf>=0.25 and P<inf>R</inf>=0.5 yields the highest heat transfer and friction factor but the one at B<inf>R</inf>=0.2 and P<inf>R</inf>=1 gives the maximum thermal performance. In addition, the thermal performance of using the HB is much higher than that of the wire coil insert, in comparison with other turbulators. To understand the heat transfer mechanism, a numerical inserted-duct flow simulation is also conducted and the obtained numerical results are in good agreement with measurements. Numerical flow and heat transfer behaviors such as streamlines, temperature and Nusselt number contours of the duct flow model are also reported. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Experimental study on heat transfer in square duct with combined twisted-tape and winglet vortex generators(2014-12-01); ; The article presents an experimental investigation on thermal performance enhancement in a constant heat-fluxed square duct fitted with combined twisted-tape and winglet vortex generators. The experiments are carried out for the airflow rate through the tested square duct fitted with both the vortex generators for Reynolds number from 4000 to 30,000. The effect of the combined twisted tape and rectangular winglet inserts on heat transfer and pressure drop presented in terms of respective Nusselt number and friction factor is experimentally investigated. The characteristics of the combined twisted-tape and winglet include two twist ratios (Y=4 and 5), three winglet- to duct-height ratios, (R<inf>B</inf>=0.1, 0.15 and 0.2), four winglet-pitch to tape-width ratios, (R<inf>P</inf>=2, 2.5, 4 and 5) and a single attack angle of winglet, α=30°. The experimental results reveal that the Nusselt number and friction factor for the combined twisted-tape and V-winglet increase with increasing R<inf>B</inf> but decreasing R<inf>P</inf>. The inserted duct at R<inf>B</inf>=0.2, R<inf>P</inf>=2 and Y=4 provides the highest heat transfer rate and friction factor but the one at R<inf>B</inf>=0.1, R<inf>P</inf>=2 and Y=4 yields the highest thermal performance. The application of combined vortex-flow devices gives thermal performance around 17% higher than the twisted tape alone.