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Enhanced stability of pulverized biomass flames using an expanded primary port with bluff body
(2026-01-01)
Laphirattanakul, Ponepen
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Siripoom, Pongsakorn
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Keawchompoo, Chatchalerm
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Charoensuk, Jarruwat
The impact of bluff body geometry combined with primary exit port expansion on the flame stability of a biomass pulverized fuel burner was investigated through numerical simulations. The expansions, applied at 1.25 and 1.5 times the original port size while maintaining a constant blockage ratio, were intended to reduce the momentum ratio between primary and secondary air streams. However, this adjustment concurrently led to a decrease in the swirl number, primarily due to the reduction in the secondary air exit area. Experimental results from the base case configuration were employed for model validation. Among the turbulence models considered, the SST k-ω model demonstrated the best agreement with experimental data in terms of temperature distribution and emission characteristics. The simulation results revealed that the base case exhibited flame anchoring behind the bluff body, supported by a pronounced reverse velocity region in its wake. Flame stability was also achieved in the 1.5SB case, attributed to a sufficiently reduced momentum ratio. This reduction enhanced the entrainment of the secondary air stream, promoting greater dispersion of fuel particles and enabling early-stage volatile combustion. The 1.5SB configuration achieved the highest temperature among all cases, reaching approximately 1150 °C. In contrast, the 1.25SB case exhibited flame blowout, resulting from a combination of reduced swirl number and an insufficient reduction in momentum ratio.
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All parts overall heat transfer coefficients in correlation with design and off-design load conditions in a utility bagasse boiler
(2025-01-15)
Charoensuk, Jarruwat
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Lapirattanakun, Arwut
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Laphirattanakul, Ponepen
Overall heat transfer coefficients of the four major sections in the 73 MW bagasse-fired boiler used in sugar industry were analyzed in correlation with the operating conditions. Comprehensive measurements were provided at different operating conditions including at design and off-design in relation to load generation and combustion performance on the firing grate. At the design condition, the overall heat transfer coefficients across the different sections, namely, the furnace, superheater, back tube and bank tube zones, were found uniformly within the range of 60–80 W/m<sup>2</sup>-K. Maintaining the overall heat transfer coefficient within this narrow range ensures that each section of the boiler is contributing optimally to the overall thermal efficiency. The optimal range of heat transfer coefficient in the furnace zone is within the range of 66–72 W/m<sup>2</sup>-K with 90 % of heat transfer in this zone occurring through radiation. While the high convection resulting from a high flue gas flow rate during off-designed condition leads to insufficient heat transfer in the furnace zone. Approximately 60 % of the heat uptake is instead absorbed by the bank tube section, which is strategically designed to capture the bypassed heat from the preceding section. It was also found that the overall radiative factor providing efficient heat transfer ranged from 0.48 to 0.63.
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Axial loading during supine MRI for improved assessment of lumbar spine: comparison with standing MRI
(2023-01-01)
Charoensuk, Jarruwat
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Laothamatas, Jiraporn
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Sungkarat, Witaya
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Worapruekjaru, Ladawan
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Hooncharoen, Boonthida
Background: There are no studies comparing the morphologic changes of lumbar spines between supine axial-loaded and 90° standing magnetic resonance imaging (MRI) examinations of patients with spinal stenosis. Purpose: To determine whether axial-loaded MRI using a compression device demonstrated similar morphology of intervertebral disc, dural sac, and spinal curvature as those detected by 90° standing MRI in individuals with suspected spinal stenosis. Material and Methods: A total of 54 individuals suspected of having spinal stenosis underwent both axial-loaded and standing MRI studies. The outcome measures included seven radiologic parameters of the lumbar spine: measures of the intervertebral disc (i.e. cross-sectional area [DA], disc height [DH], and anteroposterior distance [DAP]), dural sac (cross-sectional area [DCSA]), spinal curvature (i.e. lumbar lordosis [LL] and L1-L3-L5 angle [LA]), and total lumbar spine height (LH). Results: For agreement between the two methods, intraclass correlation coefficient (ICC) ≥ 0.8 was found for all seven radiologic parameters. Supine axial-loaded MRI underestimated LL but remained correlated (ICC = 0.83) with standing MRI. Minor differences between the two methods (≤5.0%) were observed in DA, DCSA, DAP, LA, and LH, while a major difference was observed in LL (8.1%). Conclusion: Using a compression device with the conventional supine MRI to simulate weight-bearing on the lumbar spine generated MRI morphology, which was strongly correlated with those from a standing MRI.
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Improvement of Discharge Flow Structure by Bluff-Body Insert and Size Reduction of a Mixed-Flow Irrigation Pump
(2022-03-01)
Wasinarom, Kittipass
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Boonchauy, Dachdanai
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Noosomton, Jaruphant
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Charoensuk, Jarruwat
This paper concerns efficiency improvement of an 8-in. mixed-flow irrigation pump by modification of discharge flow channel. First, computational fluid dynamics (CFD) modeling was validated with the experimental results using an available pump. Next, an investigation on the hydrodynamics structure was carried out by CFD. The investigation revealed large recirculation around the inner annulus area next to the impeller exit plane and jet flow around the pipe wall. This leads to formation of a strong shear layer between jet and recirculation flow. Improvements were realized by reducing the impeller size by 10% to increase the flow cross-sectional area between the impeller exit plane and the tube wall to slow down the jet flow. Bluff body was introduced at the inner annulus adjacent to the discharge flow channel to alleviate a recirculation wake region. The operating speed of the scaled-down impeller was increased from 900 to 1,100 rpm to compensate for the scaling effect, and the blade angle was modified to cope with the change of inlet relative flow angle. Experimental study suggested that more than 10% improvement could be achieved through these modifications. The maximum efficiency of the proposed model was 42%, compared with the maximum efficiency of 37% for the conventional model.
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Feasibility Study of Harnessing an Urban Wind Turbine to Supply an Electric Motorbike in Thailand
(2022-01-01)
Mon, Thuzar
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Charoensuk, Jarruwat
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Hanamura, Katsunori
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Worasinchai, Supakit
This paper presents a feasibility study of the employment of a wind turbine to supply an electric motorbike in the urban area. The turbine investigated was selected based upon three dimensional numerical simulations. The turbine annual energy production (AEP) was evaluated using measured wind data which is in the form of Weibull distribution. The feasibility of the system was determined in terms of number of charges for a 1 kW motorbike. The effects the variation of the Weibull distribution was also studied. It is found that the AEP is most sensitive to the scale factor. From all investigated cases, The Weibull distribution with a shape factor of 1.9 and a scale factor of 5 provides the maximum AEP of 2,950 kWh or a total number of 2,458 charges a year.
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Lumbosacral spinal compression device with the use of a cushion back support in supine MRI
(2021-08-01)
Sungkarat, Witaya
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Laothamatas, Jiraporn
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Worapruekjaru, Ladawan
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Hooncharoen, Boonthida
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Charoensuk, Jarruwat
Background: We hypothesized that axial-loaded magnetic resonance imaging (MRI), modified with the use of a cushion placed behind the lower back (i.e. BS-MRI method), would simulate the standing position more accurately than an axial-loaded MRI without a cushion back support (BS). Purpose: To determine whether the BS-MRI method demonstrated similar morphologies on intervertebral disc (IVD), dural sac, and spinal curvature as those detected on 90° standing MRIs in individuals with suspected spinal stenosis. Material and Methods: Twenty-five subjects underwent a BS-MRI, as well as axial-loaded and standing MRI studies. Outcome measures were four radiographic parameters of the lumbar spine: IVD height (DH); dural sac cross-sectional area (DCSA); and spinal curvature (i.e. lumbar lordosis [LL] and L1-L3-L5 angle [LA]). Results: Major differences (>5%) between standing MRI and BS-MRI methods were observed in DCSA, DH, and LL. Major differences between standing and axial loaded MRIs were observed only in DCSA and LA. Although BS-MRIs demonstrate an image of the lumbar spine curvature (i.e. LA) which is closer to that when standing than axial-loaded MRIs, it is likely to overestimate both narrowing of dural sac and extent of LL. Conclusion: Using a compression device with a BS to simulate weight-bearing on the lumbar spine is not recommended due to: (i) overestimation of the narrowing of the dural sac and extent of LL; and (ii) underestimation of loss of disc height. Supine axial-loading produced DCSA and DH which were strongly correlated with those detected with standing MRIs. Exceptions were that LL and LA were underestimated.
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Axial-Loaded MRI Using a SpineMAC Device to Show Narrowing of Dural Sac and Disc Height in Lumbar Spinal Stenosis
(2020-12-01)
Sungkarat, Witaya
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Laothamatas, Jiraporn
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Worapruekjaru, Ladawan
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Hooncharoen, Boonthida
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Charoensuk, Jarruwat
Background: A lumbosacral spinal compression device has been developed by the authors (SpineMAC) to simulate normal weight-bearing by axial-loading of the lumbar spine while the patient is in the supine position. Objective: To investigate the effect of axial loading using a SpineMAC device, on lumbar spine, spinal canal, and spine curvature, in subjects with suspected spinal stenosis. Materials and Methods: The present study was prospective cross-sectional study. Forty-five (21 males and 24 females) consecutive Thai adults underwent unloaded and axial-loaded supine magnetic resonance imaging (MRI) examinations of the lumbosacral spine. Radiographic parameters included cross-sectional area of disc (DA), cross-sectional area of dural sac (DCSA), disc height (DH), anterior to posterior distance of disc (DAP), L1-L3-L5 angle (LA), and lumbar lordosis (LL). Results: During the axial-loaded MRIs, the pathologic features of the lumbar spinal stenosis such as the disc bulging, nerve root compression, narrowing of the spinal canal, and the spinal neural foramina, were frequently observed in L4-L5 and L5-S1. Radiographic parameters differences of more than 5% between unloaded and axial-loaded supine MRIs were observed in DCSA and DH. Narrowing of the dural sac due to axial compression was observed at the L4-L5 level (8.1%), while loss of DH was found at both the L5-S1 (-7.9%) and the L4-L5 (-6.8%) levels. Axial compression only slightly affected the DA and DAP of the intervertebral discs with a difference of 5% or less. Furthermore, it rarely changed the spine curvature (LL and LA) of the subjects, with a difference of 2% or less. LL decreased during axial loading and may not correlate with the findings during normal standing position. Although the authors found greater DA and DAP values in male (p<0.001) and obese (p<0.05) subjects, changes of radiographic parameters with axial loading were otherwise not correlated with sex, age, or body mass index. Conclusion: An axial-loaded MRI, using a SpineMAC device, may be superior to conventional MRI when evaluating narrowing of the dural sac and disc height of patients.
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Development of pulverized biomass combustor with a pre-combustion chamber
(2020-10-01)
Laphirattanakul, Ponepen
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Charoensuk, Jarruwat
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Turakarn, Chinnapat
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Kaewchompoo, Chatchalerm
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Suksam, Niwat
A 0.5 MW pre-combustion chamber for pulverized biomass burner was design based on a pulverized coal combustor design. The design concept, a 2D simulation guiding the construction and experimental results are discussed followed by an assessment of a 3D simulation. The difference in burning characteristics between coal and biomass were used to specify sizes of the air exits and the pre-combustion chamber. Simulation with pure biomass was used to guide fabrication of the test facility: the predicted temperature profiles suggested flame attachment within the specified operation range. Experimental results suggested that our design could achieve an anchoring flame as the measured temperature was above 800 °C within the pre-combustion chamber when operating between 0.3 and 0.5 MW. Maximum temperature at the last monitoring in the pre-combustion chamber was observed at 0.4 MW throughput, while the convection started to play negative impact at 0.5 M and the flame blow out occurred beyond this target. The 3D simulation under Reynolds-averaged Navier-Stokes assumption with its associated models agreed well with experiments which measured the axial temperature distribution in the pre-chamber. However, overestimation in the main combustion chamber suggested further improvement on model calibration as well as boundary conditions.
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CFD based Improvement of Thai Irrigation Pump
(2020-08-31)
Wasinarom, Kittipass
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Boonchauy, Dachdanai
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Charoensuk, Jarruwat
Evaluation phase which was partial fulfilment of the beginning phase of "Development of Performance test rig and Efficiency improvement of impeller in Thai irrigation pump project" is presented in this paper. Overall flow field in the pump system that consisted of inlet, impeller and stator vane of the available pump was analyzed using commercial Computational Fluid Dynamics (CFD) code. The goal of this investigation is to obtain more understanding of energy dissipation which results from shear stress that developed within the flow field in each section of the pump. The improvement measure is then conducted with the concern of manufacturing difficulties. High dissipation flow structure was observed around the impeller outlet. Jet-wake and recirculation flow were observed. The first improvement measure was conducted by adding the bluff body in the flow channel to alleviate jet-wake structure and delay flow separation. After the implementation of the optimized bluff body around the impeller exit, CFD results indicated around 3-8% improvement compared with the CFD results of the available pump for the entire range of operating conditions.
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Compact heat integrated reactor system of steam reformer, shift reactor and combustor for hydrogen production from ethanol
(2020-06-01)
Khaodee, Watcharapong
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Jiwanuruk, Tara
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Ountaksinkul, Khunnawat
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Charojrochkul, Sumittra
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Charoensuk, Jarruwat
A compact heat integrated reactor system (CHIRS) of a steam reformer, a water gas shift reactor, and a combustor were designed for stationary hydrogen production from ethanol. Different reactor integration concepts were firstly studied using Aspen Plus. The sequential steam reformer and shift reactor (SRSR) was considered as a conventional system. The efficiency of the SRSR could be improved by more than 12% by splitting water addition to the shift reactor (SRSR-WS). Two compact heat integrated reactor systems (CHIRS) were proposed and simulated by using COMSOL Multiphysics software. Although the overall efficiency of the CHIRS was quite a bit lower than the SRSR-WS, the compact systems were properly designed for portable use. CHIRS (I) design, combining the reactors in a radial direction, was large in reactor volume and provided poor temperature control. As a result, the ethanol steam reforming and water gas shift reactions were suppressed, leading to lower hydrogen selectivity. On the other hand, CHIRS (II) design, combining the process in a vertical direction, provided better temperature control. The reactions performed efficiently, resulting in higher hydrogen selectivity. Therefore, the high performance CHIRS (II) design is recommended as a suitable stationary system for hydrogen production from ethanol.

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