Charoensuk, Jarruwat

Preferred name

Alternative Name

Charoensuk, J.

Charoensuk, Jaruwat

Main Affiliation

School of Engineering

jarruwat.ch@kmitl.ac.th

Now showing 1 - 5 of 5

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Effect of self-entrainment and porous geometry on stability of premixed LPG porous burner
(2016-06-25)
Laphirattanakul, Ponepen
;
Laphirattanakul, Arwut
;
Charoensuk, Jarruwat
This paper presents findings on combustion stability of a self-entrained, rich-premixed LPG porous burner. Alumina (Al<inf>2</inf>O<inf>3</inf>) porous foams, with 15 ppi carved into bulked and hollowed cylindrical shapes were placed at a convertible burner tip, while the conventional porous-free burner was used as a base case for comparison. Visual flame propagation, temperature and the percentage of oxygen in a premixed zone were monitored at different firing rates. Initially, the tests were carried out based on basic geometry of bulky porous cylindrical foam under a free flame mode. At this part, the limitation of burner operation was realized in term of premixed equivalence ratio which was a result from self-entrainment. Later, an improvement was made on porous geometry and its effect on burner performance was considered with the previous version. It was found that propagation of flame within a porous matrix had significant contribution to temperature of the premixed zone as a result of radiation. Discussion was made relating to two competing factors controlling flame propagation within the porous burner i.e.; local flame speed and local convective effect. Combustion stability was found with domination of flame speed over convection when Φ < 4.1 in the premixed zone corresponding to illumination of the porous medium with the temperature of premixed zone being greater than 200°C. Beyond 980 kW/m2 (equivalent to 4 L/min of LPG) where convection effect dominated, heat recirculation within porous domain was broken down resulting in formation of soot burning outside porous medium corresponding to considerably drop of temperature. At this range, such short characteristic resident time, lower than 2 s, was observed with Φ > 4.1 in premixed zone. The hollowed cylinder, however, yielded stable flame throughout the operation range at the central port while propagation was maintained in a porous matrix which acted as a flame holder even at high firing rate. The temperature of premixed zone was also observed higher compared with bulked porous burner while the central port could eliminate flow blockage which otherwise gave significant adverse effect on primary air entrainment.
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Effect of central cone-shaped bluff body on performance of premixed LPG burner
(2017-03-05)
Laphirattanakul, Ponepen
;
Charoensuk, Jarruwat
Improvement of air entrainment rate for liquefied petroleum gas (LPG) premixed burner was achieved by placing a needle rod inside a circular fuel jet nozzle. To investigate the effect of needle rod on flow entrainment, selection of experimental results together with investigation on jet characteristics using CFD are presented. The predictive quality was achieved after performing grid refinement and validation of turbulent model against existing experimental results. Two modified standard k-ε turbulent models were employed for prediction of the jets. The results indicated that the annular port created narrower jet pattern with higher degree of penetration. The momentum decay rate was significantly lower with an average of 48% at z/D = 30, for instance, corresponding to lower Reynolds shearing stress associated with jet shape upstream. This corresponded to the vorticity magnitude of the inner core that caused transport of jet momentum into the central region of the jet near the exit plane. In contrast, the circular one performed more expanded pattern together with faster decay rate. This expanded jet created limitation of air entrainment when issuing into a confined duct, while deeper penetration of the annular jet created greater entrainment. An averaged improvement of air entrainment was found at 25% for the range of firing rate between 1.8 and 4.4 kW.
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Enhanced stability of pulverized biomass flames using an expanded primary port with bluff body
(2026-01-01)
Laphirattanakul, Ponepen
;
Siripoom, Pongsakorn
;
Keawchompoo, Chatchalerm
;
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
;
Lapirattanakun, Arwut
;
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/m2-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/m2-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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Development of pulverized biomass combustor with a pre-combustion chamber
(2020-10-01)
Laphirattanakul, Ponepen
;
Charoensuk, Jarruwat
;
Turakarn, Chinnapat
;
Kaewchompoo, Chatchalerm
;
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.

Charoensuk, Jarruwat

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