Charoensuk, Jarruwat

Preferred name

Alternative Name

Charoensuk, J.

Charoensuk, Jaruwat

Main Affiliation

School of Engineering

jarruwat.ch@kmitl.ac.th

Now showing 1 - 10 of 45

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Numerical simulation of metal-supported solid oxide fuel cell (mSOFC)
(2009-12-01)
Phoocharoen, Niwat
;
Charoensuk, Jarruwat
In this paper we present the numerical results of planar solid oxide fuel cell at the level of membrane electrode assembly, MEA. The study is aimed at evaluating the performance of metal-supported design versus the conventional anode-cathode support under co-flow and counter-flow conditions. We have found that the value of peak temperature is lower therefore better temperature distribution is achieved for metal supported design with counter-flow configuration. Moreover the corresponding current density at maximum power is also higher with this configuration. This later design however possesses greater concentration loss or over-potential due to fuel concentration gradient at the porous layer of supporting metal. To compensate this difference, we have proposed the modification of the current collector at the cathode side to reduce the ohmic loss, while minimizing the concentration loss at the reaction site. The result of this modification suggests an improvement of maximum power density from 0.984 W/cm2 to 1.034 W/cm2. This is slightly less than the value of an original version for only 0.132 %. At this counter-flow configuration the value of peak temperature is also lower as compared with its counterpart with co-flow configuration. Copyright © 2009 by ASME.
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Effects of convection and microwave drying schemes on the characteristics and sound absorption of acoustic oil palm boards
(2018-02-01)
Dangvilailux, Panya
;
Charoensuk, Jarruwat
This research aimed to develop economical, high-performance acoustic oil palm boards (OPB) using the convection (CV) and microwave (MW) wood drying technologies under variable thermal conditions. The results revealed that the CV and MW oven temperatures were positively correlated with moisture desorption but inversely correlated with drying time. The CV heating temperatures were inversely and positively correlated with the density and volumetric shrinkage, respectively, and the MW power output was positively correlated with density and shrinkage. Thus, the MW-treated OPB specimens exhibited stronger mechanical characteristics than the CV-treated OPB specimens. Importantly, the CV-treated OPB specimens acoustically outperformed the MW-treated counterparts, as evidenced by the former's higher noise reduction coefficients (NRC). This phenomenon was attributed to the abundance of fissures between the vascular bundles and the parenchyma. Thus, the CV technology was more operationally and economically suited to the high-performance acoustic OPB.
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Behaviour of various glass seal for planar solid oxide fuel cell
(2008-01-01)
Punbusayakul, N.
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Wongklang, W.
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Wongtida, K.
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Charoensuk, J.
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Charojrochkul, S.
One of the critical issues in designing a planar solid oxide fuel cell (SOFC) is the development of materials to hermetically seal the metal (430 series stainless steel) or ceramic interconnector with the ceramic electrolyte of the cell. The main objective of this sealing material is to achieve a low leak rate, long-term stability at operating temperature and chemical compatibility with other components. One of the compositions has been operated in an SOFC in excess of 30 minutes over the range of 600, 700, 800, and 900°C. The seal is a composition of polymer blend and glass of 1:3, 1:1 and 3:1 by weight. The leakage rate of each seal was measured simultaneously under the compressive force of 100 N, 2 bar Helium. The seal was characterized using a thermogravimetric analysis. The effect of glass composition on operating temperature and compressive forces on the leakage rate have been discussed and correlated. © 2008 Trans Tech Publications, Switzerland.
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A new method for zone development observation for updraft rice husk gasification
(2019-01-01)
Onthong, Kasemsil
;
Charoensuk, Jarruwat
Experiments were carried out with a new method for assessing an updraft gasification reactor. An attached side door enabled the investigation of zone development by stopping air supply at specific times, when the thickness of biomass, char, and ash layers were measured. Development in zone thicknesses of biomass, char, and ash with time associated with temperature distribution provided information about the speed of flame propagation inside the reactor. Initially, pyrolysis and volatile combustion occurred, as evidenced by the high mass loss rate and high growth rate of the char layer. Shrinkage in the char layer took place later, and this phenomenon was governed by char glowing, which was relatively slow in mass loss rate. Finally, the fully developed char layer was obtained. The results from four different air mass fluxes under updraft configuration were presented, showing the differences in layer development. Temperature profiles at each time step revealed that the location of peak temperature coincided with the location of ash-char interface for every air mass flux. This effect was due to the high energy release during the oxidation of fixed carbon.
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Assessment on hermetic property and mechanical compatibility of various groove-gasket sealing designs for solid oxide fuel cell stack
(2012-09-01)
Punbusayakul, N.
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Boonsiri, K.
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Charojrochkul, S.
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Fungtammasan, B.
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Charoensuk, J.
Assessment among various groove-gasket designs under solid oxide fuel cell operating condition is presented. The gasket is deformable under the stress applied by external loading between 0.13-0.67 MPa. The operating temperature is from 30 to 800 °C. It has an indicated width of 1.95 mm and depth of 2.1 mm., which is accommodated in a square, triangular and U groove channel having the dimension of 2.0 × 2.0 mm 2. From the results, the U shape configuration provides the best performance with immeasurable leak rate under the applying load represented in term of global stress of 0.67 MPa. A stress analysis using Finite Element Method (FEM) tool, ABAQUS™, suggests sufficiently high compressive stress far exceeding the elastic limit with enough coverage of such high-stress area for U-shape design. In contrast, those from square and triangular designs posses relatively lower well-distributed stress and smaller region of highly concentrated stress, respectively. The associated deformed cross section suggests that the gasket has plastically deformed toward the U-shape wall surface at a greater degree than those for triangular-shape design. It can be concluded that the greater region in deformed gasket surface can more effectively reduce interconnectivity of micro channel on the interface between the gasket and the interconnector surfaces. © 2012 Elsevier B.V. All rights reserved.
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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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Numerical analysis of heat transfer and flow field around cross-flow heat exchanger tube with fouling
(2010-07-01)
Vessakosol, Passakorn
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Charoensuk, Jarruwat
Fouling is one of the main problems of heat transfer which can be described as the accumulation on the heat exchanger tubes, i.e.; ash deposits on the heat exchanger unit of the boiler. A decrease in heat transfer rate by this deposition causes loss in system efficiency and leads to increasing in operating and maintenance costs. This problem concerns with the coupling among conduction heat transfer mode between solid of different types, conjugate heat transfer at the interface of solid and fluid, and the conduction/convection heat transfer mode in the fluid which can not be solved analytically. In this paper, fouling effect on heat transfer around a cylinder in cross flow has been studied numerically by using conjugate heat transfer approach. Unlike other numerical techniques in existing literatures, an unstructured control volume finite element method (CVFEM) has been developed in this present work. The study deals with laminar flow where the Reynolds number is limited in the range that the flow field over the cylinder is laminar and steady. We concern the fouling shape as an eccentric annulus with constant thermal properties. The local heat transfer coefficient, temperature distribution and mean heat transfer coefficient along the fouling surface are given for concentric and eccentric cases. From the results, we have found that the heat transfer rate of cross-flow heat exchanger depends on the eccentricity and thermal conductivity ratio between the fouling material and fluid. The effect of eccentric is dominant in the region near the front stagnation point due to high temperature and velocity gradients. The mean Nusselt number varies in asymptotic fashion with the thermal conductivity ratio. Fluid Prandtl number has a prominent effect on the distribution of local Nusselt number and the temperature along the fouling surface. © 2010 Elsevier Ltd. All rights reserved.
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Effects of sintering time and atmosphere on mechanical properties of injection molded Tungsten alloy
(2013-01-01)
Lamlerttham, Jittrabhanu
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Wila, Pongsak
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Morakotjinda, Monnapas
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Krataitong, Rungtip
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Vetayanukul, Bhanu
Tungsten is a promising refractory metal suitable for applications in which wear resistance, thermal stability and high weight are needed. In this work, the tungsten feedstock (94wt%W with balance of Ni-Cu-Co alloy) was used to form tensile test specimens by using metal injection molding (MIM) process. The molded specimens were debinded by catalytic debinding technique to convert to the brown specimens. After debinding, the brown parts were sintered under vacuum atmosphere (10-5 bar) with varied sintering times at sintering temperature from 1350 to 1450°C. The specimens sintered at 1450°C for 3 hours provided optimum sintered density and mechanical properties. The results showed that mechanical properties of the specimens sintered at 1450°C dramatically decreased when sintering times were longer than 3 hours. The specimens sintered at 1450°C for 8 hours showed brittleness. Physically, inferior mechanical properties were attributed to wettability and porosity of the binder phase. Chemical analyses were performed with the sintered W-(Ni-Cu-Co) specimens by using energy dispersive spectroscopy with mode of quantitative analysis. The specimens sintered at 1400°C for 3 hours showed high W content (28.95 wt. %) dissolved in the Ni-Cu-Co binder. However, penetration of the liquid binder was incomplete. The specimens sintered at 1450°C for 3 hours showed higher W content (34.28 wt. %) dissolved in the Ni-Cu-Co binder (with lower Cu content). Distribution of Cu was uniform across the whole specimen. Wetting of the liquid binder on W grains was complete without porosity. The specimens sintered at 1450°C for longer than 3 hours showed less W content (< 28.95 wt. %) dissolved in the Cu-depleted Ni-Co binder. Porosity was observed in the binder phase and in W grains. Sintering between W grains was also observed. Effects of different sintering atmospheres were also investigated. It was found that increasing the sintering chamber pressure caused detrimental effects on both physical and mechanical properties of the sintered tungsten specimens. In addition, nitrogen atmosphere gave similar results to those for increased chamber pressure. © (2013) Trans Tech Publications.
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Effect of self-entrainment and porous geometry on stability of premixed LPG porous burner
(2016-06-25)
Laphirattanakul, Ponepen
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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.

Charoensuk, Jarruwat

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