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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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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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 <sup>2</sup>. 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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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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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
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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/m<sup>2</sup> (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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Vibration characteristics of stepped beams made of FGM using differential transformation method
(2015-04-01)
Wattanasakulpong, Nuttawit
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Charoensuk, Jarruwat
The present paper is given to investigate free vibration analysis of stepped beams produced from functionally graded materials (FGMs). The differential transformation method is employed to solve the governing differential equations of the beams to obtain their natural frequencies and mode shapes. The power law distribution is used and modified for describing material compositions across the thickness of the stepped beams made of FGM. Two main types of the stepped FGM beams in which their material compositions can be described by the modified power law distribution are selected to investigate the free vibration behaviour. The significant parametric studies such as step ratio, step location, boundary conditions and material volume fraction are also covered in this paper.
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Vibration response of stepped FGM beams with elastically end constraints using differential transformation method
(2014-01-01)
Suddoung, Kittisak
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Charoensuk, Jarruwat
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Wattanasakulpong, Nuttawit
In this paper, free vibration response of stepped beams made from functionally graded materials (FGMs) is investigated. The beams are supported by various types of elastically end constraints. The differential transformation method (DTM) is employed to solve the governing differential equations of such beams in order to obtain natural frequencies and mode shapes. The power law distribution is used and modified to describe material compositions across the thickness of the beams made of FGMs. Two main types of the stepped FGM beams in which their material compositions can be described by using the modified power law distribution are selected to investigate their vibration behaviour. The significant parametric studies such as step ratio, step location, boundary conditions, spring constants and material volume fraction are taken into investigation. © 2013 Elsevier Ltd. All rights reserved.
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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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TWO-DIMENSIONAL AXISYMMETRIC NUMERICAL STUDY OF THE PREMIXED COMBUSTION INSIDE THE POROUS MEDIA BURNER
(2021-01-04)
Vithean, K.
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Charoensuk, J.
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Hanamura, K.
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Sesuk, T.
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Lilavivant, V.
Porous media combustion is one of the most efficient and has a wide-ranging application. Despite this, more investigation needs to be done in order to improve its efficiency and pollutant emission. In this research, the commercial simulation software is used to model and couple together the significant phenomena such as combustion, heat transfer, and fluid flow in porous media, which occur in this type of system. The free and porous media flow module was used to estimate fluid flow inside both fluid and porous media. Species formation and heat release during combustion were modeled by the transport of concentrated species module. Local thermal equilibrium was assumed for the energy equation and calculated by heat transfer in porous media module. Each physic was coupled together by two mechanisms—first, reaction flow, which coupled together between free and porous media flow and transport of concentrated species. Finally, nonisothermal flow coupled free and porous media flow with heat transfer in porous media. The combustion chamber, which is entirely filled with aluminum oxide pellets, is created for two dimensional axisymmetric. Physics-controlled mesh with finer element size is applied to generate mesh by the software to meet the specified need for each physic. Combustion behavior, velocity and temperature profile, and species formation are achieved from this simulation study.

Charoensuk, Jarruwat

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