Chandraambhorn, Walairat

Preferred name

Alternative Name

Chandra-Ambhorn, Walairat

Chandra-ambhorn, Walairat

Chandra-Ambhorn, W.

Main Affiliation

School of Engineering

walairat.ch@kmitl.ac.th

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Novel Method for Determining Standard Enthalpy and Entropy of Volatilisation of Chromia Exposed to Humidified Oxygen at 298 K Based on Transport Theory of Multicomponent Gas Mixtures
(2025-02-01)
Thublaor, Thammaporn
;
Tengprasert, Watcharapon
;
Suparapinyopapkul, Grid
;
Nilsonthi, Thanasak
;
Chandra-ambhorn, Walairat
Based on the transport theory of multicomponent gas mixtures, we proposed an expression for determining the standard volatilisation enthalpy and entropy of chromia exposed to humidified oxygen at 298 K. The use of this expression could lead to the quantification of those thermodynamic quantities when the mass flux of Cr loss due to the volatilisation of chromia is determined. We thus experimentally measured the mass fluxes of Cr loss due to volatilisation in humidified atmospheres at 873–1073 K. As a result, the standard enthalpy and entropy of the volatilisation of chromia subjected to humidified oxygen at 298 K were quantified, giving the values of 61.1 ± 1.0 kJ mol−1 and −43.0 ± 1.9 J K−1 mol−1, respectively. The measured and calculated mass fluxes of Cr loss due to volatilisation tended to be related to absolute temperature in the Arrhenius-like form. We proposed the use of the line of the mass flux of Cr loss due to volatilisation in an Arrhenius-like diagram, which was shifted by the different thermodynamic data used to graphically assess the reliability of the thermodynamic data obtained from this work and the literature.
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Effects of antioxidant and ceramic coating on performance enhancement and emission reduction of a diesel engine fueled by Annona oil biodiesel
(2021-08-01)
Viswanathan, Karthickeyan
;
Wu, Wei
;
Taipabu, Muhammad Ikhsan
;
Chandra-Ambhorn, Walairat
Background: A broad investigation on alternative source of energy has been going on to find a solution to multi-faceted fossil fuel concerns namely exhaustion of fuels, energy demand, harmful emissions and environmental impact. Biodiesel is an environment-friendly and renewable alternative for diesel. In the present work, Annona seed oil has been assessed as a potential feedstock for biodiesel production. Methods: A100 was characterized by FTIR and GC-MS. Propyl Gallate (PG) was characterized by morphological study using FESEM. The elemental analysis of PG was measured using EDAX analysis. YPSZ coating was found suitable to make out the potential of A100 in diesel engine. PCCU was designed to reduce the emissions by the liquid reductant in the catalyst system. The process optimization was performed by RSM and factorial experimental design. Findings: With the YPSZ coated engine, improved characteristics of combustion and performance were noticed with A100+PG. A significant diminution on CO, HC and smoke emissions were perceived with A100+PG+CE. In addition, the work was expanded with the application PCCU for the lessening of NOx. A gradual decrement in NOx was observed with A100+PG+CE. Subsequently, A100+PG+CE with PCCU was deliberated as more prominent than other fuel samples in view of its engine characteristics.
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Possibility of metallic cobalt formation in the oxide scale during high-temperature oxidation of Co-27Cr-6Mo alloy in air
(2023-01-01)
Wongpromrat, Patthranit
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Tunthawiroon, Phacharaphon
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Bumrungthaichaichan, Eakarach
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Ponpo, Phisan
;
Nilsonthi, Thanasak
Co-based alloys are known to be high oxidation-resistant material and used in several high temperature applications. During high temperature oxidation, duplex oxides containing Co and Cr were formed. It was thermodynamically elucidated that when the growing scale was thick enough, the partial pressure of O<inf>2</inf> in the scale dropped. Then, the reduction of CoO occurred for promoting O<inf>2</inf> which was responsible for Cr<inf>2</inf>O<inf>3</inf> production. This work experimentally proved this point by in situ char-acterising Co-27Cr-6Mo at high temperatures in air by X-ray diffractometer in a grazing incident mode and metallic Co was confirmed to be formed by the reduction of CoO consistent with the image taken and analysed by field emission scanning electron microscope, energy-dispersive X-ray, and electron backscatter diffraction. Furthermore, the change in lattice parameter and the phase transition were observed when the temperature was altered.
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Effects of temperature and water vapour on Cr-species volatilisation, oxidation and scale adhesion of a Type 409L stainless steel for application as interconnect of low temperature solid oxide fuel cells
(2024-06-01)
Homjabok, Wanna
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Tengprasert, Watcharapon
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Thublaor, Thammaporn
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Wiman, Panya
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Nilsonthi, Thanasak
Though the classical transport theory does not mathematically express the Arrhenius-like relation between Cr-loss flux due to volatilisation and absolute temperature, such relation was experimentally observed for 409L stainless steel exposed at 600–750 °C. Volatilisation calculation in the present cases can be estimated giving such relation because of the nearly linear relation between mass transfer coefficient and temperature. Cr-loss fluxes in O<inf>2</inf> with 20 and 40 % H<inf>2</inf>O are close to or coincided with the fluxes calculated from MnCr<inf>2</inf>O<inf>4</inf> evaporation. Increasing water vapour could enhance volatilisation contributed from the raised CrO<inf>2</inf>(OH)<inf>2</inf> pressure, reduce oxidation rate, and worsen scale adhesion.
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The roles of CO2 and water vapour on the high temperature corrosion of a type 430 stainless steel as an interconnect of bio-gas fuel intermediate temperature SOFCs
(2025-12-01)
Thublaor, Thammaporn
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Srihathai, Padungaut
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Tengprasert, Watcharapon
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Suparapinyopapkul, Grid
;
Yan, Jiayi
A Type 430 stainless steel was exposed to Ar-20 %CO<inf>2</inf> without and with water vapour at 800 °C up to 96 h. Increasing water vapour content from 5 % to 40 % helped reduce mass gain, enhance volatilisation, and improve scale adhesion with fewer pores at scale/steel interface. Mechanisms for Cr and Mn volatilisations including the direct reactions between Cr-containing oxide and CO<inf>2</inf> were suggested with the aid of the XPS results. Mathematical relations that express the role of water vapour on concentrations of defects responsible for scale growth were proposed to help explain the reduced oxidation rate.
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Reduction of chromium volatilisation from stainless steel interconnector of solid oxide electrochemical devices by controlled preoxidation
(2016-05-01)
Wongpromrat, Wichitra
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Berthomé, Grégory
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Parry, Valérie
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Chandra-ambhorn, Somrerk
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Chandra-ambhorn, Walairat
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Corrosion behaviour of AISI 430 stainless steel in O2-40%H2O at 800 °C
(2022-07-15)
Wiman, Panya
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Thublaor, Thammaporn
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Rojhirunsakool, Tanaporn
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Bidabadi, Mohammad Hassan Shirani
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Yang, Zhi Gang
Less mass gain and poorer scale adhesion assessed by the tensile test of the AISI 430 stainless steel exposed to O<inf>2</inf>-40%H<inf>2</inf>O at 800 °C were observed in comparison with the exposure to O<inf>2</inf>. The reduced mass gain was partly due to Cr-species volatilisation while the worse scale adhesion related to pores formed at scale/steel interface. The Brouwer diagrams were proposed to help discuss the water vapour effect on altering defect concentrations that could affect the oxidation rate and scale adhesion of the studied steel.
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Characterisation and pickling behaviour of thermal oxide scale on low carbon steel produced from a thin slab
(2011-01-01)
Chandra-Ambhorn, Somrerk
;
Somphakdee, Tanongsak
;
Chandra-Ambhorn, Walairat
Thin slab interested in this work was the one with the thickness of ca. 50 mm and mainly made from recycled steel. Chemical composition of the studied steel strip produced from such slab was Fe with 0.077 wt% C, 0.233 wt% Mn, 0.191 wt% Si, 0.159 wt% Cu and 0.052 wt% Ni. Scale retained on that steel after hot rolling was studied. The hot-rolled sample was pickled in 10%v/v HCl aqueous solution at 80 °C. Weight loss and relative XRD peaks of hematite-per-iron and magnetite-per-iron were measured at different pickling periods of time. It was observed that the as-received scale was crack-free. Hematite-and-iron ratio approached zero at the pickling time of 3 seconds. Magnetite-per-iron ratio gradually decreased with increased pickling time and approached zero later. These results indicated that pickling solution attacked the outermost hematite layer resulting in removing of this layer first. Sublayers of scale consisting of magnetite were completely pickled later. Pickling behaviour was not merely volumetric since scale was crack-free. Mechanical adhesion of scale on steel substrate was additionally investigated by tensile test to help characterise the oxide scale. © (2011) Trans Tech Publications.
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Microstructure and high-temperature oxidation behaviour of AISI 304L stainless steel welds produced by gas tungsten arc welding using the Ar–N2–H2shielding gas
(2025-01-01)
Chueaprakha, Sompong
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Thublaor, Thammaporn
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Siripongsakul, Thamrongsin
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Wiman, Panya
;
Chandra-Ambhorn, Walairat
In the present work, we added 1.5 and 5% v/v hydrogen gas to an Ar–7% N<inf>2</inf> shielding gas for the gas tungsten arc welding of AISI 304L stainless steel to investigate its effect on the weld microstructure and oxidation rate. By using Ar–7% N<inf>2</inf> as a shielding gas, the weld metal contained 2.1% of delta ferrite in an austenite matrix. The addition of 1.5 and 5% hydrogen gas in the shielding gas provided the welds with a higher ratio of delta ferrite to austenite matrix, ranging from 3.8 to 6.9%, thus helping reduce the risk of hot cracks. The weld metals were further subjected to an oxidation test in synthetic air at 700°C, and the parabolic oxidation kinetics were observed. The parabolic rate constant of the weld metal produced using the Ar–7% N<inf>2</inf> shielding gas was 5.44 × 10–13 g2 cm–4 s–1. When 1.5 and 5% hydrogen gas was added to the Ar–7% N<inf>2</inf> shielding gas, the rate constants were reduced to 64% and 24% of that of the weld produced using only Ar–7% N<inf>2</inf> shielding gas, indicating the promising role of the presence of hydrogen in the Ar–7% N<inf>2</inf> shielding gas on improving the weld metal oxidation resistance for high temperature services.
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Optimisation of metallic interconnects for hydrogen production by high temperature water vapour electrolysis
(2012-01-01)
Ardigo, M. R.
;
Parry, V.
;
Popa, I.
;
Chevalier, S.
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Chandra-Ambhorn, W.
For economical and environmental reasons, hydrogen is considered as a major energetic vector for the future. Hydrogen production via high temperature water vapour electrolysis (HTE) is a promising technology. A major technical difficulty related to high temperature water vapour electrolysis is the development of interconnects working efficiently for a long period. Working temperature of 800°C enables the use of metallic materials as interconnects. Chromia forming alloys are among the best candidates. The interconnect material chosen in the present study is a ferritic stainless steel with 18% chromium content. High temperature corrosion resistance and electrical conductivity of the alloy was tested in both cathode (H<inf>2</inf>/H<inf>2</inf>O) and anode (O<inf>2</inf>/H<inf>2</inf>O) atmospheres. Corrosion products were then characterized by SEM-EDX and XRD. Moreover chromium evaporation measurements were carried out under anode atmosphere. © (2012) Trans Tech Publications.

Chandraambhorn, Walairat

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