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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
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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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Economic and environmental analyses for achieving net-zero CO2 emissions of a green diesel production process
(2024-12-01)
Pongboriboon, Nattapat
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Mariyappan, Vinitha
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Wu, Wei
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Chandra-Ambhorn, Walairat
Background: In this study, palm oil hydrotreating for producing green diesel has been thoroughly explored, emphasizing high yields, reduced environmental impact, and lower energy consumption, particularly with solar collectors. Methods: This study addresses these gaps by evaluating impacts on multiple fronts, including carbon revenue, GHG emissions, and overall environmental effects. The Life Cycle Assessment (LCA) technique, utilizing the CML method developed by Centrum voor Milieukunde Leiden (the Center for Environmental Science at Leiden University, The Netherlands) in SimaPro®, is employed to assess the environmental impact of green diesel production processes. The CML method evaluates environmental impacts through three phases: characterization, which quantifies environmental loads; midpoint, which assesses intermediate impact stages such as global warming potential; and damage, which evaluates potential harm to human health, ecosystems, and resource availability. The scope of work includes simulating the production process and incorporating a CO<inf>2</inf> capture unit with Aspen Plus®. Additionally, kinetic parameters for the palm oil hydrotreating reaction were validated, and energy consumption was optimized using the Aspen Energy Analyzer. Significant findings: The net-zero emissions of the green diesel (GD) production from crude palm oil (CPO) is achieved by using an integration of an evacuated tube solar collector (ETSC), heat exchanger network, and a post-separation CO<inf>2</inf> capture process. Through the life cycle assessment (LCA), the terrestrial ecotoxicity potential (TEIP) is identified as a significant environmental factor due to chemical pesticides used in the oil palm cultivation. The carbon neutrality is validated by producing 1 kg of GD from CPO down to 0.0617 kg total CO<inf>2</inf> emissions since the net CO<inf>2</inf> sequestration for palm oil from oil palm plantation is taken into account. Referring to the Guthrie method, the economic indicators including the net present value (NPV) and the payback period are estimated at around 0.9 M$ in the 15th year and 9 years, respectively, if the CPO purchase price and the GD selling price are assumed to be $0.47/kg CPO and $1.98/kg GD, respectively, and the increased annual carbon credit is taken into account.
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Novel CO2-negative design of palm oil-based polygeneration systems
(2023-02-01)
Wu, Wei
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Supankanok, Rasa
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Chandra-Ambhorn, Walairat
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Taipabu, Muhammad Ikhsan
A palm oil-based polygeneration system (POPS), which is a combination of a fixed bed hydrotreating reactor (FBHTR), a three-phase separator, and a series of cryogenic separators, is co-production process of green diesel and liquefied petroleum gas (LPG) named Design 1. The FBHTR model is validated by experiment data and its optimal operating parameters are determined by solving the response surface methodology-based optimization algorithm. Two CO<inf>2</inf>-negative designs for the POPS named Designs 2 and 3 adopt approaches of (i) the evacuated tube solar collector (ETSC) for reducing 35% flue gas from the furnace, (ii) the amine-based CO<inf>2</inf> capture process coupling with pre- or post-separation system for producing the high-purity CO<inf>2</inf> product, and (iii) the heat integration design for reducing the energy duties of hot/cold utilities. Design 2 is validated to achieve the maximum negative net CO<inf>2</inf> emissions. Design 3 not only ensures the negative net CO<inf>2</inf> emissions, but also it produces three high-purity products (98.3% green diesel, 100% LPG, and 99.9% CO<inf>2</inf>) simultaneously.
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Process design and economic evaluation of biomass-based negative emission technologies
(2023-01-01)
Wu, Wei
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Supankanok, Rasa
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Chandra-Ambhorn, Walairat
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Pongboriboon, Nattapat
A palm oil-based polygeneration system (POPS) is simulated to produce the main product of high-purity green diesel as well as the liquefied petroleum gas (LPG) as a by-product. The CO<inf>2</inf>-negative design includes approaches of (i) a series of cryogenic separators for the recovery of approximately 65.5% of hydrogen feedstock, (ii) the evacuated tube solar collector (ETSC) for reducing 35% flue gas from the furnace, (iii) the amine-based CO<inf>2</inf> capture process for pursuing the high-purity CO<inf>2</inf> product. The economic analysis of POPS shows that the process becomes economically attractive if the diesel price and crude palm oil should be around 1.98 and 0.47 $kg-1, respectively.
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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
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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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Corrosion Resistance Enhancement of Reinforced Concrete in Marine Environment by Partial Replacement of Black Rice Husk Ash
(2023-01-01)
Chandra-Ambhorn, Walairat
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Bumrungthaichaichan, Eakarach
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Rotchan, Chayanit
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Haema, Narunat
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Wongpromrat, Patthranit
In this work, the black rice husk ash (BRHA), a pozzolanic material, was used as a partial replacement in concrete with the weight percentages of 0%, 10%, 20%, 30%, 40% and 50% for enhancing the corrosion resistivity in the marine environment. The compressive strength, corrosion by accelerated corrosion test by impressed voltage (ACTIV), and chloride (Cl− ) penetration of concrete specimens were investigated after 28 days of curing. For corrosion and chloride penetration analyses, the 20% of BRHA replacement specimen was the most effective concrete specimen because the deformation was not observed within 19 days of the test. The cement specimens with lower BRHA percentages were cracked due to the development of stress by the rust formation. For higher BRHA percentages, the protective Fe2O3 was dissolved due to the acidic environment caused by higher chloride accumulation in the cement specimens. The steel rebar was then aggressively attacked by the chloride and it was finally broken. Therefore, the optimization of the BRHA percentage is needed to minimize corrosion. However, the longer curing time of 20% BRHA replacement specimen is required for increasing the compressive strength because its compressive strength is slightly lower than the standard.
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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
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Wu, Wei
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Taipabu, Muhammad Ikhsan
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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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Modification of a solar thermal collector to promote heat transfer inside an evacuated tube solar thermal absorbe
(2021-05-01)
Supankanok, Rasa
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Sriwong, Sukanpirom
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Ponpo, Phisan
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Wu, Wei
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Chandra-Ambhorn, Walairat
Evacuated-tube solar collector (ETSC) is developed to achieve high heating medium temperature. Heat transfer fluid contained inside a copper heat pipe directly affects the heating medium temperature. A 10 mol% of ethylene-glycol in water is the heat transfer fluid in this system. The purpose of this study is to modify inner structure of the evacuated tube for promoting heat transfer through aluminum fin to the copper heat pipe by inserting stainless-steel scrubbers in the evacuated tube to increase heat conduction surface area. The experiment is set up to measure the temperature of heat transfer fluid at a heat pipe tip which is a heat exchange area between heat transfer fluid and heating medium. The vapor/ liquid equilibrium (VLE) theory is applied to investigate phase change behavior of the heat transfer fluid. Mathematical model validated with 6 experimental results is set up to investigate the performance of ETSC system and evaluate the feasibility of applying the modified ETSC in small-scale industries. The results indicate that the average temperature of heat transfer fluid in a modified tube increased to 160.32 °C which is higher than a standard tube by approximately 22 °C leading to the increase in its efficiency by 34.96%.
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Effect of water vapour on the high temperature oxidation of stainless steels
(2020-01-01)
Chandra-Ambhorn, Somrerk
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Wongpromrat, Patthranit
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Thublaor, Thammaporn
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Chandra-Ambhorn, Walairat
This chapter primarily reviews the nature of water vapour when it presents in bulk gas. The change in a ratio between water vapour and corresponding dissociated hydrogen, which determine the thermodynamic stability of the oxide formation, is analysed when the oxidation kinetics are linear and parabolic. When water vapour reaches the solid/gas interface, chromium species volatilisation and oxidation controlled by surface reaction can occur. The adsorbed water vapour can be further incorporated into the oxide possibly in the form of hydrogen defects. The role of these defects on altering the defect structure of the oxide is discussed. Finally, characteristics of the oxide scale on stainless steels formed in the atmosphere containing water vapour are reviewed.
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Development of sofc interconnect stainless steels
(2020-01-01)
Chevalier, Sébastien
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Combemale, Lionel
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Popa, Ioana
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Chandra-Ambhorn, Somrerk
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Chandra-Ambhorn, Walairat
The chapter introduces components and working principle of solid oxide fuel cells (SOFCs). It is followed by the explanation on the choices of materials focussing on ferritic stainless steels. The review is further made on the required properties of these steels, i.e. low oxidation rate, low chromium species volatilisation rate, high electrical conductivity and good scale adhesion. For the oxidation aspect, the behaviour of stainless steel interconnect in cathode, anode (hydrogen and biogas), and dual atmospheres are described. Surface modification by pre-oxidation and coatings to improve the oxide electrical conductivity and to reduce chromium species volatilisation is finally reviewed.

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