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Effect of Curing Parameter on the Mechanical Properties and Bond Strength at Propellant-Liner Interfaces in Rocket Motors
(2025-01-01)
Kitinirunkul, Thirapat
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Boonyarat, Paisarn
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Khumchoo, Wasan
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Namkanisorn, Apinan
This study investigates the effect of curing parameters (Rt) on the mechanical properties and bond strength of propellants and liners in rocket motors compared to the design values. The optimal curing parameters for the propellant and liner in interface bonding were identified. Hydroxyl-terminated polybutadiene (HTPB) was used as the binder, while toluene diisocyanate (TDI) was employed as the curing agent. Various curing parameters were tested, with Rt values for the propellant (0.75 to 1.55) and liner (0.90 to 1.70). The results showed that the best mechanical properties for the liner and propellant were achieved at Rt values of 0.90 and 1.11, respectively. Subsequent interface bonding tests and analyses determined the optimal curing parameters to be 0.90 for the liner and 1.15 for the propellant. These optimal parameters resulted in a bond strength of 0.75 MPa, with the mechanical properties of the propellant and liner exceeding the required design values. The findings from this study can be utilized to enhance the manufacturing process of rocket motors and ensure their reliable performance.
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A New Viscosity Model for Non–Newtonian Fluids: Part I – Physical Characteristics of Its Mathematical Description
(2024-01-01)
Seethao, Tupthai
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Namkanisorn, Apinan
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Wattananusorn, Santi
This research introduces a numerical approach for constructing a viscosity model, utilizing the power law model to illustrate the behavior of shear–thinning fluids in relation to fluid flow parameters. The developed viscosity model was integrated into a Computational Fluid Dynamics (CFD) tool and its performance was assessed by comparing predictions with experimental data from literature, as well as with various viscosity models such as power law, Sisko, Cross power law, and Bird–Carreau viscosity models. The results, along with the additional correlation obtained from a 100:1 planar channel flow simulation, demonstrated stability and efficiency.
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CFD prediction of mixing performance for circular and non-circular jet mixing tanks
(2022-06-01)
Namkanisorn, Apinan
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Wattananusorn, Santi
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Sakdasri, Winatta
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Bumrungthaichaichan, Eakarach
Our previous CFD predictions of the circular, elliptic, and square jet mixing tanks were re-analyzed to investigate the highest performance jet mixing tank design and the appropriate mixing performance criterion. So, the mixing performance indicated by overall mixing time and maximum mixing time criteria of these jet mixing tanks was compared. These CFD predictions were carefully developed by using our previous reliable jet mixing tank CFD model. For model validation, reasonable agreement between the predicted mixing times and measurements was observed. The results revealed that circular and non-circular jet flow phenomena were significantly different in the near field jet regions. Further, the elliptic jet mixing tank provided the highest mixing performance because of its highest entrainment and turbulence kinetic energy near the jet boundary. Finally, it can be concluded that the maximum mixing time criterion is a suitable mixing performance indicator.
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Scrubbed Palm Fatty Acid Distillate as Vitamin E Concentrate
(2022-01-01)
Soontornchatchawate, Amnart
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Chintanalert, Supachai
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Kitchaiya, Prakob
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Namkanisorn, Apinan
Vitamin E (VitE) production from crude palm oil (CPO) has been extensively studied and industrially conducted. VitE in CPO is in the range of 600 to 1,000 ppm, and is usually produced from one of the main by-products of edible palm oil production, namely palm fatty acid distillate (PFAD). PFAD contains 4,000 to 5,500 ppm of VitE, and is produced from deodorization process of palm oil purification. This paper presents an innovative process of VitE concentrate production from CPO. A scrubber was designed and installed between the deodorizer and conventional PFAD scrubber. The main objective of this new scrubber was a recovery of glycerides from PFAD. This new scrubber is operated at 150 to 160℃. The scrubbed oil is named as Scrubbed Palm Fatty Acid Distillate (S-PFAD). This simple and efficient modified process can retrieve glycerides as S-PFAD at 0.3% recovery and it enhances VitE concentration in S-PFAD to the range of 28,000 to 32,000 ppm, which is the highest concentration of VitE that has ever been produced in the palm oil production. Fatty acids and glycerides in S-PFAD were esterified and transesterified to methyl esters. The methyl esters were evaporated from S-PFAD, and S-PFAD residue oil contained 24.7% VitE.
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CFD Simulations of High Efficiency Gas Cyclones: An Influence of Dustbin Geometry
(2021-01-01)
Pechmanee, Pitiwat
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Namkanisorn, Apinan
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Wattananusorn, Santi
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Bumrungthaichaichan, Eakarach
The unsteady state simulation of gas-solid cyclone separator was carried out to investigate the performances of 0.29 m diameter (D<inf>B</inf>) cyclones with five different dustbin geometries, including dustbin without dipleg (cylindrical bin) and dustbins with 0.5D<inf>B</inf>, 1.0D<inf>B</inf>, 1.5D<inf>B</inf>, and 2.0D<inf>B</inf> (divergent conical bin) height divergent conical diplegs. The diameter and total height of five dustbins were 1D<inf>B</inf> and 2D<inf>B</inf>, respectively. The gas flow and turbulence fields inside the cyclones with the Reynolds number of 280,000 were simulated by Reynolds averaged Navier-Stokes equations (RANS) with Reynolds stress model (RSM). The collection efficiencies were investigated by using discrete phase model (DPM). For model validation, the simulated velocity profiles of the cyclone with cylindrical dustbin have been compared to the previous experimental data available in literature and were in good agreement with the previous results. Further, the simulated results revealed that the Stairmand cyclone with divergent conical and simple cylindrical dustbins respectively represented the highest and lowest collection efficiencies indicated by 50% cut-off diameter, which corresponded to the diameters of 1.692 and 1.744 microns, respectively.
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Sustainable drying of galangal through combination of low relative humidity, temperature and air velocity
(2020-02-01)
Namkanisorn, Apinan
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Murathathunyaluk, Siripan
Galangal (Alpinia galanga) is a herb commonly grown in Southeast Asia. The galangal rhizomes contain compounds that have antimicrobial and antioxidative properties. Longer storage of galangal can be achieved by drying. In the household-based industry, farmers use tray dryers because they are relatively cheap and easy to use. However, the quality of the products is low due to inappropriate temperature and drying time. The drying process is also energy intensive. This study investigated the effects of drying conditions such as air velocity, drying temperature and relative humidity on the drying characteristics and product quality. Drying of galangal was carried out at the following conditions: air velocities 0.25 and 0.5 m/s, drying temperatures 45 and 75 <sup>∘</sup>C and relative humidity at 15 and 70 %RH, respectively. The mathematical modeling of thin layer drying kinetics of galangal was performed using Page model. The active ingredients in dried galangal were best preserved using a drying condition at air velocity of 0.25 m/s, 45 °C and 15%RH, in which the highest values of inhibition of free radicals by DPPH, total phenolic content (TPC) and 1’-acetoxychavicol acetate (ACA) content were 79.2 ± 1.3%, 91.9 ± 3.9 mg<inf>GAE</inf>/100 g and 384.1 ± 17.6 mg/100 g, respectively. Switching the relative humidity from low to high while keeping both air velocity and temperature low yielded a low drying rate. Hence, a combination of low relative humidity and low drying temperature at the optimum air velocity is promising for the design of more energy efficient dryer that gives desirable drying characteristics and product quality.
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CFD modelling of pump-around jet mixing tanks: a discrepancy in concentration profiles
(2018-10-03)
Bumrungthaichaichan, Eakarach
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Namkanisorn, Apinan
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Wattananusorn, Santi
Jet mixing tanks are important in chemical processes. Over the past two decades or so, computational fluid dynamics (CFD) has been employed to study jet mixers. The shortfalls of the previous CFD models were the discrepancy in concentration profiles between simulation and experiment and the absence of exact inlet turbulence conditions. So, in our present work, the CFD model was developed to investigate the proper conditions for jet mixing tank simulation and improve the accuracy of concentration profile prediction by using an appropriate grid arrangement, a realizable k-epsilon model, and a second-order upwind discretization scheme. The results revealed that the CFD model with proper inlet conditions predicted the overall mixing time well and somewhat improved the predicted concentration profiles. Further, the reasons for discrepancies in concentration profiles were inappropriate inlet turbulence conditions and overprediction in total momentum available for mixing due to the flat top liquid surface assumption. In addition, this discrepancy may be caused by the dynamic response of concentration measuring device.
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Influence of jet discharge velocity profile on CFD simulation of pump-around jet mixing tank
(2018-08-14)
Jorakit, Thanwa
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Phaiboonsilpa, Natthanon
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Namkanisorn, Apinan
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Ponpo, Phisan
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Bumrungthaichaichan, Eakarach
The present paper shows the effect of jet discharge velocity profile (or jet nozzle configuration) on CFD simulation of an open 45° inclined side entry pump-around jet mixing tank. The CFD model was carefully developed by using appropriate grid arrangement, boundary conditions, and numerical methods. The two different jet discharge velocity profiles, including top hat and fully developed profiles, were simulated by using the inlet mass flow rate of about 0.22 kg·s<sup>-1</sup>. The overall mixing times and normalized concentration profiles predicted by two different jet discharge velocity profiles were compared with the previous reliable experimental data. The results revealed that the different jet discharge velocity profiles resulted in different jet flow and mixing patterns inside the vessels.
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Outer-tubes Falling Film Evaporator with Well-Mixed Surface Renewal
(2017-01-01)
Lerkkasemsan, Nuttapol
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Lerssubsuree, Kuntaphon
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Chotiviriyavanich, Boonchai
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Benjangkaprasert, Ruenruedee
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Kitchaiya, Prakob
A falling film evaporator with a liquid flowing laminarly outside vertical cylindrical tubes was studied by a mathematical modeling in order to describe the performance of the system and the results are later used for a design of a falling film evaporator. In this study a mathematical model was developed from mass and energy as well as momentum transfer processes in an evaporation of a sugar solution. The equations were solved by using a numerical technique known as implicit method. This model yields the prediction of velocity, temperature and concentration profiles of solution as well as rate of mass evaporation and energy required in this process. Evaporation limitation was disclosed to be based on water mass transfer across the liquid thin film. Renewable surface was proposed to enhance the evaporation by adding a collector for liquid mixing before further evaporation. Adding only one collector at the half height of the evaporation tube could increase water evaporation rate by 1.3 and 2.1 % in case of the liquid perfect mixing, respectively.
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Fracture toughness of a silane coupled polymer-metal interface: Silane concentration effects
(2005-03-01)
Berry, Douglas H.
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Namkanisorn, Apinan
Fracture toughness of joints made from a glassy, 343,000 molecular weight poly-styrene block bonded to chromic-sulfuric acid etched or phosphoric acid anodized aluminum are investigated. The fracture tests are performed with a 90-degree peel apparatus under "dry" laboratory conditions and "wet" conditions created by submerging the apparatus in a temperature controlled water bath. The bond strengths are controlled using various concentrations of styrl silane coupling agent added directly into the styrene monomer solution that polymerizes against the aluminum. Ellipsometric measurements on smooth silicon surfaces verify that the thickness of bound polymer is controlled by the silane to polystyrene mole ratio. X-ray photoelectron spectroscopy (XPS) analysis of fractured surfaces indicates that the fracture is near the aluminum surface. Both the wet and dry fracture energy as a function of bound polymer thickness on acid etched aluminum joints resemble quite closely the adhesion literature results obtained by fracturing pairs of fused, immiscible glassy polymers. Reasons for this similarity are discussed. Copyright © Taylor & Francis Inc.

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