Bumrungthaichaichan, Eakarach

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School of Engineering

eakarach.bu@kmitl.ac.th

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Influence of grid distribution on CFD model of compressible flow inside the primary nozzle and mixing chamber used in refrigeration application
(2018-08-14)
Ruangtrakoon, Natthawut
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Bumrungthaichaichan, Eakarach
In this study, the influence of grid distribution on CFD model of the primary nozzle and mixing chamber used in refrigeration application was primarily investigated. The only one geometry of primary nozzle and mixing chamber was modeled. The two different grid distributions, fine near-wall grid and regular grid with the identical total grid number, were simulated to investigate the flow phenomena inside the considered system. The appropriate boundary conditions and numerical methods were carefully employed. The simulated entrainment ratios obtained by two different grid arrangements were validated by comparing with the reliable experimental data. The results revealed that the Mach number distributions of these models were different. Further, the outlet total pressure predicted by fine near-wall grid was about 1.3% higher than that obtained by regular grid.
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A review on numerical consideration for computational fluid dynamics modeling of jet mixing tanks
(2016-11-01)
Bumrungthaichaichan, Eakarach
Over two decades or so, the computational fluid dynamics (CFD) modeling of various jet mixing tank configurations was developed and published. Further, the studies of various parameters used in experimental and CFD works were also reviewed to obtain the optimal design procedure. However, the numerical setup for jet mixing tank modeling was not studied and reported. Hence, in this review paper, the important numerical setup for CFD simulation of jet mixing tanks, including numerical solution techniques, turbulence model selection, boundary conditions, numerical methods, solution strategy, and CFD grid, are clearly demonstrated to achieve the comprehensive CFD modeling guideline for jet mixing tank. Further, the validations for jet mixing tank models are also represented.
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Simple Empirical Relation for an Evacuated-Tube Solar Collector Performance Prediction from Solar Intensity
(2023-09-01)
Pongboriboon, Nattapat
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Wu, Wei
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Chandra-ambhorn, Walairat
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Wongpromrat, Patthranit
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Bumrungthaichaichan, Eakarach
In this paper, the effect of solar intensity on the heat pipe tip temperature in a heat pipe type—evacuated-tube solar collector (HP-ETSC) was investigated. A simple relation was proposed, relating the solar intensity to the heat pipe tip temperature generated from the experimental data. This simple empirical relation was applied in a set of heat transfer equations derived to predict the heating medium temperature at the manifold outlet of the evacuated-tube solar collector. The calculated results corresponding to two types of heating medium, i.e., palm oil and water, were compared with experimental results from the literature. The results show that the average error was 6.41% for the case of palm oil and 4.66% for the case of water. Based on the case of water as a heating medium fluid, it was found that the flow rate of the heating medium fluid affected the accuracy of prediction, as the percentage error increased with the heating medium flow rate. The maximum percentage error increased from only 1.83% for a water inlet flowing at a Reynolds number of about 2.4 × 103 to 15.23% for a water flow rate at a Reynolds number of about 2.6 × 104. The correction factor was added into the correlation to predict the heat transfer coefficients of heating medium fluids. With this correction factor, the maximum error could be reduced from 11.78% to 7.29% for the palm oil case and from 15.23% to 5.57% for the water case. The average errors corresponding to palm oil and water cases could be reduced to 0.74% and 1.26%, respectively.
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Corrigendum to “How can the appropriate near-wall grid size for gas cyclone CFD simulation be estimated?” [Powder Technology 396 (2022) 327–344, (S0032591021009128), (10.1016/j.powtec.2021.10.031)]
(2024-02-15)
Bumrungthaichaichan, Eakarach
The author regrets errors that occurred in the original article [1], which are now amended as follows: The near-wall grid size [mm] for cyclone A1 cone of “0.8764” in Table 3 of the original article [1] is corrected to be “0.6550”. The near-wall grid size [mm] for cyclone A1 vortex finder of “0.6550” in Table 3 of the original article [1] is corrected to be “0.8764”. Although the author has already described in section 3.4. Grid independent solutions and grid convergence index of the original article [1] that the experimental data of Hoekstra [2] displayed by circle symbols in Fig. 6 of the original article [1] was employed to compare with the simulated results performed in the original article [1] as “Further, the numerical uncertainties were approximated by GCI as illustrated by error bars on the normalized velocity profiles, which were compared with experimental data of Hoekstra [9], as represented in Fig. 6.” (Number “9” displayed in the brackets refers to the reference order for the Hoekstra's work [2] in the original article [1].), this information should also be added to the Fig. 6 caption of the original article [1] to prevent the confusion of readers. Therefore, the Fig. 6 caption of the original article [1] is now changed to the more appropriate Fig. 6 caption as “Radial profiles of mean tangential and mean axial velocities for cyclone B2 at z/D<inf>b</inf> = 0.75 predicted by (a) three different grid resolutions and (b) fine grid level with discretization error bars (EXP [9])”. Note that number “9” displayed in the brackets refers to the reference order for the Hoekstra's work [2] in the original article [1]. Furthermore, the same set of Hoekstra's experimental data [2] was also used in the graphical abstract of the original article [1] published on online pages as displayed by circle symbols. The name “ter Linder” in section 4.2. Mean static pressure and pressure drop of the original article [1] is corrected as “ter Linden”. An explanation of the Greek symbol “ν” in the inline equation of Stokes number represented in section 4.4. Collection efficiency of the original article [1] was not given in any section of the original article [1]. Hence, this Greek symbol is now described in this erratum as “ν is the kinematic viscosity of fluid [m2 s−1]”. The author would like to apologise for any inconvenience caused.
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How can the appropriate near-wall grid size for gas cyclone CFD simulation be estimated?
(2022-01-01)
Bumrungthaichaichan, Eakarach
In this paper, one of the frequently asked questions for gas cyclone CFD simulation, that “How can the proper near-wall grid size be estimated?”, has been answered. The wall y+ definition was adopted to estimate the near-wall grid sizes. The velocities and friction factors for barrel and cone were obtained by simplifying the previous cyclone pressure drop prediction model to estimate near-wall grid sizes. The representative positions for cyclone cones have been investigated to simplify the near-wall grid estimation. Moreover, new correlations for velocities inside the vortex finder have been developed. The gas cyclones were properly simulated and compared to the previous works to assess the capability of this grid size estimation method. The CFD models developed by the estimated near-wall grid sizes represented the reasonable mean flow properties. Finally, this research concludes that the proposed near-wall grid size estimation method is essential and suitable for gas cyclone CFD simulation.
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Performance investigation for CRMC and CPM ejectors applied in refrigeration under equivalent ejector geometry by CFD simulation
(2022-11-01)
Bumrungthaichaichan, Eakarach
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Ruangtrakoon, Natthawut
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Thongtip, Tongchana
In this paper, one of the remaining questions for ejector design, “Does the constant rate of momentum change (CRMC) ejector provide better performance than the constant pressure mixing (CPM) ejector under identical ejector area ratio, ejector length, and operating conditions?”, has been answered. Two steam ejector designs operating with the various boiler and evaporator temperatures were simulated by the SST k-omega turbulence model. The present computational fluid dynamics (CFD) model produced a reasonable agreement with our previous published experimental data. The upstream operating conditions were simultaneously considered to assess the better performance ejector design with the help of the primary expansion coefficient. The predicted results revealed that the CRMC ejector showed an advantage in entrainment ratio and a disadvantage in critical condenser pressure. However, the ejector efficiency comparison confirmed that the CRMC ejector design provided better performance than the CPM ejector design for a primary expansion coefficient greater than unity. The maximum percentage improvement of ejector efficiency was 32.418%.
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Pressurized hot water extraction of crude polysaccharides, β-glucan, and phenolic compounds from dried gray oyster mushroom
(2022-10-01)
Sakdasri, Winatta
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Arnutpongchai, Panisara
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Phonsavat, Supasuta
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Bumrungthaichaichan, Eakarach
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Sawangkeaw, Ruengwit
This study aimed to investigate the effects of temperature (100 °C–140 °C), pressure (0.4–1.0 MPa), and extraction time (20–60 min) on the extraction yield of crude polysaccharides, β-glucan, and total phenolic compounds with pressurized hot water extraction of gray oyster mushrooms (Pleurotus sajor-caju (Fr.) Singer). The extraction conditions were optimized by maximizing all responses, using a central composite design (CCD)-based response surface methodology. Temperature mainly affected the increase in the extracted yield and phenolic content. However, exceeded temperature and extraction time negatively affected the β-glucan yield. The optimal extraction conditions were at 140 °C, 0.92 MPa, and 40 min with a corresponding extraction yield of 3.20 ± 0.17 g/100 g, as well as β-glucan and total phenolic contents of 43.84 ± 3.86 mg/100 g and 8.49 ± 0.66 mg gallic acid equivalent/100 g dried extract, respectively. The antioxidant activities of extracts were estimated by in vitro biological assays. The SC<inf>50</inf> values of DPPH, NO, and ABTS assays were 1.66 ± 0.02, 1.50 ± 0.19, and 6.94 ± 1.04 mg/mL, respectively. This work demonstrates an alternative approach to valorize over-produced mushrooms.
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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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A note of caution on numerical scheme selection: Evidence from cyclone separator CFD simulations with appropriate near-wall grid sizes
(2023-09-01)
Bumrungthaichaichan, Eakarach
In this paper two things are done. (i) The appropriate numerical scheme set for computational fluid dynamics (CFD) simulations of cyclone separators with various vortex-finder-to-cone-tip diameter ratios (D⁎) has been achieved by comparing the mean flow patterns and performances simulated by two previously proposed numerical scheme sets. The predicted results revealed that the CFD simulations of different cyclone separator designs require the third-order accuracy scheme and proper near-wall grid sizes to preserve flow similarity, especially for cyclone separators with D⁎ < 1. Therefore, the present research alerts caution concerning the lower-order numerical scheme for cyclone separator CFD simulation. (ii) The present CFD work confirms that the near-wall grid size estimation method originally developed for gas cyclones is a possible method for estimating near-wall grid sizes for hydrocyclone with air core diameter (D<inf>a</inf>) ≤ 0.4D<inf>v</inf>. In addition, the capabilities of pressure-strain sub-models for cyclone separator CFD simulations were preliminarily discussed.
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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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Bumrungthaichaichan, Eakarach

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