International Journal of Thermofluids最新文献

{"title":"Optimized thermal pretreatment for lignocellulosic biomass of pigeon pea stalks to augment quality and quantity of biogas production","authors":"","doi":"10.1016/j.ijft.2024.100911","DOIUrl":"10.1016/j.ijft.2024.100911","url":null,"abstract":"<div><div>By applying heat to the feedstock during the thermal treatment of biomass for the production of biogas, the organic material's biodegradability can be greatly increased. Biogas production is a huge research area for alternate energy production technology. Increased biodegradability, improved methane yield, pathogen, and weed seed destruction, and overall process efficiency are all benefits of this type of pretreatment. It is a useful pretreatment technique for maximizing the production of biogas because it can decrease inhibitory compounds, and increase the digestibility of biomass. This work focused on increasing the efficiency of biogas production from lignocellulosic biomass of pigeon pea stalks by a novel thermal pretreatment. The pigeon pea stalk is initially imposed to physical pretreatment (PT) by an automatic hammer mill which is considered as a base for comparing performance. Thermal pretreatment was carried out for one hour, and two hours durations at different temperatures like 100 °C, 125 °C, 150 °C, 175 °C, and 200 °C. Compared to physically pretreated pigeon pea stalks, 200ᴼC thermal pretreated pigeon pea stalks for two hours have produced 88.41 % higher biogas, 16.14 % increase of cellulose, 19.9 % higher volatile solid removal, and 3.94 % lesser lignin. The enhanced chemical characteristics were ensured by analyzing the chemical composition variations through the FTIR, XRD, and SEM images. So, this is recommended for enhanced biogas production.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative numerical study on the effect of fin orientation on the photovoltaic/thermal (PV/T) system performance","authors":"","doi":"10.1016/j.ijft.2024.100909","DOIUrl":"10.1016/j.ijft.2024.100909","url":null,"abstract":"<div><div>The thermal performance of a photovoltaic (PV) system is highly influenced by cooling its surface temperature. In this study, a series of cooling modules are developed, including fin turbulators within a serpentine channel placed on the rear side of a photovoltaic/thermal (PV/T) system. These modules are designed to effectively cool the PV/T system, ensuring uniform temperature distribution and enhancing the system efficiency. The study examines fins at four different angles within the serpentine channel, namely 30°, 45°, 60°, and 90° The water was employed as a cooling fluid in the study, operated under laminar flow conditions, with five Reynolds number values, ranging from 250 to 1250 with 250 increment. Every PV/T system has 108 fins with an area of 600 mm2 for each. Numerical simulations were conducted to predict the flow fields resulting from each fin configuration in the serpentine channel. The electrical and thermal efficiency of the PV/T collector was evaluated for the fin configuration with better thermal performance. Results showed that fins oriented with 30° provided the best thermal performance, while fins at 90° orientation achieved maximum heat transfer coefficient. Moreover, the electrical efficiency of the proposed PV/T system could be improved by 0.8 % to 1.5 % compared to a standard PV/T system. In addition, the PV/T system demonstrated a remarkable thermal efficiency of up to 59 % at 90° fin orientation.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation of flow dynamics and heat transfer behavior of nanofluid in microchannel with rough surfaces","authors":"","doi":"10.1016/j.ijft.2024.100901","DOIUrl":"10.1016/j.ijft.2024.100901","url":null,"abstract":"<div><div>Microchannels containing cooling fluid are among the most widely used equipment in the cooling of microscale devices, such as heat sinks in the electronics industry. In this numerical research, the flow of water/magnesium-oxide nanofluid in a 3D rectangular microchannel is simulated and investigated. The flow field and heat transfer are analyzed for the laminar flow with Reynold number (<em>Re</em>)= 100, 300, 700, and 1000 and nanoparticle volume fraction (<em>φ</em>) =0, 0.02, and 0.04. The rough surfaces include rectangular cubic ribs arranged in three one in each row along the length with 2, 3, 4, and 5 rows. The ribbed surface is under a constant heat flux. The results include examining changes in Nusselt number (<em>Nu)</em>, pressure drop, pumping power, friction factor, and total flow entropy generation. Moreover, the contours of the temperature, pressure, and velocity distribution fields will be discussed. The results reveal that the heat transfer and physics of flow are highly dependent on hydrodynamic behavior. Increasing the number of ribs on the hot surfaces increases the pressure drop, pumping power, and heat transfer. Increasing <em>φ</em> also greatly affects the heat transfer rate. In the case of using 5 ribs and with <em>φ</em>=0.04, in <em>Re</em>=1000 and 700, the microchannel has the highest average <em>Nu</em>, pressure drop, and pumping power.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermodynamic and environmental comparative analysis of a dual loop ORC and Kalina as bottoming cycle of a solar Brayton sCO2","authors":"","doi":"10.1016/j.ijft.2024.100895","DOIUrl":"10.1016/j.ijft.2024.100895","url":null,"abstract":"<div><div>Solar energy as a thermal source has become a viable and thermo-sustainable option to generate heat, for the energy production through power cycle configurations. In this article, the balances and application of life cycle analysis (LCA) allowed to proposed thermodynamic models in order to conduct a comparative study of the energy, exergy and environmental performance of two hybrid power generation systems using a supercritical carbon dioxide Brayton with recompression, intercooling and reheating (sCO₂) as the main cycle coupled to two waste heat recovery technologies: dual loop Rankine organic cycle (DORC) and Kalina cycle (KC). The results showed that the Brayton sCO₂/DORC configuration presented better exergetic performance using Toluene (23.98%), Cyclohexane (24.01%), and Acetone (24.06%) as working fluids concerning the Brayton sCO₂/KC configuration with a 23.82%. In addition, the solar field was the component with the highest irreversibility rate (∼61.6%) when the system operated at 100% solar energy. In terms of environmental impact, the results indicate that the concentrating solar power (CSP) tower is the device that generates the most emissions in the systems studied (∼90%). Acetone was found to be 36% more polluting than the working fluid used in the sCO₂/KC system (Ammonia). In addition, aluminum as a construction material emits 5.26 % more kg CO₂-equi than steel in both systems. Also, the construction phase is the LCA stage that has the greatest impact, representing approximately 95.4% of the total emissions, followed by the decommissioning phase (4.5%) and operation (0.05%). These results show good thermo-sustainable performances that in conjunction with thermo-economic optimizations could achieve solutions applicable to the local industrial sector.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Entropy generation analysis of unsteady MHD nanofluid flow in a porous pipe","authors":"","doi":"10.1016/j.ijft.2024.100907","DOIUrl":"10.1016/j.ijft.2024.100907","url":null,"abstract":"<div><div>This article presents a numerical investigation into the entropy production of nanofluids flowing through a porous medium in a permeable conduit, focusing on water-based solutions containing Titanium Carbide (TiC) and Silicon Carbide (SiC) nanoparticles. These nanoparticles are selected for their heat transfer properties. The flow system's governing equations are developed and solved using the Runge-Kutta-Fehlberg method. The study examines the influence of key nondimensional parameters, including the solid volume fraction of nanoparticles, radiation parameters, and Reynolds number, on temperature, velocity profiles, and entropy generation. The results show that Silicon Carbide-water nanofluids perform efficiently in terms of heat transfer and entropy minimization. Additionally, Silicon Carbide exhibits low skin friction at the pipe wall, with this effect increasing as the solid volume percentage of nanoparticles rises. The study also indicates that irreversibility due to heat transfer becomes more significant near the pipe wall as the solid volume fraction decreases and increases with higher radiation parameters and Reynolds number. These findings are presented graphically and in tabular form to illustrate the physical significance of the problem.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermo-hydraulic performance of concentric tube heat exchangers with turbulent flow: Predictive correlations and iterative methods for pumping power and heat transfer","authors":"","doi":"10.1016/j.ijft.2024.100898","DOIUrl":"10.1016/j.ijft.2024.100898","url":null,"abstract":"<div><div>This research addresses the problem of predicting the thermo-hydraulic performance of concentric tube heat exchangers (CTHE) under turbulent flow conditions, a critical aspect in energy-efficient industrial systems such as HVAC, power generation, and chemical processing. Existing studies often lack accurate predictive methods for balancing heat transfer performance with pumping power requirements. To tackle this issue, novel correlations and an iterative Newton–Raphson method were developed for predicting pumping power and heat transfer rates. Three-dimensional CFD simulations of a water-to-water counter-flow CTHE were conducted, with Reynolds numbers ranging from 4000 to 8000 for both the hot and cold fluids. The simulations employed the Reynolds-Averaged Navier–Stokes (RANS) equations with the <span><math><mrow><mi>k</mi><mo>−</mo><mi>ω</mi></mrow></math></span> SST turbulence model. The results demonstrated that increasing the Reynolds number enhances both heat transfer rates and pumping power, with the cold fluid requiring consistently higher pumping power. New correlations were developed to predict pumping power, capturing the impact of both entry and fully developed flow regions. These correlations showed an average error of less than 2.33% when compared with the CFD data. The iterative Newton–Raphson method for predicting heat transfer rates demonstrated high accuracy, with an average error of 0.66% for heat transfer rate, 0.03% for hot fluid outlet temperature, and 0.01% for cold fluid outlet temperature. Additionally, we identified optimal operating conditions for efficient cooling and heating based on the heat capacity ratio (<span><math><msub><mrow><mi>C</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span>). The novelty of this work lies in the development of new, highly accurate predictive correlations and iterative methods for optimizing CTHE performance, going beyond existing literature by providing comprehensive insights into the relationship between pumping power, heat transfer efficiency, and flow conditions.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142416975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of thermal properties of ethylene glycol-based Williamson hybrid-nanofluid over stretchable/shrinking flat plate and their effects on solar panels","authors":"","doi":"10.1016/j.ijft.2024.100892","DOIUrl":"10.1016/j.ijft.2024.100892","url":null,"abstract":"<div><div>The global requirement for sustainable energy supply to enhance industrial productivity and reduce production costs has focused researchers’ attention to renewable energy in recent years. Solar energy mitigates the dangers connected with the use of fossil fuels in electricity generation. This work is set to evaluate the heat transmission capacities of Williamson hybrid nanofluid flow across a flat plate with viscous dissipation and heat source. The mathematical model explaining the flow interaction of Williamson hybrid nanofluid, combining viscous dissipation, heat source, and temperature-variation thermal conductivity and viscosity, is created using conservation laws. The specified system of non-linear coupled partial differential equations undergoes non-similarity transformation. The resulting non-dimensional model is solved using the bivariate spectral weighted residual method. The accuracy of the method is proven by comparing obtained results with those in the literature, and a good agreement is observed. Graphs are utilized to explain the thermophysical properties that are being considered. The results show that the fluid temperature rises when there is a source of heating and viscous dissipation. The velocity and the fluid parameter <span><math><mrow><mo>(</mo><mi>W</mi><mi>e</mi><mo>)</mo></mrow></math></span> have an inverse connection, whereas the temperature of the fluid has the opposite impact. Moreover, when nanoparticles are present, the thermal boundary layer rises along with the nanoparticles, thickening the velocity boundary layer and decreasing fluid velocity. Findings also show that for the <span><math><mrow><mi>V</mi><mi>d</mi><mo>∈</mo><mrow><mo>[</mo><mn>0</mn><mo>.</mo><mn>1</mn><mo>,</mo><mn>0</mn><mo>.</mo><mn>5</mn><mo>]</mo></mrow></mrow></math></span>, the skin drag force and Nusselt number retard by <span><math><mrow><mn>0</mn><mo>.</mo><mn>64</mn><mtext>%</mtext><mo>,</mo><mn>14</mn><mo>.</mo><mn>06</mn><mtext>%</mtext></mrow></math></span> for the shrinking sheet and <span><math><mrow><mn>0</mn><mo>.</mo><mn>21</mn><mtext>%</mtext><mo>,</mo><mn>6</mn><mo>.</mo><mn>57</mn><mtext>%</mtext></mrow></math></span> for the stretching sheet respectively. In the same vein, an 100% surge in the porosity parameter escalate the skin friction coefficient by 19.13% and 26.91% and the Nusselt number by 4.92% and 2.06% respectively for both the contracting and elastic sheet. The findings in the research will provide more insight in the design and improvement of solar panel plate efficiency.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of the use of metal–oxide and boron-based nanoparticles on the performance in a photovoltaic thermal module (PV/T): Experimental study","authors":"","doi":"10.1016/j.ijft.2024.100910","DOIUrl":"10.1016/j.ijft.2024.100910","url":null,"abstract":"<div><div>Renewable energy sources are constantly on the agenda because the fossil fuels used are limited and the need for energy is constantly increasing. Among these resources, solar energy stands out because it is clean and endless energy. Nowadays, heat energy and electrical energy production from solar energy are quite common. Photovoltaic (PV) solar panels can convert a limited portion of the solar energy falling on them into electrical energy. In PV panels, heat energy that cannot be converted into electricity is discharged back to the external environment. Photovoltaic thermal (PV/T) panels are used to remove this heat from the system and convert it into useful energy. Many cooling techniques are applied to reduce the surface temperature of PV/T panels and increase their electrical efficiency. One of these techniques is liquid-cooled PV/T panels. In some of the studies, forced circulation (using a pump) and in others natural circulation (thermosiphon effect) were applied. In this study, a natural circulation indirect heated PV/T system was designed. Al₂O₃, ZnO, and BN nanoparticle concentrations were added to the cooling water to increase heat transfer within the PV/T panel. According to the experimental results, using nanofluid in the PV/T panel increased the thermal and total efficiency. Total efficiencies of ZnO, BN, and Al₂O₃ were obtained as 52.8 %, 47.86 %, and 43.49 %, respectively, at 0.03 concentration. The highest exergy efficiency and sustainability index were determined as 17.155 % and 1.207, respectively, at 0.03 concentration of ZnO nanofluid.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Moderate or Intense Low-Oxygen Dilution (MILD) combustion regime: An overview on fuels","authors":"","doi":"10.1016/j.ijft.2024.100905","DOIUrl":"10.1016/j.ijft.2024.100905","url":null,"abstract":"<div><div>In this paper, an overview on the used fuels in Moderate or Intense Low-oxygen Dilution (MILD) combustion is provided including gaseous, liquid, and solid fuels in addition to fuel mixtures. In the first step, a detailed review of the definitions of this combustion regime is presented and the known different oxidation routes are explained. Next, various issues including emissions, combustion fields, and kinetics are addressed for the studied fuels in the summarized studies, followed by a comparison of the fuels in terms of emissions and combustion fields. In addition, these studies are summarized in terms of the utilized fuels and the selected experimental and numerical approaches to give an overall view on the chosen fuels in MILD regime. Finally, future prospects and directions on using fuel technologies in MILD combustion are provided, which includes the known obstacles in using different fuels under MILD regime.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comprehensive CFD Analysis of Base Pressure Control Using Quarter Ribs in Sudden Expansion Duct at Sonic Mach Numbers","authors":"","doi":"10.1016/j.ijft.2024.100908","DOIUrl":"10.1016/j.ijft.2024.100908","url":null,"abstract":"<div><div>This study aims to assess the effect of rib size, shape, and location in a suddenly expanded flow at sonic Mach number. Flow from a converging nozzle is exhausted into a larger area of duct diameter of 18 mm. The geometric parameters considered are the area ratio, duct length, rib radius, and inertia parameters, which are considered the level of expansion at critical Mach number. In the present study, duct lengths were from 1D to 6D, rib radii considered were 1 mm to 3 mm, and rib locations were 0.5D, 1D, 1.5D, 2D, and 3D. Results show that when the ribs are placed near the reattachment point with a 3 mm radius, they are efficient and capable of reducing the suction in the recirculation zone and the base pressure, which was lower than the ambient pressure in the absence of ribs, is assorted larger than the back pressure. If the requirement is to equate the pressure at the base to ambient pressure, then a 2 mm radius is the right choice. Furthermore, the 1 mm rib cannot reduce the suction in the base region, and base pressure remains sub-atmospheric for the entire range of rib locations, as well as the NPRs of the present study. When the orientation of the ribs is changed, and the flow interacts with the flat surface instead of the curved surface, there is a marginal change in the flow pattern, and there is no significant change in the base pressure values.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142416977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}