International Journal of Thermofluids最新文献

{"title":"Modeling and analysis of Casson-Carreau fluid flow past an exponentially expanding curvilinear sheet with active microorganisms","authors":"M. John Pisho ,&nbsp;G. Shankar ,&nbsp;K. Loganathan ,&nbsp;E.P. Siva ,&nbsp;Krishna Prakash Arunachalam","doi":"10.1016/j.ijft.2025.101373","DOIUrl":"10.1016/j.ijft.2025.101373","url":null,"abstract":"<div><div>This study investigates the synergistic effects of magnetohydrodynamics (MHD) and internal heat generation on heat and mass transfer in the flow of a Casson–Carreau hybrid fluid across an exponentially curved stretched sheet, while accounting for the impact of gyrotactic microorganisms. The model incorporates buoyant forces, nonlinear heat radiation, and a first-order chemical reaction to precisely depict bioconvective transport mechanisms. Utilizing similarity transformations, the complex, coupled nonlinear partial differential equations governing the flow are reduced to a system of ordinary differential equations. These are subsequently addressed numerically using a reliable BVP4c-based shooting method. The influence of key parameters, including the Casson and Weissenberg numbers, buoyancy parameter, heat source parameter, bio-Schmidt number, and bio-Péclet number, is thoroughly analyzed. The physical characteristics, including the skin friction coefficient, Nusselt number, Sherwood number, and local motile microbe density, are thoroughly evaluated and examined. These findings offer significant insights into the design of chemical processing systems, biomedical devices, and applications related to bioconvective transport.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"29 ","pages":"Article 101373"},"PeriodicalIF":0.0,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144908560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advanced exergy analysis of vapor compression systems using low-GWP refrigerants and variable-frequency compressor","authors":"Rahul Deharkar ,&nbsp;Parth Prajapati ,&nbsp;Bansi D. Raja ,&nbsp;Vivek K. Patel","doi":"10.1016/j.ijft.2025.101374","DOIUrl":"10.1016/j.ijft.2025.101374","url":null,"abstract":"<div><div>This study investigates the performance of a vapor compression refrigeration system equipped with three different expansion devices (capillary tube, thermostatic valve and an electronic valve) along with a variable-frequency compressor. The primary objective is to optimize system efficiency and identify a viable alternative to the high-global warming potential (GWP) refrigerant R134a. Conventional exergy analysis reveals that the electronic expansion valve minimizes exergy destruction across all alternative refrigerants compared to both a capillary tube and a thermostatic valve. Further insights are gained through advanced analysis, indicating that the R1234yf system exhibits 3.53 % lower exergy destruction than the R134a system. Notably, the evaporator emerges as the most sensitive component across all refrigerants, contributing the highest average exergy loss (0.88 kW) which can be substantially reduced to 0.67 kW (23.57 %) through pressure ratio optimization. These findings strongly suggest that the low-GWP refrigerant R1234yf presents the most promising alternative to R134a, offering both improved efficiency and reduced environmental impact.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"29 ","pages":"Article 101374"},"PeriodicalIF":0.0,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144886694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical investigation of a turbine working with a highly unsteady exhaust flow of a hydrogen-driven rotating detonation combustion","authors":"Majid Asli,&nbsp;Mosaab Mhgoub,&nbsp;Klaus Höschler","doi":"10.1016/j.ijft.2025.101356","DOIUrl":"10.1016/j.ijft.2025.101356","url":null,"abstract":"<div><div>Traditionally, turbomachines are designed for steady-state operations around which they achieve optimal performance and efficiency. However, in novel applications, a turbomachine may be exposed to unsteady flow forcing the machine to operate under fluctuating off design conditions. Pressure Gain Combustion (PGC) through detonation can be an extreme example of unsteady flow which affects the turbine performance adversely. The efficient way of energy extraction from PGCs is still an open question which needs extensive turbine design optimizations for such unsteady flow. Any flow field optimization problem in such applications needs a multitude of simulations, which can be too computationally expensive to be utilized as it is realized as an unsteady 3D-CFD problem. In this regard, the current study aims at proposing and evaluating an approach for optimizing a turbine working under highly unsteady exhaust flow of a Rotating Detonation Combustion (RDC). A two stage turbine is placed downstream an RDC and the turbine inlet condition is calculated by a 2D-Euler simulation tool. A turbine optimization problem is defined and three optimization processes with an objective of minimizing entropy are performed using steady-state 3D-CFD simulation as the objective function evaluator. The turbine inlet boundary conditions in the three optimization efforts include peak, mean and trough values of the RDC outlet pulsating flow condition. Finally, detailed unsteady simulations are carried out for the three new geometries and compared with the baseline turbine. The results showed that the steady-state Reynolds Averaged Navier Stocks (RANS) simulations can be utilized using either mean or trough values of the pulsating boundary condition in iterating a design optimization problem, instead of full unsteady RANS simulations applying time and circumferential location dependent boundary conditions. Given the specific RDC boundary condition and the turbine geometry in this study, the optimized turbine exhibited up to 7.71% less entropy generation and up to 7% higher output power compared to the baseline counterpart in unsteady operation. This approach enables a more efficient design optimization process while accounting for the complex dynamics of the RDC exhaust flow. Overall, the approach presented in this paper is practical for optimizing highly unsteady turbomachines specifically for the case of RDCs during any early design optimization procedure, addressing the computational challenges associated with simulating unsteady flows while ensuring the turbine’s effectiveness under real operating conditions.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"29 ","pages":"Article 101356"},"PeriodicalIF":0.0,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144830073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microorganisms induced bioconvection over a convectively heated rotating frame: a computational model of the blood-based MHD Casson hybrid nanofluid flow","authors":"P. Asaigeethan ,&nbsp;K. Loganathan ,&nbsp;V. Karthik ,&nbsp;S. Shageen Fathima ,&nbsp;D. Priyadharshini ,&nbsp;Krishna Prakash Arunachalam","doi":"10.1016/j.ijft.2025.101368","DOIUrl":"10.1016/j.ijft.2025.101368","url":null,"abstract":"<div><div>This study investigates microorganisms generated bioconvection in an MHD Casson hybrid nanofluid on a convectively heated rotating frame. The hybrid nanofluid behaves like blood because it contains <em>TiO</em>₂ and <em>ZnO</em> nanoparticles mixed in a special fluid called a non-Newtonian Casson fluid. Their interaction greatly affects nanoparticle dispersion, thermal conductivity, and flow stability. The PDEs governing momentum, energy, concentration, and motile microbe distribution are turned into ODEs by similarity transformations. We numerically solve these modified equations in MATLAB using bvp5c. The study looks at how certain factors, like the Casson parameter, magnetic parameter, thermophoresis and Brownian motion numbers, Prandtl number, Schmidt number, and bioconvection parameters, influence the flow and movement of materials. Results show that increasing the magnetic parameter and Casson fluid index decreases fluid velocity and increases temperature gradients. Hybrid nanofluid systems have 22–28 % higher Nusselt numbers than single nanoparticle solutions. The analysis looks at important ways heat moves, including thermophoresis, Brownian motion, how viscosity affects heat, the impact of magnetic fields, and the movement of microorganisms. These discoveries can improve thermal and mass transmission in heat exchangers, biomedical devices, and industrial systems that need better heat management. The results are verified with previousley published litreature and the obtained results are optimum.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"29 ","pages":"Article 101368"},"PeriodicalIF":0.0,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144886792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Significant mathematical deductions of the double-diffusive convection on the Sisko fluid dynamics model driven by peristaltic movement within ciliated channel","authors":"Muhammad Bilal Riaz ,&nbsp;S. Bilal ,&nbsp;Ayesha Saddiqa ,&nbsp;Lubna Sarwar","doi":"10.1016/j.ijft.2025.101366","DOIUrl":"10.1016/j.ijft.2025.101366","url":null,"abstract":"<div><div>This study mainly focuses on mathematical modeling of Sisko fluid through peristaltic propagation with ciliated channel walls for magnetically induced flow, including double-diffusive convection. By applying suitable transformations and making them non-dimensional, utilizing various effective parameters that have noteworthy leverage in fluid dynamics, the fundamental PDEs are converted into ODEs. Computational data is obtained using MATLAB bvp4c, the impact of Prandtl number, thermal diffusion parameter, Brownian diffusion parameter, Lewis number, Grashof number and radiation parameter is determined. The main findings include increasing the cilia parameter <em>h</em>, the Sisko nanofluid's velocity magnifies during the movement while the MHD impact dwindles the velocity. The ciliated wall does not affect the temperature of the fluid, as cilia are responsible for the mixing or movement of fluid. Engineers can control fluid flow by simulating ciliated walls in microfluidic equipment at the microscale and improve the combination or segregation procedures.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"29 ","pages":"Article 101366"},"PeriodicalIF":0.0,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144830072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal investigation of humidification process using the Poppe method, a semi-analytical method","authors":"Mohammad Behzadi-Sarok,&nbsp;Mohammad Hassan Saidi","doi":"10.1016/j.ijft.2025.101369","DOIUrl":"10.1016/j.ijft.2025.101369","url":null,"abstract":"<div><div>This study evaluates the humidification process in a humidifier using the Poppe method’s nonlinear ordinary differential equations (ODEs), which captures heat and mass transfer mechanisms with higher accuracy than conventional models. The nonlinear ODEs are extracted, non-dimensionalized, and solved numerically using the semi-analytical method. The dimensionless formulation enables a detailed analysis of outlet air relative humidity and the increase in the air mass flow rate by absorbing moisture. By use of a semi-analytical method, the influence of extracted dimensionless parameters on the performance of the humidification cycle is shown, and the mass transfer coefficient is estimated. The semi-analytical method is a fast and grid-independent tool for analyzing complex and nonlinear problems.</div><div>The effect of dimensionless parameters on the humidification performance are investigated. The results show that at higher saline water temperatures, heat and mass transfer between water and air grows, leading to higher humidification potential. Either increasing dimensionless number related to the air enthalpy and mass flow rate ratio or decreasing dimensionless number related to Lewis factor result in a higher humidification ability. In addition, reducing dimensionless number related to water vaporization decreases the energy required for water evaporation, thereby increasing the humidification potential. An increase in water mass flow per unit area means a higher ability of humidification, causing mass transfer coefficient to grow. Among all tested parameters, mass flow rate ratio and increasing dimensionless number related to the air enthalpy exhibit the highest mass transfer coefficient, which peaks at 9.38×10^-4 <em>kg/m²</em>s when optimal conditions are met.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"29 ","pages":"Article 101369"},"PeriodicalIF":0.0,"publicationDate":"2025-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144852389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement and analysis of transient heat flux on a conical surface using platinum thin film gauges","authors":"Rishikesh Goswami ,&nbsp;Rakesh Kumar ,&nbsp;Bipin Kumar Singh ,&nbsp;Amit Kumar ,&nbsp;Ashwini Kumar ,&nbsp;Jayant Giri ,&nbsp;Eman Ramadan Elsharkawy","doi":"10.1016/j.ijft.2025.101370","DOIUrl":"10.1016/j.ijft.2025.101370","url":null,"abstract":"<div><div>In this study, both experimental and numerical methods to analyse the transient surface temperature and convective heat flux on a quartz-based conical body with laboratory-fabricated platinum thin-film gauges (film thickness 0.1–1.0 µm on 6 mm <em>Ø</em> × 10 mm quartz substrates) is carried out. During fabrication, platinum paste is dried at 650 °C and silver contacts at 350 °C, yielding a gauge resistance of 4–8 Ω and a measured temperature coefficient of resistance (TCR) of 0.02727 K⁻¹. Additionally, the work covers the dynamic calibration at a steady 10 mA current is supplied to each gauge while high-speed air at 318 K and velocities of 3–5 m/s impinged on the cone for 1 s. Transient temperature histories (300.0–300.7 K) are recorded at 0.01 ms intervals and processed via a one-dimensional semi-infinite conduction model to recover surface heat flux. Numerical simulations in ANSYS Fluent, employing a standard k-ε turbulence model with 0.01 ms time steps (100 steps) and adiabatic, no-slip boundary conditions, reproduced the same flow and thermal conditions. Experimental and numerical heat-flux signals exhibited excellent agreement (maximum convective heat flux ≈ 8 kW/m² at the stagnation point, with deviations &lt; 5%), thereby validating the cost-effective gauge fabrication and calibration methodology and demonstrating its suitability for millisecond-scale surface-heat-flux measurements.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"29 ","pages":"Article 101370"},"PeriodicalIF":0.0,"publicationDate":"2025-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144813981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The integration of absorption refrigeration system, parabolic trough collectors, and ice storage system to augment power generation capability of gas turbine power plant","authors":"Somchart Chantasiriwan","doi":"10.1016/j.ijft.2025.101364","DOIUrl":"10.1016/j.ijft.2025.101364","url":null,"abstract":"<div><div>Gas turbine power plant yields reduced power output in hot climates. Cooling of inlet air that is supplied to compressor of gas turbine unit results in increasing power output. Absorption refrigeration system and parabolic trough collectors may be used to for this purpose. In this paper, a modification of this method of inlet air cooling by adding ice storage system is investigated. Cooling coils in ice storage tank work as evaporator of absorption refrigeration system. Air temperature is decreased due to heat transfer to circulating cooling water supplied by ice storage tank. The reference gas turbine power plant operating without inlet air cooling system is compared with two integrated systems. The first integrated system uses absorption refrigeration system and parabolic trough collectors. The second integrated system uses absorption refrigeration system, parabolic trough collectors, and ice storage system. The reference power plant generates 115.43 MW. Simulation results show that using absorption refrigeration system and parabolic trough collectors can increase the annual energy output by 5.03 %. Adding ice storage system can further increase the annual energy output by 1.41 %.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"29 ","pages":"Article 101364"},"PeriodicalIF":0.0,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144810120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical study on heat generation/absorption effects with activation energy and chemical reaction in tetrahedral nanoparticle flow between two orthogonal porous disks","authors":"Talha Anwar ,&nbsp;Qadeer Raza ,&nbsp;M Zubair Akbar Qureshi ,&nbsp;M Awais ,&nbsp;Bagh Ali ,&nbsp;Ehsanullah Hemati","doi":"10.1016/j.ijft.2025.101359","DOIUrl":"10.1016/j.ijft.2025.101359","url":null,"abstract":"<div><div>Nanoparticles play a crucial role in enhancing thermal management, biomedical applications, and advanced industrial processes. This study presents a detailed numerical analysis of heat and mass transfer in a reactive nanofluid containing tetrahedral nanoparticles (aluminum oxide, copper, iron oxide, and titanium oxide), flowing between two orthogonally arranged porous disks. The investigation incorporates the effects of heat generation/absorption, the Cattaneo–Christov heat flux model, activation energy, chemical reactions, and three nanoparticle shapes: spherical, brick, and platelet. Furthermore, the roles of nanolayer thermal conductivity, viscous dissipation, and Joule heating in the heat transfer process are thoroughly examined. The governing nonlinear partial differential equations are transformed into ordinary differential equations using similarity transformations and are solved numerically using the shooting method combined with the fourth-order Runge–Kutta technique. The graphical results are generated using Mathematica software. The findings reveal that the platelet-shaped nanoparticles exhibit significantly superior heat transfer performance, particularly in the suction case, as indicated by higher Nusselt number values compared to other shapes. Increasing the nanolayer thickness enhances the heat transfer rate in both injection and suction scenarios. However, a larger nanoparticle radius leads to opposite fluid behavior in suction and injection cases, as reflected in the Nusselt number values for the lower disk. Moreover, increasing the expansion ratio and magnetic field parameters reduces the radial velocity profile in the central region between the disks but enhances it within the momentum boundary layers near both porous surfaces. Higher values of heat generation or absorption lead to a reduction in the temperature profile, while an increase in activation energy improves mass transfer, as evident from the concentration profile.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"29 ","pages":"Article 101359"},"PeriodicalIF":0.0,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144867122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accurate modeling of annular gas-water flow across diverse inclination angles using an advanced drift-flux correlation","authors":"Abdulaziz AlSaif ,&nbsp;Abdelsalam Al-Sarkhi","doi":"10.1016/j.ijft.2025.101361","DOIUrl":"10.1016/j.ijft.2025.101361","url":null,"abstract":"<div><div>Drift-flux models are widely used for analyzing two-phase flows but often fail to accurately represent annular flow dynamics due to a conceptual mismatch. Traditional models assume phase dispersion characteristics that do not align with the velocity gradient-driven behavior of annular flows. This study introduces an adapted drift-flux model, redefining the drift velocity based on gas critical velocity, better reflecting annular flow mechanics. The proposed formulation is particularly suited for annular flows in inclined pipes, a critical consideration in industries such as oil and gas, chemical processing, and nuclear applications. The proposed drift-flux model exhibits excellent predictive capability, achieving an average error of 1.1 % when validated against experimental data and 1.5 % when benchmarked against the data generated by the Unified Mechanistic Model, within gas and liquid Reynolds number ranges of 38,250 - 1183,200 and 150 - 8000, respectively. Furthermore, statistical evaluations across both experimental and synthetic datasets confirm the model’s robustness, as reflected by the lowest mean absolute error (0.01 and 0.01), root mean square errors (0.01 and 0.03), standard deviations (0.01 and 0.02), and narrow 95 % confidence intervals (−0.008 ± 0.001 and 0.010 ± 0.001). To assess its generalizability, the proposed correlation was tested on blind experimental datasets featuring pipe diameters three times larger than those used during development, where it attained the lowest average error of 0.7 %. When applied to synthetic datasets covering a broad diameter range of 10–200 mm, the model consistently delivered the highest accuracy, maintaining an average error of 1.5 %.</div></div>","PeriodicalId":36341,"journal":{"name":"International Journal of Thermofluids","volume":"29 ","pages":"Article 101361"},"PeriodicalIF":0.0,"publicationDate":"2025-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144780767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}