Case Studies in Thermal Engineering最新文献

{"title":"Experimental and numerical study on cavitation flow characteristics of refrigerants with different thermophysical properties in confined micro-clearance","authors":"Shaohang Yan, Tianwei Lai, Zhen Wang, Qi Zhao, Yu Hou","doi":"10.1016/j.csite.2024.105555","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105555","url":null,"abstract":"In high-speed hydraulic machinery, its efficiency and reliability are affected by the cavitation in the bearing. Due to the confined effect of the bearing clearance, cavitation bubbles grow in a two-dimensional way. To uncover the cavitation process with confined and high speed shearing effect, the high-speed cavitation flowing of different refrigerants is researched experimentally based on the high-speed shearing test rig with micro-clearance. The influence of thermophysical properties on growth of cavitation bubble is evaluated and analyzed. The confined effect of micro-clearance and high-speed shearing effect has a significant influence on the cavitation bubbles evolution. The high-speed camera is used to record the morphology of cavitation bubbles for various refrigerants with different thermalphysical properties. Furthermore, the thermal-sensitive cavitation model is used to analyze the bubble-foam alternation from cavitation flow inside micro-clearance. For different refrigerants, the growth process of cavitation bubble area is exponential. Inside the micro-clearance, the cavitation inducing pressure drops of different refrigerants are analogous due to the similar thermodynamic properties. According to pressure drop during cavitation, different refrigerants are classified by introducing dimensionless numbers, σ·Re (Jie et al., 2009) [2] and σ·We. The pressure and temperature drop increase with the dimensionless numbers. The refrigerants with similar thermodynamic properties have a similar relationship between dimensionless number and supercooling degree.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"9 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142777464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The influence mechanism of thermal invasion on spontaneous combustion of different coals using continuous adiabatic heating and non-isothermal oxidation method","authors":"Xincheng Hu, Jiawen Cai, Yunquan Yao, Zhaoyang Yu, Jianguo Liu, Shanyang Wei, Zongqing Tang, Shengqiang Yang","doi":"10.1016/j.csite.2024.105565","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105565","url":null,"abstract":"Within deep coal mines, the elevated ground temperature has the potential to induce thermal invasion, thereby exacerbating coal spontaneous combustion (CSC). To investigate the influence mechanism of thermal invasion on CSC, experiments were conducted using coals of different metamorphic degrees (lignite, bitumite, and anthracite) with a continuous adiabatic heating and non-isothermal oxidation method in an oxidation furnace and an in-situ ESR spectrometer. Thermal invasion markedly enhanced the inherent susceptibility of spontaneous combustion of coals by increasing the oxygen consumption rate and lowering the apparent activation energy. This enhancement results from active free radicals generated during thermal invasion which accelerated coal-oxygen reactions during non-isothermal oxidation. These free radicals were found to be mainly carbon-centred radicals adjacent to an oxygen atom (alkyl radicals). An increase in both the g-factor value and free radical concentration was observed with thermal invasion temperature and invasion duration, especially in lignite, leading to a surge of free radical concentration during non-isothermal oxidation. The active free radicals generated during thermal invasion can easily react with oxygen, providing heat for coal-oxygen reactions and enabling rapid free radical generation. These findings offer insights for developing CSC evaluation and prevention strategies in deep mines where high ground temperatures are encountered.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"260 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142756148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat propagation phenomenon of compressed natural gas /air premixed laminar flame impinging on a flat surface","authors":"Kashinath Dhamudia, Shambhu Kumar Mahato, Raushan Kumar Singh, Amit Kumar, Santosh Kumar Panda, Mithilesh Kumar Sahu, S M Mozammil Hasnain, Rustem Zairov","doi":"10.1016/j.csite.2024.105571","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105571","url":null,"abstract":"In this paper the heat transfer characteristics have been determined theoretically using heat propagation phenomena of compressed natural gas (CNG)/air premixed laminar flames impinging on flat surfaces. Effects of varied equivalence ratios (Ф), Reynolds numbers (Re), separation distances (H/d) and burner diameters (d) on stagnation point heat flux have been investigated. The simulation findings were validated with the available experimental data. The flat plate with the maximum heat flux at the stagnation position is located close to the margin of the innermost premixed reaction zone (i.e., at H/d, Re and d are 5, 1000, 8 mm). The flow of heat steadily decreases in axial direction as the separating distance from the inner reaction zone's tip increases. Greater separation lengths at the stagnation region cause a subsequent increase in heat flux. The objective of this investigation is to get an idea about the impact of existence of the plate on the flame and temperature distribution and to get clarity about the reason behind higher amount of heat flux owing to tip of the innermost reaction area at stagnation region.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"16 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142777486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The thermodynamics of C-J deflagration","authors":"Yunfeng Liu","doi":"10.1016/j.csite.2024.105574","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105574","url":null,"abstract":"The mechanisms of detonation instability, detonation quenching, deflagration-to-detonation transition, and thermodynamics of C-J deflagration are fundamental issues of combustion theory. In this paper, these mechanisms are discussed by analyzing the convective flux and heat release flux of one-dimensional numerical simulation. The governing equations are Euler equation with overall one-step chemical reaction kinetics. The mixture is stochiometric H<ce:inf loc=\"post\">2</ce:inf>-air mixture at 1atm and 300K.The activation energy is increased to trigger the instability of C-J detonation. The numerical results show that the detonation instability is induced by the von Neumann spike. The von Neumann spike produces unsteady rarefaction wave, which is determined by the slope of von Neumann spike. The detonation is extinguished to a C-J deflagration abruptly under critical activation energy at one-time step because the strength of rarefaction wave is stronger than heat release under this critical condition. The C-J deflagration propagates with a relative constant velocity about half of C-J detonation velocity. The gas temperature and pressure behind the leading shock wave of C-J deflagration is too low to ignite the mixture. The Taylor wave from the end-wall ceases the mixture behind the leading shock, increases its temperature and decreases its pressure. As a result, combustion takes place at the contact surface with almost constant pressure. Therefore, the C-J deflagration is of constant-pressure combustion and this mechanism makes it propagate downstream with a relatively constant velocity for a long distance.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"13 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142777485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal characteristics of hybrid Nanofluid (Cu-Al2O3) flow through Darcy porous medium with chemical effects via numerical successive over relaxation technique","authors":"Assmaa Abd-Elmonem ,&nbsp;Qammar Rubbab ,&nbsp;Hakim AL. Garalleh ,&nbsp;Fazeelat Rehman ,&nbsp;Muhammad Amjad ,&nbsp;Fayza Abdel Aziz ElSeabee ,&nbsp;Nesreen Sirelkhtam Elmki Abdalla ,&nbsp;Wasim Jamshed ,&nbsp;Syed M. Hussain ,&nbsp;Hijaz Ahmad","doi":"10.1016/j.csite.2024.105538","DOIUrl":"10.1016/j.csite.2024.105538","url":null,"abstract":"<div><div>The flow of fluids through porous media is commonly described using the Darcy model, therefore investigating hybrid nanofluids in this setting is rather new. The present work offers insightful information on how the hybrid nanofluids behave and function in porous medium. The study's conclusions may have an impact on a lot of different engineering applications like filtration systems, chemical reactors, and environmental engineering. The study concentrates on a hybrid nanofluid which consists of <em>Cu</em> and <em>Al₂O₃</em> nanoparticles. The metallic nanoparticles such as copper have high thermal conductivity and non-metallic nanoparticles such as aluminum oxide are chemically stable and has high thermal resistance. This is the reason that the combination <em>Cu-Al₂O₃</em> is believed to give better heat transfer composite than using individual nanofluids. By employing proper similarity transformation, the governing PDEs are turned into ODEs. To discretize these ODEs, the central finite difference method is used first. Then the successive over relaxation technique is utilized to numerically solve the nonlinear equations. The findings are summarized in a graphical and tabular format. The impacts of several controlling parameters such as porosity, suction, Schmidt number and volume fraction on flow pattern, thermal properties, and concentration are investigated and discussed. The streamwise and normal velocity profiles fall and those of concentration and temperature rise with increase in the values of the porosity parameter.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"65 ","pages":"Article 105538"},"PeriodicalIF":6.4,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Corrigendum to “Influence of the welding thermal cycle on δ-ferrite evolution in the first layer of Austenitic Stainless Steel (ASS) 308L produced by WAAM-GTAW” [Case Studies Therm. Eng. 64 (2024) 105489]","authors":"Moch Chamim, Djarot B. Darmadi, Anindito Purnowidodo, Teguh Dwi Widodo, Zuhdi Ismail","doi":"10.1016/j.csite.2024.105575","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105575","url":null,"abstract":"","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"4 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142777483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transient heat transfer analysis of airflow in a thermal water-bearing tunnel considering airflow turbulence and surrounding rock seepage effects","authors":"Shujie Chen, Zhengguo Zhu, Yong Zhao, Guangyan Gu, Ben-Guo He","doi":"10.1016/j.csite.2024.105568","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105568","url":null,"abstract":"In deep tunnels traversing fractured water-rich strata, surface water descend, heats up at depth, and then rises into the tunnel, resulting in a ‘thermal water-bearing’ tunnel. This paper investigates the transient temperature evolution of such tunnels through laboratory-scale model experiment and numerical simulation, considering the convective heat transfer of thermal water in the surrounding rock. The experimental model was designed using similarity criteria derived from the equation analysis method. The 3D numerical model simulates the interaction between thermal water-saturated surrounding rock and tunnel airflow. The thermal field of the surrounding rock accounts for the coupling effects of the flow field, which follows Darcy's law. The tunnel airflow is governed by the RANS (Reynolds-Averaged Navier-Stokes) equations and the <mml:math altimg=\"si1.svg\"><mml:mrow><mml:mi>k</mml:mi><mml:mo linebreak=\"goodbreak\" linebreakstyle=\"after\">−</mml:mo><mml:mi>ω</mml:mi></mml:mrow></mml:math> turbulence model, combined with the LRNM (Low-Reynolds Number Modeling) method for near-wall treatment. This approach is coupled with the energy balance equation to calculate the airflow temperature. The numerical model is validated using monitoring data from experimental measurements of grouted tunnel wall and airflow temperatures. Finally, parameter studies are conducted for both ungrouted and grouted tunnels, demonstrating the effectiveness of grouting in controlling airflow temperature by blocking thermal water.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"37 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142756227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unique thermal architecture integrating heliostat solar fields with a dual-loop power generation cycle employing thermoelectric; thermal/financial study and GA optimization","authors":"Amr S. Abouzied ,&nbsp;Xiaoming Guo ,&nbsp;Azher M. Abed ,&nbsp;Mohammed A. Alghassab ,&nbsp;Fahad M. Alhomayani ,&nbsp;Baseem Khan ,&nbsp;Yasser Elmasry ,&nbsp;Ahmad Almadhor ,&nbsp;Salem Alkhalaf ,&nbsp;Albara Ibrahim Alrawashdeh","doi":"10.1016/j.csite.2024.105563","DOIUrl":"10.1016/j.csite.2024.105563","url":null,"abstract":"<div><div>This study delineates the development of a solar energy system that leverages concentrated solar power (CSP) technology to supply both electricity and potable water for residential applications. The proposed thermal architecture uniquely integrates heliostat solar fields with a dual-loop power generation cycle, augmented by a seawater desalination system that employs reverse osmosis (RO) membranes. To bolster electricity production, a thermoelectric generator (TEG) has been incorporated into the system's design framework. A comprehensive analysis of the system has been performed, encompassing thermodynamic and economic evaluations. Furthermore, a parametric analysis has been executed to investigate the effects of critical parameters on the system's operational efficiency. The efficacy of the system was rigorously assessed through a case study that examined its capabilities for daily production outputs. This research, grounded in the analytical projections from Saudi Arabia and the favorable environmental conditions characteristic of the region, explores the operational performance of the system within this specific geographical context. The primary objective of this inquiry is to determine the ideal operational parameters by employing multi-criteria optimization methods tailored to the established system. Variations in compressor pressure ratios were found to significantly affect the performance of the Brayton cycle and the exergetic efficiency of the system, with optimal economic efficiency being realized at a specific pressure ratio. Furthermore, increasing the inlet temperatures in the organic Rankine cycle has been shown to improve system efficiency up to a certain limit, beyond which potential reliability issues could arise. The case study demonstrated that electricity generation peaks during the summer months, particularly in June, aligning with a high volume of freshwater production totaling 264,530 m³. The optimization efforts achieved an exergetic efficiency of 17.69 % and an overall cost of $359.58 per hour.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"65 ","pages":"Article 105563"},"PeriodicalIF":6.4,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Entropy optimized radiative boundary layer flow and heat-mass transfer of [formula omitted] water based nanofluid with Binary chemical reaction over a wedge","authors":"Samia Nasr, Sohail Rehman, Naeem Ullah, Taoufik Saidani, Iskandar Shernazarov","doi":"10.1016/j.csite.2024.105535","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105535","url":null,"abstract":"The study of boundary layer flow (BLF) with heat-mass transfer of binary chemical processes and nanofluids (NF) over a wedge is essential for improving heat transfer and reaction kinetics in applications including processing of material technologies, chemical reactors, and energy-efficient cooling mechanisms. This paper examines the entropy optimized BLF of silver <mml:math altimg=\"si1.svg\"><mml:mrow><mml:mi>A</mml:mi><mml:mi>g</mml:mi><mml:mo linebreak=\"goodbreak\" linebreakstyle=\"after\">−</mml:mo></mml:mrow></mml:math> water based nanofluid with binary chemical species over a wedge surface. The Tiwari-Das model is executed in this model which account the load of <mml:math altimg=\"si1.svg\"><mml:mrow><mml:mi>A</mml:mi><mml:mi>g</mml:mi><mml:mo linebreak=\"goodbreak\" linebreakstyle=\"after\">−</mml:mo></mml:mrow></mml:math> nanomaterials. The flow of NF over a moving wedge subject to favorable and adverse pressure differential is addressed by Naiver-Stokes equation. This model accounts the homogeneous heat reaction, viscous dissipation, joule heating and thermal radiations. The dimensionless equations for flow, for heat, and concentration are formulated and solved numerically using the fourth ordered Rung-Kutta approach. The findings suggest that fluid concentration is lowered with a rise in Schmidt number and homogenous chemical reaction. Thermal distribution improve with heterogonous reaction, magnetic parameter and deteriorate with wedge parameter. The skin friction rises from 25.277 % to 26.455 % with a material load of 3 % and magnetic parameter. The Nusselt decline with a radiative parameter from 10.984 % to 2.9748 % when particle load of 3 % is accounted.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"66 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142777494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Artificial intelligence based emission and performance prediction, and optimization of HHO-blended gasoline SI engine: A sustainable transition","authors":"Muhammad Nasir Bashir, Muhammad Usman, Fahid Riaz, Touqeer Ahmad, Yasser Fouad, M. Shameer Basha, Muhammad Mujtaba Abbas, Joon Sang Lee","doi":"10.1016/j.csite.2024.105562","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105562","url":null,"abstract":"In striving for sustainable alternatives to gasoline, Oxyhydrogen (HHO) has emerged as a promising substitute for Internal Combustion Engines (ICEs). HHO blends not only improve engine efficiency but also reduce harmful emissions. On-site, HHO utilization in the engine, eradicates low energy density and storage challenges. The current study combined cutting-edge machine learning (ML) techniques like Artificial Neural Network (ANN) and Gradient-based optimization to effectively utilize HHO with gasoline. Experimentation involved a single-cylinder spark ignition (SI) engine fueled by varying HHO-gasoline blends across different loads and speeds. Iterative tuning of the loss function led to the identification of the optimal architecture, denoted as 2HL-10N (2 hidden layers with 10 neurons each), with impressive correlation coefficients (0.99481 for training, 0.9781 for validation, 0.96914 for testing, and overall, 0.98819). Subsequently, ANN led Gradient-based optimization unveiled key performance metrics along with emissions. Upon implementing optimized conditions (HHO: 3.78 l/m, load: 100 %, and 3465 rpm), notable enhancements were observed. The torque and efficiency increased by 11.8 %, and 7.1 %, respectively. Furthermore, brake-specific fuel consumption, carbon monoxide, and hydrocarbon emissions showed a reduction of 11.5 %, 27.1 %, and 36.6 %, respectively. ANN based optimal engine operation revealed HHO as a potential replacement for conventional gasoline.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"27 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142777491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}