Case Studies in Thermal Engineering最新文献

{"title":"Multi-objective optimization of graphene far-infrared paddy drying process based on response surface methodology","authors":"Jiyou An, Yuanjie Du, Jianchun Yan, Hai Wei, Huanxiong Xie","doi":"10.1016/j.csite.2024.105588","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105588","url":null,"abstract":"Graphene exhibits exceptional electrothermal conversion efficiency, making it a promising candidate as a novel heat source for far-infrared drying. This study examined the impacts of infrared radiation temperature (45–55 °C), air flow (300–460 m<ce:sup loc=\"post\">3</ce:sup>/h), and grain flow rate (6–8 kg/min) on the stress cracking index (SCI), specific energy consumption (SEC), and thermal efficiency. The Box–Behnken response surface methodology and expectation function method were employed to model and optimize the quality of far-infrared drying of paddy graphene. The findings indicate that both the drying rate and SCI of paddy increased with an increase in the infrared temperature and grain-flow rate; higher values of these parameters resulted in improved thermodynamic properties. Conversely, the SEC decreased with an increase in the infrared temperature and grain flow, whereas the thermal efficiency exhibited an inverse relationship. The influence of airflow on dried samples was negligible. Under specified constraints, the optimized drying parameters to yield a maximum expected factor were an infrared radiation air temperature of 51 °C, air flow of 377.690 m<ce:sup loc=\"post\">3</ce:sup>/h, and grain flow rate of 8 kg/min. With this optimized combination of drying-process parameters, the minimum SCI reached approximately 35.4, and the minimum SEC was approximately 3734.9 kJ/kg, resulting in a maximum thermal efficiency of approximately 62.7 %. These results provide a foundation for the future development of graphene-based far-infrared grain-drying equipment.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"66 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142777479","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":"Direct-supply chilled-water radiant-floor cooling system coupled with an earth‒air heat exchanger system: A case study in a building","authors":"Jiaming Yang, Huiqing Cao, Zhenwei Wang, Yue Liu, Wei Song, Jiankai Dong","doi":"10.1016/j.csite.2024.105586","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105586","url":null,"abstract":"To date, the use of shallow geothermal energy to directly cool and dehumidify a building in summer via a direct-supply chilled-water radiant-floor cooling (DS-RFC) system coupled with an earth‒air heat exchanger (EAHE) system has not been investigated. In this study, a physical test was performed in a real-world application room, where the cooling and dehumidification characteristics of DS-RFC and EAHE systems were individually studied to evaluate their application potential. The changes in the indoor air temperature and humidity and in the soil temperature when the two systems were operated independently were quantitatively analyzed. Additionally, the effects of the coupled DS-RFC/EAHE system on the indoor environment were evaluated for three air-supply inlet locations. The results showed that the DS-RFC system had a superior cooling effect but almost no dehumidification ability; the change in the humidity ratio was less than 2.00 g/kg. The EAHE system had a superior dehumidification effect, where the change in the humidity ratio exceeded 5.00 g/kg. When the DS-RFC system was operating, different air-supply inlet positions significantly affected the change states of the indoor-air state parameters. The indoor temperature was primarily concentrated at 25–27 °C, and the relative humidity was 83–88 %. This study provides rational support for a building cooling model in which a DS-RFC system coupled with an EAHE system is supplied directly by shallow geothermal energy in summer.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"30 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815841","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":"Experimental analysis and design optimization of an empty diffuser for performance Enhancement in DAWT","authors":"Mustafa A. Almaliki ,&nbsp;Ihab Omar ,&nbsp;Mohanned Mohammad Naji ,&nbsp;Tabarak Jassim Alwan","doi":"10.1016/j.csite.2024.105590","DOIUrl":"10.1016/j.csite.2024.105590","url":null,"abstract":"<div><div>With the increasing demand for clean energy, and because of the acute problems caused by fossil fuels on the environment. It has become very necessary to search for alternative energy that is inexhaustible and safe at the same time. Researchers believe that diffuser-assisted wind turbines can play an important role in solving energy problems, especially in residential areas. As it is known that energy is proportional to the cube of velocity, that is, as the air velocity increases slightly, the energy increases exponentially. This paper has focused on the flanged diffuser because it can increase the pressure drop at the outlet of the diffuser, which increases the flow velocity. The study also focused on 5 variables in the diffuser to obtain the ideal design for the diffuser, namely the length of the diffuser, the angle of inclination of the diffuser, the angle of inclination, the angle of the lip and the height of the lip. Using the CFX 3D turbulent model (SSTK-ω) ANSYS 20. The results showed that the diffuser with a 50 bevel in addition to an entry flange at an angle of 30, L/D = 0.6 and H/D = 0.3 gives a speed increase of 5 times compared to the flange normal.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"65 ","pages":"Article 105590"},"PeriodicalIF":6.4,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759126","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":"Numerical investigation of trihybrid nanofluid heat transfer in a cavity with a hot baffle","authors":"Rajab Alsayegh","doi":"10.1016/j.csite.2024.105584","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105584","url":null,"abstract":"Trihybrid nanofluids, which combine the benefits of three distinct types of nanoparticles, have significant potential to enhance heat transfer in various thermal management applications. Understanding their behaviour in confined geometries with complex boundary conditions, such as a free surface and heated obstacle, is important to optimize their performance. This study investigates the heat transfer characteristics of a Cu-Al<ce:inf loc=\"post\">2</ce:inf>O<ce:inf loc=\"post\">3</ce:inf>-MWCNT-oil trihybrid nanofluid within a square cavity featuring a hot baffle and a free surface. Using numerical simulations and Patankar's blocked-off region method, a parametric study was conducted, varying the Rayleigh number (5000–50,000), nanoparticle volume fraction <mml:math altimg=\"si1.svg\"><mml:mrow><mml:mi mathvariant=\"normal\">Φ</mml:mi></mml:mrow></mml:math> (0–0.06), obstacle size and aspect ratio (h:w from 0.7 to 9), and Marangoni number (−10,000 to 10,000). The results reveal that negative Marangoni (Ma) numbers enhance convective heat transfer due to the synergistic interaction between the thermocapillary and buoyancy forces. Conversely, positive Marangoni numbers hinder heat transfer owing to competition between these forces. With increasing Rayleigh number (Ra), heat transfer enhancements of up to 45 %, 18 % with nanoparticle addition, and 22 % with varying obstacle sizes were observed. Therefore, these parameters can be varied to optimize the thermal design.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"28 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142777468","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 conduction behavior and prediction model of scrap tire rubber-sand mixtures","authors":"Tao Zhang, Yang Chen, Yu-Ling Yang, Cai-Jin Wang, Guo-Jun Cai","doi":"10.1016/j.csite.2024.105581","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105581","url":null,"abstract":"Increasing stockpile of scrap rubber tires imposes a serious threat to the safety of surrounding ecological environment. Rubber particle of excellent thermal insulating properties with comparison of granular soils makes it an ideal candidate for developing sustainable construction materials. While thermal conduction behaviors of rubber-sand mixtures have not been clearly revealed. Several series of thermal probe tests were conducted on scrap rubber tire-sand mixtures with varied rubber contents, moisture contents, and dry densities. A predictive model was proposed by resorting to the artificial neural network technology to capture the thermal conductivity data. The results showed that an obvious decrease in thermal conductivity is taken after the addition of rubber, and the decreasing rate is related to moisture content of mixtures. The presence of pore water is beneficial to the improvement of thermal conductivity. The critical moisture content of investigated rubber-sand mixtures is approximately 8 %, further increase in moisture content leads to a faint increment of thermal conductivity. Rubber-sand mixtures of high dry density have good particle contact behaviors, exhibiting a high thermal conductivity value. The influences of rubber content, moisture content, and dry density on thermal conductivity are intertwined together that should be comprehensively analyzed. The developed model exhibits satisfactory accuracy for thermal conductivity prediction, as reflected by correlation coefficient higher than 85 % and relative error being controlled under 10 %. Additional study is recommended to evaluate the thermo-mechanical behaviors and durability of rubber-soil mixtures. The outcomes of this study provide one of available answers for reusing scrap rubber tire in engineering fields.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"13 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142777470","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":"Solar-assisted radiant heating system with nano-B4C enhanced PCM for nearly zero energy buildings","authors":"Muhammed Gür, Ezgi Gürgenç, Hakan Coşanay, Hakan F. Öztop","doi":"10.1016/j.csite.2024.105544","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105544","url":null,"abstract":"This investigation centers on the design and performance of a solar-assisted domestic radiator optimized for nearly zero-energy buildings (nZEBs), combining experimental and numerical approaches. The system is powered by a Photovoltaic/Thermal (PV/T) collector, customized to the climatic specifics of Elazığ, Turkey. The study introduces nano-enhanced Phase Change Materials (NEPCM) embedded with Boron Carbide (B4C) nanoparticles to improve efficiency. The NEPCM demonstrating the highest thermal conductivity and specific heat capacity, was selected for numerical analysis. These NEPCM were strategically integrated into the radiator system to maintain ambient room temperatures without additional energy input, particularly during non-solar periods like nighttime. The analysis, conducted under turbulent flow conditions using the finite volume method, reveals that NEPCM significantly improves indoor temperature regulation. The most notable temperature differential, 2.82 K, was observed between configurations with and without PCM. However, the comparison between NEPCM and pure PCM with halved thickness shows a minimal temperature difference of 0.62 K, indicating a slight improvement due to nanoparticle inclusion. These findings highlight both the potential benefits and the limitations of integrating NEPCM into domestic heating systems for sustainable building applications.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"7 7 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142777469","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 performance of a micropolar fluid flowing around a vertical cone with consideration of spatially varying heat source","authors":"Vinoth Kumar B, Sreenivasulu P, Bilal S, Poornima T","doi":"10.1016/j.csite.2024.105576","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105576","url":null,"abstract":"Here, we have modeled a situation analyse energy transfer in a rotating elastic fluid flow along a vertical cone. Flow from the isothermal cone wall gradually transits into a persistent layer where the fluid motion is driven by buoyancy forces. This layer exhibits smooth, continuous flow (laminar) with variations in temperature and flow properties that are not directly proportional to changes in other variables and not constant across the layer. The scenario is formulated as a system of boundary equations and for parameters reduction, it is said to utilize similarity variables. Then the reduced system was solved using MATLAB and the finite difference method (Keller Box approach), along with the relevant boundary conditions. Assessments are conducted across various parameters on flow affecting quantities. Our analysis reveals several interesting trends. Thermal boundary layer thins when the relaxation period is longer than retardation period since the fluid cools down faster. However, the fluid's overall movement (both linear and angular momentum) increases. Conversely, increasing the Deborah number (elasticity parameter) leads to higher temperatures and micro-rotation, but reduces heat transfer efficiency and flow speed and makes it linear. This study underlines the importance of viscoelastic-micropolar fluids which finds applications as environmental flows, biomedical engineering, polymer processing, rheology. This research shows that longer relaxation periods thin the thermal boundary layer and enhance fluid movement, while higher Deborah numbers increase temperatures and micro-rotation but reduce heat transfer efficiency and flow speed. These findings underscore the importance of viscoelastic-micropolar fluids in applications like environmental flows and biomedical engineering.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"5 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815837","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":"A novel shell-and-tube heat exchanger design with alternative inclined baffles","authors":"Huy Minh Khoi Hoang, Hai-Lam Cao, Phuoc Minh Quang Pham, Ahmad Hajjar, Vu Linh Nguyen","doi":"10.1016/j.csite.2024.105542","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105542","url":null,"abstract":"This paper proposes a novel single-shell-pass shell-and-tube heat exchanger design with alternative inclined baffles. The design includes paired semi-ellipse shapes with baffle cut along the vertical axis such that the segments are interlocked in a crossed pattern. The new exchanger is structured to overcome the weakness of single segmental baffles (SG-STHX) by achieving lower pressure drop and higher thermal efficiency. This advantage is achieved using spiral flow to reduce dead zones and make the flow distribution within the heat exchanger's shell more uniform. The relatively simple arrangement and design of baffles in the proposed exchanger offer a significant advantage compared to continuous helical baffles (CH-STHX) in terms of the complexity of manufacturing and consequent high cost. In this paper, the equations governing the flow and thermal transfer in the exchanger are presented, and the parameters used to evaluate the exchanger's performance are also developed. The finite-volume method is used in numerical simulations to verify the equations and compare the performance of the novel design to SG-STHX and CH-STHX under similar geometrical and thermo-hydraulic conditions. Different mass flow rates are considered to cover a wide range of Reynolds numbers and ensure the accuracy of the comparison. Flow velocity and temperature distributions across the shell side are plotted to address the impact of geometry on the fluid behavior during the flow. The results show that the proposed heat exchanger significantly improves comprehensive performance, especially energy efficiency, compared to conventional SG-STHX or CH-STHX. The proposed heat exchanger also has a lower pressure drop than traditional ones. With the same mass flow rate, the XX-STHX demonstrates an average pressure drop approximately 44 % lower than the CH-STHX and 49 % lower than the SG-STHX. Moreover, with the same pump power, the performance evaluation factor of the XX-STHX, on average, surpasses that of the CH-STHX by roughly 1.48 times and the SG-STHX by about 1.70 times.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"21 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815838","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":"Fluid and thermal effect on temperature-dependent power increase of electric vehicle's permanent magnet synchronous motor using compound water cooling method","authors":"Zichao Zhang,&nbsp;Qiang Song,&nbsp;Bilal Ahmed,&nbsp;Yuecheng Han","doi":"10.1016/j.csite.2024.105543","DOIUrl":"10.1016/j.csite.2024.105543","url":null,"abstract":"<div><div>Taking advantage of compound housing water jacket (HWJ) and hollow-shaft water jacket (SWJ) cooling based on the temperature-dependent power of permanent magnet synchronous motor (PMSM) is a solution for enhanced electric vehicle (EV) performance. The fluid and temperature field of a 40 kW PMSM at three typical continuous working points were studied, covering low to high speeds of EVs. The influence of different coolant flowrates on power of motor was obtained by multi-physics field coupling analysis method. The impact of current control modes was also investigated. 3D computational fluid dynamics (CFD) conjugate heat transfer calculation combined with 3D lumped parameter thermal network (LPTN) was adopted to calculate the flow and temperature. Temperature-dependent material properties were taken into consideration in electromagnetic finite element analysis (FEA). The models were modified and validated by experiments. Once compounding SWJ on the basis of a strong HWJ cooling, the PM temperature can continue to decrease over 20 degC. The insensitive characteristic of PM temperature towards SWJ flow rate was observed. Under constant current control mode, 3.8 %, 6 % and 4 % PMSM power enhancement by compound cooling were proved at three typical working points. Under current open-loop, 7 %, 16 %, and 10 % increases with compound cooling were confirmed.</div></div>","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"65 ","pages":"Article 105543"},"PeriodicalIF":6.4,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759119","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":"Thermodynamic coupling performance analysis and simulation of aerated oil medium steel-BMC joint surface","authors":"Jiaxing Shen, Aoke Li, Zihao Pan","doi":"10.1016/j.csite.2024.105550","DOIUrl":"https://doi.org/10.1016/j.csite.2024.105550","url":null,"abstract":"In order to study the thermal coupling properties of aerated oil medium steel-basalt mineral composite (BMC) joint surface and establish an accurate and convenient simulation analysis method. The calculation method of the actual contact area ratio weight matrix of the aerated oil medium steel-BMC joint surface was studied. The virtual material theory model of the thermal coupling performance of the aerated oil medium steel-BMC joint surface was established by combining it with the virtual material theory. Based on the virtual material method, the thermodynamic coupling performance of the aerated oil medium steel-BMC joint surface was studied by finite element simulation, and compared with the experiment and numerical simulation methods of fractal theory. The results show that the temperature and strain changes of BMC specimen with virtual material method have a good coincidence with the experimental results, and the relative error is minimal. At the same time, the virtual material simulation model is simple, less computation and higher efficiency. It is proved that the method in this paper has better precision and convenience.","PeriodicalId":9658,"journal":{"name":"Case Studies in Thermal Engineering","volume":"20 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142777476","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}