Journal of Thermal Analysis and Calorimetry最新文献

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Effect of sample mass on the thermal decomposition of 2,4-DNT under sealed condition 密封条件下样品质量对2,4- dnt热分解的影响
IF 3 3区 工程技术
Journal of Thermal Analysis and Calorimetry Pub Date : 2024-11-27 DOI: 10.1007/s10973-024-13842-w
Peng Chen, Liping Chen, Juan Zhou, Wenqian Wu, Zichao Guo, Wanghua Chen
{"title":"Effect of sample mass on the thermal decomposition of 2,4-DNT under sealed condition","authors":"Peng Chen,&nbsp;Liping Chen,&nbsp;Juan Zhou,&nbsp;Wenqian Wu,&nbsp;Zichao Guo,&nbsp;Wanghua Chen","doi":"10.1007/s10973-024-13842-w","DOIUrl":"10.1007/s10973-024-13842-w","url":null,"abstract":"<div><p>Thermal analysis and calorimetry techniques with sealed sample cells are frequently employed to investigate the thermal stability of hazardous materials. However, the influence of sample mass on thermal decomposition is often ignored. To investigate the effect of sample mass on autocatalytic decomposition substances under sealed condition, 2,4-DNT was chosen for test and analysis. The techniques including differential scanning calorimetry (DSC), rapid screening calorimetry(RSC), high-performance liquid chromatography-mass spectrometry (HPLC–MS), and gas chromatography-mass spectrometry (GC–MS) were utilized for in-depth research on the decomposition of 2,4-DNT. The results revealed that an increase in sample mass led to an significant elevation in gaseous products such as CO<sub>2</sub> and CO with a negative heat of formation (ΔH<sub>f</sub>). Then the system pressure and decomposition heat of 2,4-DNT increase significantly, thereby enhancing the thermal decomposition process. After that, it has been determined that o–nitrotoluene, m–nitroaniline, and o–nitrobenzoic acid can catalyze the decomposition of 2,4-DNT. Finally, it is advisable to increase the sample mass as much as possible when testing and analyzing such nitro compounds which would help ensure that the predicted results are closer to the actual conditions of production, transport, storage.</p></div>","PeriodicalId":678,"journal":{"name":"Journal of Thermal Analysis and Calorimetry","volume":"149 24","pages":"14715 - 14725"},"PeriodicalIF":3.0,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142890024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Polymorphic crystallization and transformation pathways of 1,2-dipalmitoyl-3-oleoyl-rac-glycerol (PPO) during a liquid–solid-liquid journey 1,2-二棕榈酰-3-油酰-丙三醇(PPO)在液-固-液过程中的多晶化和转化途径
IF 3 3区 工程技术
Journal of Thermal Analysis and Calorimetry Pub Date : 2024-11-26 DOI: 10.1007/s10973-024-13844-8
Jorge Macridachis, Laura Bayés-García, Teresa Calvet
{"title":"Polymorphic crystallization and transformation pathways of 1,2-dipalmitoyl-3-oleoyl-rac-glycerol (PPO) during a liquid–solid-liquid journey","authors":"Jorge Macridachis,&nbsp;Laura Bayés-García,&nbsp;Teresa Calvet","doi":"10.1007/s10973-024-13844-8","DOIUrl":"10.1007/s10973-024-13844-8","url":null,"abstract":"<div><p>The polymorphic behavior of triacylglycerol (TAG) crystals formed during the manufacturing process of lipid-based food products relates directly to their textural and melting properties. In this work, we analyzed the polymorphic crystallization and transformation behavior of 1,2-dipalmitoyl-3-oleoyl-<i>rac</i>-glycerol (PPO), a widespread TAG in edible fats and oils, during the application dynamic thermal treatments of cooling and heating. By implementing calorimetric, <i>X</i>-ray diffraction, and microscopy techniques, we mapped the polymorphic occurrence and the polymorphic transformation pathways of PPO as a function of the rate of thermal treatments. The results obtained were later compared to that reported for diverse TAGs in previous studies. Despite the overall crystallization and transformation behavior of PPO following a similar trend to other TAGs close in fatty acid composition, we can highlight the much lower influence of varying cooling and heating conditions on the crystallization properties of this TAG. In more detail, crystalline forms of low stability were generally promoted during crystallization, whereas transformations occurred always through the melt independently of the heating conditions. One may expect this behavior to influence the industrial processing and final properties of food products based on edible fats containing PPO.</p></div>","PeriodicalId":678,"journal":{"name":"Journal of Thermal Analysis and Calorimetry","volume":"150 1","pages":"187 - 199"},"PeriodicalIF":3.0,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10973-024-13844-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143423431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Study of velocity slip impact combined with dissipative heat on the Williamson hybrid nanofluids with the Cattaneo–Christov heat flux framework 基于Cattaneo-Christov热流通量框架的Williamson混合纳米流体速度滑移与耗散冲击研究
IF 3 3区 工程技术
Journal of Thermal Analysis and Calorimetry Pub Date : 2024-11-26 DOI: 10.1007/s10973-024-13769-2
S. R. Mishra, Rupa Baithalu, Surender Ontela, Subhajit Panda
{"title":"Study of velocity slip impact combined with dissipative heat on the Williamson hybrid nanofluids with the Cattaneo–Christov heat flux framework","authors":"S. R. Mishra,&nbsp;Rupa Baithalu,&nbsp;Surender Ontela,&nbsp;Subhajit Panda","doi":"10.1007/s10973-024-13769-2","DOIUrl":"10.1007/s10973-024-13769-2","url":null,"abstract":"<div><p>The investigation of velocity slip combined with the dissipative heat corresponds to the non-Newtonian Williamson hybrid nanofluids utilizing the “Cattaneo-Christov heat flux model” is crucial in advanced applications in several sectors. The proposed analysis focuses on the hybrid nanofluid comprised of magnesium oxide (MgO) and zirconium dioxide (ZrO<sub>2</sub>) in water which boosts the thermal conductivity along with the performance of the fluid. The magnetized Williamson fluid is a particular type of non-Newtonian fluid that exhibits essential applications to biomedical engineering. The insertion of magnetization along with porosity suggests considering the dissipative heat impact associated with Joule and Darcy which energies the heat transport phenomena. The limitation of classical Fourier laws is addressed by the consideration of the Cattaneo–Christov heat flux framework along with the thermal radiation. The designed flow model with dimensional terms is transformed into a corresponding non-dimensional form by implementing similarity functions. Further, these transmuted equations are solved numerically via the shooting-based Runge–Kutta technique. The parametric analysis of the flow phenomena is obtained and arranged graphically. The validation with earlier investigation displays a valid association in particular scenarios. The main outcomes reveal that the resistivity characteristics produced by the interplay between permeability and magnetization regulate fluid velocity, especially when combined with the non-Newtonian Williamson parameter. Furthermore, in both nanofluid and hybrid nanofluid scenarios, the fluid temperature is greatly raised by the effects of thermal radiation and the Eckert number.</p></div>","PeriodicalId":678,"journal":{"name":"Journal of Thermal Analysis and Calorimetry","volume":"149 24","pages":"15305 - 15322"},"PeriodicalIF":3.0,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10973-024-13769-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142889844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Research on rectangular mini-channel flow instability using bubble coalescence and entropy generation 利用气泡聚结和熵生成研究矩形小通道流动不稳定性
IF 3 3区 工程技术
Journal of Thermal Analysis and Calorimetry Pub Date : 2024-11-25 DOI: 10.1007/s10973-024-13818-w
Jianchang Yang, Yunxin Zhou, Hao Tang, Jianxin Xu, Hua Wang
{"title":"Research on rectangular mini-channel flow instability using bubble coalescence and entropy generation","authors":"Jianchang Yang,&nbsp;Yunxin Zhou,&nbsp;Hao Tang,&nbsp;Jianxin Xu,&nbsp;Hua Wang","doi":"10.1007/s10973-024-13818-w","DOIUrl":"10.1007/s10973-024-13818-w","url":null,"abstract":"<div><p>Optimizing the process of flow boiling and improving heat transfer efficiency require preventing the onset of flow instability (OFI) during the operation. The aim of this work was to examine the instability of upward flow in a rectangular mini-channel with a cross-section of 2 <span>(times )</span> 2 mm when the heat flux and mass flux were gradually increased. The study examined the periodic transition of flow patterns during OFI, calculated the impact of bubble coalescence on OFI using the growth rate of bubbles with the potential to form gas columns, and introduced entropy generation to assess the irreversibility and disorder of the system. The findings revealed that the formation of gas columns during OFI is the main cause of the periodic transition of flow patterns. When the inlet subcooling <span>({Delta T}_{text{sub}})</span> is 12.1 <span>(text{K})</span>, the average number of bubble coalescences during OFI is 240% higher than during stable flow. Pressure drop fluctuations are significantly impacted by bubble coalescence, which also contributes to the formation of gas columns and an increase in system instability. The pressure drop and the heat transfer coefficient are inversely related. Lowering the inlet subcooling and reducing mass flux are like to cause OFI. Entropy generation analysis indicates that reducing inlet subcooling and increasing fluid velocity can reduce the system's irreversibility. When OFI occurs, entropy generation rises sharply.</p></div>","PeriodicalId":678,"journal":{"name":"Journal of Thermal Analysis and Calorimetry","volume":"149 24","pages":"15007 - 15023"},"PeriodicalIF":3.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142889883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Combined thermal calorimetry and quantum chemical evaluation of effect of hydrogen peroxide on the thermal decomposition of N-methylmorpholine-N-oxide 热量热法与量子化学联合评价过氧化氢对n -甲基- n -氧化物热分解的影响
IF 3 3区 工程技术
Journal of Thermal Analysis and Calorimetry Pub Date : 2024-11-24 DOI: 10.1007/s10973-024-13812-2
Jiancun Gao, Yunyang Dang, Wei Wang, Naixin Kang, Yujing Li
{"title":"Combined thermal calorimetry and quantum chemical evaluation of effect of hydrogen peroxide on the thermal decomposition of N-methylmorpholine-N-oxide","authors":"Jiancun Gao,&nbsp;Yunyang Dang,&nbsp;Wei Wang,&nbsp;Naixin Kang,&nbsp;Yujing Li","doi":"10.1007/s10973-024-13812-2","DOIUrl":"10.1007/s10973-024-13812-2","url":null,"abstract":"<div><p>The effect of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) on the thermal decomposition characteristics of <i>N</i>-methylmorpholine-<i>N</i>-oxide (NMMO) was investigated using thermal experiments and quantum chemical calculations. The thermal decomposition characteristics of the NMMO and NMMO/H<sub>2</sub>O<sub>2</sub> systems were determined at different heating rates using a microreaction calorimeter. Firstly, H<sub>2</sub>O<sub>2</sub> decreased the onset temperature and increased the reaction enthalpy of NMMO decomposition. Secondly, the apparent activation energy decreased from 97.49–76.79 kJ mol<sup>−1</sup> to 80.76‒89.87 kJmol<sup>−1</sup> based on the Kissinger and Starink models. Finally, density functional theory was used to investigate the effect of H<sub>2</sub>O<sub>2</sub> on NMMO decomposition from a microscopic perspective. It was found that the length of the N–O bond in NMMO increased, and the ability of oxygen atoms to obtain electrons was enhanced in the presence of H<sub>2</sub>O<sub>2</sub>, decreasing the stability of the NMMO molecules. The nucleophilicity of the oxygen atom in the NMMO molecule was enhanced in the NMMO/ H<sub>2</sub>O<sub>2</sub> system, which is beneficial for electron transfer to the H<sub>2</sub>O<sub>2</sub> molecule. The energy-gap of the frontier molecular orbital decreased under the influence of H<sub>2</sub>O<sub>2</sub>, intensifying the interaction between H<sub>2</sub>O<sub>2</sub> and NMMO to form π bonds. Overall, the stability of the NMMO molecular structure was reduced and the reactivity of NMMO was enhanced at lower temperatures in the presence of H<sub>2</sub>O<sub>2</sub>, which provides a theoretical reference for the safe production of NMMO.</p></div>","PeriodicalId":678,"journal":{"name":"Journal of Thermal Analysis and Calorimetry","volume":"149 24","pages":"14865 - 14876"},"PeriodicalIF":3.0,"publicationDate":"2024-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142889600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Marangoni convection with variable thermal conductivity and impact of inertial drag on radiative tri-hybrid nanofluid flow over a Riga plate with non-uniform heat emission/release 变导热率的马兰戈尼对流和惯性阻力对辐射三混合纳米流体在非均匀热发射/释放的里加板上流动的影响
IF 3 3区 工程技术
Journal of Thermal Analysis and Calorimetry Pub Date : 2024-11-24 DOI: 10.1007/s10973-024-13766-5
Rupa Baithalu, S. R. Mishra, Subhajit Panda
{"title":"Marangoni convection with variable thermal conductivity and impact of inertial drag on radiative tri-hybrid nanofluid flow over a Riga plate with non-uniform heat emission/release","authors":"Rupa Baithalu,&nbsp;S. R. Mishra,&nbsp;Subhajit Panda","doi":"10.1007/s10973-024-13766-5","DOIUrl":"10.1007/s10973-024-13766-5","url":null,"abstract":"<div><p>A broad and impactful application in designing and optimizing thermal system in engineering is due to the utility of the nanoparticles. These include advanced cooling technologies in electronics and enhanced recovery processes where managing heat flow in porous medium. Based on the above-mentioned features and utilities, a study is carried out in examining the flow characteristics involving the Marangoni convection of a radiative tri-hybrid nanofluid passing via a Riga plate by considering the variable thermal conductivity and the effect of Darcy–Forchheimer inertial drag. The incorporation of heat source/sink relating to both space and temperature dependent with the imposition of a magnetic field enriches the flow phenomena of a nanofluid consisting of composite nanoparticles. The thermal properties combined with the effect of thermal conductivity, density, etc., enrich the transport phenomena. The utilization of the specific similarity rules is effective in transforming the designed model into a dimensionless. Further, a numerical technique is introduced for the solution of these transmuted equations and the numerical values correlating to the established results show a good relationship in a particular case. The important characteristics of several factors about the flow phenomena are presented briefly through graphs. The observations reveal that the enhanced Hartmann number gives rise to increase the fluid velocity and the radiative heat for the inclusion of thermal radiation also favours in enhancing the fluid temperature.</p></div>","PeriodicalId":678,"journal":{"name":"Journal of Thermal Analysis and Calorimetry","volume":"149 24","pages":"15291 - 15304"},"PeriodicalIF":3.0,"publicationDate":"2024-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142889602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Modeling of nanofluid effect of performance of PVT system in existence of TEG 存在TEG时纳米流体对PVT系统性能影响的建模
IF 3 3区 工程技术
Journal of Thermal Analysis and Calorimetry Pub Date : 2024-11-23 DOI: 10.1007/s10973-024-13793-2
Ahmad Shafee, Ali Basem, Hussein A. Z. AL-bonsrulah, Saad Althobaiti, Walid Aydi
{"title":"Modeling of nanofluid effect of performance of PVT system in existence of TEG","authors":"Ahmad Shafee,&nbsp;Ali Basem,&nbsp;Hussein A. Z. AL-bonsrulah,&nbsp;Saad Althobaiti,&nbsp;Walid Aydi","doi":"10.1007/s10973-024-13793-2","DOIUrl":"10.1007/s10973-024-13793-2","url":null,"abstract":"<div><p>This paper presents a detailed numerical modeling of a hybrid photovoltaic-thermal (PVT) unit combined with a TEG (thermoelectric generator), focusing on two key performance indicators: profit and CO<sub>2</sub> mitigation (CM). The study investigates how the unit's electrical and thermal outputs vary with different geometrical configurations of the cooling duct's cross sections. Four distinct geometries—circular, elliptical, triangular, and square—were analyzed, with results highlighting the effects of these shapes on system performance. The cooling medium used in the ducts is a hybrid nanofluid composed of copper and aluminum oxide nanoparticles suspended in water. This hybrid nanofluid was selected for its enhanced heat transfer properties, which directly impact the system's efficiency. The findings reveal that among the examined geometries, the triangular duct provides the best overall performance in terms of both profit and CM. Transitioning from a circular to a triangular duct results in a profit increase of approximately 2.58%, while CM improves by around 2.14%. Furthermore, increasing the inlet velocity of the coolant within the duct contributes to further gains, with profits and CM both enhanced by approximately 6% and 5%, respectively. The importance of current work lies in its demonstration that optimizing the cooling duct geometry, coupled with the use of hybrid nanofluids, can substantially improve both the economic and environmental performance of PVT-TEG systems.</p></div>","PeriodicalId":678,"journal":{"name":"Journal of Thermal Analysis and Calorimetry","volume":"149 24","pages":"14963 - 14970"},"PeriodicalIF":3.0,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142889688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Phase transitions in medium-Mn alloy: thermodynamic simulation and experimental verification 中锰合金相变:热力学模拟与实验验证
IF 3 3区 工程技术
Journal of Thermal Analysis and Calorimetry Pub Date : 2024-11-23 DOI: 10.1007/s10973-024-13824-y
Adam Skowronek, Aleksandra Kozłowska
{"title":"Phase transitions in medium-Mn alloy: thermodynamic simulation and experimental verification","authors":"Adam Skowronek,&nbsp;Aleksandra Kozłowska","doi":"10.1007/s10973-024-13824-y","DOIUrl":"10.1007/s10973-024-13824-y","url":null,"abstract":"<div><p>The present work explores a design process of new medium-Mn alloy for forgings and its heat treatment optimization by thermodynamic simulations and experimental approach. The selection of specific chemical composition was performed on the basis of thermodynamic simulation for alloys with different additions of Mn and Al. The aim was to design an alloy allowing for production of at least 25% retained austenite in an intercritical annealing process, without deteriorating technological properties and economic indicators. Next simulations of intercritical annealing in a temperature range between 600 and 1000 °C, and their experimental verification were performed. For the thermodynamical simulations of different chemical compositions of steel and its intercritical annealing in a wide temperature range the JMatPro software was used. To verify the characteristic temperatures of steel such as A<sub>c1</sub>, A<sub>c3</sub> and M<sub>s</sub>, and for experimental investigation of intercritical annealing in a temperature range from 660 to 740 °C dilatometry was used. Obtained microstructures were characterized by means of X-ray diffraction and scanning electron microscopy. It was observed that with an initial increase in soaking temperature a fraction of retained austenite increases; however, its stability decreases, which leads to formation of large martensite fraction during cooling after soaking at high temperatures. The results of thermodynamic simulations and experimental tests showed the moderate agreement. Large differences were revealed for A<sub>c1</sub>, M<sub>s</sub> temperatures and the amount of retained austenite obtained at a given annealing temperature. The results clearly indicate that at the moment of software development and available databases for novel medium-Mn steels, simulations of their heat treatment can only be used to estimate results and be a guide for experimental research. However, they cannot be used to optimize heat treatment.</p></div>","PeriodicalId":678,"journal":{"name":"Journal of Thermal Analysis and Calorimetry","volume":"150 2","pages":"1059 - 1068"},"PeriodicalIF":3.0,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10973-024-13824-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143875347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Enriched nanofluid with IERO process in modified radiator tube for high heat transfer rate 改进散热器管内IERO工艺富集纳米流体,提高传热率
IF 3 3区 工程技术
Journal of Thermal Analysis and Calorimetry Pub Date : 2024-11-23 DOI: 10.1007/s10973-024-13779-0
M. Ravikrishnan, G. R. Kannan, P. Selvakumar
{"title":"Enriched nanofluid with IERO process in modified radiator tube for high heat transfer rate","authors":"M. Ravikrishnan,&nbsp;G. R. Kannan,&nbsp;P. Selvakumar","doi":"10.1007/s10973-024-13779-0","DOIUrl":"10.1007/s10973-024-13779-0","url":null,"abstract":"<div><p>Nanofluids have the potential to improve heat transfer in automobile radiators, but issues such as scale formation in nanofluids, and inefficient tube design limit their effectiveness. Hence, this research introduces an Enriched Nanofluid with IERO process and Waist Tube Heat exchanger to enhance heat transmission in heat exchangers and disables the limitations of conventional nanofluids. The existing nanofluids faces issues with scale generation due to nanoparticle interaction with coolant ions, resulting in lower system efficiency and possible overheating. To address these challenges, the Enriched Nanofluid with IERO approach is used for eliminating the efficiency concerns and the risk of overheating. In this nanofluid contains Al<sub>2</sub>O<sub>3</sub> nanoparticles in a mixture of water and ethylene glycol, and it is stabilized with a graphene oxide (GO) surfactant for ensuring optimal dispersion of nanoparticles. The Ion Exchange Reverse Osmosis (IERO) process continues to treat the coolant using Organic Polymers, reducing scale growth and improving coolant purity, which further mitigates overheating risks for improving system efficiency. Moreover, insufficient heat exchange and airflow coverage in the existing wasp waist tubes leads to flow separation of the tube surfaces. Thus, a novel wasp waist elliptic section tube design is implemented with an elliptical back end to reduce flow separation and the airflow line covers a larger area of the tube, thereby improving heat transfer efficiency. As a result, the proposed design surpasses existing heat exchanger designs with a higher pressure drop of 5100 Pa at Reynolds number 6500, heat transfer coefficient of 182 W/m<sup>2</sup>K, and greatest heat transfer rate of 85 W.</p></div>","PeriodicalId":678,"journal":{"name":"Journal of Thermal Analysis and Calorimetry","volume":"149 24","pages":"14943 - 14962"},"PeriodicalIF":3.0,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10973-024-13779-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142889687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Investigation on the heat transfer and pressure loss of flow boiling in smooth and microfin tubes using machine learning methods 用机器学习方法研究光滑和微翅片管内流动沸腾的传热和压力损失
IF 3 3区 工程技术
Journal of Thermal Analysis and Calorimetry Pub Date : 2024-11-23 DOI: 10.1007/s10973-024-13794-1
Şükrü Sezer, Cihan Sezer, Ali Celen, Aykut Bacak, Ahmet Selim Dalkılıç
{"title":"Investigation on the heat transfer and pressure loss of flow boiling in smooth and microfin tubes using machine learning methods","authors":"Şükrü Sezer,&nbsp;Cihan Sezer,&nbsp;Ali Celen,&nbsp;Aykut Bacak,&nbsp;Ahmet Selim Dalkılıç","doi":"10.1007/s10973-024-13794-1","DOIUrl":"10.1007/s10973-024-13794-1","url":null,"abstract":"<div><p>The estimation of heat transfer coefficients (HTC) and pressure drop (ΔP) in flow boiling processes is essential for the effective design and operation of refrigeration systems. In this study, the artificial neural network (ANN), locally weighted regression (LWR), and gradient boosted machine (GBM) methods are employed to predict the boiling heat transfer coefficient (HTC) and pressure drop (<span>(Delta P)</span>) in flow boiling of R134a. The study focuses on horizontally positioned both straight and microfin tubes. The ANN, LWR, and GBM methodologies are utilized to ascertain the parameters of boiling HTC and ΔP as outputs. These parameters are determined by considering the mass flux, saturation pressure, heat flux, vapor quality, Reynolds number, Lockhart–Martinelli parameter, Froud number, Weber number, and Bond number as inputs. The training dataset is partitioned into 5 sections for the purpose of hyperparameter tweaking for each model. Out of these sections, 4 parts, consisting of approximately 111 samples, are utilized for training, while 1 part, including around 27 samples, is allocated for validation. The optimal hyperparameters are determined by calculating the average R<sup>2</sup> score over the 5 validation sets. Using raw measurements, HTC and ΔP are successfully modeled using a relatively much smaller dataset of 174 measurements, with 82.4% R<sup>2</sup> score and 0.7% weighted average relative deviation for HTC, and 88.9% R<sup>2</sup> score and 4.1% weighted average relative deviation for ΔP across multiple tube types, achieved by LWR algorithm. Model performances are validated with an extrapolation test and found to be consistent with traditional train–validation–test sampling scheme with 75.9% R<sup>2</sup> score and −6.2% weighted average relative deviation for HTC, and 89.3% R<sup>2</sup> score and −3.9% weighted average relative deviation for ΔP, showing the consistency of the hypotheses created by a hybrid of parametric and nonparametric model families even outside the observed measurement range for multiple tube types. Local weighted regression models are the most performant, especially for limited data availability. However, calculated measurements increase error rates, suggesting that HTC and ΔP models work best with raw measurements.</p></div>","PeriodicalId":678,"journal":{"name":"Journal of Thermal Analysis and Calorimetry","volume":"149 24","pages":"15121 - 15141"},"PeriodicalIF":3.0,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142889689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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