The thermal and electrical properties of photovoltaic cell (PVC) under linear phenomenological heat transfer law between it and the environment is studied through finite time thermodynamics and the volt-ampere characteristic equation. The properties of PVC are affected by heat transfer between PVC and environment. There are optimal solar radiation intensity and PVC output voltage (OV), which make the photoelectric conversion efficiency (PECE) of PVC reach the highest value. When OV and solar radiation intensity are 28.50 V and 700 W/m2, the maximum PECE is 0.156. There is also the best solar radiation intensity, which makes the open-circuit voltage (OCV) reach the maximum. When solar radiant intensity is 669 W/m2, the maximum OCV is 33.14 V. The values of power output and short-circuit current (SCC) are monotonically increasing with solar radiation intensity. Given solar radiation intensity, the power output and OV exhibit a parabolic shape. The operating temperature falls first and then grows with the OV. However, the change of operating temperature with OV is not much. Band gap is a decreasing function of operating temperature. This article can give theoretical support for the design and use of PVCs.
通过有限时间热力学和伏安特性方程，研究了光伏电池（PVC）与环境之间线性现象传热规律下的热特性和电特性。聚氯乙烯的特性受聚氯乙烯与环境之间热传递的影响。存在最佳太阳辐射强度和聚氯乙烯输出电压（OV），使聚氯乙烯的光电转换效率（PECE）达到最高值。当 OV 和太阳辐射强度分别为 28.50 V 和 700 W/m2 时，PECE 最大，为 0.156。还有一个最佳的太阳辐射强度，它使开路电压（OCV）达到最大值。当太阳辐射强度为 669 W/m2 时，最大开路电压为 33.14 V。功率输出和短路电流（SCC）值随太阳辐射强度单调递增。在太阳辐射强度一定的情况下，功率输出和 OCV 呈现抛物线形状。工作温度先下降，然后随 OV 增长。不过，工作温度随 OV 的变化不大。带隙是工作温度的递减函数。本文可为聚氯乙烯的设计和使用提供理论支持。
{"title":"Thermal and electrical properties of photovoltaic cell with linear phenomenological heat transfer law","authors":"Jun Li, Lingen Chen","doi":"10.1515/jnet-2023-0056","DOIUrl":"https://doi.org/10.1515/jnet-2023-0056","url":null,"abstract":"The thermal and electrical properties of photovoltaic cell (PVC) under linear phenomenological heat transfer law between it and the environment is studied through finite time thermodynamics and the volt-ampere characteristic equation. The properties of PVC are affected by heat transfer between PVC and environment. There are optimal solar radiation intensity and PVC output voltage (OV), which make the photoelectric conversion efficiency (PECE) of PVC reach the highest value. When OV and solar radiation intensity are 28.50 V and 700 W/m<jats:sup>2</jats:sup>, the maximum PECE is 0.156. There is also the best solar radiation intensity, which makes the open-circuit voltage (OCV) reach the maximum. When solar radiant intensity is 669 W/m<jats:sup>2</jats:sup>, the maximum OCV is 33.14 V. The values of power output and short-circuit current (SCC) are monotonically increasing with solar radiation intensity. Given solar radiation intensity, the power output and OV exhibit a parabolic shape. The operating temperature falls first and then grows with the OV. However, the change of operating temperature with OV is not much. Band gap is a decreasing function of operating temperature. This article can give theoretical support for the design and use of PVCs.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":6.6,"publicationDate":"2024-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139110209","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}
The paper evaluates a passive method for heat transfer improvement in heat exchangers, which implies the use of nanofluids. All calculations were carried out with a constant volumetric flow rate. The study examines three fluids with 0–4 % volume concentrations of CuO, MgO, and Al2O3 particles. The results indicate an increase in the heat transfer coefficient with increasing temperature. An Al2O3 nanofluid (4 % concentration) contributed to the best thermal performance. The incorporation of a 4 % content of MgO yielded an augmentation in heat transfer ranging from 15 % to 22 %, whereas an analogous concentration of CuO led to a more substantial enhancement of 25 %. Notably, the introduction of nanoparticles of Al2O3 produces a remarkable augmentation in heat transfer performance, with potential improvements of up to 36 %. The Nusselt number increases with increasing particle volume fraction and Reynolds number, according to results obtained for several nanoparticles (Al2O3, CuO, SiO2, and ZnO) with volume percentages in the range of 1–4 % and nanoparticle diameters of 25–70 nm. For all nanofluids, the time-averaged Nusselt number rises with a solid phase volume fraction increase of less than 5 %.
{"title":"Strategies to improve the thermal performance of solar collectors","authors":"Bader Alshuraiaan","doi":"10.1515/jnet-2023-0040","DOIUrl":"https://doi.org/10.1515/jnet-2023-0040","url":null,"abstract":"The paper evaluates a passive method for heat transfer improvement in heat exchangers, which implies the use of nanofluids. All calculations were carried out with a constant volumetric flow rate. The study examines three fluids with 0–4 % volume concentrations of CuO, MgO, and Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> particles. The results indicate an increase in the heat transfer coefficient with increasing temperature. An Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> nanofluid (4 % concentration) contributed to the best thermal performance. The incorporation of a 4 % content of MgO yielded an augmentation in heat transfer ranging from 15 % to 22 %, whereas an analogous concentration of CuO led to a more substantial enhancement of 25 %. Notably, the introduction of nanoparticles of Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> produces a remarkable augmentation in heat transfer performance, with potential improvements of up to 36 %. The Nusselt number increases with increasing particle volume fraction and Reynolds number, according to results obtained for several nanoparticles (Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>, CuO, SiO<jats:sub>2</jats:sub>, and ZnO) with volume percentages in the range of 1–4 % and nanoparticle diameters of 25–70 nm. For all nanofluids, the time-averaged Nusselt number rises with a solid phase volume fraction increase of less than 5 %.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":6.6,"publicationDate":"2024-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139110268","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}
The consequences of introducing the fourth order orientation tensor as an independent variable in addition to the second order one are investigated. In the first part consequences of the Second Law of Thermodynamics are exploited. The cases with the second order alignment tensor in the state space on one hand and with the second and fourth order alignment tensors on the other hand are analogous. In the latter case differential equations for the second and fourth order tensors result from linear force-flux relations with a coupling arising due to coupling terms in the free energy. In the second part the differential equations for the second order orientation tensor or the second and fourth order orientation tensors, respectively are given explicitly in the special case of a rotation symmetric orientation distribution. The Folgar-Tucker equation with a quadratic closure relation leads to a Riccati equation for the second order parameter. In comparison the Folgar-Tucker equation and the differential equation for the fourth order parameter are considered. The fourth order parameter is eliminated later. The resulting equation for the second order parameter is a Duffing equation with a behavior of solutions completely different from the solutions of the Riccati equation.
{"title":"On the influence of the fourth order orientation tensor on the dynamics of the second order one","authors":"Christina Papenfuss","doi":"10.1515/jnet-2023-0066","DOIUrl":"https://doi.org/10.1515/jnet-2023-0066","url":null,"abstract":"The consequences of introducing the fourth order orientation tensor as an independent variable in addition to the second order one are investigated. In the first part consequences of the Second Law of Thermodynamics are exploited. The cases with the second order alignment tensor in the state space on one hand and with the second and fourth order alignment tensors on the other hand are analogous. In the latter case differential equations for the second and fourth order tensors result from linear force-flux relations with a coupling arising due to coupling terms in the free energy. In the second part the differential equations for the second order orientation tensor or the second and fourth order orientation tensors, respectively are given explicitly in the special case of a rotation symmetric orientation distribution. The Folgar-Tucker equation with a quadratic closure relation leads to a Riccati equation for the second order parameter. In comparison the Folgar-Tucker equation and the differential equation for the fourth order parameter are considered. The fourth order parameter is eliminated later. The resulting equation for the second order parameter is a Duffing equation with a behavior of solutions completely different from the solutions of the Riccati equation.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":6.6,"publicationDate":"2023-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138679097","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}
Brian Straughan, Vincenzo Tibullo, Francesca Passarella
We review models for convective motion which have a flux law of Cattaneo type. This includes thermal convection where the heat flux law is a Cattaneo one. We additionally analyse models where the convective motion is due to a density gradient caused by a concentration of solute. The usual Fick’s law in this case is replaced by a Cattaneo one involving the flux of solute and the concentration gradient. Other effects such as rotation, the presence of a magnetic field, Guyer–Krumhansl terms, or Kelvin–Voigt theories are briefly introduced.
{"title":"Buoyancy driven convection with a Cattaneo flux model","authors":"Brian Straughan, Vincenzo Tibullo, Francesca Passarella","doi":"10.1515/jnet-2023-0078","DOIUrl":"https://doi.org/10.1515/jnet-2023-0078","url":null,"abstract":"We review models for convective motion which have a flux law of Cattaneo type. This includes thermal convection where the heat flux law is a Cattaneo one. We additionally analyse models where the convective motion is due to a density gradient caused by a concentration of solute. The usual Fick’s law in this case is replaced by a Cattaneo one involving the flux of solute and the concentration gradient. Other effects such as rotation, the presence of a magnetic field, Guyer–Krumhansl terms, or Kelvin–Voigt theories are briefly introduced.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":6.6,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138582570","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}
The equivalence between irreversibility and dissipation entails that the Onsager reciprocal relations hold unconditionally, requiring the part of the phenomenological matrix describing dissipative phenomena to be symmetric. The antisymmetric part of the phenomenological matrix corresponds to the Casimir’s variant of the reciprocal relations and describes reversible phenomena. Further, we discuss the relationship of the reversibility and entropy production, including the role of the level of description, and we use the chemotaxis as an illustrative example.
{"title":"Onsager-Casimir reciprocal relations as a consequence of the equivalence between irreversibility and dissipation","authors":"Václav Klika, Sylvain D. Bréchet","doi":"10.1515/jnet-2023-0069","DOIUrl":"https://doi.org/10.1515/jnet-2023-0069","url":null,"abstract":"The equivalence between irreversibility and dissipation entails that the Onsager reciprocal relations hold unconditionally, requiring the part of the phenomenological matrix describing dissipative phenomena to be symmetric. The antisymmetric part of the phenomenological matrix corresponds to the Casimir’s variant of the reciprocal relations and describes reversible phenomena. Further, we discuss the relationship of the reversibility and entropy production, including the role of the level of description, and we use the chemotaxis as an illustrative example.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":6.6,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138635103","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}
We employ the generalized bracket formalism of nonequilibrium thermodynamics by Beris and Edwards to derive Lorentz-covariant time-evolution equations for an imperfect fluid with viscosity, dilatational viscosity, and thermal conductivity. Following closely the analysis presented by Öttinger (Physica A, 259, 1998, 24–42; Physica A, 254, 1998, 433–450) to the same problem but for the GENERIC formalism, we include in the set of hydrodynamic variables a covariant vector playing the role of a generalized thermal force and a covariant tensor closely related to the velocity gradient tensor. In our work here, we derive first the nonrelativistic equations and then we proceed to obtain the relativistic ones by elevating the thermal variable to a four-vector, the mechanical force variable to a four-by-four tensor, and by representing the Hamiltonian of the system with the time component of the energy-momentum tensor. For the Poisson and dissipation brackets we assume the same general structure as in the nonrelativistic case, but with the phenomenological coefficients in the dissipation bracket describing friction to heat and viscous effects being properly constrained for the resulting dynamic equations to be manifest Lorentz-covariant. The final relativistic equations are identical to those derived by Öttinger but the present approach seems to be more general in the sense that one could think of alternative forms of the phenomenological coefficients describing friction that could ensure Lorentz-covariance.
{"title":"Relativistic hydrodynamics from the single-generator bracket formalism of nonequilibrium thermodynamics","authors":"Vlasis G. Mavrantzas","doi":"10.1515/jnet-2023-0068","DOIUrl":"https://doi.org/10.1515/jnet-2023-0068","url":null,"abstract":"We employ the generalized bracket formalism of nonequilibrium thermodynamics by Beris and Edwards to derive Lorentz-covariant time-evolution equations for an imperfect fluid with viscosity, dilatational viscosity, and thermal conductivity. Following closely the analysis presented by Öttinger (Physica A, 259, 1998, 24–42; Physica A, 254, 1998, 433–450) to the same problem but for the GENERIC formalism, we include in the set of hydrodynamic variables a covariant vector playing the role of a generalized thermal force and a covariant tensor closely related to the velocity gradient tensor. In our work here, we derive first the nonrelativistic equations and then we proceed to obtain the relativistic ones by elevating the thermal variable to a four-vector, the mechanical force variable to a four-by-four tensor, and by representing the Hamiltonian of the system with the time component of the energy-momentum tensor. For the Poisson and dissipation brackets we assume the same general structure as in the nonrelativistic case, but with the phenomenological coefficients in the dissipation bracket describing friction to heat and viscous effects being properly constrained for the resulting dynamic equations to be manifest Lorentz-covariant. The final relativistic equations are identical to those derived by Öttinger but the present approach seems to be more general in the sense that one could think of alternative forms of the phenomenological coefficients describing friction that could ensure Lorentz-covariance.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":6.6,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138492091","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}
Based on finite-time-thermodynamic theory and the model established in previous literature, the multi-objective optimization analysis for an endoreversible closed Atkinson cycle is conducted through using the NSGA-II algorithm. With the final state point temperature (T2) of cycle compression process as the optimization variable and the thermal efficiency (η), the dimensionless efficient power (ĒP ${bar{E}}_{P}$ ), the dimensionless ecological function (Ē $bar{E}$ ) and the dimensionless power (P̄ $bar{P}$ ) as the optimization objectives, the influences of T2 on the four optimization objectives are analyzed, multi-objective optimization analyses of single-, two-, three- and four-objective are conducted, and the optimal cycle optimization objective combination is chosen by using three decision-making methods which include LINMAP, TOPSIS, and Shannon Entropy. The result shows that when four-objective optimization is conducted, with the ascent of T2, P̄ $bar{P}$ descends, η ascends, both
基于有限时间热力学理论和前人建立的模型，利用NSGA-II算法对内可逆封闭Atkinson循环进行多目标优化分析。以循环压缩过程最终状态点温度(t2)为优化变量，以热效率(η)、无量纲效率功率(E′P ${bar{E}}_{P}$)、无量纲生态函数(E′$bar{E}$)和无量纲功率(P′$bar{P}$)为优化目标，分析了t2对4个优化目标的影响，单、采用LINMAP、TOPSIS和Shannon熵三种决策方法，选择最优周期优化目标组合。结果表明，在进行四目标优化时，随着t2的增大，P $bar{P}$减小，η增大，E $ $bar{E}$和E $ P ${bar{E}}_{P}$均先增大后减小。在这种情况下，香农熵决策方法的偏差指数最小，为0.2657，因此其优化结果为最优。多目标优化结果可为实际闭式阿特金森循环热机的设计提供一定的指导。
{"title":"Multi-objective optimization of an endoreversible closed Atkinson cycle","authors":"Zheng Gong, Yanlin Ge, Lingen Chen, Huijun Feng","doi":"10.1515/jnet-2023-0051","DOIUrl":"https://doi.org/10.1515/jnet-2023-0051","url":null,"abstract":"Based on finite-time-thermodynamic theory and the model established in previous literature, the multi-objective optimization analysis for an endoreversible closed Atkinson cycle is conducted through using the NSGA-II algorithm. With the final state point temperature (<jats:italic>T</jats:italic> <jats:sub>2</jats:sub>) of cycle compression process as the optimization variable and the thermal efficiency (<jats:italic>η</jats:italic>), the dimensionless efficient power (<jats:inline-formula> <jats:alternatives> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <m:msub> <m:mrow> <m:mover accent=\"true\"> <m:mrow> <m:mi>E</m:mi> </m:mrow> <m:mo>̄</m:mo> </m:mover> </m:mrow> <m:mrow> <m:mi>P</m:mi> </m:mrow> </m:msub> </m:math> <jats:tex-math> ${bar{E}}_{P}$ </jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_jnetdy-2023-0051_ineq_001.png\" /> </jats:alternatives> </jats:inline-formula>), the dimensionless ecological function (<jats:inline-formula> <jats:alternatives> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <m:mrow> <m:mover accent=\"true\"> <m:mrow> <m:mi>E</m:mi> </m:mrow> <m:mo>̄</m:mo> </m:mover> </m:mrow> </m:math> <jats:tex-math> $bar{E}$ </jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_jnetdy-2023-0051_ineq_002.png\" /> </jats:alternatives> </jats:inline-formula>) and the dimensionless power (<jats:inline-formula> <jats:alternatives> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <m:mrow> <m:mover accent=\"true\"> <m:mrow> <m:mi>P</m:mi> </m:mrow> <m:mo>̄</m:mo> </m:mover> </m:mrow> </m:math> <jats:tex-math> $bar{P}$ </jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_jnetdy-2023-0051_ineq_003.png\" /> </jats:alternatives> </jats:inline-formula>) as the optimization objectives, the influences of <jats:italic>T</jats:italic> <jats:sub>2</jats:sub> on the four optimization objectives are analyzed, multi-objective optimization analyses of single-, two-, three- and four-objective are conducted, and the optimal cycle optimization objective combination is chosen by using three decision-making methods which include LINMAP, TOPSIS, and Shannon Entropy. The result shows that when four-objective optimization is conducted, with the ascent of <jats:italic>T</jats:italic> <jats:sub>2</jats:sub>, <jats:inline-formula> <jats:alternatives> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <m:mrow> <m:mover accent=\"true\"> <m:mrow> <m:mi>P</m:mi> </m:mrow> <m:mo>̄</m:mo> </m:mover> </m:mrow> </m:math> <jats:tex-math> $bar{P}$ </jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_jnetdy-2023-0051_ineq_004.png\" /> </jats:alternatives> </jats:inline-formula> descends, <jats:italic>η</jats:italic> ascends, both <jats:inline-formula> <jats:alternatives> <m:math xmlns:m=\"http:","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":6.6,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138437513","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}
The article utilizes the fractional bioheat model in spherical coordinates to explain the transfer of heat in living tissues during magnetic hyperthermia treatment for tumors. Maintaining therapeutic temperature is crucial in magnetic fluid hyperthermia, which requires accurate estimations of power dissipation to determine the appropriate number of magnetic particles required for treatment. To address this problem, a hybrid numerical approach that combines Laplace transforms, change of variables, and modified discretization techniques is proposed in this paper. The study investigates the impact of the fractional parameter and differences in thermophysical properties between diseased and healthy tissue. The numerical temperature results are presented in a graph, and their validity is demonstrated by comparing them with previous literature.
{"title":"The effects of fractional time derivatives in bioheat conduction technique on tumor thermal therapy","authors":"Ibrahim Abbas, Aatef Hobiny, Alaa El-Bary","doi":"10.1515/jnet-2023-0065","DOIUrl":"https://doi.org/10.1515/jnet-2023-0065","url":null,"abstract":"The article utilizes the fractional bioheat model in spherical coordinates to explain the transfer of heat in living tissues during magnetic hyperthermia treatment for tumors. Maintaining therapeutic temperature is crucial in magnetic fluid hyperthermia, which requires accurate estimations of power dissipation to determine the appropriate number of magnetic particles required for treatment. To address this problem, a hybrid numerical approach that combines Laplace transforms, change of variables, and modified discretization techniques is proposed in this paper. The study investigates the impact of the fractional parameter and differences in thermophysical properties between diseased and healthy tissue. The numerical temperature results are presented in a graph, and their validity is demonstrated by comparing them with previous literature.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":6.6,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138293325","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}
Pub Date : 2023-10-25DOI: 10.1515/jnetdy-2023-0040
Bader Alshuraiaan
Abstract The paper evaluates a passive method for heat transfer improvement in heat exchangers, which implies the use of nanofluids. All calculations were carried out with a constant volumetric flow rate. The study examines three fluids with 0–4 % volume concentrations of CuO, MgO, and Al 2 O 3 particles. The results indicate an increase in the heat transfer coefficient with increasing temperature. An Al 2 O 3 nanofluid (4 % concentration) contributed to the best thermal performance. The incorporation of a 4 % content of MgO yielded an augmentation in heat transfer ranging from 15 % to 22 %, whereas an analogous concentration of CuO led to a more substantial enhancement of 25 %. Notably, the introduction of nanoparticles of Al 2 O 3 produces a remarkable augmentation in heat transfer performance, with potential improvements of up to 36 %. The Nusselt number increases with increasing particle volume fraction and Reynolds number, according to results obtained for several nanoparticles (Al 2 O 3 , CuO, SiO 2 , and ZnO) with volume percentages in the range of 1–4 % and nanoparticle diameters of 25–70 nm. For all nanofluids, the time-averaged Nusselt number rises with a solid phase volume fraction increase of less than 5 %.
{"title":"Strategies to improve the thermal performance of solar collectors","authors":"Bader Alshuraiaan","doi":"10.1515/jnetdy-2023-0040","DOIUrl":"https://doi.org/10.1515/jnetdy-2023-0040","url":null,"abstract":"Abstract The paper evaluates a passive method for heat transfer improvement in heat exchangers, which implies the use of nanofluids. All calculations were carried out with a constant volumetric flow rate. The study examines three fluids with 0–4 % volume concentrations of CuO, MgO, and Al 2 O 3 particles. The results indicate an increase in the heat transfer coefficient with increasing temperature. An Al 2 O 3 nanofluid (4 % concentration) contributed to the best thermal performance. The incorporation of a 4 % content of MgO yielded an augmentation in heat transfer ranging from 15 % to 22 %, whereas an analogous concentration of CuO led to a more substantial enhancement of 25 %. Notably, the introduction of nanoparticles of Al 2 O 3 produces a remarkable augmentation in heat transfer performance, with potential improvements of up to 36 %. The Nusselt number increases with increasing particle volume fraction and Reynolds number, according to results obtained for several nanoparticles (Al 2 O 3 , CuO, SiO 2 , and ZnO) with volume percentages in the range of 1–4 % and nanoparticle diameters of 25–70 nm. For all nanofluids, the time-averaged Nusselt number rises with a solid phase volume fraction increase of less than 5 %.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135113286","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}
Debashis Panda, Ashok Kumar Satapathy, Sunil Kr. Sarangi, Upendra Behera
Abstract The Gifford-McMahon cryocoolers are considered to be prominent candidates for the cooling of high-temperature superconducting magnets, liquefaction of permanent gases, helium recondensation in magnetic resonance imaging machines, cooling of superconducting quantum interference device, etc. In this paper, multi-dimensional numerical simulation is performed to visualize the oscillating heat and fluid flow processes that happen in a mechanically driven GM cryocooler. Influence of the ideal gas equation and real gas equation of states on the cooling behaviour is explained. The minimum achievable refrigeration temperature of a uniform mesh regenerator is compared with a multi-mesh regenerator. It is noticed that a multi-mesh regenerator produces a lower refrigeration temperature as compared to a uniform mesh regenerator. In addition to this, a one-dimensional simulation is conducted and results are compared with multi-dimensional numerical simulation. The no-load temperature value calculated by the one-dimensional model and multi-dimensional model with ideal gas is lower than that of real gas equations. Additionally, the refrigerating capacity calculated by the one-dimensional model and multi-dimensional model with the ideal gas equation is higher than those of the real gas equation of state.
{"title":"Multidimensional numerical simulation of thermodynamic and oscillating gas flow processes of a Gifford-McMahon cryocooler","authors":"Debashis Panda, Ashok Kumar Satapathy, Sunil Kr. Sarangi, Upendra Behera","doi":"10.1515/jnet-2023-0026","DOIUrl":"https://doi.org/10.1515/jnet-2023-0026","url":null,"abstract":"Abstract The Gifford-McMahon cryocoolers are considered to be prominent candidates for the cooling of high-temperature superconducting magnets, liquefaction of permanent gases, helium recondensation in magnetic resonance imaging machines, cooling of superconducting quantum interference device, etc. In this paper, multi-dimensional numerical simulation is performed to visualize the oscillating heat and fluid flow processes that happen in a mechanically driven GM cryocooler. Influence of the ideal gas equation and real gas equation of states on the cooling behaviour is explained. The minimum achievable refrigeration temperature of a uniform mesh regenerator is compared with a multi-mesh regenerator. It is noticed that a multi-mesh regenerator produces a lower refrigeration temperature as compared to a uniform mesh regenerator. In addition to this, a one-dimensional simulation is conducted and results are compared with multi-dimensional numerical simulation. The no-load temperature value calculated by the one-dimensional model and multi-dimensional model with ideal gas is lower than that of real gas equations. Additionally, the refrigerating capacity calculated by the one-dimensional model and multi-dimensional model with the ideal gas equation is higher than those of the real gas equation of state.","PeriodicalId":16428,"journal":{"name":"Journal of Non-Equilibrium Thermodynamics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135365513","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}
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