Pub Date : 2024-06-05DOI: 10.3389/fther.2024.1391602
Tingzhe Pan, Zean Zhu, Hongxuan Luo, Chao Li, Xin Jin, Z. Meng, Xinlei Cai
With the increase in the integration of renewable sources, the home energy management system (HEMS) has become a promising approach to improve grid energy efficiency and relieve network stress. In this context, this paper proposes an optimization dispatching strategy for HEMS to reduce total cost with full consideration of uncertainties, while ensuring the users’ comfort. Firstly, a HEMS dispatching model is constructed to reasonably schedule the start/stop time of the dispatchable appliances and energy storage system to minimize the total cost for home users. Besides, this dispatching strategy also controls the switching time of temperature-controlled load such as air conditioning to reduce the energy consumption while maintaining the indoor temperature in a comfortable level. Then, the optimal dispatching problem of HEMS is modeled as a Markov decision process (MDP) and solved by a deep reinforcement learning algorithm called deep deterministic policy gradient. The example results verify the effectiveness and superiority of the proposed method. The energy cost can be effectively reduced by 21.9% at least compared with other benchmarks and the indoor temperature can be well maintained.
{"title":"Home energy management strategy to schedule multiple types of loads and energy storage device with consideration of user comfort: a deep reinforcement learning based approach","authors":"Tingzhe Pan, Zean Zhu, Hongxuan Luo, Chao Li, Xin Jin, Z. Meng, Xinlei Cai","doi":"10.3389/fther.2024.1391602","DOIUrl":"https://doi.org/10.3389/fther.2024.1391602","url":null,"abstract":"With the increase in the integration of renewable sources, the home energy management system (HEMS) has become a promising approach to improve grid energy efficiency and relieve network stress. In this context, this paper proposes an optimization dispatching strategy for HEMS to reduce total cost with full consideration of uncertainties, while ensuring the users’ comfort. Firstly, a HEMS dispatching model is constructed to reasonably schedule the start/stop time of the dispatchable appliances and energy storage system to minimize the total cost for home users. Besides, this dispatching strategy also controls the switching time of temperature-controlled load such as air conditioning to reduce the energy consumption while maintaining the indoor temperature in a comfortable level. Then, the optimal dispatching problem of HEMS is modeled as a Markov decision process (MDP) and solved by a deep reinforcement learning algorithm called deep deterministic policy gradient. The example results verify the effectiveness and superiority of the proposed method. The energy cost can be effectively reduced by 21.9% at least compared with other benchmarks and the indoor temperature can be well maintained.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":"62 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141381730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-15DOI: 10.3389/fther.2023.1354265
L. Dombrovsky
Solar radiative heating and melting of lake and sea ice is a geophysical problem that has attracted the attention of researchers for many years. This problem is important in connection with the current global change of the climate. Physical and computational models of the process are suggested in the paper. Analytical solutions for the transfer of solar radiation in light-scattering snow cover and ice are combined with numerical calculations of heat transfer in a multilayer system. The thermal boundary conditions take into account convective heat losses to the ambient air and radiative cooling in the mid-infrared window of transparency of the cloudless atmosphere. The study begins with an anomalous spring melting of ice on the large high-mountain lakes of Tibet. It was found that a thick ice layer not covered with snow starts to melt at the ice-water interface due to volumetric solar heating of ice. The results of the calculations are in good agreement with the field observations. The computational analysis showed a dramatic change in the process when the ice is covered with snow. A qualitative change in the physical picture of the process occurs when the snow cover thickness increases to 20–30 cm. In this case, the snow melting precedes ice melting and water ponds are formed on the ice surface. This is typical for the Arctic Sea in polar summer. Known experimental data are used to estimate the melting of sea ice under the melt pond. Positive or negative feedback related to the specific optical and thermal properties of snow, ice, and water are discussed.
{"title":"An effect of a snow cover on solar heating and melting of lake or sea ice","authors":"L. Dombrovsky","doi":"10.3389/fther.2023.1354265","DOIUrl":"https://doi.org/10.3389/fther.2023.1354265","url":null,"abstract":"Solar radiative heating and melting of lake and sea ice is a geophysical problem that has attracted the attention of researchers for many years. This problem is important in connection with the current global change of the climate. Physical and computational models of the process are suggested in the paper. Analytical solutions for the transfer of solar radiation in light-scattering snow cover and ice are combined with numerical calculations of heat transfer in a multilayer system. The thermal boundary conditions take into account convective heat losses to the ambient air and radiative cooling in the mid-infrared window of transparency of the cloudless atmosphere. The study begins with an anomalous spring melting of ice on the large high-mountain lakes of Tibet. It was found that a thick ice layer not covered with snow starts to melt at the ice-water interface due to volumetric solar heating of ice. The results of the calculations are in good agreement with the field observations. The computational analysis showed a dramatic change in the process when the ice is covered with snow. A qualitative change in the physical picture of the process occurs when the snow cover thickness increases to 20–30 cm. In this case, the snow melting precedes ice melting and water ponds are formed on the ice surface. This is typical for the Arctic Sea in polar summer. Known experimental data are used to estimate the melting of sea ice under the melt pond. Positive or negative feedback related to the specific optical and thermal properties of snow, ice, and water are discussed.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":" 15","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139620447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-08DOI: 10.3389/fther.2023.1241411
Shu-Han Hsu, Chuan-Heng Lai
This paper aims to evaluate the onset conditions of a thermoacoustic Stirling engine loaded with a commercially available audio loudspeaker. The thermoacoustic engine converts supplied heat power into mechanical power in the form of sound, without any mechanical moving parts. The simplicity of the acoustical heat engine holds great promise for high reliability and low cost. By utilizing a readily available electromagnetic device, the engine can serve as a durable solution for practical applications. In this study, we assembled a commercially available moving-coil loudspeaker as a low-cost linear alternator for the thermoacoustic Stirling engine, enabling electric generation from supplied heat. We modeled the loudspeaker using linear control equations and experimentally calibrated its acoustic impedances to estimate the acoustic load. For the part of the thermoacoustic engine, we estimated its acoustic characteristics within the framework of the linear thermoacoustic theory. By solving the characteristic equation resulting from the engine loaded with the audio speaker, we estimated the operational point of self-sustained oscillations excited by the coupling of the loudspeaker and the thermoacoustic engine system. To validate the estimations, we tested a prototype of the combined system, comprising the loudspeaker and the thermoacoustic engine. The results highlight the necessity of precise calibration and accounting for complex geometries within the acoustic load for accurate theoretical estimations, especially when incorporating a commercially available loudspeaker into a thermoacoustic engine.
{"title":"Evaluating the onset conditions of a thermoacoustic Stirling engine loaded with an audio loudspeaker","authors":"Shu-Han Hsu, Chuan-Heng Lai","doi":"10.3389/fther.2023.1241411","DOIUrl":"https://doi.org/10.3389/fther.2023.1241411","url":null,"abstract":"This paper aims to evaluate the onset conditions of a thermoacoustic Stirling engine loaded with a commercially available audio loudspeaker. The thermoacoustic engine converts supplied heat power into mechanical power in the form of sound, without any mechanical moving parts. The simplicity of the acoustical heat engine holds great promise for high reliability and low cost. By utilizing a readily available electromagnetic device, the engine can serve as a durable solution for practical applications. In this study, we assembled a commercially available moving-coil loudspeaker as a low-cost linear alternator for the thermoacoustic Stirling engine, enabling electric generation from supplied heat. We modeled the loudspeaker using linear control equations and experimentally calibrated its acoustic impedances to estimate the acoustic load. For the part of the thermoacoustic engine, we estimated its acoustic characteristics within the framework of the linear thermoacoustic theory. By solving the characteristic equation resulting from the engine loaded with the audio speaker, we estimated the operational point of self-sustained oscillations excited by the coupling of the loudspeaker and the thermoacoustic engine system. To validate the estimations, we tested a prototype of the combined system, comprising the loudspeaker and the thermoacoustic engine. The results highlight the necessity of precise calibration and accounting for complex geometries within the acoustic load for accurate theoretical estimations, especially when incorporating a commercially available loudspeaker into a thermoacoustic engine.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":"13 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138589941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.3389/fther.2023.1282028
Henrik Skoglund, Chao Fu, Simon Harvey, Elin Svensson
The pulp and paper industry has an important role in the industrial transition towards net zero or negative emissions, given its renewable biomass-based feedstock and energy supply. In particular, pulp and paper mills have large existing sources of biogenic CO 2, with a high potential to contribute to carbon dioxide removal through carbon capture and storage (CCS). To effectively navigate anticipated changes in feedstock and energy markets, there is a need for a better understanding of how different technology pathways for the pulp and paper industry interact with one another, for instance, how enhanced valorization of biomass side streams may affect the potential for carbon capture. This paper aims to investigate the effect of combining carbon capture with lignin extraction in a chemical pulp mill. Pinch analysis is used to study how the targets for heat recovery, fuel usage and electricity generation, are affected by different mill and capture configurations. Based on these results, the effect on carbon flows is evaluated. The results show that when carbon capture technology is implemented and fuel use is minimized at the case-study mill, there is still enough heat available from the recovery boilers to supply the process needs without requiring usage of a utility boiler. However, when carbon capture is combined with lignin extraction, the heat production of the recovery boilers is no longer sufficient to cover the process demands, and additional heat from a utility boiler is required. However, this case implies that some of the carbon leaves the mill embedded in the extracted lignin product, which can be expected to have a higher value than captured carbon dioxide. When back-pressure electricity production was maximized for the different mill configurations, a very high fuel-to-electricity efficiency could be achieved, but since the CO 2 emissions from the utility boiler were not assumed to be captured, this would lead to more carbon being emitted compared to the capture scenarios with minimized fuel use.
{"title":"Integration of carbon capture in a pulp mill—effect of strategic development towards better biomass resource utilization","authors":"Henrik Skoglund, Chao Fu, Simon Harvey, Elin Svensson","doi":"10.3389/fther.2023.1282028","DOIUrl":"https://doi.org/10.3389/fther.2023.1282028","url":null,"abstract":"The pulp and paper industry has an important role in the industrial transition towards net zero or negative emissions, given its renewable biomass-based feedstock and energy supply. In particular, pulp and paper mills have large existing sources of biogenic CO 2, with a high potential to contribute to carbon dioxide removal through carbon capture and storage (CCS). To effectively navigate anticipated changes in feedstock and energy markets, there is a need for a better understanding of how different technology pathways for the pulp and paper industry interact with one another, for instance, how enhanced valorization of biomass side streams may affect the potential for carbon capture. This paper aims to investigate the effect of combining carbon capture with lignin extraction in a chemical pulp mill. Pinch analysis is used to study how the targets for heat recovery, fuel usage and electricity generation, are affected by different mill and capture configurations. Based on these results, the effect on carbon flows is evaluated. The results show that when carbon capture technology is implemented and fuel use is minimized at the case-study mill, there is still enough heat available from the recovery boilers to supply the process needs without requiring usage of a utility boiler. However, when carbon capture is combined with lignin extraction, the heat production of the recovery boilers is no longer sufficient to cover the process demands, and additional heat from a utility boiler is required. However, this case implies that some of the carbon leaves the mill embedded in the extracted lignin product, which can be expected to have a higher value than captured carbon dioxide. When back-pressure electricity production was maximized for the different mill configurations, a very high fuel-to-electricity efficiency could be achieved, but since the CO 2 emissions from the utility boiler were not assumed to be captured, this would lead to more carbon being emitted compared to the capture scenarios with minimized fuel use.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":"74 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135271211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-18DOI: 10.3389/fther.2023.1265490
Adithya Legala, Venkata LakkiReddy, Phillip Weber, Xianguo Li
Diesel Particulate Filter (DPF) in the diesel engine exhaust stream needs frequent regeneration (exotherm) to remove captured particulate matter (PM, or soot) without damaging to the porous DPF structure by controlling the peak temperatures and temperature gradients across the DPF. In this study, temperature distribution in a DPF is measured at 42 strategic locations in the test DPF under various regeneration conditions of exhaust flow rates, regeneration temperatures and soot loads. Then a data-based model with feed-forward neural network architecture is designed to model the thermal gradients and temperature dynamics of the DPF during the regeneration process. The neural network feature vector selection, network architecture, hyperparameter calibration process, measured data preprocessing, and experimental data acquisition procedure are evaluated. Over 7,400 experimental data points at various regeneration temperatures, flow rates and soot loads are used in training and validating the neural network model. It is found that the neural network model can accurately predict the 42 DPF bed temperatures simultaneously at different locations, and the time series analysis of both model-predicted and experimentally measured temperatures shows a good correlation. This indicates that the currently developed neural network model can provide spatial distribution of temperature in the DPF, and comprehend the nonlinearity of the temperature dynamics due to DPF soot load at exothermic conditions. These results demonstrate that the data-based model has capability in predicting thermal gradients within a DPF, aiding in determining a safer DPF regeneration strategy, onboard diagnostics and DPF development.
{"title":"Modeling of diesel particulate filter temperature dynamics during exotherm using neural networks","authors":"Adithya Legala, Venkata LakkiReddy, Phillip Weber, Xianguo Li","doi":"10.3389/fther.2023.1265490","DOIUrl":"https://doi.org/10.3389/fther.2023.1265490","url":null,"abstract":"Diesel Particulate Filter (DPF) in the diesel engine exhaust stream needs frequent regeneration (exotherm) to remove captured particulate matter (PM, or soot) without damaging to the porous DPF structure by controlling the peak temperatures and temperature gradients across the DPF. In this study, temperature distribution in a DPF is measured at 42 strategic locations in the test DPF under various regeneration conditions of exhaust flow rates, regeneration temperatures and soot loads. Then a data-based model with feed-forward neural network architecture is designed to model the thermal gradients and temperature dynamics of the DPF during the regeneration process. The neural network feature vector selection, network architecture, hyperparameter calibration process, measured data preprocessing, and experimental data acquisition procedure are evaluated. Over 7,400 experimental data points at various regeneration temperatures, flow rates and soot loads are used in training and validating the neural network model. It is found that the neural network model can accurately predict the 42 DPF bed temperatures simultaneously at different locations, and the time series analysis of both model-predicted and experimentally measured temperatures shows a good correlation. This indicates that the currently developed neural network model can provide spatial distribution of temperature in the DPF, and comprehend the nonlinearity of the temperature dynamics due to DPF soot load at exothermic conditions. These results demonstrate that the data-based model has capability in predicting thermal gradients within a DPF, aiding in determining a safer DPF regeneration strategy, onboard diagnostics and DPF development.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":"144 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135884166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-22DOI: 10.3389/fther.2023.1239800
Michael Huylo, Kaiwu Huang, A. Noble, R. Yoon, Rui Qiao
Dewatering of fine coal is a significant industrial challenge with economic and environmental implications. Due to the lack of suitable dewatering technologies, fine coal particles are often discarded to waste impoundments, leading to substantial loss of valuable natural resources while creating environmental problems. The hydrophobic-hydrophilic separation (HHS) process is a unique solution to this problem. In this process, a recyclable solvent is used to simultaneously remove inorganic impurities (ash) and water from a run-of-mine fine coal slurry. A small amount of recyclable oil (or solvent) is added to a fine coal slurry so that the solvent can spontaneously displace the water from the surface of coal particles. The spent solvent is subsequently recovered and recycled in a closed loop. Here, we report the results obtained using two different solvents, i.e., pentane and hexane, to de-ash and dewater ultrafine coal and recover the spent solvent by filtration, followed by steam stripping. Most of the spent solvent can be recovered during the filtration step at 20 psig N₂ and at a 60 s filtration time. The residual solvent left in the cake was then recovered using steam under different conditions. The results showed that the residual solvent concentration could be reduced to <1,400 ppm after 10 s of steam stripping at 150°C and 15 psig.
{"title":"Solvent recovery from solvent-fine coal slurries by filtration and steam stripping","authors":"Michael Huylo, Kaiwu Huang, A. Noble, R. Yoon, Rui Qiao","doi":"10.3389/fther.2023.1239800","DOIUrl":"https://doi.org/10.3389/fther.2023.1239800","url":null,"abstract":"Dewatering of fine coal is a significant industrial challenge with economic and environmental implications. Due to the lack of suitable dewatering technologies, fine coal particles are often discarded to waste impoundments, leading to substantial loss of valuable natural resources while creating environmental problems. The hydrophobic-hydrophilic separation (HHS) process is a unique solution to this problem. In this process, a recyclable solvent is used to simultaneously remove inorganic impurities (ash) and water from a run-of-mine fine coal slurry. A small amount of recyclable oil (or solvent) is added to a fine coal slurry so that the solvent can spontaneously displace the water from the surface of coal particles. The spent solvent is subsequently recovered and recycled in a closed loop. Here, we report the results obtained using two different solvents, i.e., pentane and hexane, to de-ash and dewater ultrafine coal and recover the spent solvent by filtration, followed by steam stripping. Most of the spent solvent can be recovered during the filtration step at 20 psig N₂ and at a 60 s filtration time. The residual solvent left in the cake was then recovered using steam under different conditions. The results showed that the residual solvent concentration could be reduced to <1,400 ppm after 10 s of steam stripping at 150°C and 15 psig.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48071174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-03DOI: 10.3389/fther.2023.1253718
Yatao Ren, Sundeep Singh, S. Soni
{"title":"Editorial: Computational modeling of various procedures in thermal therapy of human tumors","authors":"Yatao Ren, Sundeep Singh, S. Soni","doi":"10.3389/fther.2023.1253718","DOIUrl":"https://doi.org/10.3389/fther.2023.1253718","url":null,"abstract":"","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47517320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-07DOI: 10.3389/fther.2023.1195740
N. N. Liu, Y. Alekhina, A. Pyatakov, M. Zharkov, D. E. Yakobson, N. Pyataev, G. Sukhorukov, N. Perov, A. Tishin
Introduction: The development of magnetic agents for magnetic fluid hyperthermia application is a complex task requiring simultaneous optimization of chemical, biomedical, magnetic, and, in particular, thermal properties of magnetic nanoparticles (MNPs). In the majority of papers, the magnetothermal measurements are carried out on bare MNPs suspended in deionized water with subsequent optimization of the required physiological and medical properties, including toxicity and biocompatibility. However, in real hyperthermia practice, the stable fluids or colloids of magnetic MNPs are used, and the colloidal stabilization can significantly modify their magnetic properties, including magnetothermal ones.Methods: This paper is focused on the study of ZnxMn1-xFe2O4 MNPs stabilized by oleic acid/sodium oleate in this context.Results and Discussion: Our research demonstrates the crucial changes in the magnetic properties and magnetothermal response of ZnMn ferrite MNPs after the colloidal stabilization: while bare MNPs demonstrate significant coercivity, nonzero remanent magnetization, and superquadratic dependence of heat generation on the magnetic field amplitude, the magnetic properties of colloidal ZnMn ferrite MNPs are typical for superparamagnetic ones and their magnetothermal response is described by a conventional quadratic dependence on magnetic field amplitude. Various factors such as size distribution, magnetic anisotropy, and interparticle dipole–dipole interaction are considered as the origins of such an impact on magnetic MNPs’ properties.
{"title":"Impact of colloidal stabilization of MnZn-ferrite nanoparticles by oleic acid on their magnetothermal properties","authors":"N. N. Liu, Y. Alekhina, A. Pyatakov, M. Zharkov, D. E. Yakobson, N. Pyataev, G. Sukhorukov, N. Perov, A. Tishin","doi":"10.3389/fther.2023.1195740","DOIUrl":"https://doi.org/10.3389/fther.2023.1195740","url":null,"abstract":"Introduction: The development of magnetic agents for magnetic fluid hyperthermia application is a complex task requiring simultaneous optimization of chemical, biomedical, magnetic, and, in particular, thermal properties of magnetic nanoparticles (MNPs). In the majority of papers, the magnetothermal measurements are carried out on bare MNPs suspended in deionized water with subsequent optimization of the required physiological and medical properties, including toxicity and biocompatibility. However, in real hyperthermia practice, the stable fluids or colloids of magnetic MNPs are used, and the colloidal stabilization can significantly modify their magnetic properties, including magnetothermal ones.Methods: This paper is focused on the study of ZnxMn1-xFe2O4 MNPs stabilized by oleic acid/sodium oleate in this context.Results and Discussion: Our research demonstrates the crucial changes in the magnetic properties and magnetothermal response of ZnMn ferrite MNPs after the colloidal stabilization: while bare MNPs demonstrate significant coercivity, nonzero remanent magnetization, and superquadratic dependence of heat generation on the magnetic field amplitude, the magnetic properties of colloidal ZnMn ferrite MNPs are typical for superparamagnetic ones and their magnetothermal response is described by a conventional quadratic dependence on magnetic field amplitude. Various factors such as size distribution, magnetic anisotropy, and interparticle dipole–dipole interaction are considered as the origins of such an impact on magnetic MNPs’ properties.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46302785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-05-09DOI: 10.3389/fther.2023.1203906
L. Dombrovsky
In the study of many heat transfer processes, it is necessary to consider the interaction of heat conduction, natural or forced convection, and heat transfer by thermal radiation. The greatest difficulties in the computational modeling of combined heat transfer are related to time-consuming calculations of radiative transfer in absorbing and scattering media. Such media are, for example, gases or liquids with suspended particles, as well as dispersed materials and solids with microcracks or bubbles. Natural objects of study include the Earth’s atmosphere and ocean, snow and ice, powders or dust, ordinary sand, and even biological tissues with optically heterogeneous living cells. In thermal engineering, these are combustion products containing soot and fly ash particles, porous ceramics and heatshielding materials, particles in thermochemical reactors, and melt droplets from a possible severe nuclear reactor accident. Thermal radiation has a wide spectral range in which the optical properties of substances and materials are usually substantially dependent on the radiation wavelength. Therefore, in order to calculate the contribution of thermal radiation to heat transfer, radiative transfer calculations must be carried out for a large set of different wavelengths. In the numerical solution of transient heat transfer problems, such calculations, carried out at each time step, are the main factor influencing the computation time. It is also important that the numerical solution of the integrodifferential radiative transfer equation (RTE) regarding the radiation intensity, which is dependent not only on the coordinates but also on the direction, is a very complex procedure (Coelho, 2014). This means that the use of simple but sufficiently accurate models of radiative transfer in scattering media is absolutely essential for solving many problems of combined heat transfer. Fortunately, heat transfer problems (unlike optical diagnostics problems) have a number of physical features that allow simpler mathematical models. Note that we are usually dealing with multiple scattering of radiation in a medium when the angular distribution of the radiation in a single scattering is irrelevant. In this case, the so-called transport approximation can be used (Dombrovsky, 2012); the integral term in RTE is missing and the scattering anisotropy is taken into account by a transport scattering coefficient. The high accuracy of the transport approximation has been confirmed for diverse problems (Dombrovsky, 2010; Dombrovsky, 2019). OPEN ACCESS
{"title":"Editorial: Editor’s challenge in heat transfer mechanisms and applications: 2022","authors":"L. Dombrovsky","doi":"10.3389/fther.2023.1203906","DOIUrl":"https://doi.org/10.3389/fther.2023.1203906","url":null,"abstract":"In the study of many heat transfer processes, it is necessary to consider the interaction of heat conduction, natural or forced convection, and heat transfer by thermal radiation. The greatest difficulties in the computational modeling of combined heat transfer are related to time-consuming calculations of radiative transfer in absorbing and scattering media. Such media are, for example, gases or liquids with suspended particles, as well as dispersed materials and solids with microcracks or bubbles. Natural objects of study include the Earth’s atmosphere and ocean, snow and ice, powders or dust, ordinary sand, and even biological tissues with optically heterogeneous living cells. In thermal engineering, these are combustion products containing soot and fly ash particles, porous ceramics and heatshielding materials, particles in thermochemical reactors, and melt droplets from a possible severe nuclear reactor accident. Thermal radiation has a wide spectral range in which the optical properties of substances and materials are usually substantially dependent on the radiation wavelength. Therefore, in order to calculate the contribution of thermal radiation to heat transfer, radiative transfer calculations must be carried out for a large set of different wavelengths. In the numerical solution of transient heat transfer problems, such calculations, carried out at each time step, are the main factor influencing the computation time. It is also important that the numerical solution of the integrodifferential radiative transfer equation (RTE) regarding the radiation intensity, which is dependent not only on the coordinates but also on the direction, is a very complex procedure (Coelho, 2014). This means that the use of simple but sufficiently accurate models of radiative transfer in scattering media is absolutely essential for solving many problems of combined heat transfer. Fortunately, heat transfer problems (unlike optical diagnostics problems) have a number of physical features that allow simpler mathematical models. Note that we are usually dealing with multiple scattering of radiation in a medium when the angular distribution of the radiation in a single scattering is irrelevant. In this case, the so-called transport approximation can be used (Dombrovsky, 2012); the integral term in RTE is missing and the scattering anisotropy is taken into account by a transport scattering coefficient. The high accuracy of the transport approximation has been confirmed for diverse problems (Dombrovsky, 2010; Dombrovsky, 2019). OPEN ACCESS","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42297119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：