Pub Date : 2022-11-09DOI: 10.3389/fther.2022.954511
Avinash Alagumalai, O. Mahian
Energy is crucial to a country’s economic progress and development. Domestic, industrial, and commercial sectors have seen tremendous growth in recent years, resulting in increased energy demand. Despite increased energy production, the growing demand for energy has outstripped supply. Energy scarcity and variable power availability stymie societal progress. The rise in energy demand and peak shortages has harmed a variety of industries. Because of increased energy demand, price volatility of fossil fuels, climate mitigation, and an impending energy crisis due to the depletion of fossil fuels, renewable energy has emerged as a key option. The unpredictability of the output of renewable energy conversion systems, on the other hand, necessitates the use of robust, reliable, and efficient technologies. Such systems can generate savings by reducing energy consumption and replacing fossil fuel expenses. Renewable energy storage is important for achieving a zero-carbon future because it allows us to build a reserve of storage options that can be used anytime needed to fulfill user demand and control the energy supply during peak usage periods. By figuring out ways to store energy in this way, we can address some of the problems that arise frequently when employing renewable energy sources. Since the last 3 decades, there has been an augmented demand for space heating. Energy policies in many countries prioritize the development of renewable energy sources. Among various renewable energy techniques, thermal energy storage is an effective peak demand reduction technique. Thermal energy storage systems link the gap between the supply and demand for energy. Improvements in thermal energy storage decrease the need for infrastructure and lower the price of heating and cooling systems. Thermal energy storage makes it possible to store and use energy at a different period. The heat energy produced during the day can be used at night, and the cool nighttime breeze can be used to chill indoor rooms during the day. Thermal energy storage systems, such as heat pumps, solar energy, waste heat from power plants, and engine waste heat, offer resilience against varying energy sources. Thermal energy storage systems can aid in the daily, weekly, and even seasonal balance of energy demand and supply. Besides, thermal energy storage can improve overall energy system efficiency by lowering peak demand, reduction in energy consumption, abatement of CO2 emissions, and reduction in costs. Thermal energy storage is gaining attention towards energy storage, particularly in conjunction with concentrating solar power plants. The global OPEN ACCESS
{"title":"Specialty grand challenge in thermal science and energy systems","authors":"Avinash Alagumalai, O. Mahian","doi":"10.3389/fther.2022.954511","DOIUrl":"https://doi.org/10.3389/fther.2022.954511","url":null,"abstract":"Energy is crucial to a country’s economic progress and development. Domestic, industrial, and commercial sectors have seen tremendous growth in recent years, resulting in increased energy demand. Despite increased energy production, the growing demand for energy has outstripped supply. Energy scarcity and variable power availability stymie societal progress. The rise in energy demand and peak shortages has harmed a variety of industries. Because of increased energy demand, price volatility of fossil fuels, climate mitigation, and an impending energy crisis due to the depletion of fossil fuels, renewable energy has emerged as a key option. The unpredictability of the output of renewable energy conversion systems, on the other hand, necessitates the use of robust, reliable, and efficient technologies. Such systems can generate savings by reducing energy consumption and replacing fossil fuel expenses. Renewable energy storage is important for achieving a zero-carbon future because it allows us to build a reserve of storage options that can be used anytime needed to fulfill user demand and control the energy supply during peak usage periods. By figuring out ways to store energy in this way, we can address some of the problems that arise frequently when employing renewable energy sources. Since the last 3 decades, there has been an augmented demand for space heating. Energy policies in many countries prioritize the development of renewable energy sources. Among various renewable energy techniques, thermal energy storage is an effective peak demand reduction technique. Thermal energy storage systems link the gap between the supply and demand for energy. Improvements in thermal energy storage decrease the need for infrastructure and lower the price of heating and cooling systems. Thermal energy storage makes it possible to store and use energy at a different period. The heat energy produced during the day can be used at night, and the cool nighttime breeze can be used to chill indoor rooms during the day. Thermal energy storage systems, such as heat pumps, solar energy, waste heat from power plants, and engine waste heat, offer resilience against varying energy sources. Thermal energy storage systems can aid in the daily, weekly, and even seasonal balance of energy demand and supply. Besides, thermal energy storage can improve overall energy system efficiency by lowering peak demand, reduction in energy consumption, abatement of CO2 emissions, and reduction in costs. Thermal energy storage is gaining attention towards energy storage, particularly in conjunction with concentrating solar power plants. The global OPEN ACCESS","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45336052","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 : 2022-11-01DOI: 10.3389/fther.2022.1005117
Mauricio Céspedes Tenorio, Carlos A. Wattson Sánchez, Diego S. Dumani
Photothermal therapy (PTT) is a type of cancer treatment capable of damaging tumors using laser irradiation. This procedure can be a promising approach to complement current cancer therapies, due in part to its minimal invasiveness. One of the challenges of photothermal therapy is the potential collateral damage to the surrounding healthy tissue, as well as excessive temperature increase in the target tumor region that can cause tissue carbonization and evaporation. With the aim of increasing the performance of photothermal therapy in damaging targeted tumor while keeping healthy nearby tissue unaffected, this research proposes the use of a feedback control system that considers the cumulative thermal damage to both types of tissue. Two separate control algorithms (fuzzy logic and PI) were designed and tested in silico using simulations made in MATLAB® and Python. Results showed that both controllers successfully accomplished the proposed goals. Therefore, the feasibility of using these automated systems to improve the efficacy and safety of PTT was demonstrated.
{"title":"Tissue damage-tracking control system for image-guided photothermal therapy of cancer","authors":"Mauricio Céspedes Tenorio, Carlos A. Wattson Sánchez, Diego S. Dumani","doi":"10.3389/fther.2022.1005117","DOIUrl":"https://doi.org/10.3389/fther.2022.1005117","url":null,"abstract":"Photothermal therapy (PTT) is a type of cancer treatment capable of damaging tumors using laser irradiation. This procedure can be a promising approach to complement current cancer therapies, due in part to its minimal invasiveness. One of the challenges of photothermal therapy is the potential collateral damage to the surrounding healthy tissue, as well as excessive temperature increase in the target tumor region that can cause tissue carbonization and evaporation. With the aim of increasing the performance of photothermal therapy in damaging targeted tumor while keeping healthy nearby tissue unaffected, this research proposes the use of a feedback control system that considers the cumulative thermal damage to both types of tissue. Two separate control algorithms (fuzzy logic and PI) were designed and tested in silico using simulations made in MATLAB® and Python. Results showed that both controllers successfully accomplished the proposed goals. Therefore, the feasibility of using these automated systems to improve the efficacy and safety of PTT was demonstrated.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48276413","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 : 2022-10-26DOI: 10.3389/fther.2022.1049857
Andrew Carnovale, Xianguo Li
Electric vehicles, as a major strategy for climate change mitigation, uses lithium-ion batteries extensively as the power source. However, the operation, performance and lifetime of lithium-ion batteries depend on the battery temperature, which can have a wide range due to heat generation within the battery and significant variations in the ambient conditions due to changes in seasons and geographical locations where electric vehicles are operated. In the present study, thermal management methods/strategies on the capacity fade of lithium-ion batteries are assessed through a validated capacity fade model for lithium-ion batteries along with a thermal model for the heat generation in the battery and dissipation over battery surface, represented by various thermal management methods. The driving conditions are simulated through a constant and various standard drive cycles. It is shown that battery temperature has the predominant impact on the capacity fade, and it can be controlled through effective thermal management. A much more significant spread in battery capacity fade occurs with various thermal management methods for a lower initial battery temperature (20°C) compared to the higher temperatures (35°C and 50°C), hence, thermal management is much more effective in reducing capacity fade at battery temperatures close to 20°C, which is considered the optimum operating temperature for lithium-ion batteries. Further, the results indicate that using a lower charge voltage can result in slightly less capacity fade over cycling. Regenerative braking makes it more realistic to use lower charge voltages, since the battery can be recharged during operation, thereby increasing driving range, while preventing increased capacity fade. Effective thermal management is more imperative for realistic intense and aggressive driving behaviors.
{"title":"Numerical assessment of thermal management on the capacity fade of lithium-ion batteries in electric vehicles","authors":"Andrew Carnovale, Xianguo Li","doi":"10.3389/fther.2022.1049857","DOIUrl":"https://doi.org/10.3389/fther.2022.1049857","url":null,"abstract":"Electric vehicles, as a major strategy for climate change mitigation, uses lithium-ion batteries extensively as the power source. However, the operation, performance and lifetime of lithium-ion batteries depend on the battery temperature, which can have a wide range due to heat generation within the battery and significant variations in the ambient conditions due to changes in seasons and geographical locations where electric vehicles are operated. In the present study, thermal management methods/strategies on the capacity fade of lithium-ion batteries are assessed through a validated capacity fade model for lithium-ion batteries along with a thermal model for the heat generation in the battery and dissipation over battery surface, represented by various thermal management methods. The driving conditions are simulated through a constant and various standard drive cycles. It is shown that battery temperature has the predominant impact on the capacity fade, and it can be controlled through effective thermal management. A much more significant spread in battery capacity fade occurs with various thermal management methods for a lower initial battery temperature (20°C) compared to the higher temperatures (35°C and 50°C), hence, thermal management is much more effective in reducing capacity fade at battery temperatures close to 20°C, which is considered the optimum operating temperature for lithium-ion batteries. Further, the results indicate that using a lower charge voltage can result in slightly less capacity fade over cycling. Regenerative braking makes it more realistic to use lower charge voltages, since the battery can be recharged during operation, thereby increasing driving range, while preventing increased capacity fade. Effective thermal management is more imperative for realistic intense and aggressive driving behaviors.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46264965","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 : 2022-10-24DOI: 10.3389/fther.2022.1042347
A. Pearson
Despite continual development over more than two centuries there is still great scope for significant development in the realms of mechanical cooling and heating. This paper reviews the nature of the historical development and identifies key motivations for technical development. It seeks to highlight where there is greatest need for future development in this ubiquitous technology. The story of the development of mechanical refrigeration is dominated by the choices made with regard to the working fluid used in the system. These choices dictate the operating parameters of temperature and pressure that the system must withstand as well as introducing constraints related to material compatibility, so the agenda for the mechanical development of systems is set by the selection of the refrigerant. All of these systems are classed as heat pumps because they extract heat from one location and deliver it to another. The commercial demand for mechanical cooling in the 19th century meant that all of these early heat pump systems were used for cooling. The concept of using the same cycle to deliver useful heat was not commercialised until the mid-twentieth century and in some ways this application of the heat pump is still in the early stages of development, particularly with regard to market penetration.
{"title":"Development of refrigeration and heat pump systems","authors":"A. Pearson","doi":"10.3389/fther.2022.1042347","DOIUrl":"https://doi.org/10.3389/fther.2022.1042347","url":null,"abstract":"Despite continual development over more than two centuries there is still great scope for significant development in the realms of mechanical cooling and heating. This paper reviews the nature of the historical development and identifies key motivations for technical development. It seeks to highlight where there is greatest need for future development in this ubiquitous technology. The story of the development of mechanical refrigeration is dominated by the choices made with regard to the working fluid used in the system. These choices dictate the operating parameters of temperature and pressure that the system must withstand as well as introducing constraints related to material compatibility, so the agenda for the mechanical development of systems is set by the selection of the refrigerant. All of these systems are classed as heat pumps because they extract heat from one location and deliver it to another. The commercial demand for mechanical cooling in the 19th century meant that all of these early heat pump systems were used for cooling. The concept of using the same cycle to deliver useful heat was not commercialised until the mid-twentieth century and in some ways this application of the heat pump is still in the early stages of development, particularly with regard to market penetration.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41536394","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 : 2022-10-20DOI: 10.3389/fther.2022.1045838
Xianguo Li
According to Merriam-Webster Dictionary (Merriam-Webster, 2022), the word “thermal” means relating to or caused by heat or by changes in temperature, or being or involving a state of matter dependent upon temperature; the word “engineering”means the application of science and mathematics by which the properties of matter and the sources of energy in nature are made useful to people through the design, manufacture, and use of complex products. Therefore, thermal engineering deals with the transport and utilization of thermal energy (often referred to as heat in daily language) in the design, manufacture, and use of products. In thermodynamics (Cengel and MA, 2006), thermal energy represents the energy stored or contained within a system (or matter) in a microscopically disorganized manner, while heat denotes the energy transfer between systems in a microscopically disorganized manner. Since systems can be chosen in an arbitrary manner suitable for analysis for different analysts, in daily language thermal energy and heat are often mixed in an interchangeable fashion. Heat or heat transfer can occur through a medium or in vacuum. It can occur through a medium with or without macroscopically observable motion, commonly referred to as convection and conduction, respectively. Thermal radiation can propagate most efficiently in vaccum, but it is also possible through a medium that might be solid or gas. Further, heat can be transferred, with or without chemical reaction during the transfer process, into or from other forms of energy, such as chemical, mechanical, electrical, and so on. Therefore, thermal engineering is multi-disciplinary, involving fluid flow, heat and mass transfer, chemical reaction, and properties of the medium through which heat transfer occurs. The quantity and direction of heat transfer are governed by thermodynamics. The first law of thermodynamics states that the energy can be transferred or transformed into another form of energy, but the total quantity of energy remains the same (i.e., conserved), while the second law of thermodynamics dictates the direction of heat transfer from a higher temperature system (or region) to a lower temperature one, and the quality of energy is degraded during the energy transformation process. The degraded energy (often referred to as waste energy, commonly in the form of heat) is dumped into our environment, causing environmental damage if the resilient limit of the environment is exceeded. The impact on the environment arising from waste energy dumping can exhibit in many different forms, such as local and global environmental changes like OPEN ACCESS
{"title":"Field grand challenge for thermal engineering","authors":"Xianguo Li","doi":"10.3389/fther.2022.1045838","DOIUrl":"https://doi.org/10.3389/fther.2022.1045838","url":null,"abstract":"According to Merriam-Webster Dictionary (Merriam-Webster, 2022), the word “thermal” means relating to or caused by heat or by changes in temperature, or being or involving a state of matter dependent upon temperature; the word “engineering”means the application of science and mathematics by which the properties of matter and the sources of energy in nature are made useful to people through the design, manufacture, and use of complex products. Therefore, thermal engineering deals with the transport and utilization of thermal energy (often referred to as heat in daily language) in the design, manufacture, and use of products. In thermodynamics (Cengel and MA, 2006), thermal energy represents the energy stored or contained within a system (or matter) in a microscopically disorganized manner, while heat denotes the energy transfer between systems in a microscopically disorganized manner. Since systems can be chosen in an arbitrary manner suitable for analysis for different analysts, in daily language thermal energy and heat are often mixed in an interchangeable fashion. Heat or heat transfer can occur through a medium or in vacuum. It can occur through a medium with or without macroscopically observable motion, commonly referred to as convection and conduction, respectively. Thermal radiation can propagate most efficiently in vaccum, but it is also possible through a medium that might be solid or gas. Further, heat can be transferred, with or without chemical reaction during the transfer process, into or from other forms of energy, such as chemical, mechanical, electrical, and so on. Therefore, thermal engineering is multi-disciplinary, involving fluid flow, heat and mass transfer, chemical reaction, and properties of the medium through which heat transfer occurs. The quantity and direction of heat transfer are governed by thermodynamics. The first law of thermodynamics states that the energy can be transferred or transformed into another form of energy, but the total quantity of energy remains the same (i.e., conserved), while the second law of thermodynamics dictates the direction of heat transfer from a higher temperature system (or region) to a lower temperature one, and the quality of energy is degraded during the energy transformation process. The degraded energy (often referred to as waste energy, commonly in the form of heat) is dumped into our environment, causing environmental damage if the resilient limit of the environment is exceeded. The impact on the environment arising from waste energy dumping can exhibit in many different forms, such as local and global environmental changes like OPEN ACCESS","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44978430","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 : 2022-10-11DOI: 10.3389/fther.2022.982768
P. Mariappan, Gangadhara B , Ronan Flanagan
Numerous liver cancer oncologists suggest bridging therapies to limit cancer growth until donors are available. Interventional radiology including radiofrequency ablation (RFA) is one such bridging therapy. This locoregional therapy aims to produce an optimal amount of heat to kill cancer cells, where the heat is produced by a radiofrequency (RF) needle. Less experienced Interventional Radiologists (IRs) require a software-assisted smart solution to predict the optimal heat distribution as both overkilling and untreated cancer cells are problematic treatments. Therefore, two of the big three partial differential equations, 1) heat equation (Pennes, Journal of Applied Physiology, 1948, 1, 93–122) to predict the heat distribution and 2) Laplace equation (Prakash, Open Biomed. Eng. J., 2010, 4, 27–38) for electric potential along with different cell death models (O’Neill et al., Ann. Biomed. Eng., 2011, 39, 570–579) are widely used in the last three decades. However, solving two differential equations and a cell death model is computationally expensive when the number of finite compact coverings of a liver topological structure increases in millions. Since the heat source from the Joule losses Q r = σ|∇V|2 is obtained from Laplace equation σΔV = 0, it is called the Joule heat model. The traditional Joule heat model can be replaced by a point source model to obtain the heat source term. The idea behind this model is to solve σΔV = δ 0 where δ 0 is a Dirac-delta function. Therefore, using the fundamental solution of the Laplace equation (Evans, Partial Differential Equations, 2010) we represent the solution of the Joule heat model using an alternative model called the point source model which is given by the Gaussian distribution. Q r x = ∑ x i ∈ Ω 1 K ∑ i c i e − | x − x i | 2 2 σ 2 where K and c i are obtained by using needle parameters. This model is employed in one of our software solutions called RFA Guardian (Voglreiter et al., Sci. Rep., 2018, 8, 787) which predicted the treatment outcome very well for more than 100 patients.
许多癌症肿瘤学家建议桥接疗法来限制癌症的生长，直到捐赠者可用。包括射频消融（RFA）在内的介入放射学就是这样一种桥接疗法。这种局部治疗旨在产生最佳的热量来杀死癌症细胞，其中热量是由射频（RF）针产生的。经验不足的介入放射科医生（IRs）需要软件辅助的智能解决方案来预测最佳热分布，因为过度杀伤和未经治疗的癌症细胞都是有问题的治疗方法。因此，三大偏微分方程中的两个，1）预测热分布的热方程（Pennes，Journal of Applied Physiology，1948，193-122）和2）电势的拉普拉斯方程（Prakash，Open Biomed.Eng.J.，2010，4，27-38）以及不同的细胞死亡模型（O'Neill et al.，Ann。生物识别。Eng.，2011，39570–579）在过去三十年中被广泛使用。然而，当肝脏拓扑结构的有限紧致覆盖物的数量以百万计增加时，求解两个微分方程和细胞死亡模型的计算成本很高。由于焦耳损失的热源Q r=σ|ŞV|2是由拉普拉斯方程σΔV=0得到的，因此称为焦耳热模型。可以用点源模型代替传统的焦耳热模型来获得热源项。该模型背后的思想是求解σΔV=δ0，其中δ0是狄拉克德尔塔函数。因此，使用拉普拉斯方程的基本解（Evans，偏微分方程，2010），我们使用称为点源模型的替代模型来表示焦耳热模型的解，该模型由高斯分布给出。Q r x=∑x i∈Ω1 K∑i c i e−| x−x i |2 2σ2其中K和c i是通过使用针状参数获得的。该模型被用于我们的一个名为RFA Guardian的软件解决方案（Voglreiter等人，Sci.Rep.，2018，8787），该解决方案很好地预测了100多名患者的治疗结果。
{"title":"A point source model to represent heat distribution without calculating the Joule heat during radiofrequency ablation","authors":"P. Mariappan, Gangadhara B , Ronan Flanagan ","doi":"10.3389/fther.2022.982768","DOIUrl":"https://doi.org/10.3389/fther.2022.982768","url":null,"abstract":"Numerous liver cancer oncologists suggest bridging therapies to limit cancer growth until donors are available. Interventional radiology including radiofrequency ablation (RFA) is one such bridging therapy. This locoregional therapy aims to produce an optimal amount of heat to kill cancer cells, where the heat is produced by a radiofrequency (RF) needle. Less experienced Interventional Radiologists (IRs) require a software-assisted smart solution to predict the optimal heat distribution as both overkilling and untreated cancer cells are problematic treatments. Therefore, two of the big three partial differential equations, 1) heat equation (Pennes, Journal of Applied Physiology, 1948, 1, 93–122) to predict the heat distribution and 2) Laplace equation (Prakash, Open Biomed. Eng. J., 2010, 4, 27–38) for electric potential along with different cell death models (O’Neill et al., Ann. Biomed. Eng., 2011, 39, 570–579) are widely used in the last three decades. However, solving two differential equations and a cell death model is computationally expensive when the number of finite compact coverings of a liver topological structure increases in millions. Since the heat source from the Joule losses Q r = σ|∇V|2 is obtained from Laplace equation σΔV = 0, it is called the Joule heat model. The traditional Joule heat model can be replaced by a point source model to obtain the heat source term. The idea behind this model is to solve σΔV = δ 0 where δ 0 is a Dirac-delta function. Therefore, using the fundamental solution of the Laplace equation (Evans, Partial Differential Equations, 2010) we represent the solution of the Joule heat model using an alternative model called the point source model which is given by the Gaussian distribution. Q r x = ∑ x i ∈ Ω 1 K ∑ i c i e − | x − x i | 2 2 σ 2 where K and c i are obtained by using needle parameters. This model is employed in one of our software solutions called RFA Guardian (Voglreiter et al., Sci. Rep., 2018, 8, 787) which predicted the treatment outcome very well for more than 100 patients.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48418115","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}
The present paper investigates the thermal mixing and cooling processes in a passive micromixer, which is applicable for the cooling of electronic devices. Employing a porous block and testing different configurations for the mixing channel is considered to enhance the mixing process and cooling performance. A 2D lattice Boltzmann thermal model is utilized to investigate the thermal performance of a T-micromixer with a porous block. Two different types of mixing channel configurations, including a step-shaped and a zigzag-shaped channel, are considered, and the obtained results are compared with those of the simple mixing channel. The thermal mixing and cooling of two miscible fluids, at 50 and 25°C entering the micromixer, are investigated. The results show that changing the mixing channel configuration may create a chaotic laminar flow, which enhances the heat transfer rate between the mixed flow and the channel wall. Whatever the Reynolds number, the step-shaped mixing channel exhibits better mixing performance than the zigzag-shaped one. For the T-micromixer with a zigzag-shaped and step-shaped mixing channel, the cases with h/H = 0.5 and h/H = 0, respectively, exhibit better thermal mixing and cooling performance.
{"title":"Thermal mixing in T-shaped micromixers with a porous block by the lattice Boltzmann method: Influence of the mixing channel configuration","authors":"Seyed Soheil Mousavi Ajarostaghi, Sébastien Poncet","doi":"10.3389/fther.2022.961083","DOIUrl":"https://doi.org/10.3389/fther.2022.961083","url":null,"abstract":"The present paper investigates the thermal mixing and cooling processes in a passive micromixer, which is applicable for the cooling of electronic devices. Employing a porous block and testing different configurations for the mixing channel is considered to enhance the mixing process and cooling performance. A 2D lattice Boltzmann thermal model is utilized to investigate the thermal performance of a T-micromixer with a porous block. Two different types of mixing channel configurations, including a step-shaped and a zigzag-shaped channel, are considered, and the obtained results are compared with those of the simple mixing channel. The thermal mixing and cooling of two miscible fluids, at 50 and 25°C entering the micromixer, are investigated. The results show that changing the mixing channel configuration may create a chaotic laminar flow, which enhances the heat transfer rate between the mixed flow and the channel wall. Whatever the Reynolds number, the step-shaped mixing channel exhibits better mixing performance than the zigzag-shaped one. For the T-micromixer with a zigzag-shaped and step-shaped mixing channel, the cases with h/H = 0.5 and h/H = 0, respectively, exhibit better thermal mixing and cooling performance.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49059116","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 : 2022-09-12DOI: 10.3389/fther.2022.870077
G. Tripathi, A. Dhar
Methane is a popular alternative fuel for internal combustion engines due to its availability in many forms such as methane hydrates, natural gas, biogas, compressed natural gas, liquid natural gas, synthetic natural gas, and pipe natural gas. Methane can be effectively used in existing diesel engines in dual-fuel mode with few modifications. Dual-fuel technology helps bridge existing conventional fuel and alternative gaseous fuel-powered conventional engines. The properties of methane, including its higher calorific value, abundant diffusion, and wider flammability limit make it a suitable fuel for improving the performance of compression ignition engine in dual-fuel mode. Methane-diesel dual-fuel engines are an effective technology for reducing vehicle pollution and partially replacing conventional fuels for transport applications. Therefore, a comprehensive review is needed to document the various pathways for the utilization of methane in dual-fuel engines. This study critically compared the combustion, noise, performance, and emission characteristics of various methane-fueled engines to identify the current challenges and future perspectives for the synergistic use of methane to reduce emissions from internal combustion engines.
{"title":"Performance, emissions, and combustion characteristics of methane-diesel dual-fuel engines: A review","authors":"G. Tripathi, A. Dhar","doi":"10.3389/fther.2022.870077","DOIUrl":"https://doi.org/10.3389/fther.2022.870077","url":null,"abstract":"Methane is a popular alternative fuel for internal combustion engines due to its availability in many forms such as methane hydrates, natural gas, biogas, compressed natural gas, liquid natural gas, synthetic natural gas, and pipe natural gas. Methane can be effectively used in existing diesel engines in dual-fuel mode with few modifications. Dual-fuel technology helps bridge existing conventional fuel and alternative gaseous fuel-powered conventional engines. The properties of methane, including its higher calorific value, abundant diffusion, and wider flammability limit make it a suitable fuel for improving the performance of compression ignition engine in dual-fuel mode. Methane-diesel dual-fuel engines are an effective technology for reducing vehicle pollution and partially replacing conventional fuels for transport applications. Therefore, a comprehensive review is needed to document the various pathways for the utilization of methane in dual-fuel engines. This study critically compared the combustion, noise, performance, and emission characteristics of various methane-fueled engines to identify the current challenges and future perspectives for the synergistic use of methane to reduce emissions from internal combustion engines.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43394818","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 : 2022-09-02DOI: 10.3389/fther.2022.953051
G. A. Riley, C. Méndez, Munonyedi Egbo, G. Hwang, M. Derby
This paper investigates the effects of hemispherical mounds on filmwise condensation heat transfer in micro-channels. Also investigated were the impacts that spatial orientation of the three-sided condensation surface (i.e., gravitational effects) on steam condensation, where the cooled surfaces were either the lower surface (i.e., gravity pulls liquid towards the condensing surfaces) or upper surface (i.e., gravity pulls liquid away from the condensing surfaces). Two test coupons were used with 1.9-mm hydraulic diameters and either a plain copper surface or a copper surface modified with 2-mm diameter hemispherical mounds. Heat transfer coefficients, film visualization, and pressure drop measurements were recorded for both coupons in both orientations at mass fluxes of 50 kg/m2s and 125 kg/m2s. For all test conditions, the mounds were found to increase condensation heat transfer coefficients by at minimum 13% and at maximum 79%. When the test section was inverted (i.e., condensing surface on the top of flowing steam), minimal differences were found in mound performance, while the plain coupon reduces heat transfer coefficients by as much as 14%. Flow visualization suggests that the mounds enhanced heat transfer due to the disruption of the film as well as by reducing the thermal resistance of the film. Pressure drops followed parabolic behavior with quality, being higher in the mound coupon than the plain coupon. No significant pressure drop differences in the inverted orientation were observed.
{"title":"Visualizing and disrupting liquid films for filmwise flow condensation in horizontal minichannels","authors":"G. A. Riley, C. Méndez, Munonyedi Egbo, G. Hwang, M. Derby","doi":"10.3389/fther.2022.953051","DOIUrl":"https://doi.org/10.3389/fther.2022.953051","url":null,"abstract":"This paper investigates the effects of hemispherical mounds on filmwise condensation heat transfer in micro-channels. Also investigated were the impacts that spatial orientation of the three-sided condensation surface (i.e., gravitational effects) on steam condensation, where the cooled surfaces were either the lower surface (i.e., gravity pulls liquid towards the condensing surfaces) or upper surface (i.e., gravity pulls liquid away from the condensing surfaces). Two test coupons were used with 1.9-mm hydraulic diameters and either a plain copper surface or a copper surface modified with 2-mm diameter hemispherical mounds. Heat transfer coefficients, film visualization, and pressure drop measurements were recorded for both coupons in both orientations at mass fluxes of 50 kg/m2s and 125 kg/m2s. For all test conditions, the mounds were found to increase condensation heat transfer coefficients by at minimum 13% and at maximum 79%. When the test section was inverted (i.e., condensing surface on the top of flowing steam), minimal differences were found in mound performance, while the plain coupon reduces heat transfer coefficients by as much as 14%. Flow visualization suggests that the mounds enhanced heat transfer due to the disruption of the film as well as by reducing the thermal resistance of the film. Pressure drops followed parabolic behavior with quality, being higher in the mound coupon than the plain coupon. No significant pressure drop differences in the inverted orientation were observed.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44165763","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 : 2022-08-05DOI: 10.3389/fther.2022.931160
Z. Duan, G. Zhang, J. F. Zhang, Z. Qu
All-vanadium redox flow battery (VRFB) is a promising energy storage technique. Flow fields play a crucial role in distributing the electrolyte into the electrode uniformly, but their performance characteristics under different electrode parameters are still unclear. In this work, taking the total pressure drop and total overpotential as performance characterizations, the influence of electrode parameters and operating conditions on the performance of serpentine flow field (SFF) and interdigitated flow field (IFF) are experimentally investigated. It is found that the battery with IFF exhibits lower pressure drop than that with SFF because of the shunt effect of IFF on electrolyte. In terms of promoting the uniform distribution of the electrolyte into the electrode, the SFF outperforms IFF when the electrode porosity is higher than 0.810, but the performance of SFF and IFF could be reversed as the electrode porosity decreases to 0.714, indicating that there may be a performance reversal between SFF and IFF when the electrode porosity decreases from 0.810 to 0.714. Moreover, the increase of current density, the decrease of electrolyte input, and the decrease of electrode thickness strengthen the performance reversal at low electrode porosity. The results well explain the debate on the superiority of IFF and SFF and the discussion on the preference between flow fields and electrode thickness in literatures and provide guidance for the selection of optimal flow field in VRFBs.
{"title":"Experimental Investigation on the Performance Characteristics of Flow Fields in Redox Flow Batteries Under Various Electrode Parameters","authors":"Z. Duan, G. Zhang, J. F. Zhang, Z. Qu","doi":"10.3389/fther.2022.931160","DOIUrl":"https://doi.org/10.3389/fther.2022.931160","url":null,"abstract":"All-vanadium redox flow battery (VRFB) is a promising energy storage technique. Flow fields play a crucial role in distributing the electrolyte into the electrode uniformly, but their performance characteristics under different electrode parameters are still unclear. In this work, taking the total pressure drop and total overpotential as performance characterizations, the influence of electrode parameters and operating conditions on the performance of serpentine flow field (SFF) and interdigitated flow field (IFF) are experimentally investigated. It is found that the battery with IFF exhibits lower pressure drop than that with SFF because of the shunt effect of IFF on electrolyte. In terms of promoting the uniform distribution of the electrolyte into the electrode, the SFF outperforms IFF when the electrode porosity is higher than 0.810, but the performance of SFF and IFF could be reversed as the electrode porosity decreases to 0.714, indicating that there may be a performance reversal between SFF and IFF when the electrode porosity decreases from 0.810 to 0.714. Moreover, the increase of current density, the decrease of electrolyte input, and the decrease of electrode thickness strengthen the performance reversal at low electrode porosity. The results well explain the debate on the superiority of IFF and SFF and the discussion on the preference between flow fields and electrode thickness in literatures and provide guidance for the selection of optimal flow field in VRFBs.","PeriodicalId":73110,"journal":{"name":"Frontiers in thermal engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44477326","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}
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