Thermal Heat Research Articles

Entropy generation and activation energy on nonlinearly thermo-radiative and magnetohydrodynamic heat transfer of Jeffrey nanofluid with non-uniform heat source/sink using SQLM

ABSTRACT Entropy generation and activation energy analysis on MHD heat and mass transfer of Jeffrey nanofluid under the impact of nonlinear thermal radiation and heat source/sink (non-uniform) over a linearly stretching sheet has been investigated numerically using Spectral Quasilinearization Method (SQLM). The Brownian motion with thermophoretic effects has been utilized. The basic equations concerned with the problem are solved numerically. The impacts of different governing physical parameters are analyzed on the velocity, temperature, and concentration fields, along with entropy generation, and Bejan number profiles are analyzed graphically. It is found that the concentration profiles have a mixed tendency with magnetic parameters. In addition, the temperature profiles increase in the presence of Brownian motion with thermophoresis effects, whereas the composite behavior is noticed on the entropy generation profiles. It is also found that both the temperature and concentration profiles diminish for various values of Deborah number while the velocity profile increases. Also, it is noticed that both the temperature profiles increase for enhanced values of the space-dependent and time-dependent parameters. Due to activation energy, the Bejan number profiles decrease, whereas the entropy generation profiles increase far away from the expandable sheet but decrease closer to the sheet.

Active heating of greenhouse integrated semitransparent photovoltaic thermal system with series connected semitransparent photovoltaic thermal air collectors

In order to fulfill the demand of energy and food security, active heating of controlled environment greenhouse integrated semitransparent photovoltaic thermal (GiSPVT) system with N-semitransparent photovoltaic thermal (SPVT) air collector for cold climatic condition has been analyzed in this paper. The proposed SPVT air collectors are connected in series and integrated with GiSPVT. It is used to generate thermal as well electrical energy to meet daily requirement of users. Based on energy balance equation which is a function of design and climatic parameters, an analytical expression for various variable parameters namely plant, room air and solar cell temperatures have been derived. Numerical computation has been made in Matlab for computing thermal, electrical and overall exergy of the proposed system. Based on numerical computation, the following observations have been made: (i) From thermal point of view, the packing factor (0.5, 0.8) of semitransparent PV module plays an important role and it has to be optimized for maximum thermal heating. (ii) The selection of number of collector N is an important parameter to generate electrical energy as well as thermal heating of GiSPVT room air in an optimum way.

High-Throughput Roll-to-Roll Processed Large-Area Perovskite Solar Cells Using Rapid Radiation Annealing Technique.

The development of a stable roll-to-roll (R2R) process for flexible large-area perovskite solar cells (PSCs) and modules is a pressing challenge. In this study, we introduced a new R2R PSC manufacturing system that employs a two-step deposition method for coating perovskite and uses intensive pulsed light (IPL) for annealing. This system has successfully fabricated small-sized cells and the first-ever large-sized, R2R-processed flexible modules. A key focus of our work was to accelerate the conversion of PbI2 to perovskite. To this end, we utilized IPL annealing and incorporated additives into the PbI2 layer. With these modifications, the R2R-processed perovskite films achieved a power conversion efficiency (PCE) of 16.87%, representing the highest reported value for R2R two-step processed PSCs. However, these cells exhibited hysteresis in reverse and forward PCE measurements. To address this, we introduced a dual-annealing process consisting of IPL followed by a 2-min thermal heating step. This approach successfully reduced hysteresis, resulting in low-hysteresis, R2R-processed flexible PSCs. Moreover, we fabricated large-scale flexible modules (10 × 10 cm2) with a PCE of 11.25% using the dual-annealing system, marking a significant milestone in this field.

Synergistic effect of stearic acid/bismuth oxychloride/cupric oxide for thermal storage applications: preparation, stability, rheological and thermophysical analysis

Abstract The present study reports the preparation of nanophase change materials (NPCMs) using a two-step method with an optimized ratio of 0.5 wt.% of nanoparticles for thermal storage applications. Bismuth oxychloride (BiOCl), cupric oxide (CuO), and a mixture of BiOCl/CuO (composite) were used as nanoparticles, and stearic acid was used as the PCM. The crystallography, chemical/functional groups and morphologies of the prepared NPCMs have been analysed by XRD, FT-IR and SEM, respectively. Observations revealed that the presence of nanoparticles in NPCMs did not affect crystal formation or chemical disruption of molecular interactions. TGA was used to analyse the thermal stability and rate of deterioration of the NPCMs. The deterioration of the PCM occurs at 243℃ with a weight loss of 1.3% while 0.5 wt.% concentrated BiOCl, CuO, and composite NPCMs exhibit weight losses of 1.8%, 2.3%, and 3.4%, respectively at 257℃, 262℃ and 258℃. In the DSC study, the phase-changing attributes of the NPCMs manifested in the onset temperature range between 53.4°C and 59.8°C. The potential enthalpy of the PCM is 209.1 kJ/kg, whereas those of the 0.5 wt.% concentrated BiOCl, CuO, and composite NPCMs are 204.6, 198.3, and 201.7 kJ/kg, respectively. However, the enhanced thermal conductivities of 0.5 wt.% concentrated BiOCl, CuO, and the composite NPCMs are 0.18, 0.22, and 0.20 W/(m.℃), respectively, which are 5.9%, 29.4% and 17.6% greater than that of PCM. Additionally, the congruent melting rate increased by 31% for 0.5 wt.% CuO concentrated NPCM; therefore, it is a potential candidate than other NPCMs/PCM. Cyclic tests were conducted to assess the reliability of the NPCMs, and compatible results were obtained even after 500 cycles. The findings of this work indicate that all the prepared NPCMs could be a viable option for practical applications, including thermal comfort buildings, solar heating, and electronic cooling.

Sensitive detection of low doses beta particles using quartz crystal oscillators

The demand for developing a cheap and novel ionizing radiation detection technique has recently increased. This work aims to establish a new detection method for β particles based on a quartz tuning fork (QTF). QTF coated and uncoated with 40 nm of aluminum (Al) were used to evaluate the system under different conditions. All samples were exposed to different doses of beta using a 90Sr β source. The results confirmed that a clear frequency shift was observed during Beta irradiation. Once the radiation source was removed, the frequency returned to normal behavior. This effect is more pronounced with the Al-coated sample due to more tensile stress caused by thermal heating induced by Beta radiation. Before and after beta irradiation, the optical properties of SiO2 wafers (quartz) were also studied using spectroscopic ellipsometry (SE) measurements. The SE results were largely consistent with the QTF resonance frequency shift results. In conclusion, experiment results proved the probability of using QTF as sensitive, accurate, and easy-to-use sensing for low-dose Beta radiation.

Experimental optimization of conical solar distillers using graphite pin fins as sensible heat storage materials: Energy, exergy, and exergo-economic approach

Fresh water and energy are essential for the development and prosperity of societies. Solar stills are easy to build, operate, and maintain, but their disadvantage is low daily productivity. This work aims to optimize and enhance the performance of conical solar stills by integrating innovative graphite pin fins that function as extended surfaces and sensible energy storage in the distillation basin. Graphite is inexpensive, available locally, natural properties, and has good thermal characteristics and heat capacity. Four different alternates spacing between the graphite pin fins ranging from 10 to 70 mm have been investigated and optimized to achieve maximum daily water production. Three identical conical solar distillers were designed, manufactured, and tested, under the same weather conditions in El Oued city, Algeria (33.3676◦ N and 6.8516◦ E). Energy, economy, exergy, and exergo-economics approach were performed to evaluate the economic feasibility of modified conical distillers. The results showed that reducing the distance between the pin fins leads to a decrease in the productivity of the distiller due to the increase in the shadow area. Among the pin fin distances evaluated, the 50 mm distance achieved the highest daily water production with reasonable economic feasibility. Adding graphite pin fins to conical distiller basin increases daily productivity and thermal efficiency by 52.16–90.78% and 33.44–63%, respectively. The production cost and payback time of the modified conical distillers with pin fins are reduced by 35.49–79.72% and 35.48–79.72%, respectively compared to the traditional conical stiller.

Unsteady MHD flow analysis of hybrid nanofluid over a shrinking surface with porous media and heat generation: Computational study on entropy generation and Bejan number

The use of hybrid nanofluids in real-world situations is essential for enhancing the efficiency of heat transmission, especially in cooling semiconductor technology and industrial processes. The entropy generation on unsteady Al2O3-Cu/H2O hybrid nanofluid flow over a three-dimensional shrinking sheet is addressed numerically in this study, taking into account the effects of magnetohydrodynamic (MHD), nonlinear thermal radiation, porous media, heat generation, viscous dissipation, joule heating, and convective conditions. Using well-known non-similarity transformations, the model is carefully converted from partial differential equations (PDEs) to ordinary differential equations (ODEs). Afterwards, the behaviors of critical physical characteristics are uncovered across different parameter configurations by a numerical solution using the finite difference technique in bvp4c MATLAB. The velocity profiles of hybrid nanofluid grow proportionately with increases in the values of ϕ2,M,A,K and λ parameters. As Rd,θw,Ec,Bi,H and ϕ2 increase, the temperature of the hybrid nanofluid rises, but as M and A increase, the temperature falls. The local skin friction in both the x and y- directions is increased by enhancing the unsteadiness A, nanoparticle volume fraction ϕ2, magnetic M, porous media K, and the ratio of strain rate λ parameter on the shrinking surface. The local Nusselt number is improved by cumulative the unsteadiness A, nanoparticle volume fraction ϕ2, magnetic M, and Biot number Bi parameter in the direction of a shrinking surface, while the Nusselt number decreases when Eckert number Ec, thermal radiation Rd, heat production H, and temperature ratio θw are improved. An upsurge in the magnetic parameter leads to the development of entropy generation. Increasing levels of the magnetic parameters led to a reduction in the Bejan number. At a nanoparticle volume fraction of 1 % and a nonlinearity radiation scenario, where the unsteadiness values are 0.5, the Nusselt number for hybrid nanofluid shows an estimated improvement of 10.55 % compared to regular nanofluid.

Polybutylene adipate terephthalate (PBAT) composites for thermally conductive, fire retardant, high dielectric applications using BaTiO3 and MWCNTs as fillers

This study provides a comprehensive investigation of the fabrication of novel composite materials by blending polybutylene adipate terephthalate (PBAT) with barium titanate (BaTiO3) and multiwalled carbon nanotube (MWCNT) fillers. Prior to fabricating the composites, the filler surface treatments were tailored to enhance their compatibility with the PBAT matrix. Adipic acid (AA), a monomer for PBAT, was employed on the surface of the BaTiO3 particles, while butanediol (BD) also a monomer of PBAT was used to modify the surface of the MWCNTs to ensure effective interaction with the PBAT chains during the composite fabrication process. The composite samples were produced by melt-blending at 140 °C, followed by injection molding at the same operating temperature for subsequent analysis. The results revealed remarkable improvements in the dielectric constant, thermal conductivity, fire retardancy, and tensile strength of the 40 wt% BaTiO3 and MWCNT-PBAT blends compared to pure PBAT. The incorporation of BaTiO3 additionally contributed to enhanced fire retardancy, mechanical properties, and dielectric properties, making the composite material more resistant to ignition and flame spread, thus rendering it suitable for applications requiring elevated fire safety. In addition, the inclusion of MWCNT improved thermal conductivity, enabling promising and efficient heat dissipation in various applications.

Radiofrequency Treatment Attenuates Age-Related Changes in Dermal–Epidermal Junctions of Animal Skin

The dermal–epidermal junction (DEJ) is essential for maintaining skin structural integrity and regulating cell survival and proliferation. Thus, DEJ rejuvenation is key for skin revitalization, particularly in age-related DEJ deterioration. Radiofrequency (RF) treatment, known for its ability to enhance collagen fiber production through thermal mechanisms and increase heat shock protein (HSP) expression, has emerged as a promising method for skin rejuvenation. Additionally, RF activates Piezo1, an ion channel implicated in macrophage polarization toward an M2 phenotype and enhanced TGF-β production. This study investigated the impact of RF treatment on HSP47 and HSP90 expression, known stimulators of DEJ protein expression. Furthermore, using in vitro and aged animal skin models, we assessed whether RF-induced Piezo1 activation and the subsequent M2 polarization could counter age-related DEJ changes. The RF treatment of H2O2-induced senescent keratinocytes upregulated the expression of HSP47, HSP90, TGF-β, and DEJ proteins, including collagen XVII. Similarly, the RF treatment of senescent macrophages increased Piezo1 and CD206 (M2 marker) expression. Conditioned media from RF-treated senescent macrophages enhanced the expression of TGF-β and DEJ proteins, such as nidogen and collagen IV, in senescent fibroblasts. In aged animal skin, RF treatment increased the expression of HSP47, HSP90, Piezo1, markers associated with M2 polarization, IL-10, and TGF-β. Additionally, RF treatment enhanced DEJ protein expression. Moreover, RF reduced lamina densa replication, disrupted lesions, promoted hemidesmosome formation, and increased epidermal thickness. Overall, RF treatment effectively enhanced DEJ protein expression and mitigated age-related DEJ structural changes by increasing HSP levels and activating Piezo1.

Thermal and electrical properties of single‐phase high entropy carbide ceramics

AbstractThermal and electrical properties were investigated for five nominally phase‐pure high entropy carbide ceramics. The compositions (Hf0.2Nb0.2Ta0.2Ti0.2Zr0.2)C, (Cr0.2Hf0.2Ta0.2Ti0.2Zr0.2)C, (Hf0.2Mo0.2Ta0.2Ti0.2Zr0.2)C, (Hf0.2Ta0.2Ti0.2W0.2Zr0.2)C, and (Hf0.2Mo0.2Ti0.2W0.2Zr0.2)C were synthesized by carbothermal reduction of oxides. The thermal diffusivity and heat capacity were measured from room temperature to 1800°C. The room temperature thermal conductivity ranged from 5.1 W/mK for (Hf0.2Mo0.2Ti0.2W0.2Zr0.2)C to 9.0 W/mK for (Cr0.2Hf0.2Ta0.2Ti0.2Zr0.2)C. The thermal conductivity increased over the temperature range with maximum conductivities of 19.6 W/mK measured for (Hf0.2Mo0.2Ta0.2Ti0.2Zr0.2)C to 29.7 W/mK for (Cr0.2Hf0.2Ta0.2Ti0.2Zr0.2)C at 1800°C. The electron contribution to thermal conductivity calculated from measured electrical resistivity varied from 41% to 52% of the total thermal conductivity. The tungsten and molybdenum containing compositions had higher phonon contributions while the niobium and chromium containing compositions had nearly equal electron and phonon contributions to thermal conductivity.

Light-assisted thermochemical reduction of CuFe2O4 within a photo-thermogravimetric analyser for solar fuel production

The solar thermochemical cycle has emerged as a promising clean energy technology that enables the splitting of water for solar fuel production. However, conventional two-step thermochemical cycles using single-metal oxides require high operating temperatures above 1000 °C, especially for the reduction step. Typical solar thermal systems struggle to meet such high temperature requirements, making it vital to reduce the operating temperature. To find a solution enabling lower temperature requirements, we propose a photo-thermochemical reduction (PTR) strategy, which employs light illumination as assistance, combining both thermally induced and photo-induced effects for more generation of oxygen vacancies (VOs), within the oxygen carrier copper ferrite (CuFe2O4). Experimental studies were performed in a specially-designed photo-thermogravimetric analyser (photo-TGA) that directly measures the weight change of solid reactants under direct light illumination. The results indicate that the PTR achieves a decrease of nearly 40 °C in temperature requirements, giving a higher oxygen release of 21% compared to that driven by pure thermal heating at 800 °C. We also measured an increase of 0.09 in the non-stoichiometry parameter δ in the photo-TGA. Additionally, we observed that oxygen release increases distinctly with the light intensity of incident illumination. From the viewpoint of spectral ranges, ultraviolet and visible light illumination give the primary boost to the generation of photo-induced VOs. These results demonstrate the effective assistance of concentrated solar energy to enhance the two-step thermochemical cycle for solar fuel production at lower temperatures.

Cross-scale interaction between microturbulence and meso-scale reversed shear Alfvén eigenmodes in DIII-D plasmas

Abstract This paper reports global nonlinear gyrokinetic simulations that couple meso-scale reversed shear Alfvén eigenmodes (RSAE) driven by energetic particles (EP) and ion temperature gradient (ITG) microturbulence driven by thermal plasma, using equilibrium and profiles from DIII-D discharge #159243. In simulations focusing only on the ITG, electrostatic ITG drives a huge thermal ion heat transport, which is reduced by a factor of 10 to a level closer to the experimental value in electromagnetic simulation due to finite β effect. In the simulations coupling the RSAE and ITG, ITG can scatter the resonant EP nonlinearly trapped by the RSAE and damp the zonal flows generated by the RSAE. The regulation of the RSAE by the ITG greatly reduces the initial saturation amplitude of the RSAE but increases the RSAE amplitude and associated EP transport to experimental levels in the quasi-steady state. The RSAE effects on the ITG, specifically the stronger zonal flows generated by the RSAE and the RSAE frequency modulation of the ITG-induced thermal ion heat transport, in turn, leads to a reduction of the thermal ion heat transport by more than a factor of 2. For a stronger background ITG, the regulation of the RSAE by the ITG is stronger, while the RSAE effects on the ITG are weaker. This work highlights the importance of cross-scale coupling in the dynamics of the AE turbulence and EP transport.

Debris cover effects on energy and mass balance of Batura Glacier in the Karakoram over the past 20 years

Abstract. The influence of supraglacial debris cover on glacier mass balance in the Karakoram is noteworthy. However, understanding of how debris cover affects the seasonal and long-term variations in glacier mass balance through alterations in the glacier's energy budget is incomplete. The present study coupled an energy–mass balance model with heat conduction within debris layers on debris-covered Batura Glacier in Hunza Valley to demonstrate the influence of debris cover on glacial surface energy and mass exchanges during 2000–2020. The mass balance of Batura Glacier is estimated to be -0.262±0.561 m w.e. yr−1, with debris cover accounting for a 45 % reduction in the negative mass balance. Due to the presence of debris cover, a significant portion of incoming energy is utilized for heating debris, leading to a large energy emission to the atmosphere via thermal radiation and turbulent sensible heat. This, in turn, reduces the melt latent heat energy at the glacier surface. We found that the mass balance exhibits a pronounced arch-shaped structure along the elevation gradient, which is associated with the distribution of debris thickness and the increasing impact of debris cover on the energy budget with decreasing elevation. Through a comprehensive analysis of the energy transfer within each debris layer, we have demonstrated that the primary impact of debris cover lies in its ability to modify the energy flux reaching the surface of the glacier. Thicker debris cover results in a smaller temperature gradient within debris layers, consequently reducing energy reaching the debris–ice interface. Over the past 2 decades, Batura Glacier has exhibited a trend towards less negative mass balance, likely linked to a decrease in air temperature and reduced ablation in areas with thin or sparse debris cover.

A general ray tracing approach for solving thermal radiation in regular one-dimensional variable index media via the Monte Carlo method

In the heat transfer community, one-dimensional media refers to some media where the temperature and other thermophysical properties vary along one direction. Plane-parallel, concentric cylindrical, and concentric spherical geometries are among of regular one-dimensional media. In this paper, a general ray tracing approach is presented to track the curve paths of energy particles in regular one-dimensional variable index media. The domain of interest is limited by specular sidewalls and the medium is divided into slices with constant temperature and radiative properties. Then, the path of random energy particles emitted from boundary surfaces and volume elements are traced, element by element, until they absorb by diffuse-gray surfaces or the gray medium. After counting the number of absorbed particles by each boundary surface and volume element, the Monte Carlo method is performed to simulate thermal radiation heat transfer. The results are presented for three regular geometries, including plane-parallel, concentric cylindrical, and concentric spherical media, and the effects of radiative properties are investigated by some numerical experiments.

Numerical Analysis Study of Chemically Radiative MHD Williamson Nanofluid Flow over an Inclined Surface with Heat Source

The design and optimization of systems such as nuclear reactors, solar collectors, and thermal power plants may benefit from an understanding of the behaviour of nanofluids with chemical processes, thermal radiation, and magnetic fields over inclined surfaces with heat sources.This review looks at the magnetohydrodynamic (MHD) flow of a Williamson nanofluid over an inclinable stretched sheet and the impact of thermal radiation, heat source, and chemical processes. The outcomes of the generation of heat or absorption, as well as thermal radiation, are all factored into account in the energy equation. On the other hand, the mass transport equation also takes into account chemical interactions.The similarity substitution serves to turn the governed partial differential equations for velocity, temperature, and concentration into ordinary differential equations, which are then numerically resolved with Mathematica's NDSolve program. Changes in temperature, concentration, and dimensionless velocity as a function of various factors are graphically touched upon. The temperature diminishes while the Prandtl number accelerates as the thermal boundary layer thins and the viscosity enrichment. The temperature contour develops along with the magnetic field strength. When all the parameters were compared for a particular case, a very good association was discovered. Depending on the precise conclusions and understandings drawn from the investigation of chemically radiative MHD nanofluid flow over inclined surfaces with a heat source, the applications may range greatly. It's important to remember that such research often aids in the creation of more effective and environmentally friendly solutions in a variety of sectors.

Rice husk reuse as a sustainable energy alternative in Tolima, Colombia

Colombia has great potential to produce clean energy through the use of residual biomass from the agricultural sector, such as residues obtained from the life cycle of rice production. This document presents a mixed approach methodology study to examine the combustion of rice husks as a possible energy alternative in the Tolima department of Colombia. First, the physicochemical characteristics of the rice husk were analyzed to characterize the raw material. Next, System Advisor Model (SAM) software was used to model a bioenergy plant to obtain biochar, bio-oil, and biogas from the combustion of rice husks and generate performance matrices, such as thermal efficiency, heat rate, and capacity factor. Then, the project was evaluated for financial feasibility using a mathematical model of net present value (NPV) with a planning horizon of 5 years. Finally, a subset of the local population was surveyed to assess perspectives on the project in the region. The results of the rice husk physicochemical analysis were the following: nitrogen content (0.74%), organic carbon (38.04%), silica (18.39%), humidity determination (7.68%), ash (19.4%), presence of carbonates (< 0.01%), and pH (6.41). These properties are adequate for the combustion process. The SAM simulation showed that the heat transferred in the boiler was 3180 kW, maintaining an efficiency between 50 and 52% throughout the 12 months of the year, meaning that the rice husk can generate electricity and thermal energy. The financial analysis showed that the internal rate of return (IRR) was 6% higher than the opportunity interest rate (OIR), demonstrating economic feasibility of the project. The design and creation of a rice husk processing plant is socially and environmentally viable and has the potential to contribute to the economic development of the Tolima community and reduce greenhouse gases. Likewise, this activity has the potential to promote energy security for consumers and environmental sustainability while at the same time being economically competitive.

Thermal and cardiovascular heat adaptations in active adolescents following summer

ABSTRACT This study aimed to investigate seasonal heat acclimatization in active adolescents following summer. Fifteen (5 females) active adolescents (14.6 ± 1.0 y) completed a 45-min heat response test (HRT) walking at 60% V ˙ O2peak in 40°C and 30% relative humidity before and after summer (i.e. November 2022 and March 2023). During the HRT, gastro-intestinal temperature (Tgi), skin temperature (Tsk), heart rate, local sweat rate (LSR) and whole-body sweat loss (WBSL) were recorded. Carbon monoxide rebreathing and dual-energy X-ray absorptiometry scans determined resting hematological measures and body composition. Participants completed physical activity (PA) diaries and wore an accelerometer for two one-week periods (pre- and post-summer). Daytime wet-bulb globe temperature (WBGT) was calculated for each summer day. Data are presented as posterior mean and 90% credible intervals. Participants reported 7 ± 4 h·wk−1 of outdoor PA, and daytime WBGT was 21.2 ± 4.6°C. Following summer, resting Tgi and heart rate were reduced by 0.2°C [−0.3, −0.1; probability of direction = 99%] and 7 beats·min−1 [−10, −3; 100%], respectively. During the HRT, there was an earlier onset of sweating (−0.2°C [−0.3, −0.0; 98%]), an attenuated rise of Tgi (0.2°C [−0.5, 0.0; 92%]) and mean Tsk changed by −0.2°C [−0.5, 0.1; 86%]. There was minimal evidence for heat adaptations in LSR or WBSL, hematological parameters or perceptual measures. This is the first study to demonstrate seasonal heat adaptations in active adolescents. Reductions in resting Tgi and exercising Tsk and a lower Tgi at the onset of sweating were associated with a smaller rise in Tgi during the HRT following summer.

Exploration Of Key Approaches to Enhance Evacuated Tube Solar Collector Efficiency

Exploration Of Key Approaches to Enhance Evacuated Tube Solar Collector Efficiency

Heating and storage of medium-deep borehole heat exchangers: Analysis of operational characteristics via an optimized analytical solution model

This study focuses on investigating the thermal storage potential of medium-deep borehole heat exchanger (MDBHE) to address the issues of temperature attenuation of thermal reservoir and heating capacity reduction during the one-way heat extraction process in the heating period. By establishing an MDBHE heating system that integrates an external thermal storage source, a comprehensive analysis of the heat transfer progress and operational characteristics of the MDBHE is conducted, including optimizing burial depth, thermal storage scenarios, and aquifer conditions. The calculated solution under the typical thermal storage conditions (S60–30) in this study reveals that the average heat supply capacity increasement of a 1200 m MDBHE is 37.2 % higher than that of a 2000 m MDBHE, and the power consumption of the circulating water pump also can be reduced by 40 % in heating period. Furthermore, the enhancement of storage temperature and flow rate both contribute to a noticeable improvement in the heating performance of the MDBHE during the heating period. The heat transfer power and energy efficiency of MDBHE both increase with the elevation of seepage velocity and aquifer thickness during the energy storage and heating period. The significance of this research lies in its contribution to the enhancement of thermal storage and heat transfer efficiency in MDBHE and offering novel insights for the multi-thermal energy storage systems.

Thermal Optimization Strategies for Li-Ion Batteries: Predictive Temperature Algorithm

Abstract Performance, safety, and longevity of batteries are all strongly impacted by thermal management, which is an essential component of battery design and operation. This work examines how accurate temperature control can result in significant improvements in performance and reliability with a focus on battery thermal heating. Predicting the temperature achieved by the battery during operation not only avoids conditions that lead to thermal runaway, but also guarantees that the battery is used optimally within an optimal temperature range. Within the optimal temperature range several advantages are observed. First, battery efficiency improves significantly as electrochemical processes occur more efficiently. Furthermore, by lowering the possibility of short circuits and improving overall battery safety, thermal stability aids in the prevention of undesirable phenomena like dendrite growth. By lessening the deterioration brought on by thermal degradation processes, thermal optimization also affects battery longevity. Based on experimental tests, a Finite Element Model (FEM) is developed. A model for thermal runaway propagation is established by combining thermal runaway and conduction models with an Arrhenius law-based combustion model. The study employed a cylindrical Li-Ion cell to conduct tests, taking into account three parameters: discharge rate (CRate), ambient temperature (Tamb), and initial battery temperature (T0). An algorithm based on the three variables was developed using the simulation results. The algorithm enables the accurate prediction of rising battery temperature during use, facilitating the setting of an optimal maximum discharge rate considering initial and ambient temperatures, thereby ensuring optimal performance within the desired temperature range.