Thermal Performance Research Articles

Impact of dual nano-enhanced phase change materials on mitigating thermal runaway in lithium-ion battery cell

Thermal management remains a pivotal challenge in enhancing the safety and efficiency of lithium-ion batteries, especially under conditions prone to thermal runaway. This study investigates the performance of dual nano-enhanced phase change materials (NEPCM) in moderating extreme thermal events in battery cells. By integrating nanoparticles, specifically alumina and single-walled carbon nanotubes (SWCNT), into phase change materials (PCM), the study explores modifications in thermal behavior and phase change dynamics within a cylindrical battery enclosure. The research focuses on comparing the thermal performance of pure PCM and NEPCM, using two types of nanoparticles dispersed within the PCM matrix at various volume fractions. The findings indicate that NEPCM significantly improves heat transfer rates and accelerates the melting process. Specifically, NEPCM with 6 % SWCNT increases the melting temperature distribution by up to 15.27 % compared to pure PCM setups and enhances the liquid fraction by up to 66.54 % under similar conditions. The inclusion of SWCNT demonstrates a superior enhancement in thermal conductivity compared to alumina, leading to more effective heat absorption and dissipation. Liquid fraction analysis confirms that NEPCM configurations facilitate quicker and more uniform thermal behaviors, especially near the heat source. PCM1, positioned adjacent to the battery, exhibits an immediate increase in temperature and melting rate, significantly outperforming PCM2 in thermal regulation. This study underscores the potential of dual nano-enhanced PCM in improving the thermal management of lithium-ion batteries, particularly in scenarios at risk of thermal runaway. By optimizing the PCM formulation with nanoparticles, a robust solution is presented to control temperature spikes and improve battery safety and durability in challenging operational environments.

Floral thermal biology in relation to pollen thermal performance in an early spring flowering plant.

The floral microenvironment impacts gametophyte viability and plant-pollinator interactions. Plants employ mechanisms to modify floral temperature, including thermogenesis, absorption of solar radiation, and evaporative cooling. Whether floral thermoregulation impacts reproductive fitness, and how floral morphological variation mediates thermoregulatory capacity are poorly understood. We measured temperature of the floral microenvironment in the field and tested for thermogenesis in the lab in early spring flowering Hexastylis arifolia (Aristolochiaceae). We evaluated whether thermoregulatory capacity was associated with floral morphological variation. Finally, we experimentally determined the thermal optimum and tolerance of pollen to assess whether thermoregulation may ameliorate thermal stress to pollen. Pollen germination was optimal near 21 °C, with a 50% tolerance breadth of ~18 °C. In laboratory conditions, flowers exhibited thermogenesis of 1.5-4.8 °C for short intervals within a conserved timeframe (08:00-09:00 h). In the field, temperature inside the floral tube often deviated from ambient - floral interiors were up to 4 °C above ambient when it was cold, but some fell nearly 10 °C below ambient during peak heat. Flowers with smaller openings were cooler and more thermally stable than those with larger openings during peak heat. Thermoregulation maintained a floral microenvironment within the thermal tolerance breadth of pollen. Results suggest that H. arifolia flowers have a stronger capacity to cool than to warm, and that narrower floral openings create a distinct floral microenvironment, enhancing floral cooling effects. While deviation of floral temperature from ambient conditions maintains a suitable environment for pollen and suggests an adaptive role of thermoregulation, we discuss adaptive and nonadaptive mechanisms underlying floral warming and cooling.

Empirical correlation to analyze performance of shell and tube heat exchanger using TiO2 Nanofluid-DI water in solar water heater

Recent studies have examined the thermal stability and reliability of TiO2 nanofluid-based heat exchangers under long-term operation in solar water heating systems. This includes assessing nanoparticle sedimentation, agglomeration, and degradation over time, as well as their impact on heat transfer performance and system reliability. In this study heat transfer and fluid flow characteristics of TiO2-DI-H2O (deionized water) nanofluid used in a shell and tube exchanger with different baffle angles under turbulent regimes were numerically explored. The proposed setup was run with nanoparticle concentration of 0 %–0.2 % and Reynolds numbers (Re) from 5000 to 15,000. Baffle angles of 10°, 20°, and 30° were chosen for turbulence analysis. It was observed that nanoparticle concentration strongly impacted the thermophysical properties. The results indicated that adding modest concentrations of TiO2 to DI-H2O significantly improves heat transfer and the Nu. At the Re of 5000 and 30° baffles, the Nu was 58; however, at the Re of 15,000, the Nu value was 88. The improvement in heat transfer of 62.85 %, 70.64 %, and 75.06 % was recorded for baffle angles of 10°, 20°, and 30° respectively, Furthermore, a notable increase in friction factor of 13.6 % at Re 15,000 was observed. However, the ideal baffle angle for maximum thermal performance is 30°. Finally, with shell temperature, it was established that 30° baffle orientation could provide the best h and Nu values and improve the overall performance of the heat exchanger. The obtained Nu was also compared with the existing correlations of literature in the turbulent regime with the aid of nanoparticles and presented for case applications.

Improving Pore Characteristics, Mechanical Properties and Thermal Performances of Near-Net Shape Manufacturing Phenolic Resin Aerogels.

Thermally stable high-performance phenolic resin aerogels (PRAs) are of great interest for thermal insulation because of their light weight, fire retardancy and low thermal conductivity. However, the drawbacks of PRA synthesis, such as long processing time, inherent brittleness and significant shrinkage during drying, greatly restrict their wide applications. In this work, PRAs were synthesized at ambient pressure through a near-net shape manufacturing technique, where boron-containing thermosetting phenolic resin (BPR) was introduced into the conventional linear phenolic resin (LPR) to improve the pore characteristics, mechanical properties and thermal performances. Compared with the traditional LPR-synthesized aerogel, the processing time and the linear shrinkage rate during the drying of the PRAs could be significantly reduced, which was attributed to the enhanced rigidity and the unique bimodal pore size distribution. Furthermore, no catastrophic failure and almost no mechanical degradation were observed on the PRAs, even with a compressive strain of up to 60% at temperatures ranging from 25 to 200 °C, indicating low brittleness and excellent thermo-mechanical stability. The PRAs also showed outstanding fire retardancy. On the other hand, the PRAs with a density of 0.194 g/cm3 possessed a high Young's modulus of 12.85 MPa and a low thermal conductivity of 0.038 W/(m·K).

Computational Evaluation of Pulsating Heat Pipe for Fluid Flow Behavior and its Thermal Performance

Computational fluid analysis of a single circuit heat pipe was undertaken to ascertain the thermal efficiency of water at various fill ratios, specifically 40%, 50%, and 60% under varying heating conditions. The analysis employed the ANSYS Fluent computational fluid dynamics software, utilizing a k-epsilon to the heat pipe as the solver. The analysis was carried out on a copper tube with an internal diameter measuring 3/16 inches. During the analysis, the thermal inflow at the adiabatic region was adjusted to zero, while the condenser region’s temperature remained constant at 25°C. Meanwhile, the heat input at the evaporator region was systematically adjusted to 105°C, 110°C, 115°C, and 120°C. Key Performance characteristics of heat pipe i.e. thermal resistance, and water volume fraction were evaluated during analysis. The temperature variations noted in both regions affirmed that the pulsating pipe’s performance was influenced by the phase transition between liquid and vapor. Furthermore, the concentration of volume within the evaporator section was monitored, confirming the presence of a dual-phase phenomenon within the heat pipe. Through the analysis, it was noted that the thermal resistance of the water is minimized at a 50% fill ratio for each level of heat input. Notably, the promising results were obtained at an input temperature of 120°C with a value of 1.025°C /W which was 7.3% and 9.8% lower than thermal resistance at 40% and 60% fill ratios, respectively. The reduced thermal resistance in this scenario is attributed to the flow dynamics within the capillary, propelled by rapid phase change mechanisms. This shows the importance of Pulsating Heat Pipes (PHPs) in thermal control, as well as the intricacies of their operating mechanisms. Experimental and theoretical investigations have investigated numerous elements influencing PHP performance, with numerical modeling providing insight into thermal resistance and water volume fraction dynamics under varying heating temperatures and fill ratios.

Pristine and defective 2D SiCN substrates as anode materials for sodium-ion batteries

Exploring more high-performance anode materials for sodium-ion batteries (SIBs) can smoothly help to build a more sustainable, cleaner, and reliable energy system. This study systematically investigates the potential of 2D pristine SiCN (p-SiCN) and defective (d-SiCN) substrate as candidate materials for SIBs anodes using first-principles computational method. The computational results reveal that the p-SiCN possesses excellent thermal stability and structural cyclical performance, good conductivity, high theoretical specific capacity (1486 mAh·g−1), low diffusion barrier (0.177 eV), and appropriate open-circuit voltage (0.340 V), which allows the p-SiCN substrate more suitable as a potential anode material for SIBs. Furthermore, by investigating the effects of intentionally designed defects on p-SiCN, it is observed that the adsorption energy and diffusion barrier of the Na atom on the d-SiCN substrate increase. Our work demonstrates that investigating the effect of defects on p-SiCN can better explore the properties of anode materials, thus further optimizing the battery performances.

One-step preparation of macropore phase change materials enabled exceptional thermal insulation, thermal energy storage and long-term stability

Phase change materials (PCMs) capable of reversibly storing and releasing thermal energy have been widely used in our daily life to reduce energy consumption. However, traditional PCMs are mainly focused on the promotion of their enthalpy and thermal conductivity yet are rarely noticed on incorporating their thermal energy storage capacity with thermal insulation performance. Herein, a kind of macropore PCMs (MPCMs) was synthesized by directly adding expanded microspheres into polyethylene glycol-based PCMs, in which the microspheres can form an internal closed porous structure in matrix for realizing thermal insulation and polyethylene glycol is used as the phase change component for achieving thermal energy storage. Amazingly, the designed MPCMs have significant latent heat storage capacity reached up to130.2 J g−1 and simultaneously possess extremely low thermal conductivity of 0.08577 W m−1 K−1. The thermal power generation system test further revealed the thermal insulation capability of these MPCMs was eleven times more than that of the commercial wood. Especially, these MPCMs with relatively low density of 0.492 g cm−3 can still maintain the remarkable tensile strength of 11.74 MPa and can also exhibit good toughness via multiple cyclic shape memory analysis. The focus of this work that is to combine the thermal insulation ability of porous materials with the thermal energy storage ability of PCMs, can effectively reduce the heat conduction meanwhile can maintain the stability of internal temperature contributed to reducing energy consumption, applying in food transportation, building energy conservation and other fields.

2D Tantalum Disulfide Reduction Strategy Customized Ta2O5/rGO Heterointerface Aerogel Toward Boosting Electromagnetic Wave Absorption and Flame Retardancy.

The exceptional and substantial electron affinity, as well as the excellent chemical and thermal stability of transition metal oxides (TMOs), infuse infinite vitality into multifunctional applications, especially in the field of electromagnetic wave (EMW) absorption. Nonetheless, the suboptimal structural mechanical properties and absence of structural regulation continue to hinder the advancement of TMOs-based aerogels. Herein, a novel 2D tantalum disulfide (2H-TaS2) reduction strategy is demonstrated to synthesize Ta2O5/reduced graphene oxide (rGO) heterointerface aerogels with unique characters. As the prerequisite, the defects, interfaces, and configurations of aerogels are regulated by varying the concentration of 2H-TaS2 to ensure the Ta2O5/rGO heterointerface aerogels with appealing EMW absorption properties such as a minimum reflection loss (RLmin) of -61.93dB and an effective absorption bandwidth (EAB) of 8.54GHz (7.80-16.34GHz). This strategy provides valuable insights for designing advanced EMW absorbers. Meanwhile, the aerogel exhibits favorable thermal insulation performance with a value of 36mW m-1 K-1, outstanding fire resistance capability, and exceptional mechanical energy dissipation performance, making it promising for applications in the aerospace industry and consumer electronics devices.

Impact of different matrix systems on mechanical, thermal, and electrical properties of carbon fiber reinforced epoxy resin matrix composites

AbstractCarbon fiber reinforced epoxy resin matrix composite is one of the most important composite materials in the world. Many researchers have conducted a lot of research on epoxy resin matrix systems in recent years, mainly to improve the problem with the short curing time of the matrix system and epoxy resin's high viscosity. The final aim is to enhance various aspects of composites' performance and optimize the production process. A new type of water dispersed epoxy resin matrix system is investigated in this paper and the target is to optimize the mechanical, thermal, and electrical performances of the composites with the water dispersed epoxy resin matrix by varying different doping particles and different resin/catalyst ratios. Through a series of experiments, it is evident that varying the ratio of resin to catalyst in the matrix system will not significantly improve the mechanical as well as thermal properties of the composites. However, increasing the amount of catalyst in the matrix system can greatly improve the electrical properties of its composite samples. In addition to this, the addition of doping particles to the matrix systems has the effect of slightly enhancing the tensile modulus, thermal conductivity, and electrical conductivity of their composites.Highlights A new water‐dispersed epoxy resin matrix system improves processing technology. Increasing amount of catalyst in the matrix system improves electrical resistivity. Adding particles to matrix systems has a slight effect on different properties.

The Impact of Roughness and Partitions In Thermal Convection to Enhance the Heat Transport

Abstract This investigation delves into the profound influence of adiabatic partitions on heat transport within a square Rayleigh-Benard (RB) convection enclosure characterized by surface roughness on the lower hot and upper cold plates. These surface irregularities manifest as a rectangular base and a triangular apex. Employing two-dimensional (2D) direct numerical simulations across a Rayleigh number (Ra) range of 106 to 108 and a Prandtl number (Pr) of 1, our study focuses on strategically positioned adiabatic partitions between successive roughness elements. Notably, we uncover a significant enhancement in heat transport with the introduction of partition boards between consecutive roughness elements. As the number of partitions increases from one to four, the heat flux experiences a remarkable augmentation, reaching 2.3 times that of the classical square RB configuration. This enhancement arises from the breakdown of large-scale rolls into multiple rolls, a phenomenon intensified by increased partition height. Intriguingly, configurations featuring roughness with partitions exhibit a 2.7-fold increase in heat flux compared to the classical square RB setup. The interplay of surface roughness and partitions contributes to this improvement, with optimized gap distances between the conduction plate and partition heightening local velocity, thinning the thermal boundary layer, and augmenting overall heat flux. This study sheds light on the synergistic effects of adiabatic partitions and surface roughness in RB convection, indicating the potential for tailored design strategies involving partitions and surface modifications to optimize thermal performance across various applications.

Enhanced solar energy utilization of thermal energy storage tanks with phase change material and baffle incorporating holes

In response to the pressing need for more efficient thermal energy storage solutions, this study investigates the strategic implementation of baffles in phase change material (PCM) tanks to enhance thermal performance. PCM offers a promising solution for efficient thermal energy storage (TES); however, ensuring uniform temperature distribution inside the tanks remains challenging. Horizontal baffles with holes of varying diameters were introduced in Tanks 02, 03, and 04, while an inclined baffle with holes was used in Tank 05. The Tank 06 benefitted from an inclined baffle with holes of different diameters. A comprehensive analysis of all Tanks was evaluated by assessing PCM and water heat flux, PCM and water static enthalpy, Richardson number, velocity vectors, temperature, and liquid fraction contours. The results demonstrated that significant improvements were achieved with the addition of baffles. Tank 01, without a baffle, exhibited a melting time of 2860 s. However, the introduction of baffles resulted in reduced melting times for Tanks 02 to 06: 2360 s (17.48 %), 2350 s (17.83 %), 2400 s (16.08 %), 2320 s (18.88 %), and 2240 s (21.67 %), respectively; which led to enhance TES efficiency, and a quicker energy storage process. The study also includes a comprehensive economic analysis, evaluating the total cost (Ctotal) and performance-economic ratio (Pc). Tank 06 shows superior economic performance, with a Pc value of 0.26 despite a slightly higher cost than Tank 01 by $2 USD. These findings highlight the baffle design’s effectiveness in achieving better heat transfer and uniform temperature distribution within PCM tanks, making them more efficient for TES applications.

Prabhakar fractional model for natural convection flow of kerosene oil based hybrid nanofluid containing ferric oxide and zinc oxide nanoparticles

Based on enhanced thermal performances of hybrid nanomaterials, various multidisciplinary applications of such hybrid nanofluids are presented in the cooling processes, HVAC systems, energy sectors, boosting the energy sources, automotive thermal systems etc. Owing to such motivated applications in mind, different mathematical models are developed. However, the thermal analysis for hybrid nanofluid with help of fractional models is not focused properly. Therefore, the objective of current research is to develop a mathematical model for enhancement of heat transfer by using the hybrid nanofluid. The decomposition of zinc oxide (ZnO) and ferric oxide (Fe3O4) with kerosene oil base fluid is used for identifying the thermal reflection of hybrid nanofluid. The motivations to improve the thermal prospective of kerosene oil is due to its importance in the energy sources as a fuel and industrial applications like solvent, degreaser and operation of air craft. The vertical moving surface is used to initiates the flow. The natural convective flow is further perturbed with applications of mixed convection effects. The evaluation for heat transfer is inspected by incorporating the external heat source. The mathematical modelling of problem is presented via fractional expressions. The Prabhakar scheme is used to develop the analytical expressions. The accuracy of implemented scheme is inspected by comparing the numerical data computed via Zakian, Stehfest and Tzou's algorithms. The significance of problem is visualized in view of involved parameters like fractional parameters, nanoparticles volume fraction, Grashof number and Prandtl number. The results claim that the enhancement in heat transfer due to decomposition of zinc oxide and ferric oxide nanoparticles is more exclusive as compared to simple nanofluid. The heat transfer enhanced due to nanoparticles volume fraction.

Study of Heat Transfer Characteristics of Heat Pipe Using Water as a Working Fluid

Heat pipes are efficient and versatile thermal management devices widely used in various applications to transfer heat. This study focuses on investigating the heat transfer characteristics of a heat pipe employing de-ionized water as the working fluid. The experiment involved analyzing the thermal performance, heat transport capacity, and operational limits of the heat pipe. The aim of the experiment is to assess the heat pipe's performance under different operating conditions, such as varying heat loads. The study aimed to understand the heat transfer limitations and advantages of water-based heat pipes, which can have practical implications for numerous applications, such as electronics cooling, solar thermal systems, and space technology

Comparative study of thermal performance improvement of parabolic trough solar collector using different heat transfer fluids, economic and environmental analysis of power generation

The use of nanofluids (NFs) as heat transfer fluids (HTFs) is one way of improving the thermal performance of parabolic trough solar collectors (PTSCs). This study presents a comparative analysis of the thermal performance of a PTSC using nanofluids as HTF. Two categories of nanoparticles (NPs) (green and conventional) and two base fluids (water and Syltherm 800) giving eight nanofluids are used in a one-dimensional quasi-static thermal model, simulated from a numerical code written in Matlab. After numerical validation of the proposed model, the comparative analysis in static and dynamic regimes linked to solar radiation shows that green NPs present not only differentiated positive but also negative effects on thermal performance depending on the base fluids compared to conventional NPs, and that the combination of green nanoparticles with high thermal capacity base fluids presents more positive than negative thermal effects. The impact of conventional NPs is more significant with water, at around 0.005 MWh, than with Syltherm 800, which averages around 0.002 MWh. The use of HTF configurations based on Syltherm 800 increases production by around 1 MWh more than that of water. HTF configurations based on Syltherm 800 generate around $0.004/kWh less than water on average. HTFs based on Syltherm 800 produce around 7.5 kgCO2/year more than water.

A novel micro-combustor with dual-inlets hedging and center opening for enhancing comprehensive performance of micro thermophotovoltaic system

Micro-combustor outer wall temperature uniformity is a critical bottleneck in the widespread application of micro thermophotovoltaic system. In this study, we proposed a novel micro-combustor with dual-inlets hedging and center opening structure to improve the wall temperature distribution and achieve a stable and high-energy of micro thermophotovoltaic system output, and we applied the overall performance evaluation criteria to evaluate the performance of micro thermophotovoltaic system comprehensively. Initially, we conducted a comparative analysis among the traditional micro-combustor, the single rectangular center opening, and the double rectangular center opening micro-combustor. The findings indicate that the double rectangular center opening micro-combustor exhibits superior comprehensive thermal performance, showcasing a mean outer wall temperature and temperature standard deviation of 1362.05 K and 32.77 K, bringing better temperature uniformity. Then, the center opening distance of the double rectangular center opening micro-combustor was optimized from 0.5 mm to 3.0 mm, the results reveal that the double rectangular center opening micro-combustor with a distance of 2.5 mm possesses the best comprehensive performance, specifically, temperature standard deviation and overall performance evaluation criteria values of 23.17 K and 4.882. Ultimately, the effect of inlet velocity on the thermal performance was investigated, revealing that an increase in inlet velocity stimulates the output energy, but concurrently diminishing the energy conversion efficiency, leading to a reduction in overall thermal performance. This study introduces a novel concept for designing micro-combustor structures for promoting overall performance of micro thermophotovoltaic systems.

Efficient Emission of Highly Polarized Thermal Radiation from a Suspended Aligned Carbon Nanotube Film.

A polarized light source covering a wide wavelength range is required in applications across diverse fields, including optical communication, photonics, spectroscopy, and imaging. For practical applications, high degrees of polarization and thermal performance are needed to ensure the stability of the radiation intensity and low energy consumption. Here, we achieved efficient emission of highly polarized and broadband thermal radiation from a suspended aligned carbon nanotube film. The anisotropic nature of the film, combined with the suspension, led to a high degree of linear polarization (∼0.9) and great thermal performance. Furthermore, we performed time-resolved measurements of thermal emission from the film, revealing a fast time response of approximately a few microseconds. We also obtained visible light emission from the device and analyzed the film's mechanical breakdown behavior to improve the emission intensity. Finally, we demonstrated that suspended devices with a constriction geometry can enhance the heating performance. These results show that carbon nanotube film-based devices, as electrically driven thermal emitters of polarized radiation, can play an important role for future development in optoelectronics and spectroscopy.

Porous interlocking assembly: performance-based dry masonry construction with digital stereotomy

Architected porosity in masonry structures can be created by transforming stock materials into a lattice of interlocking units through an automated batch process. Porous masonry forms numerous enclosed cavities for thermal performance and reduces material usage while maintaining structural integrity. This work investigates the potential and limits of digital tectonics of porous masonry through a complete process of design, manufacturing, and construction. The confluence of digital fabrication with tectonic exploration opens new dimensions unattainable by traditional stereotomy. Interlocking materials inspired by Abeille vault and digital stereotomy have made rapid progress. Following the theory of poetic construction, this work proposes that masonry construction should evoke visual or haptic enhancement through the fulfillment of pragmatic functions. We formulated a design challenge for a confined dry masonry wall for the envelope of the 2226 building. It assumes batch-cutting bespoke units out of large blocks of high-strength foam. Through a process of cutting and reassembling, the stock material is topologically expanded into a porous structure. A series of prototypes were developed to explore novel articulation, structural and thermal performance, and economical manufacturing. One can perceive the logic of porous construction through visual and haptic empathy. The materialization process interacts with the design masonry units and the interlocking mechanism. For future practice in masonry, the porosity should be planned at multiple scales (molecular scale, aggerate scale, construction scale) across the life cycle of the material.

Startup and Multiphysics Analysis of a Compact kW-Class Thermal Spectrum Microreactor

Self-regulating compact nuclear microreactor concepts are being developed for use in space and at terrestrial remote sites. The current emphasis is on the development of high-assay low-enriched uranium–fueled reactors that rely on metal hydrides to achieve size, specific weight, and power parity with the legacy highly enriched uranium systems. In the case of terrestrial applications, metal hydride–moderated systems can also improve economic feasibility. The neutronic design of metal hydride–moderated high-temperature reactor cores is complicated by the need to optimize and synchronize delayed spatial and temporal reactivity feedback from outer reflectors. Zebra is a thermal spectrum proof-of-principle core designed for demonstrating the reactor dynamics of hydride-moderated spectrum reactors, which is studied in this work. The reactor, including the fuel, yttrium hydride moderator, heat pipes, central control rod, structural supports, and the beryllium reflector, weighs ~425 kg. The design shares several features common with nuclear criticality test geometries routinely used in National Criticality Experiments Research Center (NCERC) experiments such that a prototype of the reactor can be readily assembled and tested. Additional features, such as heat pipes and hydrogen barrier clads, were added to minimize the potential for large thermal gradients that in turn could induce hydrogen loss or structural deformation during extended periods of operation at ~1000 K. In this work, normal and off-normal state performance of the Zebra rector core was analyzed using MCNP and Abaqus-based Reactor Multiphysics (MARM) software. Up-to-date nuclear, thermal, and mechanical performance data were used to characterize the performance of the yttrium hydride moderator. Steady-state analyses established that at a postulated power between 20 and 50 kW(thermal), the reactor core is nearly isothermal irrespective of quality of conduction coupling between heat pipes and fuel plates. Additionally, heat pipe failure modes, including simultaneous failure of all heat pipes in a quadrant of a reactor, were examined to bound the maximum credible temperature spike in the reactor core for extreme off-normal operating conditions. Finally, we detail the startup design challenges for the hydride-moderated thermal core, and analyze load-following cases to achieve “self-regulation” using the Dynamic Analysis of Reactor Transients module of MARM. The reactor is self-regulating with a reactivity temperature coefficient of ~−1 pcm/K at the operating point based solely on nuclear cross-section feedback. It can be further strengthened using additional spectral shift neutron absorbers and incorporating design features that enhance core expansion. This work captures that hydride-moderated systems are feasible for various self-regulating applications once systematic checks are verified in order to achieve a well-engineered core design.

Optimization of heat transfer rate of trihybrid nanofluid Embedded between two horizontal coaxial cylinders by RSM

Heat pipes are heat transfer devices that carry heat from one point to another efficiently. The thermal conductivity and heat transfer performance of the heat pipe can be increased by integrating nanofluids, making them appropriate for applications such as electronics cooling, spacecraft thermal management, and heat recovery systems. The suggested work is being carried out for the approximate solution of tri-hybrid nanofluid (copper (Cu), silver (Ag) and graphene oxide (GO)) flow between two horizontal coaxial cylinders. The inner cylinder is rotating with constant velocity and the outer cylinder is fixed. Moreover, the flow is under the influence of magnetic field. The system of governing partial differential equations is converted into a set of non-linear ordinary differential equations by incorporating the suitable similarity transformation and then solved numerically by employing Runga-Kutta 4th order technique. Response surface methodology (RSM) is also incorporated in order to optimize the heat transfer rate by the various combinations of the physical parameters involved in the study. The study revealed that the temperature of the nanofluid increased by raising the strength of the Reynolds number and melting parameter. From optimization technique RSM it came to know that the heat transfer rate reached its peak value when the strength of the Reynolds number and concentration of the nanoparticle of the fluid is higher than normal.

Development and performance evaluation of paddy straw based insulating block composite for low temperature storage application

The study focuses on the conversion of crop residues into thermal insulation materials, to gain better utility with value addition. Such applications will divert the paddy straw to useful purposes, leading to reduction in the open field burning of paddy straw in various developing countries. The process was optimized for manufacturing of insulating block composite and evaluating the mechanical and thermal performance of the same. Properties like compressive strength, internal bonding strength, density, porosity, and thermal conductivity were studied for the block. The optimum physical and mechanical properties were observed as moisture content 8–10 %, a block density 450–500 kg/m3, porosity 70 % with particle size of 8–15 mm. The mixture ratio of block was optimized as paddy straw 574.9 g, clay 840 g, and seed lac 260 g with thermal conductivity, compressive strength, bonding strength, and porosity as 0.08 W/m K, 1.19 MPa, 0.028 MPa, and 70.7 %, respectively, using Response Surface Methodology. An eco-friendly, economical and sustainable technological value addition for paddy straw was obtained and used for insulation purposes in cold storages as well as drying chambers. Paddy straw insulating block can also be utilized in combination with conventional insulation materials.