Thermophysical Properties Of Materials Research Articles

Validation of 3D thermal simulations of the Double C Block, a novel composite masonry unit, using in-situ U-value measurements

Energy efficient building envelopes, particularly innovative prefabricated building components, can significantly contribute to lower the building industry energy-related emissions. In this research the composite masonry unit Double C Block (DCB) is quantitatively tested by means of three-dimensional thermal simulation validated by in-situ U-value measurements carried out in both summer and winter conditions.The simulations were enhanced by the experimental measurement of the dry thermo-physical material properties (specific heat capacity, thermal conductivity, and density) in laboratory conditions for both concrete and polyurethane. The samples were extracted from real-scale DCB prototypes. Furthermore, site-specific boundary conditions of Malta — representative a case study of a Mediterranean climate − were utilised in the simulations. Both laboratory and in-situ assessments of thermal transmittance, or U-value, had their uncertainty specified as part of the calculations.The validation exercise was performed by means of hourly recorded surface temperature and the selected indices were the root mean square error and mean absolute error. Results showed that these indices were within the recommended accuracy thresholds during both winter and summer assessments. For the hourly-based heat flux measurements, the mean bias error and coefficient of variation of the root mean square error were found lower than values reported in literature, thus supporting the robustness of the overall simulation outputs. Hence the 3D CVM simulation was experimentally validated by in-situ assessments.The convergence value of the experimental U-value provided respectively 1.51 ± 0.20 W/(m2K) (winter) and 1.44 ± 0.19 W/(m2K) (summer). Then, the validated 3D CVM model was adapted to calculate the theoretical U-value of DCB, using monthly values of recorded surface temperatures obtained by the test cells (in both seasons). The predicted thermal transmittance was of 1.47 W/(m2K), in both conditions, and this almost matches the above-mentioned experimental assessments and thresholds established in previous works.

A double-helix plane winding sensor with wire using transient plane source method

The transient plane source (TPS) method is widely used to measure thermophysical properties of various materials, and the high-precision double-helix sensor is a key technology. A novel sensor using an efficient, simple, and low-cost lacquered micron-wire-wound process is proposed to replace traditional complex micro- and nano-etching processes. The TPS test platform was built based on the Wheatstone Bridge theory. A new sensor sample of diameter 5.377 mm was wound with an enameled copper wire of diameter 0.063 mm. Owing to the characteristics of the process, a 1-mm round hole was bored inside the sensor. An analytical solution for the concentric ring heat transfer model of the sensor with a central circular hole structure was derived, and a two-dimensional concentric circle simulation model of the sensor was established. As the number of turns decreased, the average error between the analytical solution of the concentric ring model with a large center hole (LHAS) and that of the traditional concentric circle model (TAS), as well as LHAS and the simulation model, gradually increased. The maximum relative errors between LHAS and TAS, as well as between LHAS and the simulation model, were 23.69 % and 0.1 %, respectively, and the average errors of the absolute maximum were 11.86 % and −0.06 %, respectively. The LHAS exhibited excellent accuracy because of the structural characteristics of the novel sensor. The accuracy of LHAS has been validated by simulation and hot wire method. Temperature rise data of high-borosilicate glass and polytetrafluoroethylene samples at different powers were obtained. The thermal properties of the samples were determined by fitting LHAS and TAS data. The thermal conductivity errors measured by LHAS were smaller than those measured by TAS, the thermal conductivity and thermal diffusivity errors were less than 3.5 % at different powers, and the measured repeatability errors were less than 1 %, indicating the good application prospect of the proposed model.

“Skeleton”, diamond-silicon carbide composite material

The paper presents a review of exploratory and applied research carried out in Russia since the 1990s in the field of diamond-silicon carbide composite materials. A new class of isotropic ceramic materials has been created—diamond-silicon carbide composites, which have received the name Skeleton. The physical, mechanical, thermophysical and functional properties of materials depending on their composition are discussed. It is shown that the studied materials simultaneously combine mechanical, thermophysical and functional properties at a level not achieved in other materials, which allows the use of the Skeleton material in various fields of engineering.

Experimental enhancement study of thermophysical properties of ternary carbonate phase change material with multi-dimensional nanoparticles

Carbonates have great application potential as heat transfer and thermal energy storage media in the development of future phase change materials. This paper gives thermophysical properties enhancement study on ternary carbonates in liquid state by adding aluminum oxide nanoparticles, multi-walled carbon nanotubes, graphene nanosheets, and experimentally evaluate the performance strengthen ability of multi-dimensional nanoparticles. The thermal diffusivities and specific heats of the prepared samples by the water solution method are determined using the laser flash technique and the differential scanning calorimetry at liquid state, respectively. A thermogravimetric analyzer is deployed for evaluate the high-temperature thermal stability of the composite ternary carbonates. Scanning electron microscopy and Fourier transform infrared spectroscopy techniques are utilized to examine the surface morphologies and chemical structures of the samples. The results indicate that there is a cooperative reinforcement impact on the thermophysical properties of ternary carbonate by utilizing zero-dimensional Al2O3 nanoparticles and two-dimensional graphene nanosheets, with a maximum improvement of 56.7 % for thermal conductivity, and 10.3 % for specific heat, which is apparently larger than adding any single nanoparticle. The composites exhibit superior thermal cycling stability after low-high temperature experiment, and samples can maintain thermal stability until 700 °C in the thermogravimetric analysis.

Enhancing thermo-physical properties of hybrid nanoparticle-infused medium temperature organic phase change materials using graphene nanoplatelets and multiwall carbon nanotubes

Phase change materials (PCMs) have emerged as an intriguing option for the storage of thermal energy because of their remarkable capacity to store latent heat. However, the practical application of these materials is hindered by their low thermal conductivity and limited photo-absorbance. For this investigation, graphene nanoplatelets (GNP) and multiwall carbon nanotubes (MWCNT) hybrid nanoparticles were disseminated in RT-54HC organic PCMs at different weight fractions. The nanoparticles were incorporated into the base PCMs using a melt blending technique. Based on the findings, one combination of GNP to MWCNT in a 0.25:0.75 ratio has shown the highest thermal conductivity, with an increase of 40% (0.28 Wm−1 K−1) compared to other hybrid combinations. This breakthrough could potentially open new avenues in the field of thermal energy storage. The chemical stability of the hybrid nanoparticle dispersed composites was assessed through FTIR analysis. In addition, the composites exhibited excellent thermal stability, maintaining their structural integrity even at temperatures as high as 300 ℃. The melting temperature of the composites also showed minimal variation. Based on the evaluation of latent heat enthalpy, the organic PCM known as base RT-54HC demonstrated a heat storage capacity of 230 J/g. However, the composites exhibited a slight decrease in latent heat with increasing nanoparticle weight fraction. In addition, the composite with added hybrid nanoparticles demonstrated an increase in optical absorbance, accompanied by a decrease in transmissibility. Therefore, the hybrid nano-enhanced composites have demonstrated enhanced thermo-physical properties, making them not only suitable but also highly promising for use in applications with mid-range melting temperatures.Graphical

Machine learning-based price prediction for thermal insulation materials: A holistic approach integrating thermophysical, technical, and environmental attributes in the Greek construction market

This study underscores the pressing need to accelerate the energy transition in existing housing to meet the EU’s decarbonization targets. It examines the correlation between thermophysical, technical, and environmental properties of thermal insulation materials and their commercial prices in Greece. Utilizing a dataset of 500 products from technical leaflets, Environmental Product Declarations (EPDs), and market surveys, the study developed six prediction models for material retail prices. A novel aspect of this research lies in quantifying the economic ramifications of insulation material properties through supervised machine learning (ML) techniques. Accurate price prediction models can provide practical applications across stakeholders, including cost estimations for designers, customized recommendations for homeowners, pricing tools for traders, optimization of manufacturing processes, support for policymaking, educational resources for construction professionals, and improved energy efficiency certification payback estimations. Feature analysis showed that total Global Warming Potential (GWP) significantly influences material prices. The Ensemble of Trees and Gaussian Process Regression (GPR) models demonstrated robust performance, with high R2 values of 0.95 in validation and 0.95/0.93 in test sets, indicating reliability without overfitting. Recommendations include integrating more predictors, collaborative model approaches, regular updates, and adopting federated learning techniques for enhanced data privacy and stakeholder cooperation.

Development, characterization and themo-physical analysis of energy storage material doped with TiO2 and CuO nano-additives

The paper presents the results of an experimental investigation on chemical stability, surface morphology, and thermo-physical properties of phase change material integrated with nano additives. The research aims to evaluate impact of varying nano-particle concentration on thermal performance of phase change material. The phase change material magnesium dichloride hexahydrate and potassium chloride mixed in different mass ratio along with different wt% concentration of nano-additives titanium dioxide and copper oxide to prepare novel phase change material. Characterization methods such as Fourier Transform Infrared Spectroscopy, Scanning electron microscope, Energy-dispersive X-ray analysis, and Differential scanning calorimeter analysis were employed. The Fourier transform infrared spectra indicated physical interactions between phase change material and nano-additives, while Energy-dispersive X-ray analysis confirmed elemental composition, and Scanning electron microscope demonstrated uniform distribution. The improved thermal properties of samples were reflected in their phase change enthalpy (284.57 J/g to 324.63 J/g), minimal energy loss (0.91 %–2.96 %), and low supercooling (0.3 %–5.26 %). Notably, doping with 1.5 wt% of titanium dioxide and copper oxide enhanced thermal conductivity by up to 117.07 % and specific heat capacity by up to 48.09 %. The introduction of nanoparticles significantly improves heat transfer characteristics, resulting in enhanced energy retention, reduced energy loss during phase transitions, decreased supercooling, and increased physical stability. These results suggest that optimized phase change material with nano-additives is highly effective for applications requiring stable and efficient thermal management.

On the Use of a Chloride or Fluoride Salt Fuel System in Advanced Molten Salt Reactors, Part 3; Radiation Damage

Structural materials in fast reactors with harsh radiation environments due to high energy neutrons—compared to thermal reactors—potentially suffer from a higher degree of radiation damage. This radiation damage can change the thermophysical and mechanical properties of materials and, as a result, alter their performance and effective lifetime, in some cases leading to their disintegration. These phenomena can jeopardize the safety of fast reactors and thus need to be investigated. In this study, the effect of radiation damage on the vessels of molten salt fast reactors (MSFR) was evaluated based on two fundamental radiation damage parameters: displacement per atom (dpa) and primary knock-on atom (pka). Following the previous part of this article (Parts 1 and 2), an iMAGINE reactor core design (University of Liverpool, UK—chloride-based salt fuel system) and an EVOL reactor core design (CNRS, Grenoble, France, fluoride-based salt fuel system) with stainless steel and nickel-based alloy material vessels, respectively, were considered as case studies. The SPECTER and SPECTRA-PKA codes and a PTRAC card of MCNPX, integrated with a module which has been developed in MATLAB, named PTRIM and SRIM-2013 (using binary collision approximation), were employed individually to calculate and compare dpa and PKA (this master module containing all three tools has been appended to the iMAGINE-3BIC package for future use during reactor operations). Additionally, SRIM-2013 was applied in a 3D simulation of a radiation damage map on a small sample of vessels based on the calculated PKA. Our results showed a higher degree of radiation damage in the iMAGINE vessel compared to the EVOL one, which could be expected due to the harder neutron flux spectrum of the iMAGINE core compared to EVOL. In addition, the nickel alloy vessel showed better radiation damage resistance against high energy neutrons compared to the stainless steel one, although more investigations are required on thermal neutrons and alloy corrosion mechanisms to determine the best material for use in MSFR vessels.

Faster R-CNN-CA and thermophysical properties of materials: An ancient marquetry inspection based on infrared and terahertz techniques

The demand for non-invasive inspection (NII) is ever-increasing in the field of cultural heritage conservation. NII is a two-step procedure, first of data acquisition and second of defect detection. Stand-alone imaging techniques such as infrared thermography (IRT) are often insufficient for performing a complete remote analysis and diagnosis of historic structures and art pieces that are of very high cultural value. On this point, an emerging optical inspection method, terahertz time-domain spectroscopy (THz-TDS), is herein employed to provide more details of deeper defects. The imaging results from THz-TDS and IRT are compared and analyzed by employing advanced image processing methods. Next, to achieve automatic inspection of the test sample, which is an ancient marquetry, a Faster R-CNN with coordinate attention (Faster R-CNN-CA) is proposed and fitted with data from two different sources. Worth noting is that, in order to populate sufficient data for training, samples are simulated using finite element analysis and finite difference time domain method. The experiments demonstrate that the mean average precision of the Faster R-CNN-CA model improves by 6.09% over the traditional Faster R-CNN model.

Innovative silica aerogel fiberglass walls and roofs: A path to lower carbon emissions and higher energy savings

ABSTRACT Buildings account for a significant portion of global energy use and consumption. Buildings have substantial energy consumption due to the use of heating, ventilation, and cooling systems. It is evident that the insulation materials used in the design of building envelopes can efficiently reduce the cost of air conditioning by reducing external heat gains and losses. Additionally, the use of environmentally friendly and cost-effective can be beneficial from an environmental standpoint. This paper aims to evaluate the potential for cost savings in the air conditioning of buildings incorporated with silica aerogel fiberglass insulation in hollow concrete bricks (wall) and hollow roof tile (roof). Silica aerogel fiberglass insulation is extensively used for heat insulation purposes, including building insulations, due to its superior thermal insulation and flame retardant properties. The thermo-physical properties of silica fiberglass insulation and building materials were determined experimentally as per ASTM D 5334 standards. Twenty distinct building design concepts are investigated in this study, each featuring insulation-integrated concrete blocks composed of silica aerogel fiberglass: (WEM1) insulation layer in the outer side, (WEM2) insulation layer in the center, (WEM3) insulation layer in the inner side, (WEM4) insulation layers in the outer-middle, (WEM5) insulation layers in the middle-inner, and (WEM6) insulation layers in the outer-inner sides. Additionally, two arrangements of insulation-stuffed roof tiles, REM1 above the RCC and REM2 below the RCC. In addition, novel building designs integrated with insulation were analyzed numerically, related to environmental conditions that refer to two different scenarios in India (hot dry and composite climates). Thermo-economic analysis of novel wall and roof designs with silica fiberglass insulation materials on air-conditioning costs, carbon dioxide emissions, and payback time are compared with conventional roof and wall patterns. The thermo-economic analysis was carried out based on the number of degree-hours of heating and cooling to determine the building’s annual energy usage. The building model arrangement (WEM6-REM1), which consists of an insulation composite wall (WEM6) and insulation roof tile (REM1), demonstrated the greatest annual air conditioning cost savings of 3.4 $/m2/year and 1.74 $/m2/year when compared to conventional building design for climatic conditions of Kurnool and Gauhati. The building model arrangement (WEM6-REM1) composed of silica fiberglass aerogel insulation exhibits the highest reduction in carbon emissions of 65 kg/kWh and 33 kg/kWh, when compared to conventional building design analyzed in both hot-arid; (Kurnool) and composite (Gauhati) climatic conditions. The placement of insulation in the roof alone (REM1) has the shortest payback duration of 2.15 years. The results of this study point to a viable approach to enhancing building design decision-making and narrowing the performance gap in sustainable and energy-efficient strategies.

Impact of key parameters on the numerical modelling of Phase-Changing phenomena in horizontal latent heat thermal energy storage

Numerous studies have focused on numerical investigations of the performance of the shell-and-tube Latent Heat Thermal Energy Storage (LHTES). However, many studies have often overlooked rigorous assessment of key parameters’ impact on the numerical simulation accuracy relative to experimental results. Therefore, this paper aims to develop a numerical model to track the solid–liquid interface during phase-changing phenomena in a horizontal LHTES system and investigate the effects of key parameters on the simulation accuracy. For this purpose, an experimental facility was built, and the numerical model was developed in ANSYS using the enthalpy-porosity method. During the simulation of the computational model, consideration was given to thermophysical properties (constant versus variable) of phase change material, contact resistance (zero versus nonzero), and the mushy zone constant (105, 5 × 105, and 106). The simulation results were compared with experimental data obtained from the in-house studies. The results showed that, compared to using constant thermophysical properties, employing variable thermophysical properties more accurately tracked the solid–liquid interface during melting. It substantially improved the simulation accuracy with a Root Mean Square (RMS) error less than 5 % for most of the temperature-measuring locations. Conversely, variable properties did not make a significant difference in the solidification process. The contact resistance due to the air gap was determined to be 0.035 m2·K/W for the current study. Furthermore, incorporating this resistance resulted in a more accurate approximation of the solid–liquid interface during melting, with RMS errors below 5 % across all locations. The study comparing different mushy zone constants recommended utilizing a slightly higher value of 106 for melting, whereas its impact on solidification was found to be insignificant.

Inverse problem method application in building physics numerical optimization: new insight into ideal envelope properties determination

ABSTRACT Building thermal design optimization is pivotal for energy efficiency and built environment improvement. The optimal thermophysical properties for building walls remain ambiguous. This ambiguity stems from the constraints of traditional building physics, which: (1) disjoins the enhancement of wall thermal performance from the building service system management; and (2) relies on the forward method that fails to identify the ideal variable thermophysical property, the solution to which is inherently a function. This study elucidates the optimal temperature-dependent volumetric specific heat ( ρ c p ( t ) ) and thermal conductivity ( k ( t ) ) through the inverse problem and variation method. Illustrative example indicates that the optimal ρ c p ( t ) closely resembles a combination of two ‘ δ ’ functions, while the optimal k ( t ) mirrors a square wave function. Utilizing these ideal thermophysical properties, the building energy consumption can be significantly reduced by 77.1% with the optimized ρ c p ( t ) and 79.9% with the optimized k ( t ) . The ideal thermophysical properties for active buildings differ significantly from those recommended for passive buildings, underscoring that minimal energy consumption does not necessarily imply minimal discomfort. Therefore, the thermophysical properties of active and passive buildings should be optimized distinctly. This research offers valuable insights for defining ideal thermophysical properties of active building walls and construction materials.

Thermophysical Characterization of Materials for Energy-Efficient Double Diaphragm Preforming

The Double Diaphragm Preforming (DDPF) process uses vacuum pressure and heat to pre-shape dry carbon fabric reinforcements between flexible diaphragms in liquid composite molding (LCM). Accurate modeling of heat transfer within DDPF requires knowledge of the thermophysical properties of the constituent materials under processing conditions. This study investigates the thermal conductivity of silicone diaphragms and carbon fabrics with embedded thermoplastic binder webs, utilizing transient plane source (TPS) and modified transient plane source (MTPS) methods, respectively. Additionally, the specific heat of silicone, carbon fibers (both chopped and powdered), and binder were measured using differential scanning calorimetry (DSC). Mixed samples comprising chopped fibers with 1.8 wt% binder and powdered fibers with 3.6 wt% binder was also analyzed with DSC. This study also examined the influence of reheating cycles on the specific heat of carbon fiber—3.6 wt% binder samples—and the effect of compaction and vacuum on the thermal conductivity of carbon fabrics with an embedded binder. While silicone exhibited linear-specific heat behavior, the thermoplastic binder showed non-linearity due to phase change. The combined carbon fiber-binder samples demonstrated slight non-linear specific heat variations depending on reheating cycles. The thermal conductivity of the fabric preforms decreased with the addition of thermoplastic binder and under vacuum-compaction conditions. The established temperature-dependent specific heat relationships and thermal conductivity provide valuable data for optimizing DDPF preforming parameters and enhancing energy efficiency in composite manufacturing.

Measurement of thermal conductivity of thermally reactive materials for use in pyrolysis models

AbstractPyrolysis models are used in the fire science field to simulate the thermal decomposition of materials. These models require knowledge of the kinetic and thermodynamic parameters of an assumed reaction mechanism, and the thermophysical properties of the virgin material and product species. Standard test methods exist for measuring the thermal conductivity of nonreactive materials, but to date no suitable method exists that is compatible with contemporary pyrolysis models and is applicable to thermally reactive materials. In the present study, a modified methodology was presented and evaluated to address this need. The methodology involves a preliminary assessment of thermal stability, followed by a series of tests including: thermogravimetric analysis, differential scanning calorimetry, and laser flash analysis. Once a reaction mechanism has been identified, gram‐scale samples of the virgin and stable product species are isolated and independent measurements of thermal conductivity of those species are obtained. The methodology was applied to eucalyptus fiber hardboard, for which a complete set of property data for pyrolysis modeling was obtained. A pyrolysis experiment was then conducted, and that experiment was simulated using a pyrolysis model parameterized with the measured property data. Model predictions of the mass loss rate and temperature rise of a hardboard sample exposed to radiant heat flux of 35 and 60 kW m−2 were found to be a good match to measurements. These results demonstrate the suitability of the property data, the pyrolysis model, and the utility of this approach. This work will serve as a basis for property determination in future pyrolysis studies.

Enhancement of Thermo-Physical Properties of Form-Stable Nano-Enhanced Phase Change Materials: Advancing Maritime Sustainability

This paper explores the application of novel, form-stable eutectic mixtures in thermal energy storage systems for maritime environments. These advanced materials present a significant leap forward, addressing critical challenges faced by conventional phase change materials (PCMs) in marine environments. The stability, eliminating leakage and fluidity issues encountered with liquid PCMs are ensured by incorporating 2-hydroxypropyl ether cellulose (HPEC) as a gelling agent. Additionally, the thermal properties and heat transfer capacities were significantly enhanced, and eventually, overall system efficiency improved by including nano-graphene platelets (NGPs). Notably, NGPs effectively suppress supercooling, minimizing energy losses and guaranteeing consistent performance at elevated temperatures. Further, the eutectic mixture demonstrates exceptional durability through an accelerated thermal reliability test, guaranteeing optimal performance over a projected seventy-year lifespan. This enhanced thermal performance, and enduring stability combination establishes the form-stable eutectic mixture with NGPs as an up-and-coming solution for diverse maritime applications requiring efficient and reliable thermal energy storage. This research provides a compelling case for implementing form-stable eutectic mixtures with NGPs in maritime thermal energy storage systems. Its superior performance and sustainability offer significant advantages for diverse shipboard and offshore applications, contributing to improved energy efficiency, environmental sustainability, and operational resilience within the maritime sector.

Approaching the emissivity of CMAS at high temperatures by convenient thermocouple-based infrared thermography

It remains a grand challenge to probe the emissivity of calcium-magnesium-alumina-silicates (CMAS) at high temperatures. Herein, an innovative thermocouple-based infrared thermography (TBIT) method that combines a double hot thermocouple system and infrared (IR) camera is proposed to enable convenient measurement for CMAS emissivity at temperature >800 °C. To improve the measurement accuracy, a heat transfer model accounting for the possible uncertainty in temperature measurement is also developed to correct the real sample temperature on the hot thermocouple. On this basis, the feasibility of the TBIT method is verified by using the platinum-rhodium alloy as the benchmark. As a proof-of-principle demonstration, four different sets of CMAS samples, i.e., blast furnace (BF) slag are considered with their temperature-dependent emissivities characterized experimentally. It is found that the BF-like CMAS features an emissivity of 0.5–0.9 at 800–1500 °C. This research provides a fast, accurate and low-cost experiment effort to probe CMAS emissivity at high temperatures, which enriches the thermophysical properties of the CMAS materials.

Contemporary roof pattern for energy efficient buildings: Air conditioning cost alleviation, CO2 emission mitigation potential and acceptable payback period

Buildings account for a significant portion of global energy use and consumption. Buildings have substantial energy consumption due to the use of heating, ventilation, and cooling systems. It is evident that the use of insulation materials and phase change materials (PCMs) in the design of buildings can effectively reduce the cost of air conditioning by reducing external heat gains and losses. Additionally, the use of environmentally friendly, cost-effective, and natural materials can be beneficial from an environmental standpoint. This paper aims to evaluate the potential for cost savings in the air conditioning of various PCMs and insulation-stuffed building roof configurations. In that respect, four types of phase change materials (HS29, HS36, FS42, and FS30) and four insulation materials (Therma cork, sawdust, aerogel, and sheep wool) were selected. The thermophysical properties of PCMs (solid and liquid state), insulation materials, and building elements were determined experimentally as per ASTM D 5334 standards. Ten various building roof models (contemporary roof pattern) are studied with four various PCMs and four various insulations. In addition, novel building roof design integrated with PCM/insulation were analysed numerically, related to environmental conditions that refer to two different scenarios in India (hot dry and composite climates). It further analyses the reduction in greenhouse gas emissions associated with different roof configurations. The aforementioned PCM/insulation materials were stuffed in the void spaces of the contemporary roof pattern. Thermo-economic analysis of novel roof design with PCM/insulation materials on air-conditioning costs, carbon dioxide emissions and payback time are compared with conventional roofs (CR) and contemporary roof patterns (CRP). The thermo-economic analysis was carried out based on the number of degree-hours of heating and cooling to determine the building's annual energy usage. HS29 PCM stuffed roof pattern (HS29RP) saved the highest total energy cost savings of 11.89/14.71 $/m2/year when compared with conventional roof and 11.35/13.89 $/m2/year compared with contemporary roof pattern for Jabalpur/Kota climatic conditions. HS29 PCM stuffed roof pattern (HS29RP) exhibits the maximum carbon emission mitigation of 215.32/275.37 kg/kWh when compared with conventional roof and 204.95/259.57 kg/kWh for climatic conditions of Jabalpur/Kota. While considering shortest payback span, sawdust stuffed roof pattern shows the minimum payback period of 0.69 and 2.15 years when compared with conventional roof and contemporary roof pattern. The findings of this research offer significant contributions to the development of energy-efficient building envelopes applicable to a wider range of buildings, including those with and without air conditioning systems.

Thermal modeling of porous medium integrated in PCM and its application in passive thermal management of electric vehicle battery pack

The integration of a composite of porous medium with phase change material (PCM) offers significant advantages in thermal management systems, enhancing heat transfer efficiency and addressing various thermal regulation challenges. This approach utilizes the PCM's latent heat absorption and the enhanced thermal conductivity provided by the porous medium, resulting in optimized system performance. Its applicability spans across electronics cooling and building insulation systems. However, predicting the thermal behavior of this composite material is challenging, necessitating computational tools to anticipate its response under different conditions and evaluate its influence on cooling strategies. The objective of this study is to create a computational tool specifically tailored to evaluate constitutive parameters of this composite material, thereby providing a comprehensive description of its thermal behavior. To achieve this goal, the multiscale homogenization principle is employed to assess the composite's effective thermophysical material properties using the representative volume element approach. The repeating unit cell of the aluminum lattice is incorporated into the PCM to define a representative volume element. The finite element method (FEM) is utilized to solve the three-dimensional homogenization problem, yielding an orthotropic effective thermal conductivity due to the inherent symmetry of the repeating material cell. Moreover, the study leverages the apparent heat capacity method to effectively manage the phase transitions within the PCM domain, utilizing smooth and temperature-dependent functions to accurately describe the thermophysical properties of the PCM. Integrating the composite into battery pack thermal management, this study thoroughly examines thermal dynamics by comparing outcomes with and without PCM integration. The transient thermal problem is accurately tackled using the FEM, employing the evaluated effective constitutive parameters of the homogenized composite to minimize computational effort. The results indicate a notable decline in the highest temperatures of the battery pack, leading to a reduction of about 14 °C at the specific moment when the phase change material fully transitions into its liquid form. The obtained results emphasize the effectiveness and practical feasibility of the proposed thermal management strategy. The modeling approach presented provides a robust tool with significant efficiency in reducing computational time for analyzing the thermal behavior of large models, as the utilization of the homogenization technique notably decreases the computational time.

Investigation of the factors affecting the heat transfer mechanism of the centrifugal material casting

Abstract The material casting by centrifugal technique has several potential advantages over the traditional casting methods such as; time saving, accurate dimensions, good surface finishing, purities, faster solidification, and porosity. The heat transfer mechanisms of the centrifugal material casting technique is presently investigated because of its great influences in the productivity, facilities life and production energy of that technique. Consequently, the current study provides a semi-comprehensive analytical and experimental investigation for the heat transfer mechanisms of the centrifugal material casting. The present work shows that the thermophysical properties of the casting material, the rotational speeds of the centrifugal mold and the types of the centrifugal technique have deeply affected the centrifugal heat transfer mechanism. Eventually, the developing and improving the cooling systems of the centrifugal molds are indeed needs due to modify the material casting by centrifugal techniques.

Justification of the method for calculating the calibration sleeve for the production of thermoplastic pipes

The task of improving the quality of the production of pipes for engineering networks of various purposes with forecasting performance takes on special importance in the face of increased demand in modern conditions. A significant influence on the solution of this problem is found in the organization of heat exchange in the calibrated device. Based on the theoretical analysis of heat exchange during pipe calibration, an improved method is proposed, which consists of calculating the temperature field in the pipe wall during the movement of the pipe billet through different zones of the calibrator with controlled thermal resistance between the surfaces of the polymer pipe and the calibrator. This approach makes it possible to determine the intensity of heat removal, depending on the state of the pipe material during solidification at a given speed of movement of the workpiece, taking into account the change in the thermophysical properties of the pipe material and to more accurately determine the rational heat exchange surface in the calibrator, which is expressed in the length of its sleeve. The proposed method was approved when calculating the calibrator during the production of a polyethylene pipe with a diameter of 500 mm and a wall thickness of 30 mm with a pipe production speed of 8 m/min. in which the calculated length is 862 mm, the working length of the sleeve is 880 mm, the convergence is 98 %.