Thermal Features Research Articles

Intelligent Detection Algorithm Based on 2D/3D-UNet for Internal Defects of Carbon Fiber Composites

ABSTRACT Infrared thermography testing (IRT) has been widely used in the defect detection of composite materials. However, the identification of defects characteristics is unsatisfying due to the interference of factors such as uneven background and noise in the original thermal image sequence. A novel thermography-based defect detection method with the semantic segmentation network is proposed to enhance the defect contrast and extract perfect features. To Figure out the abnormal distribution of temperature field in thermal images, AG-UNet was used with a spatial self-attention gate module to extract spatial features of thermal images. The 3D-UNet network was obtained by the 3D convolution module and the temporal convolution module to extract thermal temporal and spatial features simultaneously which could help the defect segmentation in thermal videos. Compared with traditional algorithms such as principal component analysis (PCA), thermographic signal reconstruction (TSR), and fast Fourier transform (FFT), defects detection results were significantly enhanced with the proposed method, and defects of smaller diameter-to-depth ratio can be detected by deep learning models.

Impact of Joule heating on magnetohydrodynamic dissipative flow above a slendering surface with thermophoresis and Brownian movement with slip/no-slip conditions

ABSTRACT Purpose Hybrid nanofluids meet the necessities of several technological and production industries. Owing to these ample applications, a numerical investigation is accomplished to examine the thermal transmission feature of magneto-hybrid nanofluid flow due to an extending surface of varied thickness with multiple slip effects. Design/methodology The arising system of Partial Differential equations (PDEs) are exercised by adopting suitable similarities to attain the non-dimensional Ordinary Differential equations (ODEs) and the solutions are obtained by implementing bvp5c built in MATLAB package. The energy equation is loaded with Brownian motion, thermophoresis and Joule heating effects. The implication of pertinent constraints upon the flow features is discussed graphically. Findings The outcomes imply that the energy transmission rate is considerably high in no-slip case as equated with the slip case. Further, the power-law index parameter effectively uplifts the thermal and concentration gradients in both the situations. Originality The prime motive of this research is to present the relative analysis of heat transmission of hybrid nanoliquid in two different situations, namely slip and no-slip cases.

Evaluating two-phase fluid flow and heat transfer in pillow-plate heat exchangers with nanofluids for organic Rankine cycle in municipal solid waste power plant: A numerical simulation study

One of the key considerations in the design and operation of process industries nowadays is reducing energy waste. The purpose of this research is to assess fluid flow and heat transfer in pillow-plate heat exchangers (PPHEs) using nanofluids for the Organic Rankine Cycle (ORC) in Municipal Solid Waste (MSW) power plants. The thermal performance and hydraulic features of the PPHE were investigated using a two-phase numerical modeling approach. three nanoparticles of Cu, TiO2, and Al2O3 were examined. To precisely determine the temperature distribution within the heat exchanger, various boundary conditions were used. The results demonstrate a strong correlation between the velocity field and temperature, underlining the importance of boundary conditions in determining the temperature profile. Furthermore, the two-phase model illustrates that nanofluids are extremely reliant on inlet velocity and volume fraction. such that at a 2 m/s inlet velocity, increasing the volume percentage to 12.8% contributes to heat transfer coefficient improvements of 7.57%, 12.15%, and 2.71% for water_TiO2, water_Al2O3, and water_Cu, respectively. These findings give significant insight into the fluid flow and heat transfer properties of PPHEs, as well as prospective pathways for increasing thermal performance and decreasing pump power in ORC systems using nanofluids in MSW-generating plants.

Exploring Multisource Feature Fusion and Stacking Ensemble Learning for Accurate Estimation of Maize Chlorophyll Content Using Unmanned Aerial Vehicle Remote Sensing

Crop chlorophyll content measuring plays a vital role in monitoring crop growth and optimizing agricultural inputs such as water and fertilizer. However, traditional methods for measuring chlorophyll content primarily rely on labor-intensive chemical analysis. These methods not only involve destructive sampling but also are time-consuming, often resulting in obtaining monitoring results after the optimal growth period of crops. Unmanned aerial vehicle (UAV) remote sensing technology offers the potential for rapidly acquiring chlorophyll content estimations over large areas. Currently, most studies only utilize single features from UAV data and employ traditional machine learning algorithms to estimate chlorophyll content, while the potential of multisource feature fusion and stacking ensemble learning in chlorophyll content estimation research remains largely unexplored. Therefore, this study collected UAV spectral features, thermal features, structural features, as well as chlorophyll content data during maize jointing, trumpet, and big trumpet stages, creating a multisource feature dataset. Subsequently, chlorophyll content estimation models were built based on four machine learning algorithms, namely, ridge regression (RR), light gradient boosting machine (LightGBM), random forest regression (RFR), and stacking ensemble learning. The research results demonstrate that (1) the multisource feature fusion approach achieves higher estimation accuracy compared to the single-feature method, with R2 ranging from 0.699 to 0.754 and rRMSE ranging from 8.36% to 9.47%; and (2) the stacking ensemble learning outperforms traditional machine learning algorithms in chlorophyll content estimation accuracy, particularly when combined with multisource feature fusion, resulting in the best estimation results. In summary, this study proves the effective improvement in chlorophyll content estimation accuracy through multisource feature fusion and stacking ensemble learning. The combination of these methods provides reliable estimation of chlorophyll content using UAV remote sensing technology and brings new insights to precision agriculture management in this field.

Nano-composite semi-flexible polyurethane foams containing montmorillonite intercalated/exfoliated in situ during the synthesis of the intermediate polyester-polyols obtained from PET wastes

Low-cost nano-composite semi-flexible polyurethane foams with improved thermal and mechanical features were obtained using a cost-saving and environmentally friendly preparation process of an intermediate composite, obtained from polyethyleneterephthalate (PET) wastes, depolymerization/chemical modification agents from renewable resources and unmodified natural montmorillonite. The process implies tailoring the polyester-polyols chemical structure/ composition and using specific catalysts, aiming to intercalate the montmorillonite layers during the synthesis reactions, while maintaining the appropriate properties of the products required for the preparation of polyurethane semi-flexible foams, thus avoiding conventional treatments of the nanofiller, involving the use of solvents, additional energy consumption by heating and stirring, as well as longer processing time. The polyester-polyols composites and the polyurethane semi-flexible foams obtained therefrom were investigated by specific analytical methods. In this regard, the foams showed an improvement of the thermal stability, and values of Young’s moduli and compression strengths about double or higher, compared to conventional semi-flexible polyurethane foams of same density. The potential applications of such foams target shock wave damping sandwich systems for marine structures.

Molecule control and thermal degradation study of phosphazene cyclomatrix nanocrystals: For simultaneous enhancement of flame retardant and mechanical properties

Cyclotriphosphazene which possesses hexafunctional framework is a versatile building block to construct functional materials and has been used in many areas such as catalysis, biomedicine, sensing and imaging, and flame retardancy. However, the proper control of the molecules and their condense state structures, in particular via the reaction of phosphonitrilic chloride trimer (PCT) with other multifunctional co-monomers is a challenge. Herein, we developed phosphazene cyclomatrix molecules using pentarythritol (PER) as the co-monomer. Through controlling the PCT/PER molar ratio and the feeding manner, the obtained product is either monomeric/oligomeric small molecules or macromolecules. Interestingly, the macromolecules self-assembled into three-dimensional structures, forming cubic nanocrystals. The thermal study shows that all molecules possess a low temperature degradation domain (LTD, 150–400 °C) and high temperature degradation domain (HTD, 500–750 °C) due to the same chemical bonds, while the macromolecules have the highest carbon forming among all. TG-IR and TG-MS results confirm the following thermal degradation features: (1) inert gases (NH3, CO2) and H2O release after 200 °C, (2) the carbonaceous phase forms at 300–450 °C when the PER segment content in the molecule is 50 % and higher, and (3) extra phosphate/phosphite agents release after 450 °C, which renders carbonizing capability. The addition of the crystalline macromolecules into polypropylene (PP) showed that under a low loading of only 18 and 22 wt%, UL94 V2 and V0 rate was achieved for the obtained composites. This indicates the high flame retardant efficacy of the macromolecules as a standalone additive, ascribing to the cooperative effect of the above thermal features in a single molecule. The synthesized macromolecule is also able to simultaneously reinforce PP in terms of tensile modulus and flexural modulus without sacrificing the impact strength and flexural strength, leading to dual functionality, i.e., enhancement flame-retardant (FR) performance and mechanical reinforcement. This study provides constructive guideline to controllably design and synthesize functional materials using this unique building block for advanced properties and applications.

MEFNET: Multi-expert fusion network for RGB-Thermal semantic segmentation

Semantic segmentation using RGB and thermal images is crucial in a variety of applications, including autonomous driving and video surveillance. However, the validity of information differs between modalities, which is typically addressed by weighting image features using complex and inefficient networks. To address this issue, we propose a Multi-Expert Fusion Network (MEFNet) that decouples the three-dimensional attention matrix of image features into a two-dimensional modal weight matrix and a channel attention vector. This approach focuses more on modal and channel differences while excluding interferences from other factors. Specifically, MEFNet multiplies RGB and thermal features by their respective modal weights, and then uses channel attention to select important feature channels. Comprehensive experiments demonstrate that MEFNet is competitive with state-of-the-art methods, achieving 62.6% mIoU on the IR SEG dataset.

Numerical computation on MHD natural convective ternary nanofluid flow and heat transfer in a porous square cavity: Marker-and-cell technique

PurposeThe analysis of fluid flow and thermal transport performance inside the cavity has found numerous applications in various engineering fields, such as nuclear reactors and solar collectors. Nowadays, researchers are concentrating on improving heat transfer by using ternary nanofluids. With this motivation, the present study analyzes the natural convective flow and heat transfer efficiency of ternary nanofluids in different types of porous square cavities.Design/methodology/approachThe cavity inclination angle is fixed ω = 0 in case (I) and in case (II). The traditional fluid is water, and is treated as a working fluid. Ternary nanofluid's thermophysical properties are considered, according to the Tiwari–Das model. The marker-and-cell numerical scheme is adopted to solve the transformed dimensionless mathematical model with associated initial–boundary conditions.FindingsThe average heat transfer rate is computed for four combinations of ternary nanofluids: and under the influence of various physical factors such as volume fraction of nanoparticles, inclined magnetic field, cavity inclination angle, porous medium, internal heat generation/absorption and thermal radiation. The transport phenomena within the square cavity are graphically displayed via streamlines, isotherms, local and average Nusselt number profiles with adequate physical interpretations.Practical implicationsThe purpose of this study is to determine whether the ternary nanofluids may be used to achieve the high thermal transmission in nuclear power systems, generators and electronic device applications.Social implicationsThe current analysis is useful to improve the thermal features of nuclear reactors, solar collectors, energy storage and hybrid fuel cells.Originality/valueTo the best of the authors’ knowledge, no research has been carried out related to the magneto-hydrodynamic natural convective ternary nanofluid flow and heat transmission filled in porous square cavities with an inclined cavity angle. The computational outcomes revealed that the average heat transfer depends not only on the nanoparticle’s volume concentration but also on the existence of heat source and sink.

RETRACTED: A scientometric analysis on mechanical and microstructural characterization of geopolymer composites subjected to high temperatures

Class F fly ash (FA)-sourced geopolymers (GPM) are susceptible to different high-temperature phenomena, for instance, spalling, cracking, and thermal shrinkage. Protection of structural elements from fire is of great significance. These days, the construction industry is struggling to introduce sustainable binding composite materials to develop an eco-friendly environment due to the large carbon production during the manufacturing process of Portland cement. Therefore, the development of sustainable cementitious GPM is in the spotlight of the current research. The use of GPM as a substitute for Portland cement is the best replacement for sustainable development. A large number of review studies on the mechanical, durability, and microstructural features of GPM have already been performed; nevertheless, the influence of high temperatures up to 1000 °C on GPM and its exposure to fire still needs more exploration to check the suitability of GPM in the construction industry. In the present study, an extensive review of the mixing process, fresh behavior, curing conditions, shrinkage behavior, and thermal features of FA-sourced GPM subjected to fire conditions is performed. The effect of adding various alkali materials on the thermal features of GPM is elaborated. The phase formation, initial strength development, and melting temperature due to the involvement of minor elements are reviewed and deliberated. The pore interconnectivity to minimize the damaging behavior of GPM and the progression of ingredient features when the GPM is subjected to high temperature are also covered in the present study. The results of the studies presented that the potassium-sourced alkali materials depict a better thermal resistance of GPM. Concerning future works and recommendations, the reactive phases of GPM under high temperatures should be examined.

Two‐dimensional MXenes as Emerging Materials: A Comprehensive Review

AbstractBecause of their peculiar two‐dimensional layered microstructure, the existence of numerous functionalities on the surface and excellent electrical, thermal and optical features, MXenes are regarded as promising candidates for solving energy and environment related problems. It is noted that energy conversion and storge capability of MXenes could be raised by altering their dimensions, structure, surface chemistry and chemical composition. Therefore, it is critical to recognize how one can boost the relationship between structure and property from applied viewpoint. In the present study, we reviewed the synthesis, properties and potential applications of MXenes. Furthermore, several properties of MXenes including structural, chemical, optical, mechanical and thermal have been explored. In addition, the potential applications of MXenes in various areas such as photocatalysis, gas sensing, supercapacitors, electrocatalysis and environmental remediation have also been discussed. Based on reported works, it can clearly be noticed that features and potential applications of MXenes may be further improved by applying many alteration and functionalization strategies. This study also focuses on the current progresses and future prospective relating to MXene based composites, which will surely assist the scientists who are doing work in areas of academia and material sciences.

Experimental investigation of thermal characteristics of phase change material in finned heat exchangers

A significant challenge to the widespread use of practical latent heat energy storage systems based on phase change materials is the inherent low thermal conductivity of these materials. Inserting fins is considered one of the effective methods of heat transfer enhancement. In the present paper, an experimental investigation of the melting process of PCM in finned and unfinned heat exchangers is conducted. The experimental setup was constructed, and the measurement system was used to monitor the transient progress of the melting process. The heat exchanger comprises annular horizontal concentric double pipes, where the inner tube is heated by flowing water as heat transfer fluid (HTF), and the outer shell is thermally insulated. Four configurations of fins of the same fin/PCM volume ratio are attached to the inner tube. These configurations are longitudinal fin (LF), circular fin (CF), longitudinal perforated fin (LPF), and circular perforated fin (CPF). The effect of inlet HTF temperatures of 60, 70, and 80 °C is tested. The experimental findings indicate that the thermal performance of finned heat exchangers exceeds that of unfinned heat exchangers. Also, the perforated finned heat exchangers showed a higher thermal feature than the unperforated ones. In addition, the CPF achieved the lowest melting time and the highest melting rate, followed by LPF, CF, and LF. The maximum reductions of melting time are 71.1 %, 70.6 %, and 70.2 % due to using CPF HE instead of UF HE for inlet HTF temperatures of 60, 70, and 80 °C, respectively.

Significance of Joule heating for radiative peristaltic flow of couple stress magnetic nanofluid

Nanofluids are gaining more importance in heat transfer applications because of their excellent thermal features, such as larger thermal conductivity, enhanced convective heat transfer coefficients, and better thermal stability. In a range of technical applications, including cooling structures, exchangers for heat, and thermal energy storage systems, they have the potential to increase the efficiency of heat transfer. Main aim is to address the peristalsis of couple-stress nanomaterial in a channel subject to partial slip conditions. Channel walls are compliant. Buongiorno model for thermophoresis and Brownian motion is accounted. Energy equation is modeled with considering the features of Ohmic heating and thermal radiation. The model is initially developed as a set of non-linear partial differential equations (PDEs). Using th appropriate similarity transformations, these are turned into a set of dimensionless ordinary differential equations (ODEs). The governing system of ODEs is solved by using numerical technique NDsolve. Detailed analysis for concentration, temperature, velocity, heat transfer rate, pressure gradient, skin friction coefficient, Sherwood and Nusselt numbers are analyzed. Reduction of problems with small Reynolds number and large wavelength is made. Concentration and velocity have reverse trends for higher couple stress fluid parameter. In addition, the radiation and Hartman number behave in an opposite sense for temperature. Rate of heat transfer is significantly accelerated by nanoparticles. Further, Nusselt number increases enhances via Brinkman number.

Momentum and thermal transport analysis in MHD nanofluid through the thermally heated square conduit: Finite element method

ObjectiveThe purpose of this investigation is to report the thermal performance of water-based nanofluids with two different types of hybrid nanofluids for the cooling process of the radiator inside the thermally heated square cavity under the addition of thermal radiation and magnetic field by using the finite element method. Research gapThe heat transfer analysis of MHD nanofluid with the suspension of titanium alloy Ti6A14V and aluminum alloy AA7075 in cavity flow problems under the effects of thermal radiation and thermal boundary conditions by using the Galerkin finite element method is not reported before. NoveltyIn this numerical investigation, the novel mathematical model of two types of titanium alloy Ti6A14V (class of titanium) and aluminum alloy AA7075 is proposed first time in the cavity flows under the influence of a uniform magnetic field and non-uniform thermally heated bottom wall. The momentum and energy equations are updated with terms of magnetic field and thermal radiation, respectively. The cavity is filled with AA7075- Ti6A14V/water nanofluids. Two parallel vertical walls of the cavity are set at constant temperatures (Tc) and the top one is adiabatic while the temperature at the lower wall is taken as the variable. Method of solutionThe physical model is composed in terms of nonlinear differential equations and transformed into a dimensionless form by using suitable non-dimensional quantities. The Galerkin finite element method along with iterative Newton’s Raphson method is selected to simulate the problem and obtain the numerical solution with a high degree of accuracy. The results are illustrated for fixed Prandtl number Pr=10.0 throughout the calculation, Rayleigh number 1000≤Ra≤100000, nanoparticle volume friction 0.0≤ϕ≤0.05 Hartman number 0≤Ha≤10 and thermal radiation parameter 1.0≤Ra≤10.0. Both grid independence tests and comparison tests are directed to get the accuracy of the established model. Important findingsThe computational results revealed that the aluminum alloy (AA7075) alloys nanoparticles are more productive as compared to titanium (Ti6Al4V) alloy nanoparticles in terms of enhancing the thermal features of water-based nanofluid. The aluminum alloy nanofluid and titanium alloy nanofluid provide 3.9 % & 5.7 % and 2.9 % & 4.2 % more heat transfer at the bottom and side walls as compared to regular fluid. ApplicationsThe current nanofluid models are more efficient than the conventional model to control the heat transfer rate and flow phenomena. The computational results revealed that if the radiator is assembled by using the modern concept of hybrid nanofluid then that will increase the heat transfer of the engine and enhance the lifespan of the machinery.

Integrated system model of spray flash vacuum distillation with internal heat recovery

This study proposed an integrated system model for an original spray flash vacuum distillation system that enhances and leverages the thermal non-equilibrium of the flash process via active vapor extraction to realize an internal heat recovery feature, in which partial heat from hotter vapor is recovered to cooler spray residue within the same stage of feed circulation. This system contains four interlinked sub-systems: (1) an evaporation chamber in which a vacuum-promoted spray flash vaporization occurs, with an active vapor extraction and an outflow of evaporation-cooled brine, (2) a recirculation loop of feed-brine mixture, with the circulation pump, feed heater, and spray nozzle, (3) a hybrid dual-condenser combination, with the internal heat recovery from condensing vapor to the recirculating feed and a secondary cooling by an external coolant, and (4) a vacuum source that maintains vacuum conditions to the entire system as well as discharges the non-condensable gases. The pressure of vapor phase, as the major interlinked operation parameter, is in order of sequential decrease from the evaporation chamber, through condensers, to the vacuum source while the depressurization level in each sub-system is strongly coupled with other transport characteristics such as flash vapor generation in the evaporation chamber or condensing vapor flow in condensers. Thus, the integrated system model is composed of four sub-models to describe the key processes in such four sub-systems. For the modeling validation, a lab-scale experimental system is developed to provide relevant measurements. Comparisons between model predictions against measurements show a good match. Major process characteristics (such as spray flash rate, yield rate, and operating temperatures and pressures) and operational thermodynamic characteristics (such as thermal consumption and heat recovery efficiency) are investigated parametrically. The system's multivariate impacts concerning distillate yield rate and heat recovery effectiveness are also studied with varied operating parameters. Results indicate the pronounced thermal non-equilibrium feature arising from the spray flash process can be effectively utilized via the internal heat recovery design of our system to recover up to more than half of the heat from the yield vapor. Meanwhile, the developed system model can effectively analyze various operational and parametric effects, proving valuable for system design and optimized operation.

Comparative thermal analysis of Nickel and Tantalum based hybrid nanofluid using constant proportional Caputo and Atangana–Baleanu operators with time-controlled condition

The main purpose of this research work is to examine how the immersion of nickel and tantalum nanoparticles in water affects the flow and thermal properties of water, with the aim of anticipating potential enhancements. The investigation pertains to the flow behavior of a hybrid nanofluid over an extensively elongated vertical surface under the influence of a condition that varies with time. The phenomenon of heat transfer transpires due to the combined effects of natural convection and thermal radiation. An in-depth comprehension of flow patterns and heat transfer over a vertical surface is essential for optimizing heat exchange processes, designing efficient cooling systems, and enhancing overall energy efficiency. It also helps in climate modeling, weather prediction, and the improvement of the performance of solar thermal systems. The basic model is generalized using Atangana–Baleanu (AB) and constant proportional Caputo (CPC) operators. This generalization leads to the development of two different fractional settings for which separate mathematical analyses are performed. With the help of some new unit-independent quantities, exact solutions for both fractional frameworks are computed using the Laplace transform. For the elucidation of changes in velocity and thermal fields due to different physical effects, several graphical and tabular representations are produced. The outcomes illustrate that the incorporation of uniform concentrations of nickel and tantalum nanoparticles in water leads to raising its thermal efficacy up to 40.39%. The nanoparticles consisting of lamina shapes are observed to produce the maximum amelioration in thermal features. The CPC model based profiles of flow and temperature fields are lower than those procured via the AB model. As a result of nanoparticles’ intrinsic characteristics, the insignificant heat transfer capability of water is greatly amplified, leading to a notable boost in its thermal performance. Thus, the examined hybrid nanofluid can be used as a viable alternative to water in various engineering applications.

Mechanically-reinforced biocompatible hydrogels based on poly(N-isopropylacrylamide) and star-shaped polycaprolactones

The aim of this work was to improve the properties of hydrogels based on poly(N-isopropyl acrylamide) (PNIPAAm) in terms of mechanical features and functionality by combining the polymer with a star-shaped tetrafunctional polycaprolactone (PCL), which was synthesized ad-hoc and introduced into the reaction mixture. The synthesized PCL (coded as PCL-COOH), selected to maintain the biocompatibility of the final material, was designed with a star structure characterized by four strong arms ending with maleic groups to increase the functionalization potential capable of participating in the radical polymerization and adding acid groups to the system. Specifically, various hydrogels were prepared by partially replacing pentaerytritol tetraacrylate (PE-TA), a commercial crosslinker, with increasing concentrations of PCL-COOH in the presence of trihexyl(tetradecyl)phosphonium persulfate (TETDPPS) as non-gas-releasing radical initiator. In addition, frontal polymerization (FP) was employed, a fast and energy efficient technique, potentially capable of promoting the dispersibility of PCL in the polymer matrix.The influence of the star-shaped PCL on the polymerization process as well as on the hydrogel properties in terms of chemical structure, swelling behaviour, thermal and mechanical features was investigated. Indeed, it was found that the presence of PCL allowed the formation of a stable polymerization front up to a concentration of 25 wt%. FT-IR measurements allowed to evaluate the fraction of PCL effectively bonded to the hydrogel structure, while the morphological analysis performed by FE-SEM characterization revealed that the hydrogel pore size tended to decrease as the amount of PCL in the system increased. In addition, the star-shaped PCL was found to affect the material swelling properties, by reducing the swelling ratio without affecting the thermoresponsive behavior. Mechanical tests performed on the neat PNIPAAm hydrogels and on PCL-containing hydrogels, showed a relevant increase in the material stiffness due to the PCL-COOH addition. The DSC characterization results showed a decrease in the glass transition temperature with increasing PCL-COOH content, indicating a partial miscibility of the two polymers likely due to a compatibilization effect of a copolymer formed during the polymerization process. To demonstrate the capability of the hydrogels to retain positively charged molecules, the prepared systems were contacted with solutions containing pararosaniline hydrochloride. The retention capacity as well as the kinetic release were investigated. The measurements evidenced a higher retaining capacity and a lower release rate in the PCL-containing hydrogels. Finally, the biocompatibility and the low citoxicity of the PNIPAAm/PCL hydrogels were confirmed by a cell viability assay using the SH-SY5Y cell line.

Impact of Atrium Glazing with and without BIPV on Energy Performance of the Low-Rise Building: A Central European Case Study

This article aims to investigate the impact exerted by different types of covering an atrium with glazing on the energy performance of a kindergarten building, provided by the authors as a conceptual design. The considered types of atria included an open atrium, a glazed atrium, and an atrium that operated as a hybrid system. Additionally, the following aspects were taken into consideration: the effect of a glazing-integrated PV system (BIPV); the variety of thermal features represented by the inner boundary between the conditioned and the unconditioned space (Uiu); and the atrium space air-exchange ratio (nue) on the energy balance of the building. Energy performance indicators, including energy demands for space heating and cooling (Eu), delivered energy (Ed), and primary energy (Ep) indicators for heating and cooling mode were estimated for the moderate climates and two locations of the building model, i.e., for Warsaw (Central Poland) and Ahlbeck (Northern Germany). The research results prove that the glazed atrium exerts the most beneficial impact on the energy performance of the building. Nevertheless, certain variables must be considered, especially the air-exchange ratio of the atrium space, as they significantly influence the total annual energy performance. The results obtained with regard to the effect exerted by the presence of BIPV systems differ from those usually expected. This is due to the effect of the total solar-energy-transmittance value (g) modulation caused by the system and, finally, by a significant reduction in passive solar-gain harvesting, which is important for heating-mode results in examined climate conditions. Taking the present analysis into account, it can be concluded that the energy and environmental effects of the glazed integrated PV systems in temperate climates are strongly influenced by the environmental conditions, and, in some cases, these solutions may prove to be not efficient enough in terms of the energy and costs.

Calibration and Uncertainty Quantification for Single-Ended Raman-Based Distributed Temperature Sensing: Case Study in a 800 m Deep Coaxial Borehole Heat Exchanger

Raman-based distributed temperature sensing (DTS) is a valuable tool for field testing and validating heat transfer models in borehole heat exchanger (BHE) and ground source heat pump (GSHP) applications. However, temperature uncertainty is rarely reported in the literature. In this paper, a new calibration method was proposed for single-ended DTS configurations, along with a method to remove fictitious temperature drifts due to ambient air variations. The methods were implemented for a distributed thermal response test (DTRT) case study in an 800 m deep coaxial BHE. The results show that the calibration method and temperature drift correction are robust and give adequate results, with a temperature uncertainty increasing non-linearly from about 0.4 K near the surface to about 1.7 K at 800 m. The temperature uncertainty is dominated by the uncertainty in the calibrated parameters for depths larger than 200 m. The paper also offers insights into thermal features observed during the DTRT, including a heat flux inversion along the borehole depth and the slow temperature homogenization under circulation.

Physical treatment of PCM in existence of nanoparticles during discharging

This work includes the finite element modeling of solidification process within the container with curved top wall. The container has three insulated wall and one cold wall which is situated on top wall and it has sinusoidal configuration. Nanoparticles with low fraction were loaded inside the water to improve the thermal features. In deriving the mathematical model, two main assumptions were incorporated: (1) neglecting the impact of velocity; (2) considering homogeneous mixture for NEPCM. To improve the accuracy of numerical approach, the variable style of grid with time has been employed and also, implicit method was considered for time-dependent two terms. Increasing fraction of nano-powders has its maximum effect when the second level of dp has been selected in which required time reduces around 41.33%. Also, in existence of maximum size of particles, changing [Formula: see text] causes reduction of time around 12.41%. With altering dp from 30 to 40[Formula: see text]nm, the freezing period reduces around 19.99% while augmenting up to 50[Formula: see text]nm can lead to reduction of time around 49.29%.

Decoupling absorption and radiative cooling in mid-wave infrared bolometric elements.

We present a spectrally selective, passively cooled mid-wave infrared bolometric absorber engineered to spatially and spectrally decouple infrared absorption and thermal emission. The structure leverages an antenna-coupled metal-insulator-metal resonance for mid-wave infrared normal incidence photon absorption and a long-wave infrared optical phonon absorption feature, aligned closer to peak room temperature thermal emission. The phonon-mediated resonant absorption enables a strong long-wave infrared thermal emission feature limited to grazing angles, leaving the mid-wave infrared absorption feature undisturbed. The two independently controlled absorption/emission phenomena demonstrate decoupling of the photon detection mechanism from radiative cooling and offer a new design approach enabling ultra-thin, passively cooled mid-wave infrared bolometers.