Thermal Losses Research Articles

Thermal regulation enhancement in multi-story office buildings: Integrating phase change materials into inter-floor void formers

Addressing the thermal loss from building envelopes is a crucial challenge and requires the exploration of various mitigation strategies. This study employs comprehensive 3D computational fluid dynamics simulations to investigate the incorporation of various bio-based Phase Change Materials (PCMs) including CrodaTherm (CT) 19, CT21, and CT24W, within inter-floor void formers between the roof-floor boundary in multi-story office buildings to optimize energy management during inactive periods in one of the adjacent units. Aside from the PCM type, the void former shape, its placement, and the combinations of PCMs and insulating layers are examined through heat flux and solid fraction plots as well as liquid fraction contours. Results highlight the exceptional performance of CT24W-integrated void formers, achieving a remarkable 36.74 % reduction in the 48-h average heat flux in comparison with the case without void formers, and offering lower heat flux values than the scenario with insulating layers for 89.38 h (endurance time). Based on the findings, with identical PCM volumes, the semi-ellipsoid PCM-integrated void former provides 11.07 % lower heat flux and 27.56 % longer endurance time compared to the one with a spherical shape. The results underscore PCM integration as a superior strategy over standalone insulation for managing thermal loss between apartment floors.

Energy and exergy analysis of a long-term nonlinear dynamic roll bond PVT solar collector model under Tunisian (North Africa) climatic conditions

Roll-bond type PVT modules drew little attention while offering a higher energy exchange area and an efficient heat transfer solution. Furthermore, comparative studies including exergetic assessment on PVT systems are very limited in the literature. In this paper, a novel and detailed nonlinear dynamic roll bond PVT model is performed under real-world weather conditions that provide reasonable and realistic system performance. By incorporating local solar, thermal, exergy, and electrical models based on five diode parameters, a thorough analysis is conducted. Likewise, a unique, rigorous exergy comparison between PV, thermal, and roll bond PVT systems is conducted. Results reveal that there appears to be a direct relationship between wind velocity and changes in ambient temperature which affect exergy efficiency. Higher irradiance and lower wind speeds lead to increased thermal losses, which lower the electrical exergy efficiency of the PV and PVT solar collectors.The exergy analysis reveals that a PVT system outperforms PV + ST, and findings show that for thermal and electrical parts, the yearly average efficiencies are 33.7 % and 12.27 %, respectively. Findings enable a fast and an accurate assessment of fill factor (FF), which is temperature-dependent, over the course of a year’s worth of PVT collector operation.

Turbine blade tip aerothermal characteristics considering the influences of cavity tip shaping

The presence of turbine blade tip clearance can cause tip leakage losses and enhance the thermal load on the tip region. The continuously increasing inlet temperature of the turbine poses a tremendous challenge for turbine blade tip design. Reasonable turbine blade tip configurations can effectively reduce the thermal load on the tip region and enhance aerodynamic characteristics. Here, surface Nu distributions of flat, cavity, and five modified tip configurations are obtained through transient liquid crystal measurement technology. Furthermore, a numerical study combined with experimental results is conducted to investigate the aerothermal characteristics of the tip regions for each configuration. The results indicate that the flat tip (FT) has the highest tip surface thermal load and maximum aerodynamic loss, and the cavity structure can effectively reduce the average Nu on the tip surface. Among the five modified configurations, the SS ribbed configuration (SRT) and the lateral ribs configuration (SLCT) exhibit relatively optimal aerothermal performance. Specifically, compared to FT, the SRT tip configuration shows an average Nu reduction of 27.4 % on the tip surface and a 16.3 % decrease in tip clearance leakage compared to FT; the average Nu on the SLCT tip surface and the tip clearance leakage relative to the FT are reduced by 27.2 and 17.3 %, respectively.

A nonlinear dynamic hysteresis model with magnetic–prestress–thermal coupling effect and dynamic electromagnetic losses of a giant magnetostrictive actuator

Compared with traditional actuators, the giant magnetostrictive actuator has the merits of fast response, high accuracy, and high reliability and has been widely applied. However, its performance is affected by the electromagnetic loss and the temperature, prestress, and magnetic coupling effect. In order to accurately analyze its performance, it is necessary to establish a nonlinear dynamic model including the electromagnetic loss and the magnetic–prestress–thermal coupling effect. First, based on the field separation approach, the magnetic fields generated by the eddy current loss and the anomalous loss are obtained and added to the Jiles–Atherton model. Second, the magnetostrictive model is given with the magnetic–prestress–thermal coupling effect. Finally, assuming the transmission of the giant magnetostrictive actuator as a mass–spring–damper system, a nonlinear dynamic hysteresis model with magnetic–prestress–thermal coupling effect and dynamic electromagnetic losses of a giant magnetostrictive actuator is developed. Based on this model, the output displacement curves of the giant magnetostrictive actuators under different driving currents and frequencies are given. The comparison with the experimental results shows that this model agrees well with the experiment.

Assessment on thermophysical properties of nano enhanced heat transfer fluid with hexagonal boron nitride nanoparticles for thermal management of photovoltaic thermal (PVT) system

One of the most promising sources of energy to meet demand and reduce pollution from fossil fuels is solar energy. To maximize energy conversion, solar technology efficiency, whether it comes from thermal systems, photovoltaic panels, or a hybrid known as photovoltaic-thermal (PVT) systems is critical. This work looks into the formulation and thermophysical of hBN-water nanofluids, with an emphasis on how they might be used as coolants in PVT systems to improve electrical performance. After a meticulous preparation process, the nanofluids exhibited exceptional stability, confirmed through visual inspection and zeta potential evaluation. Zeta potential analysis revealed consistent values across different temperatures and volume concentrations. Density decreased with temperature, while viscosity increased with volume concentration but decreased with temperature. Thermal conductivity showed a consistent increase with volume concentration and temperature. Through optimization, the 0.5 vol% concentration was identified as optimal for the PVT system. Compared to no coolant and water-based coolant scenarios, hBN-water nanofluids effectively regulated cell temperatures between 40.25°C and 46.34°C, demonstrating superior thermal conductivity and heat transfer properties. Moreover, the nanofluid coolant enhanced the PVT system's electrical performance. Open circuit voltage remained consistent (19.67 V to 20.81 V), short circuit current and output power improved with higher irradiance levels, and electrical efficiency, thermal efficiency and overall efficiency reached 5.73–5.88 %, 54.15–62.73 % and 59.88–68.62 % respectively These findings underscore the potential of hBN-water nanofluids in enhancing thermal management and electrical performance in solar energy systems. By minimizing thermal losses and maximizing electrical output, nanofluid coolants offer promising avenues for optimizing the efficiency of renewable energy technologies.

Experimental thermal performance intensification of gravitational water vortex heat exchanger using hexagonal boron nitride-water nanofluid

One of the main concerns presently is the rapid improvement of thermal technology for widespread heat exchanger applications involving energy conservation and intensification of heat transfer process. For the enhancement of heat exchange processes, nanofluids have been considered as a potential substitute for conventional fluids, which in general have subpar thermal characteristics. Therefore, the present study focusses on the heat transfer enhancement and the intensification of overall thermal performance of the developed gravitational water vortex heat exchanger (GWVHE). The experimental investigation first involves the preparation and characterization of water-based hexagonal-boron nitrides (h-BN) nanofluids as well as the computation of thermophysical properties of different volume fractions of h-BN nanofluids. Subsequently, a comparative analysis evaluating the thermal energy exchange capabilities of water-to-water and water-to-h-BN nanofluids combination of two fluids has been conducted to investigate the intensification in thermal performance of the developed GWVHE. The experimental investigation is primarily based on calculating the thermal energy balance, overall heat transfer coefficient, log-mean temperature difference (LMTD) and the effectiveness of the developed GWVHE using effectiveness-NTU method. The experimental results reported that 0.02 % volume fraction of water-based h-BN nanofluids is more suitable for further testing of the developed GWVHE to mitigate the stability concerns at higher concentrations. The minimal thermal losses, that lie within the 10 % confirms the thermal energy balance and by using the h-BN nanofluids −to-water strategy for two fluids. The maximum value of heat exchange rate significantly increased from 8490 W to 9998 W with the utilization of h-BN nanofluids-to-water as compared to water-to-water combination. Furthermore, the maximum values of LMTD employing h-BN nanofluids are found to be reduced from 21.15 K to 17.53 K compared to the water-to-water combination confirming the intensification in thermal performance of GWVHE. The overall heat transfer coefficient values are also found higher when h-BN nanofluids are substituted instead of water. The maximum value of overall heat transfer coefficient for h-BN nanofluids-to-water combination is improved from 874 W/m2K to 1142 W/m2K compared to water-to-water combination. Moreover, by utilizing the h-BN nanofluids-to-water combination, the values of effectiveness are intensified by an average of 13.5 % and 9 % in both sets of testing parameters, respectively. All these maximum improvement in findings for heat exchange, overall heat transfer coefficient, effectiveness, and reduction in LMTD values are obtained by maintaining the inlet mass flow rate of cold fluid at 0.142 kg/s, while the inlet mass flow rate of hot fluid was varied in the range from 0.092 kg/s to 0.133 kg/s. Additionally, the inlet temperatures of hot and cold fluids are kept at 330 K and 296 K, respectively. Hence, the utilization of h-BN nanofluids is proven to be highly effective for boosting thermal energy exchange and enhancing the overall thermal performance of the developed GWVHE.

An investigation of a strengthening polysaccharide interfacial membrane strategy utilizing an anionic polysaccharide-alkaline ligand interfacial assembly for all-liquid printing

The applications of polysaccharides as emulsifiers are limited due to the lack of hydrophobicity. However, traditional hydrophobic modification methods used for polysaccharides are complicated and involve significant mechanical and thermal losses. In this study, soy hull polysaccharide (SHP) and terminally aminopropylated polydimethylsiloxane (NPN) were selected to investigate the feasibility of a simple and green interfacial membrane strengthening strategy based on the interfacial polymerization of anionic polysaccharides and fat-soluble alkaline ligands. Our results show that deprotonated SHP and protonated NPN can be complexed at the water/oil (W/O) interface, reduce interfacial tension, and form a strong membrane structure. Moreover, they can quickly form a membrane at the W/O interface upon the moment of contact to produce stable all-liquid printing products with complex patterns. However, the molecular weight of NPN affects the complexation reaction. Consequently, this study has long-term implications to expanding the areas of application for anionic polysaccharides.

Numerical Simulation and Field Experimental Study of Combustion Characteristics of Hydrogen-Enriched Natural Gas

For the safe and efficient utilization of hydrogen-enriched natural gas combustion in industrial gas-fired boilers, the present study adopted a combination of numerical simulation and field tests to investigate its adaptability. Firstly, the combustion characteristics of hydrogen-enriched natural gas with different hydrogen blending ratios and equivalence ratios were evaluated by using the Chemkin Pro platform. Secondly, a field experimental study was carried out based on the WNS2-1.25-Q gas-fired boiler to investigate the boiler’s thermal efficiency, heat loss, and pollutant emissions after hydrogen addition. The results show that at the same equivalence ratio, with the hydrogen blending ratio increasing from 0% to 25%, the laminar flame propagation speed of the fuel increases, the extinction strain rate rises, and the combustion limit expands. The laminar flame propagation speed of premixed methane/air gas reaches the maximum value when the equivalence ratio is 1.0, and the combustion intensity of the flame is the highest at this time. In the field tests, as the hydrogen blending ratio increases from 0% to nearly 10% with the increasing excess air ratio, the boiler’s thermal efficiency decreases as well as the NOx emission. This indicates that there exists a tradeoff between the boiler thermal efficiency and NOx emission in practice.

Thermosetting benzoxazoles with endo-alkynyl groups: Excellent thermal stability and low dielectric loss

In this study, six thermosetting benzoxazole monomers with endo-alkynyl groups are prepared, and the effect of the endo-alkynyl groups and substituent group on the curing behavior and solubility of monomers, and on the thermal properties and dielectric properties of polybenzoxazoles are investigated. Our findings reveal that incorporating endo-alkynyl groups enhances the cross-linked network in the benzoxazole monomers, thereby improving their thermal stability, hydrophobicity, and dielectric constant. However, this modification also results in decreased solubility and curing properties of the monomers. In addition, the position of the fluorine atoms can affect the curing behavior of monomer and the dielectric properties of polybenzoxazoles. When a fluorine atom is positioned ortho to the cyano group, it impedes the curing of the cyanide group, which increases the curing reaction temperature. Moreover, while it is generally believed that the addition of fluorine typically lowers the dielectric constant of a material, the placement of fluorine atoms ortho to the cyano group can lead to overlapping electronic effects. This overlap may increase the polarity of the curing network, which increases the dielectric constant and dielectric loss of the polybenzoxazoles. Among the six thermosetting benzoxazole monomers studied, poly (2 F-JQ) containing m-diethynyl groups exhibit a 5 % thermal decomposition temperature (Td5) of 610 °C, and a low dielectric loss of 0.0045 at 1 MHz. Compared with other polybenzoxazoles, poly (2 F-JQ) possesses a moderate dielectric constant, excellent thermal stability, and extremely low dielectric loss. In summary, this study provides a new approach for preparing resins that feature high-temperature resistance and low dielectric loss.

Radiation shielding, optical, structural, morphological, and thermal features for tellurite glass ceramics

A new series of tellurite glass-ceramic was prepared for potential utilization in the radiation shielding field. The thermal features of parent glasses were assessed to choose the best heat treatment technique. The morphological and structural properties of glass ceramics were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR). The UV absorption was utilized to calculate the optical features of glass ceramics. The shielding properties were computed based on the Phy-X software. The transformation of glasses to glass ceramics enhanced the density of all glass ceramics. XRD results exhibited an orthorhombic BaTeO3 crystalline phase for the TMSB0 and TMSB5 samples. It is proved that the monoclinic molybdenum tellurium oxide (Mo5TeO16) crystalline phase for TMSB10, TMSB15, and TMSB20 samples. Also, the change in crystalline phase resulted from adding MoO3 instead of TeO2. SEM results affirmed the role of MoO3 in improving the structure of glass ceramics. The thermal stability and weight loss of TMSB20 samples are higher than other glasses. Also, the adding MoO3 led to a slight enhancement in the radiation shielding properties of the prepared samples. Data indicate that adding MoO3 to the glasses enhanced the glass-ceramic samples' thermal, structural, and radiation protection properties.

Polar bear hair inspired 3D photothermal evaporator for efficient solar steam desalination and electricity generation

While solar steam generation for desalination and electricity production is a burgeoning field, traditional systems often face challenges with rapid heat loss and salt buildup. To address these issues, we introduce a biomimetic approach, inspired by the unique thermal properties of polar bear hair. Our study presents a photothermal 3D hierarchical hollow Ppy@CuO nanorod array system, featuring a dual-structured design: a cone-shaped 3D topological structure for improved light absorption and a hollow structure for enhanced thermal insulation. This innovative approach effectively maximizes solar energy capture and reduces thermal losses, particularly in marine environments. Our system exhibits outstanding performance in solar steam generation, achieving high water evaporation rates and maintaining stability and efficiency in high-salinity settings. Under one solar illumination at a 75° tilt angle, the Ppy@CuO-3 NAs demonstrated an evaporation rate of 3.3 kg m−2 h−1 and an energy efficiency of 97.5 %. Additionally, the synergistic effect of released Cu2+ and Ppy resulted in a 99.9 % antibacterial rate against E. coli and S. aureus. This significant advancement in simultaneous, effective seawater desalination and efficient evaporation-driven electricity generation marks a crucial step toward future sustainable resource utilization.

Weathering resistance of novel sustainable prefabricated thermal insulation wall

External walls, serving as the primary medium for heat exchange between the building and the external environment, has its thermal loss comprising the largest proportion of building energy consumption. Therefore, enhancing the thermal insulation capacity of the wall is of great significance in reducing building energy consumption. In this paper, a novel sustainable prefabricated expanded polystyrene (EPS) thermal insulation wall panel with irregular column frame structures was developed. And weathering tests combined with finite element simulations were conducted to investigate its weathering performance and degradation patterns. The results revealed that In the weathering test, the panel surfaces did not exhibit apparent water seepage cracks, powdering, hollowing, peeling, etc. There was no occurrence of facing brick detachment or damage. The outer surface concrete of the wall panel experienced resistance during normal thermal expansion and contraction, generating compressive stress during expansion and tensile stress when contracted. In addition, the bond strength of the specimens decreased by 8.1% after the thermal-rain cycles, 5.1% after the thermal-cold cycles, and 12.1% after the freeze-thaw cycles. In the numerical simulations, the temperature stress at various positions on the concrete wall had a noticeable mutual restraining effect on the force deformation of the nearby concrete. There was a significant risk of cracking in the middle and around the opening, particularly in the lower part of the wall panel. This study serves as a basis for the degradation analyses and optimization design of the sandwich insulation wall panels for sustainability.

Super stable coal fly ash-based solid heat-collecting particles with excellent spectral selectivity

Solar thermal power generation has been widely employed as an effective method for efficiently harnessing solar energy, with solid heat-collecting particles serving as the medium for collecting and storing solar energy, thus holding significant developmental potential. However, challenges such as high thermal radiation losses and inadequate high-temperature stability have hindered the further advancement of solid heat-collecting particles. The present study addresses these challenges by utilizing solid waste fly ash to prepare solar-selective absorbing solid heat-collecting particles. Specifically, particles sintered at 1070℃ exhibit impressive characteristics, including an average solar absorptance of 93.26 % at room temperature, an emissivity in the mid-infrared range of 68.12 %, and a specific heat capacity of 0.82 J/(g·℃). Moreover, rigorous high-temperature stability tests demonstrate that these particles maintain a stable solar absorptance in the ultraviolet–visible-near-infrared range, consistently around 93.26 %. Additionally, the particles exhibit outstanding wear resistance and stability, further enhancing their suitability for practical applications. This research achieves the dual objectives of environmental sustainability and cost reduction by utilizing solid waste materials, while the preparation process remains simple, bolstering the feasibility of implementing these findings in real-world scenarios. In summary, this study effectively addresses the challenges of high thermal radiation losses and poor high-temperature stability in solid heat-collecting particles for solar thermal power generation.

Ultra-low dielectric loss and high thermal conductivity of PTFE composites improved by schistose and globular alumina

Polytetrafluoroethylene (PTFE) based microwave dielectric composite has been widely used because of its adjustable dielectric constant and low dielectric loss, but its low thermal conductivity can not meet the heat dissipation requirements of high-power microwave devices. Therefore, it is of great significance to develop microwave dielectric composites with high thermal conductivity and low loss. In order to obtain microwave composite materials with high thermal conductivity and low losses, schistose Al2O3/PTFE (S-A/PTFE) composites and globular Al2O3/PTFE (G-A/PTFE) composites were successfully prepared. It is compared whether S-A can combine with PTFE more fully than G-A, which can promote the dielectric properties and thermal conductivity of Al2O3/PTFE composites. Surprisingly, the S-A/PTFE composites demonstrate higher thermal conductivity, lower thermal expansion and hygroscopic properties. The S-A/PTFE composites can deliver a high thermal conductivity of 0.986 W/m K. Composite substrates with 53 wt% S-A filler exhibits excellent performance, which specifically show credible dielectric constant (εr = 4.01) and admissible dielectric loss (tanδ = 0.0014 at 10 GHz). Furthermore, the composite substrate shows a similar thermal expansion coefficient to copper, and lower water absorption rate (0.05 %). The relationship between dielectric constant of composite and filler was predicted by different theoretical modeling methods.

Influence of a double-mixer configuration on the mixing and combustion characteristics of a multibypass combustor for a turbine-based combined cycle engine

The changes in the flow field and combustion characteristics induced by the mode transition process of a turbine-based combined cycle (TBCC) engine may lead to failure of the mode transition. In this paper, the cold mixing characteristics, combustion efficiency, and cold and thermal flow losses of a TBCC multibypass combustor with a double-mixer configuration are investigated through numerical simulations, and the correlations between the thermal mixing efficiency and combustion efficiency is established. The results show that the thermal mixing efficiency of double-lobed mixer combustors is better at low ram inlet Mach numbers, but the ring-plus-lobed mixer combustor has better mixing and combustor characteristics at relatively high Mach numbers. However, the effect of the turbo core inlet Mach number on the combustion efficiency is not regular. The spacing between the double mixers that maximizes the mixing and combustion characteristics of the combustor is 75 mm. With increasing of expansion angle of the lobed mixer, the thermal mixing efficiency and combustion efficiency increase by 31.9 % and 23.3 %, respectively. In addition, the positive correlation coefficient between combustion efficiency and thermal mixing efficiency caused by changes in the inlet Mach number is greater than that caused by changes in structural parameters.

Fast ion relaxation in ITER mediated by Alfvén instabilities

We address the critical issue for future burning plasmas of whether high-energy fusion products or auxiliary heating-beam ions will be confined for a sufficiently long time to compensate for thermal plasma energy losses. This issue can be mitigated by one of the most deleterious collective phenomena—the instability of low, sub-cyclotron frequency Alfvén eigenmodes (AEs), such as toroidicity-induced AEs and reversed-shear AEs in the ITER steady-state scenario. Using a revised quasi-linear (QL) theory applied to energetic particle (EP) relaxation in the presence of AEs, we find that the AE instabilities can affect both neutral beam ions and alpha particles, although the resulting fast ion transport is expected to be modest if classical particle slowing down is assumed. On the other hand, the QL theory predicts that the AE amplitudes will be enhanced by the background microturbulence, although this topic remains outside our scope due to the significant numerical effort required to evaluate these effects. We report our results for EP relaxation dynamics obtained utilizing several tools: (i) a comprehensive linear stability study of the sub-cyclotron Alfvénic spectrum as computed by ideal magnetohydrodynamic NOVA simulations for the AE eigenproblem, (ii) drift kinetic NOVA-C calculations for wave–particle interaction and AE growth/damping rates, and (iii) predictive QL modeling coupled with the global transport code TRANSP to assess the EP relaxation on the equilibrium timescale.

Influence of geometric design variables on the performance of a novel V-shaped cavity receiver

This study presents a novel cavity receiver for parabolic trough concentrators, incorporating a triangular envelope, a trapezoidal cavity, and a semi-circular flow channel. A total of 5120 designs were examined by tuning the rim angle of parabolic mirrors, the width and angle of the receiver's opening, and the depth of the absorber for different operating flow rates and temperatures. Batch simulations of these designs were automated by coupling newly developed and validated models of Monte Carlo ray tracing and semi-analytical 1-D energy balances in SOLTRACE® and MATLAB® to determine the heat fluxes and surface temperatures of the receiver, respectively. The results show that the rim angle must be reduced to maximize sun rays' interception, and the opening angle has the largest impact on performance. All dimensions must be decreased when operating at low flow rates and high temperatures to avoid excessive thermal losses. This results in maximum energy and exergy efficiencies of 74.7 % and 40.7 %, respectively. When operating at low temperatures and large flow rates, the largest energy and exergy efficiencies increase and decrease to 80.5 % and 27 %, corresponding to optimal rim angle, absorber depth, opening width, and opening angle of 60°, 85 mm, 200 mm, and 100°, respectively.

Experimental investigation of knock control criterion considering power output loss for a PFI SI methanol marine engine

This study presents a new knock control criterion based on different loads and engine power output loss. By utilizing a modified port fuel injection (PFI) spark-ignition (SI) methanol marine engine, the suppressive effects of retarding ignition timing, reducing air-fuel ratio and delaying injection timing on knock intensity at different loads were investigated. Subsequently, a comparative analysis of three knock control strategies was conducted to determine their impacts on power output and thermal efficiency, thus proposing the optimal knock control strategy at different loads. The results show that at both low load (MAP = 73 kPa) and high load (MAP = 139 kPa), the high knock intensity in KLSA (knock-limited spark advance) +5 case is reduced to the safety limitation by retarding ignition timing and reducing air-fuel ratio, while retarding injection timing can effectively suppress knock only at low load. Furthermore, under KLSA+5 condition, there is a significant increase in the probability of severe knock for CA05 earlier than the knock boundary. As the knock tendency is mitigated, IMEP reduces monotonically. There is lower power output loss by optimizing injection timing and air-fuel ratio at low load, and optimizing ignition timing at high load, while the air dilution strategy consistently results in minimal thermal efficiency loss.

Characterization and Implementation of Cocoa Pod Husk as a Reinforcing Agent to Obtain Thermoplastic Starches and Bio-Based Composite Materials.

When the cocoa pod husk (CPH) is used and processed, two types of flour were obtained and can be differentiated by particle size, fine flour (FFCH), and coarse flour (CFCH) and can be used as a possible reinforcement for the development of bio-based composite materials. Each flour was obtained from chopping, drying by forced convection, milling by blades, and sieving using the 100 mesh/bottom according to the Tyler series. Their physicochemical, thermal, and structural characterization made it possible to identify the lower presence of lignin and higher proportions of cellulose and pectin in FFCH. Based on the properties identified in FFCH, it was included in the processing of thermoplastic starch (TPS) from the plantain pulp (Musa paradisiaca) and its respective bio-based composite material using plantain peel short fiber (PPSF) as a reinforcing agent using the following sequence of processing techniques: extrusion, internal mixing, and compression molding. The influence of FFCH contributed to the increase in ultimate tensile strength (7.59 MPa) and higher matrix-reinforcement interaction when obtaining the freshly processed composite material (day 0) when compared to the bio-based composite material with higher FCP content (30%) in the absence of FFCH. As for the disadvantages of FFCH, reduced thermal stability (323.57 to 300.47 °C) and losses in ultimate tensile strength (0.73 MPa) and modulus of elasticity (142.53 to 26.17 MPa) during storage progress were identified. In the case of TPS, the strengthening action of FFCH was not evident. Finally, the use of CFCH was not considered for the elaboration of the bio-based composite material because it reached a higher lignin content than FFCH, which was expected to decrease its affinity with the TPS matrix, resulting in lower mechanical properties in the material.

Thermal characteristics of heat-pipe-ring embedded building façades as both building-integrated and building-attached solar collectors

Solar energy utilization in buildings is crucial for energy conservation and carbon reduction. Previous studies have shown the promise of heat-pipe-ring (HPR) embedded building façades as effective modules for solar energy utilization and energy conservation in air-conditioning systems. However, research on their thermal characteristics as building-attached solar collectors is limited. This paper fills this gap by combining experimental data and numerical simulations using self-developed Fortran programs. Regression analysis of HPR modules in building integration solar systems (BISS) determines thermal efficiency and thermal loss coefficient. Results indicate the advantage of selective Cr coating in minimizing energy losses, with less pronounced impact from glass covers. Optimal HPR module designs for building-attached solar systems (BASS) in different Chinese climate regions are established, achieving yearly averaged thermal efficiencies ranging from 62.6 % to 73.5 %. The study further presents the thermal performance of HPR modules in BASS on a typical summer day in each city within each climate zone. These findings offer practical insights for selecting HPR modules in BASS systems tailored to diverse regions, promoting the integration of renewable solar energy into building applications.