Enthalpy Research Articles

A transient formulation of entropy and heat transfer coefficients of Newton's cooling law with the unifying entropy potential difference in compressible flows

The original Newton's law of cooling is considered an ideal convection model of a point source ignoring conduction, but its unknown convection conductance and inconsistent thermal potential difference make it difficult to further elucidate the transient heat transfer mechanism of convection because of the no-slip condition at the interface between a body and a fluid. For this purpose, both the convective entropy transfer theory and the hypothesis of the isothermal velocity sublayer are developed to recast Newton's law of cooling into a standard Ohm's law form via the unified entropy driving force and the unambiguous entropy transfer coefficient. An explicit expression for the transient heat transfer coefficient is presented theoretically and experimentally in compressible flows by virtue of the product of the free-stream velocity, the volumetric thermal capacity of the fluid, and the near-wall velocity constant. The unified thermal potential difference is established between the body temperature and the total temperature (reduced to the ambient temperature for incompressible fluids). The physical mechanism of convection mode in the original Newton's cooling law is reasonably explained by the entropy transfer theory and entropy transfer efficiency, and the formulae for the entropy flux vector driven by the standard entropy potential difference and the rate of entropy generation are obtained. The analytical heat transfer coefficients as well as the standard thermal driving forces are validated by comparison with the forced convection experiment with a maximum error of 4.6 % in incompressible flows and the previous Newton's benchmark cooling experiments with the maximum error of 6.7 % in compressible flows. The effects of radiation on the total heat transfer coefficient are also analyzed quantitatively.

The mechanism of interaction between tri-para-cresyl phosphate and human serum protein: a multispectroscopic and in-silico study

Organophosphate flame retardants (OPFRs) pose the significant risks to the environment and human health and have become a serious public health issue. Tricresyl phosphates (TCPs), a group of aryl OPFRs, exhibit neurotoxicity and endocrine disrupting toxicity. However, the binding mechanisms between TCPs and human serum albumin (HSA) remain unknown. In this study, through fluorescence and ultraviolet-visible (UV-vis) absorption spectroscopy, molecular docking and molecular dynamics (MD), tri-para-cresyl phosphate (TpCP) was selected to explore potential interactions between HSA and TCPs. The results of the fluorescence spectroscopy demonstrated that a decrease the fluorescence intensity of HSA and a blue shift were observed with the increasing concentrations of TpCP. The binding constant (Ka) was 2.575 × 104 L/mol, 4.701 × 104 L/mol, 5.684 × 104 L/mol and 9.482 × 104 L/mol at 293 K, 298 K, 303 K, and 310 K, respectively. The fluorescence process between HSA and TpCP involved a mix of static and dynamic quenching mechanism. The gibbs free energy (ΔG0) of HSA-TpCP system was -24.452, -25.907, 27.363, and 29.401 kJ/mol at 293 K, 298 K, 303 K, and 310 K, respectively, suggesting that the HSA-TpCP reaction was spontaneous. The enthalpy change (ΔH0) and thermodynamic entropy change (ΔS0) of the HSA-TpCP system were 291.08 J/K mol and 60.83 kJ/mol, respectively, indicating that hydrophobic force was the major driving forces in the HSA-TpCP complex. Furthermore, multispectral analysis also revealed that TpCP could alter the microenvironment of tryptophan residue and the secondary structure of HSA and bind with the active site I of HSA. Molecular docking and MD simulations confirmed that TpCP could spontaneously form a stable complex with HSA, which was consistent with the fluorescence experimental results. This study provides novel insights into the mechanisms of underlying the transportation and distribution of OFPRs in humans.

Climatology of the terms and variables of transformed Eulerian-mean (TEM) equations from multiple reanalyses: MERRA-2, JRA-55, ERA-Interim, and CFSR

Abstract. A 30-year (1980–2010) climatology of the major variables and terms of the transformed Eulerian-mean (TEM) momentum and thermodynamic equations is constructed by using four global atmospheric reanalyses: the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2); the Japanese 55-year Reanalysis (JRA-55); the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim); and the Climate Forecast System Reanalysis (CFSR). Both the reanalysis ensemble mean (REM) and the differences in each reanalysis from the REM are investigated in the latitude–pressure domain for December–January–February and for June–July–August. For the REM investigation, two residual vertical velocities (the original one and one evaluated from residual meridional velocity) and two mass streamfunctions (from meridional and vertical velocities) are compared. Longwave (LW) radiative heating and shortwave (SW) radiative heating are also shown and discussed. For the TEM equations, the residual terms are also calculated and investigated for their potential usefulness, as the residual term for the momentum equation should include the effects of parameterized processes such as gravity waves, while that for the thermodynamic equation should indicate the analysis increment. Inter-reanalysis differences are investigated for the mass streamfunction, LW and SW heating, the two major terms of the TEM momentum equation (the Coriolis term and the Eliassen–Palm flux divergence term), and the two major terms of the TEM thermodynamic equation (the vertical temperature advection term and the total diabatic heating term). The spread among reanalysis TEM momentum balance terms is around 10 % in Northern Hemisphere winter and up to 50 % in Southern Hemisphere winter. The largest uncertainties in the thermodynamic equation (about 50 %) are found in the vertical advection, for which the structure is inconsistent with the differences in heating. The results shown in this paper provide basic information on the degree of agreement among recent reanalyses in the stratosphere and upper troposphere in the TEM framework.

A detailed investigation on thermal performance and energy savings of cool roof systems for composite climates of India

ABSTRACT The rising worldwide temperatures leading to a spike in air conditioning to ensure thermal comfort in buildings is the root cause of the increase in energy demand in India's building sector. The roof of a building significantly adds to the heat gained on the top floor, accounting for 50–60% of the total heat gain. One sustainable way to reduce this heat gain is via cool roofing technology. Through examination and dynamic simulations with the Energy-Plus-based Design Builder software tool, this study explores different cool roof solutions. An experimental setup of a Reinforced Cement Concrete (RCC) roof with cement plaster, solar reflective paint, solar reflective tiles, and earthen pots have been created on the institute campus. Recordings were taken during the peak summer days and peak winter days, alongside simulations carried out to determine various factors such as Albedo, Surface Temperatures, Air Temperatures, Diurnal Heat Ingress, and the Building's Thermal Energy Consumption. The experiments have demonstrated that cool roof layers can considerably improve interior thermal comfort by minimizing heat transfer, which maintains a constant temperature over the bottom surface of the roof. By reducing heat gain by 33–71%, they can save energy by 21-26% compared to traditional RCC roof slab.

A sustainable and economical solution for CO2 capture with biobased carbon materials derived from palm kernel shells.

This study investigates the synthesize of activated carbon for carbon dioxide adsorption using palm kernel shell (PKS), a by-product of oil palm industry. The adsorbent synthesis involved a simple two-step carbonization method. Firstly, PKS was activated with potassium oxide (KOH), followed by functionalization with magnesium oxide (MgO). Surface analysis revealed that KOH activated PKS has resulted in a high specific surface area of 1086 m2/g compared to untreated PKS (435 m2/g). However, impregnation of MgO resulted in the reduction of surface area due to blockage of pores by MgO. Thermogravimetric analysis (TGA) demonstrated that PKS-based adsorbents exhibited minimal weight loss of less than 30% up to 500 °C, indicating their suitability for high-temperature applications. CO2 adsorption experiments revealed that PKS-AC-MgO has achieved a higher adsorption capacity of 155.35 mg/g compared to PKS-AC (149.63 mg/g) at 25 °C and 5 bars. The adsorption behaviour of PKS-AC-MgO was well fitted by both the Sips and Langmuir isotherms, suggesting a combination of both heterogeneous and homogeneous adsorption and indicating a chemical reaction between MgO and CO2. Thermodynamic analysis indicated a spontaneous and thermodynamically favourable process for CO2 capture by PKS-AC-MgO, with negative change in enthalpy (- 0.21 kJ/mol), positive change in entropy (2.44 kJ/mol), and negative change in Gibbs free energy (- 729.61 J/mol, - 790.79 J/mol, and - 851.98 J/mol) across tested temperature. Economic assessment revealed that the cost of PKS-AC-MgO is 21% lower than the current market price of commercial activated carbon, indicating its potential for industrial application. Environmental assessment shows a significant reduction in greenhouse gas emissions (381.9 tCO2) through the utilization of PKS-AC-MgO, underscoring its environmental benefits. In summary, the use of activated carbon produced from PKS and functionalised with MgO shows great potential for absorbing CO2. This aligns with the ideas of a circular economy and sustainable development.

Synthesis and Polymerization of the Bio‐Benzoxazine Derived from Resveratrol and Thiophenemethylamine and Properties of its Polymer

AbstractResveratrol and 2‐thiophenemethylamine have been employed in the synthesis of a novel tri‐functional benzoxazine (RES‐th) to develop the bio‐benzoxazine monomer. The chemical structure of the synthesized monomer is confirmed by various characterization technics. The polymerization behavior is monitored by in situ Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The in situ FTIR results reveal distinct reaction mechanisms for the three oxazine rings presented in RES‐th, with both ether and phenolic Mannich bridge structures observed in the products. The activation energy values of RES‐th are calculated to be 119.05, 120.97, and 119.44 kJ mol−1 by Kissinger, Ozawa, and Starink methods, respectively, which are all based on the heat flow curves at various heating temperatures. The thermal stability and flame retardancy of the resulting polybenzoxazine (poly(RES‐th)) are investigated by thermogravimetric analysis (TGA) and microscale combustion calorimeter (MCC). The values of Td5 and Td10 of polybenzoxazine are found to be 356 °C and 399 °C, respectively, with a char yield of 66.3% at 800 °C. The prepared polybenzoxazine also demonstrates nonflammability characteristics with the values of heat release capacity (HRC) and total heat release rate (THR) of 18.65 J (g K)−1 and 2.69 kJ g−1, respectively. These findings suggest that the thermoset, poly(RES‐th), is a promising candidate for fire‐resistant applications.

Comparative Assessment of Thermal Oils and Water as Working Fluids in Parabolic Trough Collectors for Enhanced Solar Power Generation

Abstract Examining the thermal behavior of specific working fluids, namely Syltherm800 and TherminolVP-1, in parabolic trough collectors (PTCs) is imperative for enhancing power generation. This study addresses a crucial gap by conducting computational fluid dynamics simulations through COMSOL Multiphysics software and experimental tests to explore the advantages of utilizing thermal oils over water as a working fluid in PTCs. Experimental tests were performed on a water-based PTC in Iraq to validate the numerical model, considering various operating conditions such as input temperature (323.15-423.15 K) and mass flow rates (0.00926-0.0556 kg/s). Key parameters including output temperature, thermal efficiency, useful heat, and total heat losses were evaluated. The numerical model was validated against experimental data, showing good agreement with an overall discrepancy of 1.7% for the current experiments and 3.18% for literature results. The results indicated that Syltherm800, particularly with a high mass flow rate, outperformed TherminolVP-1 and water in terms of overall thermal performance. The optimal PTC thermal efficiency was achieved in July with a mass flow rate of 0.0556 kg/s and an input temperature of 348.15 K. The optimal range for PTC thermal efficiency over four months was between 50% and 70%. The endorsement of thermal oils in PTCs is supported by their low vapor pressure, superior thermal stability, and extended lifespan.

Physicochemical and molecular docking studies of tween 20 in the presence of NaX salts and hydrotropes in aqueous media

An investigation has been conducted on the interaction between the plasma protein bovine serum albumin (BSA) and the surfactant T20 using various hydrotropes of sodium salt (NaX, where X is Sal and Benz). The acquired results provide a practical and efficient means to comprehend the binding process of the micellar system T20 to BSA. The predominant forces involved are hydrophobic forces and hydrogen bonding. The further study intends to investigate the impact of NaX (here, X represents Cl, Br, NO3, Sal, and Benz), on the T20 solution using various techniques including density (ρ), viscosity (η), sound velocity (U), dynamic light scattering (Dh), FT-IR spectroscopy, and molecular docking at varying temperatures. The values of ρ, η, and U increase as the concentration of Na salt increases. Conversely, when the temperature increases, the values of ρ and η fall, while the value of U increases. NaSal exhibits higher viscosity compared to other substances. The phase separation model was employed to calculate the standard Gibbs free energy ( Δ G CP 0 ), enthalpy ( Δ H CP 0 ), and entropy ( Δ S CP 0 ). The NaBenz exhibits the highest values of sound velocity while examining at different temperatures. The structural identification was performed using FT-IR data, which revealed good agreement with the available literature.

On the thermodynamics of Barium Oxyfluoride precursor in YBCO growth via MOD process

Abstract Barium Oxyfluoride plays an important role, as precursor species, in the nucleation and growth of YBa2Cu3O7-δ (YBCO) via the low fluorine Metal Organic Decomposition (MOD low-fluorine) route. In this contribution, we present a study on the thermodynamics of the Oxyfluoride by processing experimental data on the YBCO growth at LaAlO3 (LAO) substrate. The analysis allows one to determine the standard enthalpy and the standard entropy changes for Oxyfluoride formation from Barium oxide and Barium fluoride. To identify the thermodynamically more favorable route to the Oxyfluoride formation in the MOD low-fluorine process, the free energy change for the formation of the precursor, through reactions involving gas water, has been determined. The free energy of formation via fluoride and water indicates higher stability of oxygen rich Oxyfluoride for (P_HF^2)/P_(H_2 O) <10^(-6). In the framework of the nucleation theory the present results are needed to study the effect of precursor composition on film orientation.

On the thermodynamics of Barium Oxyfluoride precursor in YBCO growth via MOD process

Abstract Barium Oxyfluoride plays an important role, as precursor species, in the nucleation and growth of YBa2Cu3O7-δ (YBCO) via the low fluorine Metal Organic Decomposition (MOD low-fluorine) route. In this contribution, we present a study on the thermodynamics of the Oxyfluoride by processing experimental data on the YBCO growth at LaAlO3 (LAO) substrate. The analysis allows one to determine the standard enthalpy and the standard entropy changes for Oxyfluoride formation from Barium oxide and Barium fluoride. To identify the thermodynamically more favorable route to the Oxyfluoride formation in the MOD low-fluorine process, the free energy change for the formation of the precursor, through reactions involving gas water, has been determined. The free energy of formation via fluoride and water indicates higher stability of oxygen rich Oxyfluoride for (P_HF^2)/P_(H_2 O) <10^(-6). In the framework of the nucleation theory the present results are needed to study the effect of precursor composition on film orientation.

Polydopamine-primed FeCo-LDH endowed epoxy resin with enhanced flame retardancy and mechanical properties

The integration of layered double metal hydroxides (LDH) into epoxy resin (EP) for flame retardancy is in line with the principles of environmentally friendly and sustainable development. In this study, polydopamine (PDA)-primed intercalated LDH containing iron and cobalt ions (LDH-DBS@PDA) was prepared, and its chemical composition, structure and morphology were thoroughly characterized. Due to the synergistic flame-retardant properties exhibited by LDH and PDA, as well as the catalytic charring properties of iron and cobalt ions in both condensed and gaseous phases, EP composite with 5 wt% LDH-DBS@PDA achieved a UL-94 V-0 rating with a limiting oxygen index of 30.7 %. Moreover, EP/LDH-DBS@PDA exhibited a significant decrease in total heat release by 48 % and smoke release by 52 %, demonstrating remarkable fire safety performance. Additionally, the existence of LDH-DBS@PDA improved impact strength, tensile strength, and glass transition temperature due to strong interactions between PDA and EP matrix. This work presents a promising strategy for developing highly efficiency flame retardants with excellent compatibility for polymeric materials.

Heat Transfer Performance and Operation Scheme of the Deeply Buried Pipe Energy Pile Group

This paper describes a study on the heat transfer properties of the deeply buried pipeline energy pile group, which is an efficient and convenient geothermal development technology. Through in situ experiments and a simulation algorithm, the research investigated the heat transmission characteristics of the deeply buried pipe energy pile group and optimized different intermittent operation schemes. The findings suggest that prolonged operation of the pile cluster intensifies heat buildup within the pile foundation, thereby adversely affecting the system’s overall heat exchange efficiency. Employing an intermittent operating mode can alleviate this heat accumulation phenomenon, thereby promoting sustained heat exchange performance of the piles over time. To evaluate the comprehensive thermal interaction and energy efficiency ratio of the energy pile heat exchange system, various intermittent operation strategies were compared in the study. Among them, the intermittent operational scheme with a ratio of n = 5 was found to be optimal, with the total average heat transfer rate of the pile set only 0.51% lower than that of the continuous operational mode, but the overall energy efficiency ratio improved by 19.6%. The intermittent operational mode proposed in this study can achieve the goal of saving energy and efficiently extracting geothermal resources, providing theoretical guidance for the extraction and utilization of subsurface geothermal power by energy piles.

Smoke Suppression Properties of Fe2O3 on Intumescent Fire-Retardant Coatings of Styrene–Acrylic Emulsion

The intumescent flame-retardant coatings were prepared using ammonium polyphosphate (APP), pentaerythritol (PER), melamine (MEL), styrene–acrylic emulsion, and iron oxide yellow (FeOOH) as the base material. A cone calorimeter (CCT), smoke density meter (SDA), and scanning electron microscope (SEM) were employed to investigate the smoke suppression and flame retardancy of FeOOH in intumescent fire-retardant coatings. The thermal degradation performance of intumescent fireproofing coatings with varying FeOOH content was investigated through thermogravimetric analysis (TGA). The structure of the carbon slag in the CCT test was analyzed using a scanning electron microscope (SEM). The results of the cone calorimeter (CCT) experiments demonstrated that FeOOH significantly reduced the heat release rate (HRR), total heat release rate (THR), smoke production rate (SPR), and total smoke release rate (TSR) of the coating, while simultaneously increasing the carbon residue rate of the coating. The smoke density analysis (SDA) results demonstrate that adding FeOOH can effectively reduce smoke generation, regardless of whether a pilot flame is used. TGA results demonstrate that FeOOH can enhance the weight of coke residue at elevated temperatures. SEM results indicate that incorporating FeOOH resulted in a more compact coke residue. According to these findings, among all the samples, those containing 2 wt% FeOOH showed low levels of HRR, THR, SPR, and TSR and high levels of SOD, which proves that FeOOH can be used as a smoke inhibitor in flame-retardant coatings.

Unraveling the enigma: Probing the unconventional binding site and binding mechanism of entrectinib with human serum albumin through spectroscopic, molecular docking, and dynamic simulation analyses

Entrectinib (ENB), a novel potent tyrosine kinase inhibitor, has demonstrated promising activity against specific genetic alterations in various solid tumors. Investigating the interaction of ENB with human serum albumin (HSA) provides valuable insights into its binding characteristics and pharmacological behavior. The interaction between ENB and HSA was investigated using various spectroscopic techniques, molecular docking, and simulations approaches. Fluorescence spectroscopy revealed a consistent decrease in the intrinsic fluorescence of HSA upon binding to ENB, indicating a static binding mechanism. The binding constant calculated from Stern Volmer and double-log equations (KSV) and (K) were determined to be 4.11 x104 M−1 and 4.38 x104 M−1, respectively at 298 K, indicating moderate binding affinity. Thermodynamic analysis demonstrated a spontaneous interaction (ΔG < 0) with an enthalpy change (ΔH) of −5.59 kJ mol−1 and an entropy change (ΔS) of + 70.36 J mol−1 K−1, indicating that the interaction is primarily driven by electrostatic forces with potential involvement of hydrogen bonding. Synchronous and 3D fluorescence analysis indicated no significant changes in the microenvironment surrounding Tyr and Trp residues upon ENB binding. Near and far UV spectrophotometric analyses confirmed the formation of the ENB-HSA complex and suggested no conformational changes in the protein structure. Fluorescence measurements and binding competition analysis using site markers revealed that ENB selectively binds to the HSA Sudlow sites I and III, displacing phenylbutazone at both sites. Molecular docking studies confirmed the binding of ENB to Sudlow sites I and III and identified critical residues involved in the interaction. Molecular dynamics simulations further validated the stability of the ENB-HSA complex at both sites, with more favorable binding at site III, and minimal fluctuations observed in the root mean square deviation, root mean square fluctuation, and radius of gyration. Hydrogen bond analysis and solvent accessible surface area calculations supported the strong binding and accessibility of ENB within the HSA structure. Overall, the experimental and computational results provided valuable insights into the ENB-HSA interaction, elucidating the binding mechanism and key residues involved.

Entropy generation and heatline visualization of magnetized thermal convection in an irregular enclosure filled with nanofluid and subject to non-uniform heating: FEM-machine learning hybrid approach

This investigation's primary objective is to analyze the fluid dynamics and heat transfer enhancement in an irregular enclosure. Several physical phenomena such as Alumina-water nanofluids, magnetic field, non-uniform heating and amplitude of non-uniform heating are taken into account. A thorough investigation using machine learning algorithms (MLAs) and computational fluid dynamics (CFD) is carried out. Initially, for CFD phase the coupled non-linear dimensionless governing equations of the considered problem are solved numerically by adapting a Finite Element method (FEM) using appropriate boundary conditions. The analysis considers a range of physical parameters, such as the Hartmann number (0–20), nanoparticle volume friction (0–0.04), Ryleigh number (103-105), offset temperature (0.1–1), frequency (1-10) and non-uniform heating amplitude (0.1–1). The numerical results are explicated in the form of streamlines, isotherms, heatlines structures. The impact of these factors on entropy generation is also explored. In addition, three popular MLAs, Random Forest (RF), Artificial Neural Network (ANN) and Support Vector Machine (SVM) were used to save the computational costs. The finding explore Hartmann number and nanoparticle volume friction has decreasing trend on total entropy production and heat transfer rate. The entropy production decreases up to 42.02 % for Hartman number and for nanoparticles it decreases 12.61 %. However, the non-uniform heating amplitude has opposite effect on irreversibility factor. Also, compared to other MLAs, the ANN model demonstrates more accurate predictions. The objective is to propose novel concept for enhancing the performance of cooling systems and optimizing energy utilization across diverse technical domain.

Experimental and Theoretical Study of Heat Transfer in a Chilled Ceiling System

Radiant cooling has been growing in recent years due to energy savings and improved comfort and health. The aim of this study was to reduce energy consumption and provide comfort using a chilled ceiling panel in the zone. In the experimental part of this study, a test room was created to investigate the change in the heat transfer performance of a chilled ceiling panel according to different water temperatures, different water flow rates and different heat source values. As a result of the experimental study, it was found that optimum conditions were achieved with a heat rate of 280 Watts and the lowest supply water temperature of 14 °C, with indoor comfort conditions being achieved with water flow rates of 0.93 m3/h. In the theoretical part of this study, a thermal balance was established for ceiling panel cooling applications. An analytical model of the heat transfer between the cold ceiling panel and the room air was also developed. The convection coefficient, convective heat transfer and total heat transfer coefficient were compared using the values obtained from the experiments and those reported in the literature. It was found that the convection coefficient was within the range reported in the literature, and the radiation heat coefficient was within 99.8% of the literature values.

Preparation of bio-based trinity lignin intumescent flame retardant and its effect on burning behavior and heat transfer process of epoxy resin composites

The thermal insulation performance of intumescent coating coated on the surface of steel structure is of great significance to prevent the underlying steel structure from collapse in fire. Bio-based intumescent flame retardants gradually attract many attentions due to its environmental friendliness and rich natural sources. In this study, a new bio-based intumescent flame retardant trinity lignin intumescent flame retardant (TLI) is synthesized, which is added to epoxy resin (EP) to prepare EP/TLI epoxy intumescent coatings. The burning behavior of EP/TLI epoxy intumescent coatings is investigated by thermogravimetric (TG) analysis, limit oxygen index (LOI), vertical burning test and cone calorimeter test. Microscopic morphology of char layer is observed by scanning electron microscopy (SEM). The results show that when the TLI addition content is 20 wt% (EP/TLI-4), LOI reaches 26.5 %, UL-94 is V-0 rating. Compared to pure EP, the peak heat release rate (pHRR) and total heat release (THR) of EP/TLI-4 coating are reduced by 82.20 % and 78.27 %, respectively. The influence of chemical formulations, initial coating thickness and incident heat flux on heat transfer process of EP/TLI epoxy intumescent coatings is also investigated. At the same time, the thermal insulation mechanism of EP/TLI epoxy intumescent coating is presented.

Experimental and Theoretical Study of Heat Transfer in a Chilled Ceiling System

Radiant cooling has been growing in recent years due to energy savings and improved comfort and health. The aim of this study was to reduce energy consumption and provide comfort using a chilled ceiling panel in the zone. In the experimental part of this study, a test room was created to investigate the change in the heat transfer performance of a chilled ceiling panel according to different water temperatures, different water flow rates and different heat source values. As a result of the experimental study, it was found that optimum conditions were achieved with a heat rate of 280 Watts and the lowest supply water temperature of 14 °C, with indoor comfort conditions being achieved with water flow rates of 0.93 m3/h. In the theoretical part of this study, a thermal balance was established for ceiling panel cooling applications. An analytical model of the heat transfer between the cold ceiling panel and the room air was also developed. The convection coefficient, convective heat transfer and total heat transfer coefficient were compared using the values obtained from the experiments and those reported in the literature. It was found that the convection coefficient was within the range reported in the literature, and the radiation heat coefficient was within 99.8% of the literature values.

A stable and visualized fatty acid-based phase transition material constructed by solid-phase molecular self-assembly for thermal management.

Fatty acids are excellent thermal management materials for thermal storage, release and preventing thermal runaway. However, the leakage of fatty acids leads to instability and prevents their application in thermal management. Herein, a stable and visualized fatty acid-based phase transition material P-S/PA was constructed through solid-state molecular self-assembly strategy from polydiallyldimethylammonium chloride (PDDA), sodium dodecyl benzene sulfonate (SDBS) and palmitic acid (PA). The electrostatic interaction between PDDA and SDBS and hydrophobic interaction between PA and SDBS can prevent PA leakage during phase transition, achieving stability. After 1000 cycles, the changes in the phase transition enthalpy (ΔH M, ΔH C) were less than 1%. The structural similarity also made P-S/PA phase transition visible, and the transmittance changed significantly from 0% to 68% during phase transition. In addition, P-S/PA can be remolded by hot-pressing without performance changes, showing temperature adjustability on varying the fatty acid carbon chain length. Thus, the stable and visualized P-S/PA fatty acid-based phase transition material constructed by solid-phase molecular self-assembly has promising application in thermal management.

Exploring the molecular binding mechanism of 6-fluoro, 4-hydroxy, 2- methyl quinoline with TiO2 nanoparticles: A spectroscopic, thermodynamic, and insights into the solvatochromic effect.

This study investigates the interaction between titanium oxide nanoparticles (TiO2 NPs) and the heterocyclic fluorophore 6-fluoro,4-hydroxy,2-methylquinoline (6-FHMQ), aiming to understand fluorescence quenching mechanisms and thermodynamic characteristics. Spectroscopic techniques including spectrofluorometry (FL) and spectrophotometry (UV-Vis) were used, with a lifetime decay (τ) of 0.18ns for 6-FHMQ measured using time correlated single photon counting (TCSPC). The interaction between 6-FHMQ and TiO2 NPs revealed a mix of static and dynamic fluorescence quenching mechanisms, with increasing quenching constants (Ksv) and a higher bimolecular quenching rate constant (Kq). The dynamic nature was highlighted by a temperature-dependent increase in binding sites from 1 to ~ 2. Spontaneous complexation was affirmed by negative change in free energy (ΔG), with negative change in enthalpy (ΔH) and a positive change in entropy (ΔS) values indicating favorable electrostatic and ionic interactions. The impact of varying TiO2 NP concentrations on 6-FHMQ absorption was analyzed using the Benesi-Hildbrand equation, with a quantum yield of 0.61 determined. By forster resonance energy transfer (FRET) theory, the proximity between 6-FHMQ and TiO2 NPs was found to be less than 70Å. Ground and excited state dipole moments of 6-FHMQ in different solvents were calculated to demonstrate solvent sensing ability and charge transfer properties. Ultimately, this study serves as a testament to the power of scientific innovation in the realms of drug delivery and tissue engineering.