High solar irradiance during pre-monsoon conditions in tropical regions increases photovoltaic energy generation potential but simultaneously elevates module operating temperature, which adversely affects electrical performance and long-term reliability. Crystalline silicon photovoltaic modules exhibit a negative temperature coefficient of approximately −0.4 to −0.5 %/°C, making thermal management an important consideration for sustained operation. This study experimentally investigates the influence of selective spectral filtering on the thermal and electrical performance of 20 W monocrystalline and polycrystalline photovoltaic modules under natural outdoor conditions in Pune, India (18.9876°N, 73.9651°E). Spectral bands of 400–450 nm, 450–570 nm, 570–750 nm, and 750–1100 nm were evaluated and compared with full-spectrum exposure at 1000 W/m². The 570–750 nm spectral band transmitted 436 W/m² and produced a maximum output power of 15.49 W from the monocrystalline module. Under this condition, a band-limited photon utilization efficiency of 25% was obtained when referenced to the transmitted irradiance. However, this metric differs from conventional photovoltaic conversion efficiency, which is defined using total incident solar irradiance. When referenced to the full incident irradiance of 1000 W/m², the corresponding system-level efficiency was approximately 11.06%, compared with 14.06% under full-spectrum exposure. Selective filtering reduced module surface temperature by approximately 10°C, corresponding to an estimated power retention benefit of about 4.5% based on temperature coefficient analysis. Monocrystalline modules exhibited superior spectral response and lower recombination sensitivity than polycrystalline modules. The results indicate that selective spectral filtering functions primarily as a thermal mitigation and spectral optimization strategy rather than a power enhancement technique. The findings are based on a short-term experimental campaign conducted under pre-monsoon conditions in Pune and should be interpreted within the context of the prevailing seasonal and atmospheric conditions.
Domestic heat pump water heaters offer an energy-efficient solution for hot water production in tropical countries. This study evaluates the energy and exergy performance as well as the environmental impact of R-152a as a replacement for R-134a in a domestic heat pump water heater. The evaluation uses a thermodynamic modelling approach under fixed operating conditions, with an evaporator temperature of 10°C, a condenser temperature of 50°C, and a water heating capacity of 1.6 m³. The results indicate that R-152a achieved an actual coefficient of performance (COP) of 6.25, which was 4.3% higher than that of R-134a at 5.99. R-152a also required a lower refrigerant mass flow rate. The mass flow rate decreased from 7.595 g/s for R-134a to 4.555 g/s for R-152a, which represents a reduction of approximately 40%. The exergy analysis further showed that R-152a consistently exhibited higher exergy efficiency than R-134a across the investigated ranges of evaporator temperature and compressor efficiency. This result indicates that R-152a has a lower thermodynamic irreversibility. From an environmental perspective, R-152a also showed a much lower direct Total Equivalent Warming Impact (TEWI). Its direct TEWI was 195.3 kg CO2-eq, which was 91.3% lower than that of R-134a at 2252.25 kg CO2-eq. This reduction is mainly related to the lower Global Warming Potential (GWP) of R-152a, which is 124, compared with 1430 for R-134a. The results demonstrate that R-152a is a promising low-GWP alternative to R-134a for domestic heat pump water heaters, offering improved thermodynamic performance, higher exergy efficiency, and substantially reduced environmental impact. However, its flammability must be carefully addressed through proper safety measures before practical implementation.
Supersonic ejectors are widely used in refrigeration systems due to their potential to improve system performance. However, their performance is highly sensitive to geometric parameters, requiring both a comprehensive understanding of internal flow behavior and systematic investigation. In this study, a CFD model validated against experimental data reported in the literature is used to investigate and optimize ejector performance under fixed operating conditions with particular attention to internal flow characteristics. The effects of key geometric parameters are analyzed using single-factor analysis, followed by a multi-factor analysis using an orthogonal test method. According to the CFD results, the optimized configuration increases the entrainment ratio from 0.442 to 0.526, representing an 18.8% improvement. The critical back pressure decreases from 217.2 to 206.2 kPa, corresponding to a 5.04% reduction, indicating a trade-off between entrainment performance and the stable operating range. This study highlights the importance of linking performance to flow structure, providing a more physically grounded basis for ejector analysis and optimization.
In this study, alternative refrigerants are evaluated under a total of sixteen different operating conditions covering both heating and cooling modes by using multi-criteria decision-making methods. Seven refrigerants are compared based on the coefficient of performance as the thermodynamic performance criterion, global warming potential as the environmental impact, and flammability classification as the safety criterion. Criterion weights are determined using the Shannon Entropy, CRITIC, and equal weighting methods, and the ranking procedures are carried out using the TOPSIS, VIKOR, and EDAS techniques. Based on the sixteen operating scenarios and the three evaluation criteria considered (COP, GWP, and flammability), R1234ze(E) is the most suitable alternative under all methods and operating conditions, achieving an average COP of approximately 3.28 together with a global warming potential of only 1 compared with 1430 for R134a, corresponding to a GWP reduction of more than 99%; R134a is consequently ranked among the least favorable options in most scenarios due to its high environmental impact, despite its competitive average COP of approximately 3.22. Despite its high global warming potential, R134a ranked among the top alternatives in some evaluation scenarios when entropy-based weighting and the TOPSIS method were applied. However, the EDAS method penalized R134a regardless of the weighting approach, indicating a higher sensitivity to unfavorable environmental indicators. The EDAS method reflects this trade-off more strongly than the other methods by effectively discriminating against alternatives with high GWP values, making it more suitable for identifying balanced working fluids within a candidate pool.
Increasing the demand for greater efficiency and sustainability in corrugated plate heat exchangers has driven comprehensive research to address the drawbacks of conventional designs. This review summarizes the latest developments in enhancing plate heat exchanger performance, with a focus on plate surface geometry and working-fluid effects. The most important geometric details for thermo-hydraulic properties, such as chevron angle, corrugation pattern, plate spacing, and corrugation depth and pitch, are systematically examined with respect to their thermo-hydraulic effects. The review also covers surface coatings, including potential contributions to fouling mitigation and pressure drop reduction, as well as persistent issues related to durability, health, and environmental impact, along with their associated costs. The review also discusses the application of nanofluids as working fluids, explaining that while they can improve heat transfer, they also entail drawbacks such as increased viscosity, pressure drop, and unknown long-term effects on plate integrity. In addition to designs and material strategies, the review focuses on how they incorporate sustainable and renewable energies into plate heat exchangers to reduce dependence on fossil fuels and their negative impact on the environment, as well as reducing operational costs. Also, cutting-edge data-driven techniques, including machine learning, deep learning, and artificial intelligence, are presented as promising extensions to other CFD techniques to develop and enhance predictive models while reducing computational costs and time. Finally, several research gaps are identified, including insufficient attention to unsteady and oscillatory flow conditions, highlighting areas that require further investigation.
Water scarcity and rising energy demand in arid regions such as Basrah, Iraq, necessitate the development of highly efficient and environmentally responsible cogeneration systems. This study aims to design and optimize a solar-assisted power–water cogeneration system tailored to Basrah’s climatic and resource constraints. The proposed system integrates a Gas Turbine (GT) and Parabolic Trough Collector (PTC) solar field with a hybrid Multi-Effect Distillation (MED) and Reverse Osmosis (RO) desalination unit. A comprehensive 4E analysis (Energy, Exergy, Exergoeconomic, and Exergoenvironmental) is conducted to evaluate system performance. Thermodynamic modeling is performed using Thermoflex, and a Multi-Objective Genetic Algorithm (NSGA-III) implemented in MATLAB is employed to optimize key decision variables with the objectives of maximizing exergetic efficiency and minimizing total cost and environmental impacts. The optimized configuration increases exergetic efficiency from 47.31% to 60.12%, reduces total cost by 6.58%, and lowers environmental emissions by 4.27%. Furthermore, freshwater production rises from 120.10 to 142.87 kg/s, representing an 18.96% improvement. The novelty of this work lies in the integrated configuration coupling solar-assisted gas power with hybrid thermal-membrane desalination, specifically adapted to Basrah’s conditions. Combined with a full 4E assessment and advanced multi-objective optimization, this study bridges the gap between theoretical modeling and practical deployment in southern Iraq, demonstrating a technically viable and sustainable pathway for addressing the region’s critical water–energy nexus.
This work investigates the effect of water depth on the productivity and thermal efficiency of a double-basin solar still (DBSS). The lower basin measured 0.4 x 1 m, while the upper basin, installed above the lower basin’s glass cover, consisted of six sub-basins. Water depths in both the lower and upper basins were studied, ranging from 10 to 30 mm. The double-basin solar still DBSS configurations are denoted by two values, where the first value represents the lower-basin water depth and the second value represents the upper-basin water depth. For comparison, a single-basin still with base dimensions identical to the two-basin still was constructed. The experimental results obtained under the climatic conditions of Baghdad, Iraq (33.3° N, 44.3° E) in October 2025 are as follows: The best DBSS configuration was the 10-10 mm DBSS, which produced 8.75 L/m²·day and 83.24% daily thermal efficiency. The minimum productivity and daily thermal efficiency were for the 30-30 mm DBSS, that is, 5.138 L/m²·day and 71.59%. The maximum improvement in water productivity of the 10-10 mm DBSS was 37.5%, and the minimum of the 30-30 mm DBSS was 19%, compared to single-basin solar still SBSS at 10 mm water depth. The improvement in the daily thermal efficiency of the 10-10 mm and 30-30 mm DBSS was 24% and 12%, respectively, compared with the SBSS at 10 mm water depth. The maximum moisture content for the lower basin of the 10-10 mm DBSS was 700 g/kg dry air at 12 hr, while it was 520 g/kg dry air for the upper basin. The maximum temperature was recorded on the lower basin glass cover of the 10-10 mm DBSS, reaching about 90 °C.
Passive daytime radiative cooling (PDRC) offers a promising route for reducing building cooling demand, yet practical deployment requires balancing cooling performance with visual compatibility and environmental robustness. In this study, a fully simulation-based framework is developed to design coating-oriented PDRC structures under simultaneous constraints of solar reflectance, mid-infrared emissivity, color compatibility, and degradation tolerance. Spectral performance is evaluated over the solar (0.3-2.5 & micro;m) and mid-infrared (5-25 & micro;m) ranges, and a multi-objective optimization procedure is employed to identify Pareto-optimal solutions that balance cooling performance, color compatibility, and degradation tolerance rather than a single idealized design. The representative solutions achieved solar-weighted reflectance values of 0.80-0.95, atmospheric-window emissivity values of 0.88-0.98, and ideal-condition net radiative cooling power values of 60-85 W/m2. Among the selected reference designs, D1, D2, and D3 yielded net cooling powers of approximately 85, 70, and 60 W/m2, respectively, reflecting different trade-off regions within the Pareto front. Under the degradation scenarios considered, these designs retained approximately 76%, 71%, and 67% of their initial cooling capability. The results show that coating-compatible PDRC designs can preserve meaningful daytime cooling performance while satisfying additional non-thermal constraints, and that robustness to humidity-and soiling-related degradation can be incorporated directly at the design stage. The proposed simulation-based multi-objective design methodology offers a transferable approach for developing radiative cooling coatings that account for aesthetic constraints and degradation-related performance losses.
A hybrid desiccant air conditioning system combines a rotary solid desiccant dehumidifier with a vapor compression refrigeration cycle to effectively address both latent and sensible cooling demands. In this study, a comprehensive energy and exergy analysis of a hybrid desiccant air conditioning system using molecular sieve desiccant was carried out. The system consisted of a rotary solid desiccant dehumidifier integrated with a vapor compression refrigeration system and a coupled regeneration strategy using condenser waste heat and auxiliary electric heating. The experiments were conducted at fixed mass flow rates of process and regeneration air of 0.107 kg/s and 0.054 kg/s, respectively, with a constant desiccant wheel speed of 65 RPH. The system performance was evaluated in terms of coefficient of performance (COP), dehumidification effectiveness, exergy destruction, and exergy efficiency under varying process air inlet temperature (29-37 degrees C) and humidity ratio (0.0165-0.0182 kg/kg). The results showed that the COP decreased with increasing inlet air temperature but increased with increasing humidity ratio, while dehumidification effectiveness followed a similar trend. Exergy analysis revealed that the desiccant wheel and regeneration heater were the major sources of thermodynamic irreversibility in the system. The overall system exergy efficiency reached a maximum value of approximately 21.5%. The results demonstrate the potential of hybrid desiccant cooling systems for energy-efficient air conditioning applications in hot and humid climates.
This study experimentally investigates the performance characteristics of a light-duty gas turbine engine operating on Kapok Flabellifer Methyl Ester (KFME) biodiesel blends as potential alternative aviation fuels. Five fuel blends such as KFME20, KFME40, KFME60, KFME80, and neat KFME (KFME100)-were evaluated over a range of engine load conditions to examine their effects on thermal efficiency, thrust-specific fuel consumption (TSFC), and emissions behavior. The experimental results indicate that lower biodiesel blending ratios deliver superior overall performance. In particular, KFME20 and KFME40 exhibit an optimal balance between combustion efficiency and fuel economy. Among all tested fuels, KFME20 achieved the highest thermal efficiency, with an improvement of up to 27.8% compared to neat KFME, primarily due to improved oxygen-fuel mixing, enhanced atomization, and increased combustion stability. Additionally, KFME20 demonstrated a reduction in TSFC of approximately 20%, reflecting more effective energy conversion and improved fuel utilization. Conversely, higher biodiesel concentrations were associated with increased NOx emissions, attributed to elevated combustion temperatures and intensified oxidation reactions inherent to oxygenated fuels. Based on the combined assessment of performance and emissions, KFME20 is identified as the most promising blend for light-duty gas turbine applications. For operational scenarios subject to stringent NOx emission limits, KFME20 or KFME40 are recommended, offering acceptable trade-offs between engine efficiency and environmental compliance.
Renewable synthetic fuels such as methanol and diethylene glycol dimethyl ether (DGM), produced via atmospheric CO2 capture, represent a promising strategy to reduce fossil fuel consumption in compression ignition (CI) engines. However, their effects on engine performance and exhaust emissions under conventional operating conditions remain insufficiently understood and require further investigation, particularly in small diesel engines operating with ternary methanol/DGM/diesel blends. In this context, this study systematically investigates the effects of blending synthetic fuels with diesel fuel on CI engine performance and emissions. Experimental tests were conducted using four fuel blends: M10D90 (10% methanol and 90% diesel), M20D80 (20% methanol and 80% diesel), DG15M5D80 (15% DGM, 5% methanol, and 80% diesel), and DG5M10D85 (5% DGM, 10% methanol, and 85% diesel), all tested at a constant load and engine speed of 2600 rpm. Pure diesel was also evaluated as a baseline. Engine performance parameters and exhaust emissions were assessed under steady-state conditions without engine modifications, using the standard fuel injection system. The results indicate reductions in pollutant emissions, with CO decreasing by up to 10% and NOX by 2.3% for the M10D90 blend compared to the baseline, without significant changes in fuel conversion efficiency and with a slight increase in specific fuel consumption. Additionally, a slight reduction in CO2 emissions was observed. Thus, this work contributes to improving the understanding of the use of synthetic fuels blended with conventional diesel and their potential to reduce fossil fuel consumption in CI engines.
This study presents a thermodynamic performance assessment of a single-effect H2O-LiBr absorption refrigeration system (ARS) specifically driven by a parabolic trough solar collector for air conditioning applications in Ho Chi Minh City, Vietnam. The methodology involved developing a detailed mass and energy balance model for the absorption cycle, which was successfully validated against existing literature, showing a Coefficient of Performance (COP) of 0.7195. The system's performance and collector area requirements were then analyzed against key operating parameters and local climate data. Key findings reveal a strong influence of temperatures on system viability: the COP significantly improves (from 0.5 to 0.78) while the required solar collector area (Acollector) decreases drastically (from 65 m2 to 41 m2) as the condenser temperature (T8) is lowered (from 48 degrees C to 39 degrees C). Conversely, higher generator outlet temperatures (T7) and increased solution heat exchanger effectiveness (eta(SHX)) both lead to substantial increases in COP and a corresponding reduction in Acollector. The results confirm that optimizing the heat rejection temperature (T8) and maximizing heat recovery (via eta(SHX)) are critical factors for achieving high system efficiency and minimizing the expensive solar collection area, thereby proving the feasibility of solar-driven H2O-LiBr air conditioning in the hot, sunny climate of Ho Chi Minh City.
A cascade system integrates two vapor compression cycles connected through an intermediate heat exchanger, enabling effective heat transfer between the stages while minimizing exergy losses. This paper presents the experimental analysis of a two-stage cascade refrigeration system using R134a and R32 as refrigerants in the low and high temperature cycles, respectively. The objective is to achieve ultra-low temperature refrigeration with enhanced energy efficiency and reduced environmental impact. In this study, two different capillary tube combinations of different diameters were employed to evaluate and compare the performance of cascade system. The cascade system's performance was tested under varying ambient temperatures. In our present experimental work, performance evaluation of cascade system was carried out by measuring key parameters such as coefficient of performance, refrigeration capacity, compressor input work and heat rejection rate. The results showed that maximum actual refrigeration capacity of 0.991 kW and heat rejection rate of 5.496 kW was achieved at an ambient temperature of 32 degrees C. At this condition, the system also exhibited the lowest compressor work of 1.238 kW with minimum temperature attained as-24 degrees C. The experimental results indicate that the cascade system offers superior thermodynamic efficiency compared to conventional single-stage systems, particularly at lower temperature ranges. R134a/R32 refrigerant combination proved to be a viable and environmentally friendly option, making the system suitable for applications like biomedical storage, cryogenics and low-temperature industrial processes.
Coastal regions are under pressure globally due to the complex balance between increasing energy demand, food production, and environmental sustainability. This study presents a numerical model and feasibility analysis of an integrated system that aims to simultaneously reduce the environmental impacts of energy production and marine aquaculture. The proposed model creates a multifunctional circular production concept by combining an Ocean Thermal Energy Conversion (OTEC) system with a fish farming unit and a symbiotic anemone-zooxanthellae-based bioremediation module. The model was developed for the conditions of Turkiye's southeastern Aegean coastline and simulates base load energy production via the Organic Rankine Cycle (ORC) even at low temperature differences, as well as the removal of inorganic nutrients (ammonia, nitrate) from fish farms by the symbiotic system and the release of photosynthetic oxygen into the environment during this process. Based on advection-diffusion-reaction equations, this model combines physical and biological processes within a single computational framework to evaluate the system's thermodynamic efficiency, biomass dynamics, and economic feasibility. The results show that with a depth difference of 40 m and a flow rate of 600 kg/s, approximately 9.96 GWh of energy can be produced annually, with a LCOE of 0.03 USD/kWh and a positive net present value (NPV approximate to 6.8 million USD). Furthermore, it was determined that the system could reduce carbon emissions by up to 4,682 tons of CO2 per year and contribute to eutrophication control through nutrient removal. In this regard, the study presents an applicable model for sustainable coastal development within the scope of blue growth strategies by bringing together energy, food, and environmental components on a single integrated platform.
In this paper, we extend Energy Structure Theory (EST) to a time-periodic isolated thermodynamic system consisting of two interacting subsystems and derive the necessary and sufficient thermodynamic conditions for the emergence of macroscopic time crystals. The total energy of the system is conserved, Utotat = a, where one activated component is taken as the independent variable and the other depends on it according to uB(t) = a-uA(t). The independent component is assumed to vary periodically in time, uA(t) = uo + Asinwt. Based on the energy-structure formulation, a quasi-statistical entropy is defined as S[Sq_s(t)] = KmsS[ln(UA(t))], where Kms is a constant and UA(t) is the rate of energy exchange between the subsystems. When this rate remains constant, UA(t) const., the quasi-statistical entropy is invariant, indicating a completely reversible thermodynamic oscillation-a time-crystalline state in macroscopic form. Analytical results demonstrate that such periodic dynamics are fully consistent with both energy conservation and the second law of thermodynamics, thus establishing a unified, self-consistent macroscopic framework for time crystals. To evaluate stability, a small irreversibility is introduced by adding a rate-dependent energy term to the EST equations. Under this perturbation, the time-crystal structure does not collapse; instead, it transitions into a quasi-periodic regime, revealing inherent robustness under weak non-equilibrium conditions. Finally, potential experimental realizations are discussed-particularly micro-electromechanical systems (MEMS) with tunable coupling and thermally insulated cyclic heat engines capable of simulating quasi-steady oscillatory behavior. These findings provide a unified thermodynamic foundation for macroscopic time crystals and offer clear pathways for experimental validation and further theoretical generalization.
This study presents a comprehensive investigation of blood flow embedded with magnetic nanoparticles (Fe203 and Fe3O4) over an exponentially stretching surface, incorporating the effects of a tilted magnetic field, Joule heating, and thermal radiation. The exponential stretching model captures nonlinear vascular wall deformation and stent expansion, while the tilted magnetic field offers a more realistic representation of biomedical device orientations. A mathematical model governing the flow is formulated and transformed into a system of ordinary differential equations using suitable similarity transformations, which are solved numerically using the MATLAB bvp4c solver. Numerical simulations elucidate the influence of magnetic-field inclination, thermal radiation, and Joule heating on velocity and temperature distributions. Results reveal that thermal convection and radiation enhance flow velocity, whereas increased magnetic field strength and local porosity induce significant flow resistance due to enhanced drag forces. The study highlights the critical role of optimizing nanoparticle properties and external magnetic stimuli to regulate thermal behavior while minimizing hydrodynamic resistance. These findings contribute to improved heat transfer performance in microfluidic systems, advanced thermal management in electronic devices, and optimized biomedical applications such as magnetic hyperthermia and targeted drug delivery, where precise control of blood-flow dynamics is essential.
Greenhouses in arid and semi-arid regions simultaneously face two major challenges: severe water scarcity and excess humidity, the latter causing condensation on the inner surfaces and the dripping of droplets onto crops, which encourages fungal diseases and physiological stress. Existing studies typically address these issues separately and often rely on energy-intensive cooling or dehumidification systems. In this work, we propose a fully passive and autonomous condensation-based strategy that combines a geometrically optimized roof inclination with a naturally cooled surface supplied by a Canadian well. The 7 degrees inclination is selected based on a prior comparative study demonstrating its ability to channel buoyancy-driven humid air toward the roof apex of the greenhouse, where condensation can be maximized. A 3-D transient CFD (Computational Fluid Dynamics) model coupling airflow, heat transfer, radiation, and vapor transport is used to evaluate the impact of three cooling temperatures (20, 16, and 12 degrees C) on the internal thermo-hygrometric dynamics. Results show that lowering the cooling temperature intensifies upward convection, enhances moisture accumulation at the roof apex, and significantly increases the condensation potential. The 12 degrees C configuration produced the strongest airflow acceleration and the highest vapor recovery efficiency, aligning with the natural cooling potential provided by a Canadian well. This parametric analysis establishes the optimal operating temperature for future integration of a passive condensation-recovery system aimed at improving both microclimate regulation and freshwater generation in arid-climate greenhouses.
The purpose of the present research is to quantitatively assess the combustion characteristics of three types of food-processing biomass-pumpkin shells (PS), bean pods (BP), and cherry stalks (CS)-analyzed both as individual feedstocks and in composite mixtures containing 10% spent coffee grounds (SCG) namely: M1SCG (PS10%SCG); M2SCG(BP10%SCG); M3SCG(CS10%SCG) and 10% waste engine oil (WEO): M1WEO (PS10%WEO); M2WEO (BP10%WEO); M3WEO (CS10%WEO). Additionally, a goal of this study was to evaluate the suitability of two ternary blends M4SCG (30%PS+30%BP+30%CS+10%SCG) and M4WEO (30%PS+30%BP+30%CS+10%WEO) for pellet production according to European solid biofuel standards. Calorific values were measured with a model 6200 combustion calorimeter in accordance with ASTM D5865. Nitrogen content was evaluated through the formation of nitric acid, while sulphur content was examined by converting it to sulphates and determining BaSO4 gravimetrically. Ash and moisture content, bulk density (CEN/TS 15103), porosity index, volatile matter (EN ISO 18123:2015), and fixed carbon (ASTM D3172-13) were determined using standardized procedures. Energy density, fuel value index, and combustion efficiency were computed following the established methods reported in the literature. The combustion and physicochemical characteristics of all individual biomasses and biomass-additive mixtures were found to be in accordance with the European standards set. The two composite mixtures M4SCG and M4WEO demonstrated improved calorific performance along with advantageous density-related attributes. Both M4SCG and M4WEO fulfilled essential quality standards, which suggests their technical feasibility as pelletizable biofuels and their potential as sustainable alternatives to fossil fuels. This study provides the first systematic characterization of pumpkin shells, bean pods, and cherry stalks as solid biofuel feedstocks. The first comparative evaluation of SCG and WEO as fixed 10% additives under identical experimental conditions is performed. By integrating underutilized food-processing residues with waste-derived additives, the results extend current knowledge on biomass pelletization, additive-assisted combustion enhancement, and circular waste-to-energy strategies.
The environmental concerns around synthetic refrigerants have prompted the investigation of novel and environmentally friendly cooling systems. With an emphasis on its distinct thermodynamic characteristics and refrigeration cycle performance, this study investigates the viability of employing electrons as a refrigerant. Critical processes were theoretically modelled, including expansion, constant-pressure heating, and adiabatic compression. Combining theoretical understanding with empirical support, the study lays the groundwork for further investigation and improvement and provides a fundamental understanding of electron gas as a refrigerant. A specially designed experimental setup was created to validate these models, allowing for accurate monitoring of temperature variations, heat transfer effectiveness, and overall system performance. Compared to traditional refrigeration techniques, the experimental findings showed a better Coefficient of Performance (COP) of 20.65, indicating higher energy efficiency. These results demonstrate the electron (electron gas)'s potential as a practical and best substitute for conventional refrigerants, tackling critical environmental issues. The result shows that this work marks a substantial leap in creating more environmentally friendly and effective refrigeration technologies. In the future, this work will be studied for both commercial and residential settings.
In the present work, the use of various calorimetric methods (combustion calorimetry, mixing (C80), differential scanning calorimetry (DSC) and coupled method thermogravimetry-differential scanning calorimetry (TG-DSC)) were illustrated as a powerfull techniques that can provide valuable thermodynamic properties of an important component of collagen, namely L-hydroxyproline (4-hydroxy-L-proline). The thermal behavior of 4-hydroxy-L-proline was studied in the temperature range between 20 degrees C to 500 degrees C, the transformation (melting-decomposition) point, weight loss, purity and the associated thermal effects were determined from the DSC, TG-dTG curves respectively. The values of 4-hydroxy-L-proline enthalpies of combustion and formation in solid state were calculated; information about the thermodynamic stability were obtained. Spectral characterization of the sample applying Fourier Transformed Infrared (FT-IR) method was performed. The thermal effects of the amino acid solution in water at 25 degrees C were calculated.
