Improvement In Thermal Efficiency Research Articles

Low-grade heat utilization for combined cycle power plants using organic rankine cycle

This paper presents a comprehensive thermodynamic analysis of trinary power plants, focusing on the efficiency of Organic Rankine Cycle (ORC) configurations and regenerative heating methods. Despite advancements in nuclear and renewable energy, fossil fuels still dominate electricity generation, necessitating improved efficiency in existing power plants. The study reveals that low-pressure mixing-type heaters provide higher efficiency compared to surface heaters, with net efficiencies of 0.099%, 0.227%, and 0.425% at deaerator pressures of 0.12, 0.3, and 0.7 MPa, respectively. The analysis highlights the impact of feedwater temperature on the thermal efficiency of steam turbine units (STUs), noting that while optimal feedwater temperatures enhance efficiency, they can reduce STU capacity. The study identifies configurations for regenerative heating that optimize exhaust gas temperatures, facilitating additional electricity production through a low-boiling working fluid in the ORC. The findings indicate that R245fa refrigerant is optimal for ORC without recuperative heater, achieving maximum net power at a feedwater temperature of 115°C. For ORC with a recuperative heater, R236ea is preferred for temperatures between 115°C and 154.5°C, while R245fa is optimal for higher temperatures. The results also demonstrate that trinary power plants with recuperators achieve greater efficiency and net capacity compared to double-circuit systems, with notable improvements in thermal efficiency attributed to effective regeneration schemes. This research underscores the potential for optimizing existing domestic power units to enhance their efficiency and performance without significant financial or technical burden, thereby contributing to more sustainable energy generation.

Improving Thermal Efficiency Using Vibration Monitoring and Nanofluids in Solar Evacuated Tube Collectors

Improving Thermal Efficiency Using Vibration Monitoring and Nanofluids in Solar Evacuated Tube Collectors

Estimating the potential for thermal energy efficiency in the industrial sector: A hybrid model integrating exergy analysis and long-term technology diffusion scenarios

Thermal energy for heating and cooling accounts for a significant portion of the total energy consumed in the industrial sector, and is predominantly provided by fossil fuels. Thus, effective thermal energy management is essential for reducing overall energy consumption, operational costs, and emissions in the industrial sector. While previous studies have explored energy efficiency in this sector, there is a lack of research specifically addressing the challenges of modeling thermal energy efficiency in industry. Therefore, this study proposes a novel hybrid methodological approach that integrates macroeconomic perspectives with detailed end-use analysis and exergy considerations, allowing for a more accurate assessment of recoverable energy in industrial processes in alternative technology diffusion scenarios over a long-term horizon. An empirical study focusing on the pulp and paper subsector in Brazil demonstrated the applicability of the proposed model and revealed significant potential for thermal energy efficiency improvements. The model identified that through optimal technology diffusion scenarios, the sector could achieve up to 25 % reduction in thermal energy consumption by 2050, with heat recovery systems accounting for approximately 40 % of these savings. Cost-effective technology adoption curves indicated that 60 % of this potential could be realized through economically viable investments with payback periods under 3 years. Overall, this study contributes to the field of industrial energy efficiency by offering a hybrid methodological approach that can be adapted to different industrial settings, and can help policymakers and industry stakeholders develop effective strategies to improve thermal energy efficiency and reduce emissions in the industrial sector.

Numerical Investigation of Pyramid Solar Stills with PCM‐Nanoparticles and Absorber Fins: Enhanced Thermal Performance for Sustainable Water Desalination

ABSTRACTIn arid regions facing challenges of limited access to potable water and electricity, solar desalination stands out as a promising solution for producing clean water from brackish sources. This research intends to examine and enhance an innovative and sustainable solar desalination system. A computational study is conducted on a pyramid solar still (PSS) combined with a phase‐change material incorporated with nanoparticles, with a variety of absorber fins. The study investigates three configurations: a traditional pyramid–shaped solar still, one with square absorber fins, and another with circular fins. Paraffin wax mixed with Al2O3 nanoparticles is used beneath the absorber fins. Conservation equations are solved using COMSOL Multiphysics. Simulation outcomes demonstrate that the incorporation of finned absorbers, coupled with elevated water temperatures, significantly enhances the yield of the improved PSS compared with its conventional counterpart. The square‐finned absorber PSS exhibits a substantial increase in total accumulated productivity over the conventional design. Moreover, the PSS with square‐finned absorbers demonstrates an impressive average peak daily thermal efficiency improvement of 49.19% compared with a conventional solar still. This study highlights the effectiveness of the modified PSS as a superior option for household water generation.

Heat transfer enhancement in a solar air heater utilizing novel rotating spiral baffles

This study presents a substantial enhancement in the performance of solar air heaters (SAH) through the introduction of innovative rotating spiral-shaped baffles on the absorber plate, designed to optimize airflow within the duct and improve heat transfer. The results underscore the critical importance of fine-tuning geometric parameters, including relative roughness height (e/H: 0.4–1) and relative roughness pitch (P/e: 4–10), as well as the Reynolds number (Re: 4000–12 000), to achieve superior thermal efficiency. The optimization of these parameters is essential for maximizing performance while effectively managing flow resistance and turbulence. Experimental testing, conducted under a solar simulator (EN-12975-2 standard: irradiance uniformity of 10.47%, average solar irradiance of 955 W/m2), identified the configuration of P/e-8, e/H-0.8, and Re-12000 as the optimal combination. This setup yielded a maximum reduction of 17.29% in plate temperature (Tp), a 7.48% increase in outlet temperature (To), 63.33% augmentation in useful heat gain (Qu), and a 64.86% improvement in thermal efficiency (η) compared to a smooth duct. These findings provide key insights for advancing the design and operational efficiency of SAH systems. A field study to evaluate the practical applicability of this modification is recommended as the next step for further investigation.

Innovative solar-assisted direct contact membrane distillation system: Dynamic modeling and performance analysis

The study presents an innovative solar-assisted dual-tank direct contact membrane distillation (DCMD) system designed to enhance the operational stability and efficiency of solar-powered desalination. The proposed system integrates a dual thermal storage tank configuration, allowing for continuous operation by alternating between two tanks that store pre-heated water, thereby mitigating the impact of solar energy fluctuations. The dynamic modeling approach used in this study predicts the system's performance under varying solar conditions, focusing on key parameters such as permeate flux, evaporation efficiency, and specific thermal energy consumption. The simulation results show that the system achieves an average permeate flux of 14.4 L/h m² and a thermal efficiency of 53.3 % at a hot water temperature of 60 °C, with a corresponding average specific thermal energy consumption of 1567 kWh/m³. These findings highlight a substantial improvement in both thermal efficiency and water production compared to conventional single-tank systems.The dual-tank DCMD system is particularly suited for deployment in remote or arid regions where stable and efficient freshwater production is critical. This research provides a comprehensive analysis of a novel solar-assisted desalination technology, contributing to the advancement of sustainable water resources management by providing a reliable and scalable solution that can maintain high operational efficiency even in remote areas with variable solar conditions.

Evaluating the energy and economic performance of hybrid photovoltaic thermal system integrated with multiwalled carbon nanotubes enhanced phase change material

Photovoltaic thermal (PVT) systems represent an advanced evolution of traditional photovoltaic (PV) modules designed to generate electrical and thermal energy simultaneously. However, achieving optimal and commercially viable performance from these systems remains challenging. To overcome this issue, in this research, multiwalled carbon nanotube (MWCNT) enhanced phase change materials (PCMs) integrated with PVT system to enhance electrical and thermal performance has been studied. An experimental investigation with three different configurations, PVT, PCM integrated PVT (PVTPCM), and MWCNT enhanced PCM integrated PVT (PVTNePCM) systems, was carried out under varying solar radiations and a water flow rate of 0.013–0.016 kg/s compared to conventional PV system. A two-step technique was employed to formulate the nanocomposites, and the energy performance of both PV and PVT systems assessed experimentally. The performance of PVTPCM and PVTNePCM systems was evaluated using the TRNSYS simulation technique. The formulated nanocomposite exhibited a 71.43% enhancement in thermal conductivity, a significant reduction in transmittance up to 92% and remained chemically and thermally stable. Integration of NePCM in the PVT system resulted in a notable decrease in panel temperature and a 25.03% increase in electrical efficiency compared to the conventional PV system. The highest performance ratio and overall efficiency for PVTNePCM were 0.55 and 81.62%, respectively, at a flow rate of 0.013 kg/s. The energy payback periods of PVTNePCM, PVTPCM, and PVT setup were 4.7, 4.8 and 5.6 years, respectively. Additionally, a significant improvement in thermal efficiency were observed for PVTPCM and PVTNePCM systems compared to water-based PVT systems, due to the energy stored in the thermal energy storage material.

Simulation study of R1234ze and its mixed working medium in TEG‐ORC combined cycle

AbstractThermoelectric generation (TEG) and organic Rankine cycle (ORC) technologies both have their respective limitations in recovering waste heat from ships. However, the combination of TEG and ORC is an effective approach to achieve cascaded waste heat recovery and improve heat utilization efficiency. There has been some progress in research on waste heat recovery in maritime applications based on TEG‐ORC combined cycles. The selection of a working medium is a crucial element that directly influences the design and performance of the entire system, but there is limited research on the impact of different working fluids on combined cycle systems. In this study, a simulation model of a TEG‐ORC combined cycle system was established to examine its output potential using two different working fluids R1234ze and a mixture of R245fa/R1234ze. The results demonstrate that compared to employing the R1234ze working medium, the combined cycle system with the mixed working medium achieved a 13% increase in maximum output power, a 102% improvement in optimum thermal efficiency, and a 53% reduction in optimum power production cost. Additionally, the power output distribution in the system utilizing the mixed working fluid was more uniform compared to the system employing a single working medium. This confirms the great potential of using a mixed working fluid in a combined cycle system.

Maximizing desalination performance in pyramid distiller: Integration of vertical wick still and enhanced phase change material by nanoparticle and emerging fins

The growing global water crisis, driven by population growth and dwindling freshwater resources, demands innovative solutions for sustainable desalination. While traditional solar still designs have been explored, their efficiency remains limited. This study introduces an advanced approach to solar distillation by integrating a modified pyramid solar still (MPSS) with two key innovations: a vertically positioned wick still (VWSS) and phase change material (PCM) enhanced with silver nanomaterials (PCM-Ag Nano). In addition, the design features two absorber plate configurations—flat and finned—coupled with emerging fins (EF) within the PCM unit to improve heat conductivity, addressing a common limitation in solar distillation systems. By incorporating PCM-Ag Nano and finned absorbers, the MPSS achieved significant improvements in desalination performance. The combined system of MPSS-FA-PCM-Ag-EF and VWSS produced a total distillate volume of 12,870 ml, representing a 154 % increase over a conventional pyramid solar still (PSS). Specifically, daily outputs of 9,270 ml, 5,050 ml, and 3,600 ml were recorded for MPSS, PSS, and VWSS, respectively. Furthermore, the enhanced MPSS configuration attained the highest thermal efficiency at 60.5 %, and the desalination cost was reduced to $0.0142/L, compared to $0.019/L for the PSS. These results underscore the potential of this novel MPSS design, which combines PCM-Ag Nano and VWSS, to deliver substantial improvements in freshwater production, thermal efficiency, and cost-effectiveness. This innovative system offers a promising alternative to traditional desalination techniques, contributing to the global effort to mitigate water scarcity.

Graphene-enhanced sustainable fuel from Calophyllum inophyllum for premixed charge compression ignition engines: Advancing circular economy and emission reduction

This study investigates the impact of modifying a conventional compression ignition (CI) engine by inducting pentanol in inlet manifold and injecting graphene-blended tamanu biodiesel into the cylinder. These modifications significantly enhance ignition quality and expand operational capabilities within the premixed charge compression ignition (PCCI) engine. The use of graphene-enhanced biodiesel in PCCI mode demonstrates potential for improved combustion efficiency and emission reduction. Dispersed graphene nanoparticles in tamanu biodiesel notably improve brake thermal efficiency due to their increased surface area, which enhances fuel-air mixing. Graphene-suspended biodiesel at a concentration of 100 ppm in PCCI mode results in an 11.5 % peak pressure rise and an 8.4 % rise in heat release rate with respect to pure biodiesel in CI mode. This nano-suspension biodiesel also shows significant thermal efficiency improvements, with an 8.20 % increase and a 22.08 % reduction in fuel consumption with respect to neat biodiesel in CI mode. The combination of pentanol and graphene-blended tamanu biodiesel improves combustion quality, yielding a 13 % reduction in carbon monoxide emissions, a 34.67 % reduction in hydrocarbon emissions, a notable 65.84 % lower in nitrogen oxide, and a 33.91 % reduction in smoke with respect to neat tamanu biodiesel in CI mode of operation.

Investigation of performance and emission values of new type of fuels obtained by adding MgO nanoparticles to biodiesel fuels produced from waste sunflower and cotton oil

Biodiesel was produced using the transesterification method from waste sunflower and cotton oil. As a result of the analysis of the new type of nanoparticle-added biodiesel fuels we produce, the parameters with a decrease in emissions are CO, HC, and smoke emissions. There is a partial increase in NOx emissions. In addition, nanoparticle addition made a positive contribution by increasing thermal efficiency. The produced MgO nanoparticle-doped biodiesel fuel samples were compared with diesel fuel. As seen in these comparisons, nanoparticle additives contributed positively to reducing emission values. These improvements were observed as a 31.25 % reduction in CO in the WSOB5+ 100 ppm MgO fuel sample, 41.6 % reduction in HC in the COB5+ 100 ppm MgO fuel sample and 36.92 % reduction in smoke (soot) in COB5+ 100 ppm MgO fuel sample. A comparison was made between the fuel samples in our study, biodiesel produced from waste sunflower and cotton, and fuels produced with nanoparticle additives of 50, 75, and 100 ppm. It was observed that the most efficient fuel sample in terms of emission values and performance was COB5 + 100 ppm MgO nanoparticle additive fuel. The biodiesel fuel sample produced with COB5 + 100 ppm MgO nanoparticle additives provided a 3.25 % improvement in thermal efficiency compared to biodiesel without additives. A positive effect on the heat transfer coefficient was observed as a result of the data on the new type of nanoparticle doped biodiesel. With the impact of this contribution, parameters such as positive contribution to in-cylinder temperature, ignition delay, and combustion time were positively affected in the same direction. Another positive effect of nanoparticle additive to biodiesel, thermal efficiency, increased by 1.1 % in the COB5 + 100 ppm MgO fuel sample. Depending on the decrease in emission rate, it was concluded that the nanoparticle additive added to the fuel greatly benefits the environment.

Hydrothermal behaviour of hybrid nanofluid flow in two types of shell and helical coil tube heat exchangers with a new design. Numerical approach

High-efficiency thermal energy systems are very important in meeting the growing demand for thermal energy. As a result, several heat transfer improvements have been proposed. Some promising methods include flow heat transfer in shell and spiral tube exchangers.In a shell-and-coil heat exchanger, utilizing a meticulously designed coil instead of a basic one significantly boosts heat transfer and overall thermal efficiency. This is due to the enhanced fluid dynamics and increased turbulence facilitated by the advanced coil design, making it ideal for space-constrained applications. Moreover, the helical configuration helps minimize fouling and maintenance, and may also provide self-cleaning benefits. Consequently, helical coils are highly regarded in industrial contexts for their superior performance, maintenance ease, and design adaptability.This study conducts a numerical evaluation of the heat transfer and fluid flow properties of two distinct shell-and-coil heat exchangers with specialized designs. The fluids analyzed include water-based hybrid nanofluids, specifically Water/MgO-TiO2and Ag-HEG/water, with results compared to those obtained using pure water. The investigation spans Reynolds numbers from 500 to 2000 and is divided into two segments.The first segment examines the influence of spiral coil geometry and fluid type on the heat exchanger's endothermic performance, utilizing nanoparticle volume concentrations of φ1 = φ2 = 0.3. In the second segment, the optimal geometric and fluid model is chosen based on the findings from the first part. Following this, the impact of various hybrid nanofluids on thermal performance is assessed, comparing fluids with volume concentrations of φ1 = φ2 = 0.3 to pure water (φ1 = φ2 = 0).The findings reveal that Case [A], featuring a unique geometry with Water/Ag_HEG, achieves the highest thermal performance across all examined Reynolds numbers. At the lowest Reynolds number, the thermal efficiency improvements for Case [A], Case [B], and Case [C] were 137 %, 113 %, and 56 %, respectively, compared to the baseline. Additionally, the second part of the study demonstrates that at the lowest Reynolds number, the thermal efficiencies of Water/MgO-TiO2 and Water/Ag_HEG nanohybrid fluids increased by 76 % and 49 %, respectively.

Development and optimization of dual-objective PVT modules for a smart residential building using inclined fins

According to the sustainable development strategy, air-based photovoltaic-thermal (PVT) modules integrated with smart buildings are an effective and environmentally safe option for producing electricity and heating purposes to overcome the problem of scarcity and environmental pollution resulting from fossil fuels. Despite the importance of PVT modules, this technology has not achieved the required diffusion rates compared to other solar energy technologies due to its low overall efficiency. Therefore, the present study aims to develop the design of a heat transfer system integrated with PVT modules. To achieve this goal, the design of a heat transfer system was developed by adding 45° inclined fins integrated with the cooling channel to generate swirling movement near the back surface of PVT modules and increase the heat transfer area. To illustrate the best location for installing 45° inclined fins that achieve the highest performance improvement of PVT modules, we suggested two positions for installing 45° inclined fins and compared them with the dual-objective classical PVT modules (DO-CPVT) without fins. The first case is dual-objective PVT modules with top-inclined fins (DO-PVT&TIF). The second case is the dual-objective PVT modules with bottom-inclined fins (DO-PVT&BIF). The results presented that, dual-objective PVT modules with top-inclined fins (DO-PVT&TIF) represent a good design that achieves the highest performance. The improvement in thermal efficiency, electricity generation, overall energy efficiency, total exergy efficiency, and sustainability index for using DO-PVT&TIF modules reached 231 %, 11.5 %, 133.8 %, 19.3 %, and 4.3 %, respectively compared to classical DO-CPVT.

The Impact of 3D Printing Technology on the Improvement of External Wall Thermal Efficiency—An Experimental Study

Three-dimensional printing technology continues to evolve, enabling new applications in manufacturing. Extensive research in the field of biomimetics underscores the significant impact of the internal geometry of building envelopes on their thermal performance. Although 3D printing holds great promise for improving thermal efficiency in construction, its full potential has yet to be realized, and the thermal performance of printed building components remains unexplored. The aim of this paper is to experimentally examine the thermal insulation characteristics of prototype cellular materials created using 3D additive manufacturing technologies (SLS and DLP). This study concentrates on exploring advanced thermal insulation solutions that could enhance the energy efficiency of buildings, cooling systems, appliances, or equipment. To this end, virtual models of sandwich composites with an open-cell foam core modeled after a Kelvin cell were created. They were characterized by a constant porosity of 0.95 and a pore diameter of the inner core of the composites of 6 mm. The independent variables included the different material from which the composites were made, the non-uniform number of layers in the composite (one, two, three, and five layers) and the total thickness of the composite (20, 40, 60, 80, and 100 mm). The impact of three independent parameters defining the prototype composite on its thermal insulation properties was assessed, including the heat flux (q) and the heat transfer coefficient (U). According to the experimental tests, a five-layer composite with a thickness of 100 mm made of soybean oil-based resin obtained the lowest coefficient with a value of U = 0.147 W/m2·K.

Effect of absorber shape on energy, exergy efficiency and enviro‐economic analysis of solar air collector: An experimental study

AbstractThe efficiency of solar air collectors, which are intended to convert solar energy into thermal energy, is the subject of numerous studies that aim to assess and improve it. Solutions for sustainable energy heavily rely on these systems. Making the right choice regarding the best method for absorbing solar radiation and reducing heat losses is what will ultimately lead to their improved performance. In this work, wavy and corrugated absorbers were suggested inside a solar air collector. The aim of this article is to study experimentally the thermal performance of the solar air collector when using wavy shape of absorber and corrugated shape of absorber instead of the flat shape of absorber under the same weather conditions of Sfax region central‐eastern of Tunisia. The suggested shapes of absorber augmented sun exposure and heating area. The results obtained from this experimental study show that switching from a flat plate absorber to both wavy and corrugated absorbers resulting significant performance gains. The absorber with waves showed a significant improvement in daily thermal efficiency of 22.89%, and the absorber with corrugations showed an even greater improvement of 40.56%. Comparable patterns were noted in daily exergy efficiency, where the corrugated absorber demonstrated an astounding 44.83% increase and the wavy absorber provided a 23.24% improvement. Notably, when total cost savings and monthly CO2 reduction were taken into account, the corrugated absorber turned out to be the best option. These findings highlight the importance of absorber form in optimizing thermal and energy efficiency, which may have positive effects on the economy and environment.

Design and Preliminary experiment of an Off-axis aequilate-mirrors linear Fresnel concentrator with sunlight self-adaptive feature

The Off-Axis Linear Fresnel Reflector (LFR) is an innovative, compact solar concentrator designed to reduce device height and wind-load without compromising efficiency. It is crucial in applying LFR devices to applications such as building façades. To this aim, The Off-axis LFR design is introduced to addressing the inter-mirror blocking issue that diminishes the efficiency of conventional LFRs. Initially, an optimized Aequilate-mirrors design was proposed to reduce manufacturing complexity and cost. Subsequently, a crank-slider mechanism was introduced as a solution to the issue of inconsistent angle adjustment among the mirrors. Additionally, the paper details the sunlight self-adaptive feature of the Off-axis LFR concentrator, where the LFR mirrors can independently rotate to track the sun’s position, adaptively altering the mirror array’s profile and sunward aperture. This feature maximizes the device’s sunlight harvesting capacity, particularly in angled sunlight conditions. A prototype of the Off-axis LFR device was designed and built for assessment, featuring a focus length of just 78 mm and an overall 145 mm housing height. The paper then discusses how the sunlight self-adaptive features enhance the efficiency during the early morning and twilight hours. Comprehensive testing, including mechanical driving, laser focusing, and outdoor full-function verification, was conducted. Ultimately, comparative photo-thermal efficiency tests with a similarly sized conventional LFR concentrator demonstrated that the Off-axis LFR concentrator could achieve a significant increase in efficiency, with an all-day average thermal efficiency improvement of over 10 %. Based on the previous theoretical study, this study has completed the engineering prototype design and validation. And confirmed a thermal concentration efficiency of 44.36 % within a height of 145 mm in experiments.

Collaborative effects of fuel properties and EGR on the efficiency improvement and load boundary extension of a medium-duty engine

EGR dilution combustion has problems such as weakened anti-knock capability at high load, slow combustion speed and poor combustion stability, which results in limitations in the thermal efficiency improvement and load boundary extension of medium-duty highly-downsized engines. It is necessary to combine EGR dilution and other measures to collaboratively control the in-cylinder thermodynamic state and combustion process. The experimental investigations in this study isolate the effect of the ethanol blending ratio in ethanol gasoline on the anti-knock performance, combustion performance and thermal efficiency, and verifies the potential of collaborative optimization of fuel properties and EGR in improving the thermal efficiency and extending the load boundary for a medium-duty highly-downsized engine. The results show that as the load increases, the improvement effect of increasing the blending ratio of ethanol in the anti-knock performance, combustion speed, and the turbine inlet temperature reduction will become more obvious. At high load, using E20 fuel can improve the EGR tolerance, advance the spark timing and CA50, and thus increase the BTE. As the speed decreases, the thermal efficiency improvement effect of E20 fuel gradually increases, and the improved load range extends. The collaborative optimization of E20 fuel and EGR can further extend the high thermal efficiency area of the engine. And the Max. achievable load is 0.11 MPa higher than that of E10, which effectively extends the upper load limit during the stoichiometric combustion.

Enhancing thermal energy and exergy harvesting in concentrated solar power systems using graphene-ZrO2/water hybrid nanofluid: An experimental study

Recent research has witnessed a significant increase in studies investigating the impact of nanofluids on enhancing the efficiency of sustainable energy systems. According to the details that were provided, the present study aims to enhance the heat and exergy efficiency of parabolic trough solar collectors (PTSCs) by using a water-based hybrid nanofluid with dispersed Graphene-ZrO2 at various volume concentrations (water, 0.05 %, 0.075 %, 0.1 %, and 0.125 %) as the working fluid. This research employs the hybrid nanofluid to improve heat transfer characteristics within the C.S.P. system, enhancing thermal energy extraction and exergy utilization. The proposed nanofluid underwent Fourier transform infrared spectroscopy (FTIR) analysis to determine its transmission spectrum across various frequencies. X-ray diffraction analysis was also conducted to elucidate the structural characteristics of two identical water and hybrid working fluids. The maximum thermal efficiency of 68.7 % was achieved for the PTSC system by adding 0.125 % of ZrO2 nanoparticle concentration with a mass flow rate of 3 L/min. Exergy efficiency was found for maximum volume concentration compared to distilled water fluid. Experimental results indicate significant improvements in thermal energy (68.72 %) and exergy harvesting efficiency (16.7 %), demonstrating the potential of graphene-ZrO2/Water hybrid nanofluids as a viable solution for enhancing the performance of C.S.P. systems.

Okra functional biomimetic composite phase change materials integrated with high thermal conductivity, remarkable latent heat, and multicycle stability for high temperature thermal energy storage

High-temperature phase change materials (h-PCMs) offer viable solutions for efficient thermal energy storage systems within large-scale industrial facilities. However, h-PCMs still face enormous challenges owing to low thermal conductivity and restricted thermal storage efficiency. Herein, we report okra functional biomimetic high-temperature composite phase change materials (h-CPCMs) that exhibit excellent comprehensive thermal storage properties and operational reliability, inspired by the okra seed storage process. The okra biomimetic SiC ceramic skeleton, featuring unique macropores and crosslinked axially fibrous thermal transfer pathways, significantly boosts the thermal storage efficiency of loaded molten-salt-based h-PCMs. The resulting h-CPCMs exhibit excellent thermal conductivity with a maximum value of 31 W/(m·K) accompanied by a notable latent heat of 207 J/g. Of note, the h-CPCMs with high porosity maintain superior thermal storage properties after 500 cycles. The overall thermal storage performance under 400–700 °C outperformed that of h-CPCMs reported in previous works. Furthermore, utilizing a self-designed thermal storage performance testing device, the thermal storage power density of h-CPCMs performs a 101 % enhancement compared to pure h-PCMs, suggesting a significant improvement in thermal storage efficiency. This work provides valuable insights and advancements for the further design of highly performance h-CPCMs.

Thermal analysis of fuel cells in renewable energy systems using Generative Adversarial Networks (GANs) and Reinforcement learning

This research introduces a novel in silico thermal management strategy for fuel cell systems that combines Generative Adversarial Networks (GANs) and Reinforcement Learning (RL). The framework utilises the unconditional generation ability of GANs to produce realistic thermal management, which can be used to train an RL agent to control system parameters dynamically. A GAN can be trained on historical data or simulation results to generate realistic and diverse scenarios of the complex relationship between the working point and the thermodynamics of a fuel cell. Once the adversarial network is trained to output realistic data, it can feed an RL agent that tunes the parameters influencing cooling, such as coolant flow rates, air stoichiometry or reactant humidification in response to a generated working point. We conduct experiments and simulations to show that GANs can improve the performance and resilience of RL agents to uncertainty. This approach can be applied to a real-world system, demonstrating significant thermal efficiency, durability and robustness improvements. Adopting such a strategy for thermal management in a fuel cell system is just one example of a new class of intelligent, data-driven control approaches that will enable improved understanding and behaviour of systems, leading to better performance and reliability.