Thermal Efficiency Enhancement Research Articles

Fouling Reduction and Thermal Efficiency Enhancement in Membrane Distillation Using a Bilayer-Fluorinated Alkyl Silane–Carbon Nanotube Membrane

In this study, we report the robust hydrophobicity, lower fouling propensity, and high thermal efficiency of the 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FAS)-coated, carbon nanotube-immobilized membrane (CNIM) when applied to desalination via membrane distillation. Referred to as FAS-CNIM, the membrane was developed through a process that combined the drop-casting of nanotubes flowed by a dip coating of the FAS layer. The membranes were tested for porosity, surface morphology, thermal stability, contact angle, and flux. The static contact angle of the FAS-CNIM was 153 ± 1°, and the modified membrane showed enhancement in water flux by 18% compared to the base PTFE membrane. The flux was tested at different operating conditions and the fouling behavior was investigated under extreme conditions using a CaCO3 as well as a mixture of CaCO3 and CaSO4 solution. The FAS-CNIM showed significantly lower fouling than plain PTFE or the CNIM; the relative flux reduction was 34.4% and 37.6% lower than the control for the CaCO3 and CaCO3/CaSO4 mixed salt solution. The FAS-CNIM exhibited a notable decrease in specific energy consumption (SEC). Specifically, the SEC for the FAS-CNIM measured 311 kwh/m3 compared to 330.5 kwh/m3 for the CNIM and 354 kwh/m3 for PTFE using a mixture of CaCO3/CaSO4. This investigation underscores the significant contribution of the carbon nanotubes’ (CNTs) intermediate layer in creating a durable superhydrophobic membrane, highlighting the potential of utilizing carbon nanotubes for tailored interface engineering to tackle fouling for salt mixtures. The innovative design of a superhydrophobic membrane has the potential to alleviate wetting issues resulting from low surface energy contaminants present in the feed of membrane distillation processes.

Fouling Reduction and Thermal Efficiency Enhancement in Membrane Distillation Using a Bilayer-Fluorinated Alkyl Silane–Carbon Nanotube Membrane

Fouling Reduction and Thermal Efficiency Enhancement in Membrane Distillation Using a Bilayer-Fluorinated Alkyl Silane–Carbon Nanotube Membrane

Analysis of parabolic trough solar collector thermal efficiency with application of a graphene oxide nanosheet‐based nanofluid

AbstractNowadays, clean energy production and reconciliation with nature is one of the best solutions known to rectify the global warming issue. Solar energy, as a clean and green one, has recently been drawing scientists' attention to itself more than ever. Applying parabolic trough solar collectors (PTSCs) is one of the state‐of‐the‐art ways to extract energy from the sun. As one of the most interesting research topics, the thermal efficiency enhancement of PTSCs is studied. The current study demonstrates how the thermal efficiency of PTSCs is enhanced through the application of graphene oxide (GO) nanosheets, as an inexpensive nanomaterial with superb thermal conductivity and unique structure, in thermal oil, namely, Behran oil, as heat transfer fluid, within the effective volume fraction range of 0.05. The above‐mentioned analysis is based on the theoretical calculations performed through a mathematical model based on the Taylor series approximation. All the calculations are performed with respect to a PTSC unit of a solar–thermal power plant situated in Shiraz, Iran, as the research case study. In addition, the Nan et al. model is used to analytically predict how the increase in the volume fraction of GO nanosheets raises the thermal conductivity and consequently increases the convection heat transfer coefficient of the nanofluid, leading to the thermal efficiency enhancement of PTSCs. The results reveal a maximum thermal efficiency of 71.10% for the volume fraction of 0.05. In comparison to the thermal efficiency of the real‐world case‐study mentioned above with pure thermal oil, that is, 67.71%, the thermal efficiency enhancement by about 5.5%, is achieved. Moreover, it is discussed how the thermal efficiency achieved from GO nanosheets surpasses the ones obtained from the application of particle shape nanomaterials, or carbon nanotubes in the same conditions.

Twisted tape inserts in parabolic trough solar collectors: Assessment of Energy, Exergy, and Environmental impacts

The parabolic trough solar collector is a solar technology extensively employed to focus and harness solar energy for diverse heating purposes. One effective technique to enhance its thermal performance involves the insertion of swirl generators within its absorber tube. In this research, experimental investigation on performance enhancement of parabolic trough solar collector using single twisted tape and dual twisted tape insert across Reynolds number values ranging from 1,000 to 9,000 is performed. Collector efficiency, Nusselt number, friction factor, performance improvement factor, and exergy efficiency are examined for single twisted tape inserts with pitch to width ratios (y/w) of 1, 1.5, 2, 2.5, and 3, and dual twisted tape inserts with y/y0 ratios of 2, 3, and 4. Maximum enhancement in collector efficiency is reported at the lowest flow rate for both inserts. The single twisted tape insert with pitch to width ratio of 1 and the dual twisted tape insert with a pitch ratio of 2 exhibit the most notable enhancements in the evaluated performance parameters. Specifically, at lower flow rates (Re < 4400), the dual twisted tape insert (y/y0 = 2) outperforms the single twisted tape insert (y/w = 1). This dual twisted tape insert configuration provides a thermal efficiency enhancement of 14 %, while the Nusselt number and friction factor enhancement are found to be 372 % and 1600 % compared to bare tube. Additionally, the exergy efficiency exhibits a peak increase of 20.8 % at the lowest flow rate using the dual twisted tape insert (y/y0 = 2). This improvement translates to an annual CO2 reduction between 1.53 tons/year offering a highest enviro-economic benefit of 22.19 US dollars per year.

Thermal and electrical analysis of the performance of a skeleton-shaped tubes via hybrid PVT cooling system

The study investigates methods to mitigate the decrease in performance of solar panels caused by increased cell temperatures. Using commercial computational fluid dynamics (CFD) analysis, two cooling methods for photovoltaic/thermal (PVT) modules are compared. Configuration 1 employs longitudinally connected tubes beneath the solar panels, while configuration 2 utilizes skeleton-shaped aluminum tubes inserted into the cells from below. Both configurations undergo cooling with air (case 1) and water (case 2) at a mass flow rate of 0.0025 kg/s. Results indicate that configuration 2, employing skeleton-shaped tube cooling, surpasses configuration 1 in both thermal and electrical efficiency. In case 1, configuration 2 achieves a notable improvement of approximately 24.3 % in thermal efficiency and a marginal increase of 0.16 % in electrical efficiency compared to configuration 1. In case 2, with water cooling, configuration 2 demonstrates a 7.27 % enhancement in thermal efficiency and a more substantial increase of 3.98 % in electrical efficiency over configuration 1. The hybrid PVT system utilizing skeleton-shaped tube cooling with water at a mass flow rate of 0.0025 kg/s proves highly effective in maintaining peak thermal and electrical efficiency.This work addresses the critical issue of solar panel performance decline due to increased cell temperatures, proposing innovative cooling methods and quantifying their effectiveness. The study’s novelty lies in the utilization of skeleton-shaped aluminum tubes for cooling, which outperforms traditional cooling configurations. These findings underscore the importance of advanced cooling techniques in optimizing PVT module performance, offering valuable insights for future research and practical applications in the renewable energy sector.

Heating and storage of medium-deep borehole heat exchangers: Analysis of operational characteristics via an optimized analytical solution model

This study focuses on investigating the thermal storage potential of medium-deep borehole heat exchanger (MDBHE) to address the issues of temperature attenuation of thermal reservoir and heating capacity reduction during the one-way heat extraction process in the heating period. By establishing an MDBHE heating system that integrates an external thermal storage source, a comprehensive analysis of the heat transfer progress and operational characteristics of the MDBHE is conducted, including optimizing burial depth, thermal storage scenarios, and aquifer conditions. The calculated solution under the typical thermal storage conditions (S60–30) in this study reveals that the average heat supply capacity increasement of a 1200 m MDBHE is 37.2 % higher than that of a 2000 m MDBHE, and the power consumption of the circulating water pump also can be reduced by 40 % in heating period. Furthermore, the enhancement of storage temperature and flow rate both contribute to a noticeable improvement in the heating performance of the MDBHE during the heating period. The heat transfer power and energy efficiency of MDBHE both increase with the elevation of seepage velocity and aquifer thickness during the energy storage and heating period. The significance of this research lies in its contribution to the enhancement of thermal storage and heat transfer efficiency in MDBHE and offering novel insights for the multi-thermal energy storage systems.

Optical and thermal performance enhancement of parabolic dish collector: Effects of cavity receiver's surface modification and covering aperture

Regarding the increasing demand for renewable energy sources, especially solar energy, researchers are trying to develop more efficient solar energy systems. Parabolic dish collectors are solar thermal collectors that can be utilized in various thermal energy system applications. Cavity receivers of the dish collectors are one of the crucial parts of these collectors, and the studies on their thermal performance improvement and heat loss reduction are critical. The current study follows the experimental investigation of the glass covering of cylindrical-conical cavity receiver along with the cavity's coil surface modification with various geometries. According to the results, applying the glass covering enhanced the thermal efficiency by 18.42%, with a maximum thermal efficiency of 52.61% and optical efficiency of 57.89%. Rectangular-triangular geometry for the surface modification of the cavity's coil resulted in a maximum optical efficiency of 59.17%. Overall, rectangular geometry had the best thermal and optical efficiency enhancement results.

The utilization of novel jet extension designs in multi-jet impingement for crossflow mitigation and thermal efficiency enhancement

The aim of this study is to mitigate the distorting effect of crossflow on jet flow and to enhance heat transfer performance in multi-jet impingement heat transfer. To accomplish this objective, novel jet extension designs are proposed: a design with uniform jet extension, a design with linear jet extension in the streamwise direction, a design featuring an initial increase followed by a decrease, a design featuring an initial decrease followed by an increase, and a design where the last five jets exhibit a uniform extension inside the region mostly influenced by crossflow. The effects of various novel jet extension designs on flow and heat transfer are analyzed numerically in this study, focusing on the following: velocity contours, streamlines and velocity vectors, Local Nusselt number variations, variations of the average Nusselt number, friction coefficient, and thermal enhancement factor with Reynolds number. The study findings indicate that the investigated nozzle extension designs yield a notable enhancement of 13.26% in heat transfer. However, it is important to note that these designs may also lead to a substantial rise of 39% in the friction coefficient. In relation to thermohydraulic performance, it is found that all extension designs exhibit better results when compared to the reference state. Notably, the uniform extension design with dimensionless nozzle length of 2 demonstrates a higher degree of thermohydraulic performance.

Combustion characteristics optimization and thermal efficiency enhancement by stratified charge of hydrogen direct injection for argon power cycle hydrogen engine

Argon power cycle hydrogen engine is a novel approach to increasing the thermal efficiency of hydrogen engines while achieving zero CO2 emissions. This paper presents a combination of experiments and simulations used to examine the effects of hydrogen direct injection on the combustion characteristics and thermal efficiency of argon power cycle engines. The results of the study indicate that, in comparison to port hydrogen injection, hydrogen direct injection produces a delay of CA50 exceeding 12.36°CA at an engine speed of 1000 r/min. This delay optimizes combustion and diminishes knock intensity to below 0.1 MPa by creating a stratified mixture, which in turn decelerates the combustion rate. Through adjusting hydrogen direct injection timing and incorporating super lean combustion, a maximum gross indicated thermal efficiency of 53.72% is achieved. By optimizing the first injection timing, the second injection timing, and the second injection ratio, dual hydrogen direct injection can significantly suppress knock and increase thermal efficiency compared with original single hydrogen injection conditions.

Experimental Analysis of the Improvement of Heat Transfer in Tube Heat Exchangers via Passive Flow Generators Using Wire Coil Inserts

Abstract Due to their high performance and low-cost demands, internally treated tube heat exchanger surfaces are one of the passive heat transfer enhancements that have caught the industry&amp;#39;s attention. At bulk temperatures of 30 &amp;#176;C, an experiment for the insertion of 1 mm and 0.5 mm wire coils with a constant pitch length of 8 mm was carried out in this study. The results on the improvement of heat transfer, including the velocity profile, Nusselt number, friction factor, and thermal enhancement efficiency, were significant. Based on a lower surface temperature recorded beyond the uncertainty value, the results demonstrated an improvement in heat transfer for smaller diameters of wire coil inserts. Interestingly, this improvement is concentrated at low Reynolds numbers, indicating that there may be a point at which an increase in wire thickness does not necessarily result in an equivalent improvement in heat transfer. For both wire thicknesses, a Nusselt number increase of up to 5 times was observed. The friction factor penalty, however, varies depending on the wire thickness, with a higher magnitude (3.2-fold increase) obtained for 1mm as opposed to a 1.8-fold increase for the lower counterpart. This distinction results in the 0.5 mm coil insert gaining better overall performance with an average of 2.2 for the thermal performance ratio, further solidifying the advantage of this technique for enhancing heat transfer in conduits.

Numerical investigation on knock intensity, combustion, and emissions of a heavy-duty natural gas engine with different hydrogen mixing strategies

With the continuous development of hydrogen energy technology, mixing hydrogen has become a potential method to enhance the performance of natural gas engines and reduce emissions. Aiming to offer guidance for optimizing strategies for mixing hydrogen from the perspectives of knock control and thermal efficiency enhancement, a three-dimensional model of a commercial heavy-duty natural gas engine is constructed based on the actual boundary conditions from a high load bench test. In this study, simulations were conducted under conditions where the hydrogen volume fraction ranged from 0% to 40%. The study explored the effects of two injection strategies, port fuel injection of hydrogen-enriched natural gas (PFI) and port fuel injection of natural gas combined with direct injection of hydrogen into the cylinder (PFI + DI), on engine knocking, performance, and emissions. Results indicate that for various injection strategies, there is an increasing trend in knock intensity (KI) with the higher hydrogen mixing ratio. When the hydrogen volume fraction exceeds 20%, the timing of direct hydrogen injection significantly affects KI. This effect is mainly caused by the distribution of unburned hydrogen at the knock onset crank angle (KOCA). Compared to other injection strategies, the PFI + DI strategy when the direct hydrogen injection time at 120°CA BTDC results in a high concentration of hydrogen near the spark plug at the ignition moment, combined with good mixture uniformity in the cylinder. This leads to the shortest CA0-10 and CA10-90, and achieves a maximum indicated thermal efficiency (ITE) of 44.68% under 20% hydrogen volume fraction. Compared to the original natural gas engine, the ITE increased by 2.9% and the NOx emissions increased by 166%, while the HC and CO emissions decreased by 88% and 53%.

6-Stroke water injection engine literature review with an introduction of heat transfer and thermodynamic analysis

AbstractInternal combustion engines have played a crucial role in the advancement of society. Consequently, there has been a persistent need to enhance their efficiency and performance. The water-injected six-stroke engine is based on conventional four-stroke engines, producing additional power by injecting water into the hot combustion products during the expansion stroke, thereby increasing the overall engine efficiency. However, a comprehensive review that consolidates existing knowledge and identifies future research opportunities in six-stroke engine technology is lacking. This study addresses this gap by thoroughly examining the thermodynamic operation of six-stroke engines and analyzing the impact of water injection on engine performance. The review covers literature from 1994 to 2023, categorizing studies based on the modeling approach, working fluid, thermodynamic cycle, and consideration of heat transfer. Among the 18 analyzed articles, predominantly published from 2015 to 2019, half utilize analytical models, while the rest employ experimental models addressing heat transfer losses. Notably, water injection exhibits a substantial influence, manifesting as a 5.18% increase in brake power and a 1.55% enhancement in thermal efficiency, particularly with acetylene as the working fluid. Finally, a literature overview of water injection in hot gas environments within the engine cylinder was conducted in addition to a preliminary thermodynamic analysis of the Otto and Diesel cycles to compare different configurations outlined in the literature. The lack of studies, experimental setups, and non-idealized models that consider factors such as heat transfer or water evaporation during injection is evident. By critically synthesizing the available literature, this study offers valuable insights into the potential advantages, limitations, and prospects of six-stroke engine studies.

Improving solar still efficiency through integration of cellulose-based water absorbers and Peltier condensation unit

This study involves a series of experiments aimed at assessing the impact of incorporating water-absorbent materials on the productivity of solar stills. It is worth mentioning that the performed experiments examine the effects of both materials and their location inside solar still unit. The solar still used for the experiments comprised a black-painted metal case and a glass layer positioned at a 30° angle relative to the horizontal. To enhance evaporation performance, a Peltier cooling module was integrated into the system. Furthermore, to prevent thermal losses and improve efficiency, the solar still case was insulated using Styrofoam material. From a scientific standpoint, the variations in this context can be ascribed to three primary variables as, integration Peltier condensation unit, use of water absorber materials like hemp and high-absorbent papers, and the incorporation of absorber dark colors. Throughout the experiments, constant test conditions were established using an artificial light source. In the reference setup, a total of 25 g of clean purified water was obtained, whereas in Case 5 (utilizing black high-absorbent papers on a triangle metal frame) and Case 6 (employing high-absorbent papers in the form of upright columns), which yielded the most efficient results, the amounts of purified water obtained were approximately 34 and 40 g, respectively. The results indicated a remarkable enhancement in thermal efficiency for Case 5 and Case 6, with approximately 29% and 45% increases, respectively, compared to the reference setup. Furthermore, a cost assessment has been conducted, demonstrating that the productivity gained through the use of internal materials contributes to improvements in cost efficiency. In comparison to the reference case, Case 6 exhibits a cost reduction for cost per liter exceeding 35%.

Part-load thermal efficiency enhancement in gas turbine combined cycles by exhaust gas recirculation

Gas turbine power plants are popular for offshore power generation due to high power density and their reliability. However, growing usage of renewable energies put gas turbines in a load following backup operation. These power plants suffer part-load efficiency losses when operating at less than full capacity, resulting in higher carbon dioxide (CO2) emission from natural gas combined cycles or higher consumption of carbon-free fuels in decarbonized gas turbines. In this article, a solution is proposed for enhancement of power plant part-load thermal efficiency based on exhaust gas recirculation in the gas turbine cycle. Recirculating exhaust gas into the gas turbine have been studied by several researchers and engineers due to its benefit for carbon-free combustion and carbon capture mechanisms. The proposed operation strategy is evaluated for single-spool and two-spool gas turbines operating jointly with a steam bottoming cycle harvesting the waste heat for further power production. In the suggested strategy, eliminating the necessity to cool down the recirculated gas resulted in less equipment footprint for the power plant which makes it more favorable for offshore applications. An in-house design and simulation tool is developed for evaluating gas turbines with modern gas recirculating systems and a flexibility in operation with carbon-free fuel mixtures. The enhancement in efficiency boost, emission reduction, and fuel consumption is quantified demonstrating the improvements with the proposed solution.

Real‐time thermal performance investigation of a thermal energy storage integrated direct absorption solar collector under tropical climate

AbstractIn the last two decades, metallic particles of nano sizes (~10−9 m) have been tested profoundly in volumetric absorption solar collectors (VASC) due to their excellent optical properties and broadband absorption in the entire solar spectrum. However, very limited studies are available for understanding the performance of integrated energy storage VASC systems using nanofluids. For the experimental work presented here, a hybrid nanofluid of gold nanoparticles in Azadirachta indica leaves extract has been synthesized by chemical route. The prepared hybrid nanofluid has shown good absorption in 400 to 700 nm wavelength range and hence achieved high photo‐thermal conversion efficiency for tested VASC system. Furthermore, commercially available paraffin wax is used as a phase change material (PCM) in thermal energy storage (TES) and further integrated with VASC to analyze the thermal performance of the system even after sunshine hours. The real‐time experiments were conducted using different working fluids, and at three mass flow rates, that is, 0.008 kg/s, 0.016 kg/s, and 0.033 kg/s, respectively, during mild winter days in the tropical climate of India. The study revealed a photo‐thermal efficiency enhancement of about 17.1% when hybrid heat transfer fluid was used in the VASC system with TES as compared to base fluid water but without TES. During the heating period, the maximum thermal gain of the hybrid nanofluid was observed to be about 15°C higher than the ambient temperature at mass flow rate of 0.033 kg/s. Thermal efficiency enhancement of about 23.8%, 24%, and 24.1% was observed with hybrid nanofluid compared to base fluid water at a mass flow rate of 0.008 kg/s, 0.016 kg/s, and 0.033 kg/s, respectively, when PCM was kept inside the tank. Furthermore, a maximum zero loss efficiency of 83.8% was estimated at an optimal mass flow rate of 0.033 kg/s for the TES‐integrated VASC system.

Expanded graphite nanoparticles-based eutectic phase change materials for enhancement of thermal efficiency of pin–fin heat sink arrangement

This experimental work foresights the synthesis and characterization of the expanded graphite (EG) enhanced organic-organic eutectic PCM (EGePCM) with different weight percentages of the EG (ϕ = 1–5 %). In particular, the expanded graphite nanoparticles were exfoliated from the graphite flakes by acid protonation followed by extraction from the traditional co-precipitation synthesis. A series of EGePCM nanocomposites were fabricated through the homogeneous suspension of EG nanoparticles in the eutectic mixture (1:1) of organic PCM. The surface texture, physical morphology and chemical interaction of individual elements present inside the nanocomposites were thoroughly examined by FTIR, XRD, SEM, and FESEM. Conversely, the physical attributes, thermal stability, thermal degradation, and charging-discharging performance were also investigated. The EGePCM nanocomposite with 3 wt% of EG nanoparticles expresses a favourable increase of thermal conductivity by 232.24 %, with a nominal reduction in the latent heat storage capacity (176.5 J/g) of the PCM. In conjunction with the thermal attribute intensification, the incorporation of EG in nanocomposite reduces the supercooling degree to 9.16 °C with a phase change enthalpy of 174.8 J/g in cooling and 176.5 J/g in heating stage for 3 wt% of EG. A comprehensive experimental methodology was employed to investigate the thermal enactment features of different EGePCM nanocomposites inside a regular pin–fin arrangement imperilled with steady-state heat transfer. The effectiveness of the cooling rate was also encompassed under a variable range of heat flux (1.6–3.2 KW/m2) and EGePCM mixture (ϕ = 1–5 %). The heat transfer effectiveness was optimal at a mass fraction of 5 wt%, resulting in a 30 °C base temperature drop of the heat sink and a decrease in the charging-discharging duration of the nano PCM composite. This observation suggests an improvement in the thermal conductivity of the system with an incorporation of high thermal conductive EG nanoparticles. The enhanced thermal performance and notable thermal, physical and chemical stability facilitate the phase transition progression and render it highly advantageous for electronic or micro-electronic thermal cooling applications.

Indoor thermal nonuniformity of atrium-centered public building: Monitoring and diagnosis for energy saving

Heating ventilation and air conditioning system accounts for over one third of building energy usage, especially for public buildings due to large indoor heat source and high ventilation and thermal comfort requirement compared to residential buildings. Natural ventilation shows high application potentials in public buildings because of its high-efficient ventilation effect and energy saving potential for indoor heat dissipation. In this paper, the building design is conducted for a science museum and library with atrium-centered natural ventilation consideration. The floor layout, building orientation and internal structure are optimized to make full use of natural ventilation for space cooling under local climatic conditions. A natural ventilation model is established through building field tests to evaluate the air flow and thermal environment under indoor and outdoor pressure differences. The preliminary results show that Building A's courtyard exhibited overheating issues, likely attributed to outdoor solar radiation, whereas Building B's courtyard experienced localized cooling, possibly due to indoor air conditioning system controls. Addressing these concerns necessitates modifications in courtyard design and structure. Moreover, both courtyards displayed vertical temperature gradients, emphasizing the need for effective management of outdoor heat influx and enhancements in indoor ventilation and shading strategies. To mitigate these issues, the study proposed three distinct roof design models and more refined indoor air conditioning system control strategies. The optimization of architectural design can achieve a maximum energy-saving rate of 46.54 %. Furthermore, aligning functional zones with thermal comfort areas was recommended to enhance overall building thermal comfort. The findings and proposed solutions from this study are anticipated to contribute to the enhancement of thermal comfort, energy efficiency, and vertical temperature distribution in large public buildings, catering to user requirements while reducing energy consumption. This research holds significant implications for advancing sustainability and environmental preservation in the realm of architecture.

Optimization of solar air heaters performance using parallel porous wire mesh: energy, exergy, and enviro-economic analyses

This research conducts an experimental analysis of a solar air heater (SAH) with and without a porous wire mesh, focusing on energy, exergy, and enviro-economic aspects. Measurements are carried out using both a conventional solar air collector and modified one by adding a porous wire mesh. Various wire mesh lengths (20, 40, and 60 cm) are used to determine the optimum one considering different mass flow rates (ṁ = 0.022, 0.033, and 0.045 kg/s). The impact of specific loss sources on exergy efficiency, including exergy destruction between the environment and system components, between the fluid and absorber, and between the absorber and the sun is pointed out. The findings reveal a remarkable enhancement in thermal efficiency, reaching 86 % by using a 60 cm wire mesh atṁ = 0.045 kg/s. The integration of the wire mesh into the SAH results in reduced exergy efficiency due to increased losses and exergy destruction rates. Using 60 cm wire mesh yields beneficial effects on thermo-hydraulic performance by enhancing convection heat transfer and increasing the overall effectiveness of the collector. Enviro-economic analysis shows significant environmental benefits. In Case4, operating at ṁ = 0.045 kg/s, the highest embodied energy value is observed and the highest annual useful energy output of 5480 kWh/year at the lowest energy cost of 0.0105 ($/kWh) is achieved. Additionally, the incorporation of a 60 cm porous wire mesh leads to an annual mitigation of approximately 1370.21 tons of CO2 and an improved environmental cost of 68.51 $/year compared to the conventional solar air collector's cost (28.15 $/year).

Investigation of various hybrid nanofluids to enhance the performance of a shell and tube heat exchanger

&lt;abstract&gt; &lt;p&gt;In this study, we aim to investigate the heat transfer and flow characteristics of diverse hybrid nanofluids (CuO-ZnO-Water, EG-Water, CuO-EG-Water, SiO&lt;sub&gt;2&lt;/sub&gt;-EG-Water, and Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;-EG-Water) as coolants across eight discrete inlet velocities in a shell and tube heat exchanger. Various materials (copper, stainless steel, titanium, and carbon steel) have been employed for the tubing to optimize system performance. The impact of Reynolds number concerning hybrid nanofluids on Nusselt number and friction factor was assessed in this research. The results of the numerical simulations are found to agree well with experimental results within an average deviation of 1.8%. The results indicated the superior heat transfer capabilities of the hybrid nanofluid compared to the base fluid across all conditions. The outcomes revealed the superior heat transfer capabilities of the CuO-ZnO-Water hybrid nanofluid under all tested conditions. When employing CuO-ZnO-Water as a coolant, a substantial increase of over 9% in temperature reduction was observed, as opposed to the approximately 6% attained by other hybrid nanofluids at a lower velocity of 0.5 m/s. Notably, higher Reynolds numbers corresponded to increased Nusselt numbers and decreased friction factors. The decline percentage of the friction factor was 43% at Reynolds number ranging between 10,000 to 40,000. We emphasize the imperative need to optimize nanoparticle types for crafting hybrid nanofluids to enhance the performance of industrial heat exchangers and their coolant efficiency. Ultimately, the utilization of hybrid nanofluids in conjunction with shell and tube heat exchanger systems has yielded a notable enhancement in the overall thermal efficiency of these systems.&lt;/p&gt; &lt;/abstract&gt;

ANALYTICAL EXAMINATION OF NANO-FLUID-ASSISTED COOLING RATE ENHANCEMENT IN A CAR RADIATOR

In recent years, nanofluids have been extensively utilized to improve heat transmission in various mediums. The use of nanofluids can enhance the thermal efficiency of thermosyphons. This study focuses on analyzing the thermal efficiency of automobile radiators by utilizing three different types of nanofluids. In this study, we conducted a thermal performance analysis of a car radiator by examining the effects of three different types of nanoparticles mixed with water: CuO-water, ZnO-water, and MgO-water nanofluids. The thermal performance of these three nanofluids was compared and analyzed. The experimental setup included a radiator with a hydraulic diameter of 0.0191 m and a total length of the radiator channel of 10.5354 m. The analyses are conducted at different volume fractions, ranging from 0.5% to 3%, and a constant inlet velocity of 0.24 m/s is maintained. The findings demonstrated a substantial enhancement in thermal efficiency when employing CuO-water nanofluid as a coolant for vehicle engine cooling in the radiator. Conversely, ZnO-water and MgO-water nanofluids exhibited very limited improvements in comparison to pure water. The thermal conductivity of CuO-water nanofluid is greater than that of pure water. The CuO-water nanofluid yields the most significant enhancements in terms of the mass flow rate and heat transfer coefficient, as revealed by this investigation. Hence, it is advisable to utilize CuO-water nanofluid in automobile radiators to achieve optimal heat transfer efficiency in comparison to the base fluid.