This study numerically investigates the thermal-hydraulic performance of sharp-nose tube profiles for heat exchanger applications. Six geometries, including rounded and sharp-nose tubes with angles ranging from 20 degrees to 45 degrees, were analyzed at inlet velocities of 4 m/s and 12 m/s (Re = 7895-23,685). A thermal-hydraulic performance metric was used to evaluate the proposed designs against a drop-shaped tube. The results indicate that sharp-nose and double-nose profiles exhibit enhanced performance by 4-25% compared to the drop-shaped tube. The optimal configuration with a nose angle of theta=25 degrees achieves the highest improvement in the thermal-hydraulic performance metric by 25.3% compared to the drop-shaped tube at Re = 7895. At lower Reynolds numbers, all sharp-nose configurations outperform the drop-shaped geometry, while performance converges at higher angles due to geometric similarity. The findings indicate that values calculated by employing the area-weighted average skin friction coefficient Cf & oline; and the associated flow separation behavior play a central role in determining the thermal-hydraulic performance of the tube profiles. These findings highlight the potential of sharp-nose geometries for heat exchanger performance enhancement.

Conventional vertical-axis wind turbines (VAWTs) rely on rigid blades that are heavy and require expensive materials and manufacturing processes to withstand aerodynamic loads. This study explores flexible sail-type blades as a low-cost alternative capable of achieving comparable performance. Small-scale sail-type VAWTs employing blades made out of fabric similar to maritime sails were designed, fabricated, and tested in a wind tunnel. One edge of each sail was hemmed to a vertical rod, while the opposite edge was secured at its end to top and bottom end disks. The turbine radius and height were fixed at 19 cm and 21 cm, respectively. Experiments were conducted in a wind tunnel and measurements included wind speed, turbine rotational speed, and the generator current and voltage. A total of 36 configurations were evaluated by varying four design parameters: number of sails (2, 3, and 6), chord length (10 cm and 15 cm), pitch angle (0°, 15°, 30°, and 45°), and blade shape (rectangular or trapezoidal). Performance was assessed using power output (P), power coefficient (Cp), and tip-speed ratio (TSR). Experimental results were validated by comparison with test data for a conventional rigid-bladed VAWT. The best-performing configuration was a three-sail turbine with rectangular blades, 15 cm chord length, and 0° pitch angle, producing 547 mW at 177 RPM, corresponding to a Cp of 0.053 at a TSR of 0.59. Numerical predictions using state-of-the-art codes were used to further assess sail-type VAWT performance. Under the test conditions considered, the sail-type VAWT not only showed better performance but also comparable self-starting capability compared to a rigid-bladed VAWT. However, due to the maximum wind speed limitation of the test facility, the complete Cp-TSR characteristic curve could not be determined. Moreover, preliminary estimates indicate a potential 24% reduction in total turbine capital cost and an overall 30% reduction in turbine mass of sail-type turbines over conventional HAWTs, demonstrating that flexible sail blades are a promising low-cost option that needs further investigation to realize their full potential.

High-concentration photovoltaic (HCPV) systems present significant thermal management challenges due to the intense heat fluxes generated under concentrated solar irradiation, especially in arid environments. Effective heat dissipation is critical to prevent performance degradation and structural failure. This study investigates the thermal performance and design optimization of an enhanced HCPV module, integrating numerical, analytical, and experimental methods. A coupled optical-thermal-electrical model was developed to simulate ray tracing, heat transfer, and temperature-dependent electrical behaviour, with predictions validated under real-world desert conditions. Compared to a baseline commercial module operating at 106 circle C, the optimized design achieved a peak temperature reduction of 16 circle C, lowering the cell temperature to 90 circle C under a concentration ratio of 961 & times; and direct normal irradiance (DNI) of 950 W/m2. The total thermal resistance was reduced from 0.25 to 0.15 K/W (a 40% improvement), and the electrical efficiency increased from 37.5% to 38.6%, representing a relative gain of approximately 3.1%. The system consistently maintained a fill factor exceeding 78%, underscoring stable performance under high thermal load. These findings demonstrate that targeted thermal design, informed by integrated modeling, is essential for unlocking the reliability and efficiency of high-flux solar energy systems.

This study presents the design, fabrication, and performance assessment of a novel, small-scale (30–70 W), hybrid ocean energy system that captures energy from wave-induced heave motion using a point-absorber buoy and from ocean currents via a vertical axis water turbine (VAWT). Key innovations include a custom designed and built dual-rotor generator that accepts independent mechanical input from both subsystems without requiring complex mechanical coupling and a bi-directional mechanical motion rectifier with an overdrive. Numerical simulations using ANSYS AQWA (2024R2) and QBLADE(2.0.4) guided the design optimization of the buoy and turbine, respectively. Wave resource assessment for the Khobar coastline, Saudi Arabia, was conducted using both historical data and field measurements. The prototype was designed and built using readily available 3D-printed components, ensuring cost-effective construction. This mechanically simple system was tested in both laboratory and outdoor conditions. Results showed reliable operation and stable power generation under simultaneous wave and current input. The performance is comparable to that of existing hybrid ocean wave–current energy converters that employ more complex flywheel or dual degree-of-freedom systems. This work provides a validated pathway for low-cost, compact, and modular hybrid ocean energy systems suited for remote coastal applications or distributed marine sensing platforms.

In this paper, the thermo-optical performance using novel cooling strategy improvements for a hybrid photovoltaic/parabolic dish concentrator with a conical thermal receiver using a beam splitter filter (PV/PDC-CTR-BSF) is investigated. The study’s main goal is to improve the cooling effectiveness of the serpentine-shaped cooling duct by investigating the effect of the cross-section shape and positioning of the cooling duct under the PV panel. Typical cooling pipes have either a rectangular or circular cross-section and are usually attached to the back sheet of the PV panel using off-the-shelf adhesives that have very low thermal conductivity. With the advent of 3D printing technology, the back sheets could be 3D-printed with integral cooling ducts of different cross-sections at different locations and orientations within the back sheet that allow for increased heat transfer from the back sheet and thus improve PV/PDC-CTR-BSF’s thermos-optical performance. For this purpose, the study investigates and compares the thermal performance of four different cooling duct cross-sections that include: rectangular, semi-circular, semi-elliptical and triangular. For each of the cooling duct cross-sections, several positions and orientations, which include flush below the back sheet layer and embedded inside the back sheet but positioned at the bottom, middle and top of the back sheet, are examined. Numerical simulations using the commercial software ANSYS FLUENT(R2019) are performed to assess the performance of the cooling ducts and, in turn, the thermo-optical performance of the PV/PDC-CTR-BSF system. The semi-elliptical cross-section duct embedded in the middle of the back sheet was found to yield the best cooling performance since its rate of heat removal from the PV back sheet was found to be the highest.

The present research discloses a novel hybrid water-cooled Photovoltaic/Parabolic Dish Concentrator coupled with conical cavity receiver and spectral beam splitter (PV/PDC-CCR-BSF). In effect, a compact co-generating solar-concentrating PV system involving a subsequent optical interface has been fully developed and numerically tested. The optical performance of the proposed hybrid solar-concentrating system was modeled and assessed using the RT 3D-4R method while the thermal yield of the system was examined using the Finite Element Method. In addition to that, different configurations of serpentine-shape embedded water-cooling pipes (rectangle, semicircle, semi-ellipse and triangle) have been tested and optimized for maximum heat collection and minimum operating cell temperature. The performance of all the tested serpentine-shape embedded water-cooling pipes was evaluated with respect to conventional serpentine-shape water-cooling pipes. The outcomes indicated that the triangular cross-section outperforms other shapes in terms of heat dissipation capabilities, with about −446 W and maximum useful thermal power in the medium of the heat transfer fluid of 11.834 kW.

The parabolic dish is considered the most performant concentrating solar power (CSP) technology since it fits a wide range of domestic and industrial processes and offers better modular deployment than other CSP technologies such as thermal power receivers. The parabolic dish has been widely employed to produce steam and electricity especially when it works in conjunction with Stirling engines; however, the extreme complexity of the latter makes the power generation cost of this technology unfavorable against other competing solutions. In this paper, a comprehensive and detailed optical and thermal performance analysis and optimization study of a hybrid photovoltaic/parabolic dish concentrator with a conical thermal receiver using a beam splitter filter (PV/PDC‐CTR‐BSF) are carried out. A complete modeling module is developed to assess and optimize the overall yields of the PV/PDC‐CTR‐BSF. The present work is unique since it encompasses a sophisticated simulation tool enabling performance potential assessment of a novel PV/PDC‐CTR‐BSF system coupled with a novel conical‐shaped helical coiled‐tube heat exchanger for steam production and paves the avenue for higher electrical yield using single‐junction PV cells mounted over the tip surface area of the paraboloid mirrors. The concentrated solar density (CSD) distribution, optical efficiency, temperature distribution, and steam fraction have particular interest in the performance assessment of the innovative PV/PDC‐CTR‐BSF package system. As a result, the maximum value of the CSD at the conical cavity receiver and the PV cells is 40 and 8 kW/m2, respectively. The optical efficiency of the proposed design has a breakthrough in the record of the typical hybrid designs reaching the value of 67%. Moreover, the maximum surface solar cells temperature was 80°C, while the temperature reached 170°C at the conical cavity receiver. The optical new hybrid design has maximized the steam productivity up to a steam volume fraction of 98%.

Membrane desalination (MD) is preferred over other desalination techniques since it requires a lower temperature gradient. Its performance can be further enhanced by preheating the intake of saline water. In this context, a novel solar-assisted air gap membrane desalination (AGMD) system was hypothesized. The motivation was derived from the fact that the use of solar energy to provide power and a pre-heating source for the intake of saline water can offer a sustainable alternative that can further enhance the acceptance of MD systems. Since solar panels suffer from a loss of efficiency as they heat up during operation, a solar-assisted air gap membrane desalination (AGMD) system can help to improve the overall system performance by (1) providing the necessary pumping power to operate the system and (2) improving solar panel performance by exchanging heat using water that is (3) used to pre-heat the saline water necessary for increased performance of the AGMD system. To verify the hypothesis, a solar-assisted AGMD system for freshwater production was theoretically designed, fabricated locally, and then tested experimentally. The effect of the process operating parameters and the ambient conditions on the overall performance of the proposed solar-assisted AGMD desalination unit is presented in detail, both theoretically and experimentally. The results indicated a direct correlation between the permeate flux, saline hot feed temperature, and hot feed flow rate. In addition, an inverse relationship between the cold feed temperature, cold feed flow rate, and the air gap thickness of the module was also observed and reported, thus, validating the hypothesis that a solar-assisted air gap membrane desalination (AGMD) system can help to boost performance.

One of the major challenges in the photovoltaic (PV) industry is to have effective and viable means of cooling the PV panel to maintain its temperature within the desired level during its operation. The commercially available racking structures are primarily designed to fulfil only the mechanical support requirement; however, modifying the racking structure to additionally serve as a heat sink is a novel idea. The present study introduces a dualfunction PV panel racking structure that simultaneously serves as racking structure and heat sink. The proposed structure facilitates effective thermal contact between the metallic purlins and the panel's backside while acting as mechanical support. Numerical analysis of its heat transfer performance has been performed using fluid flow and heat transfer modules of Ansys Fluent, a state-of-the-art CFD tool, and the results have been validated by data obtained in real field experiments conducted in Dammam, Saudi Arabia. The results showed that the modified structure could reduce the panel temperature by up to 6.3 degrees C, which eventually increased the panel efficiency by 3%. Also, the new system could reduce the levelized cost of electricity by 5%.

Many approaches exist today that employ hot-air from aircraft compressor bleed for anti-icing critical aircraft surfaces. This paper introduces and numerically analyzes the novel application of an inner or etched channel to augment heat transfer from a hot-air jet impinging on a curved surface representing the inner surface of an aircraft wing’s leading edge or slat. The study shows that proper positioning, geometry, and flow characteristics of a channel along the inner surface of the leading edge can significantly enhance heat transfer, boost the anti-icing system performance, and greatly enhance flight safety during critical icing weather conditions. Commercially available CFD software, ANSYS Fluent is used to model and analyze the effect of different geometric and flow parameters typical of those found in small to medium category commercial transport aircraft to help determine the optimum arrangement. These parameters include: (1) jet nozzle height-to-slot diameter ratios from 4 to 8, (2) channel width-to-slot diameter ratios from 0.4 to 1.8, and (3) inner-channel inlet location angles from 10° to 60°. Each configuration resulting from a combination of the above parameters was simulated at Reynolds numbers based on jet-slot diameter of 30,000, 60,000, and 90,000. Empirical relations based on available experimental data are used to validate the results. The main findings of the study reveal that the jet height-to-slot diameter ratio of 6, inner channel height-to-slot diameter ratios of 1.8, and inner-channel inlet angular locations of 10° combination resulted in the highest heat transfer at all Reynolds number as well as higher at increased Reynold numbers.

Conventionally, the CFC-type refrigerants were used until Montreal Protocol which stated that CFC refrigerants cause ozone depletion and should be replaced with alternative refrigerants. The alternative refrigerants are safe for ozone but they have comparatively high degrees ammability, toxicity and global warming potential. Thus they need careful handling. In Kyoto Protocol, it was stated that the currently used refrigerants with high global warming potential need to be replaced with yet other alternative refrigerants with low global warming potential. This paper comprehensively reviews those recent studies that focused on the possible replacement of currently in-use refrigerant with a comparatively more environmental-friendly alternative refrigerant. Initially, the progression of refrigerants through different generations has been described and discussed. A list of currently in-use refrigerants has been presented. Then, the scientific developments for the replacement of listed refrigerants are thoroughly reviewed and critically analyzed. From the comprehensive review, it was found that R1234yf has the most potential to be a suitable low-flammable replacement for R134a for domestic refrigeration and automotive air-conditioning systems. Also, R32 has the most potential to be a suitable alternative of R410A.

This paper presents the details of development of an efficient interactive design tool for aircraft engine sand separator systems. The development of such a tool was felt necessary to address the problem of sand ingestion in gas turbine engines; a vital concern for the aviation and gas-turbine based electricity generation industry communities operating in desert environments as it can seriously affect the operation, performance and life cycle of a turbine engine. The design tool makes use of state-of-the-art practical geometry design and analysis technique, namely the inverse airfoil design method for the design of specific profiles for engine air intakes. The sand separator design is achieved by giving a specific contour to the intake profile, such as a highly curved bend in the duct, so that the contaminants because of their inertial momentum are forced away from the central flow. Since the sand particles can rebound of the air intake walls and enter the engine, the method takes into account sand particle rebound or restitution characteristics in the design. The design is accomplished with the aid of optimization techniques in both the inverse aerodynamic design as well as in the sand separator system design. In addition, to facilitate the analysis and design in an interactive manner, a MATLAB GUI has been developed. Details of the analysis and design tool are presented along with simple but practical design examples to demonstrate the usefulness and utility of the method and the interactive tool

Growing quantities of low-cost wind power still require predictable, supportive regulatory environments and appropriate market designs. The challenge of integrating greater amounts of variable wind power into the grid is a growing concern that must be addressed. For offshore wind-still at early stages of the deployment journey-much remains to be accomplished to develop and integrate large-scale systems and to reduce costs. In this study, aerodynamic performance and feasibility of multi-megawatt vertical axis wind turbines (VAWTs) is compared to existing, similarly rated horizontal axis wind turbines. Two types of three-bladed VAWTs have been designed, one with the Darrieus (H-type) and the other with the Troposkien (Phi-type) rotor configuration, in the 2, 4, and 6 MW rated capacity range based on an optimal parametric study. This comparative performance study shows that VAWTs are not only characterized by superior performance but also exhibit a very simple design that is cost effective from both manufacturing and maintenance perspectives.

This paper presents an analysis based on computational fluid dynamics of vertical axis wind turbines when placed in close proximity in a linear array. It has been noticed that VAWTs placed close to each other with counter rotation motions have a higher coefficient of power than a single turbine. This was termed the “coupled vortex effect”. Two mechanisms have been identified to cause this increase in efficiency: the streamtube contraction effect and the vortex effect. The first is due to the blockage effect from neighboring turbines while the later is related to the neighboring turbine acting as a vortex that induces an increased flow field. This paper analyzes each of these effects and studies the influence of the turbine size and the rotation speed. The change of torque on each blade due to these effects is investigated for two different sizes of wind turbines.

214 Published By: Blue Eyes Intelligence Engineering & Sciences Publication Pvt. Ltd. Abstract— The paper presents the results of an experimental and numerical investigation to determine aerodynamic characteristics in terms of lift, drag, side force, pitching moment, yawing moment and rolling moment coefficients for 65-deg delta and 65/40-deg double-delta wings at various pitch and sideslip angles. The study was carried out due to scarcity of such data in literature. The experimental tests were conducted at the KFUPM low-speed wind tunnel facility whereas the numerical tests were performed using the commercial CFD software FLUENT. Results for zero sideslip angles from both experiments and numerical predictions were compared with experimental data found in literature as well as to the theory of Polhamus. The comparison of force and moment data, surface pressure coefficient distribution and vortex breakdown location show good agreement with experiments and CFD predictions found in literature as well as theoretical calculations at zero sideslip angles. Experimental and computational results for non-zero sideslip angles at various pitch angles were then determined and have been reported in this study.

This paper presents a numerical study of a low Reynolds number flow around a thick airfoil (Eppler's E863 airfoil) with and without an upper-surface vortex-trapping cavity. The numerical model of flow is constructed using an O-grid computational domain around the airfoil and analyzed using four different turbulence models: namely standard k-epsilon, RNG k-epsilon, SST k-omega and the one-equation Spallart-Almaras (SA). Enhance wall treatment is employed for the two-equation turbulence models with the non-dimensional first cell height y(+) at the wall region kept close to 1. The Reynolds number is kept constant at 354000. Results of lift & drag coefficient as well as velocity profiles are presented for four different angles of attack from 0 to 15 deg. The RNG k-epsilon model is found to better predict the flow field and airfoil lift and drag characteristics as compared to the other turbulence models taken into consideration in this paper.. The presence of the vortex-trapping cavity midway on the upper-surface of the airfoil is found to yield higher lift coefficients as well as prevent flow separation but at the cost of increase the drag coefficient.