Absorber Plate Research Articles

Finite element based computational analysis to study the effects of baffle and fin on the performance assessment of solar collector

The present work aims to develop an ideal solar collector layout through a finite element-based parametric study. The thermohydraulic performance factor of the solar collector was investigated with the placement of baffles and fins on the absorber plate. The cross-flow, channel, and twist designs of three alternative baffle/fin configurations were parametrised, and the heat transfer throughout the collector was analysed using COMSOL Multiphysics software. The parametrised design for cross-flow was the angle of solid baffle as 30°, 35° and 40°; whereas, for channel and twist design, the distance between the fins was varied at 50, 100 and 150 mm. The simulated result manifested that channel design had highest convective heat transfer coefficient of 21–27 W m−2 K−1, followed by cross-flow and twist design. Contrarily, twist and cross-flow design had lowest pressure drops of 0.6–1.27 Pa and 0.60–1.06 Pa, respectively, while channel design showed maximum pressure loss (35–467 Pa). The average overall thermal efficiency for cross-flow, channel, and twist design was 76.16 %, 74.26 %, and 70.65 %, respectively. The average thermohydraulic performance factor for cross flow and twist design was 11.25 % and 0.48 % higher, whereas 248.22 % lower for channel design compared to flat plate collector. The performance of the cross-flow 30 design was best out of all the designs in terms of the thermohydraulic performance factor, outlet temperature, pressure drop, and flow homogeneity inside the collector. Cross-flow 30 demonstrated a minimum friction factor of 0.004, comparable to a flat plate collector and had a double heat transfer coefficient.

Thermohydraulic performance parameter based experimental investigation of frustum shaped roughened solar air heater

An outdoor experimental investigation was conducted to explore the thermohydraulic characteristic (Nusselt no. and friction factor) of artificial roughened solar air heater (ARSAH) having frustrum shaped roughened element on absorber plate. Data were recorded and further processed to generate Nusselt number and friction factor correlation to predict the effect of flow and roughness parameter on performance of ARSAH. The investigation was conducted by varying Reynolds number in range of 2500–12,500. Dimensionless parameter for Frustrum shaped roughness was relative frustum height (e/Dh) from 0.013 to 0.054, relative frustum pitch (p/e) from 8 to 14, Relative frustum height to base diameter (e/d1) from 0.37 to 0.75, relative frustum diametral ratio (d1/d2) from 1 to 3. Maximum performance for ARSAH was obtained corresponding to the optimum value of flow and geometric parameter. The geometric orientation of the proposed roughness geometry produced tremendous rise in Nu with an acceptable rise in friction (f). Maximum enhancement in Nu for varying p/e, e/Dh, e/d1, and d1/d2 was, 4.58, 5.21, 6.62 and 6.09 times and that of friction was 5.59, 4.69, 4.92 and 4.66 times respectively over conventional SAH. Maximum Thermohydraulic performance was 3.7, 3.6, 3.9 and 3.8 at p/e = 12, e/Dh = 0.054, e/d1 = 0.75 and d1/d2 = 3.

Parametric optimization of solar air heaters with dimples on absorber plates using metaheuristic approaches

The performance optimization analysis of artificially roughened solar air heaters (SAH) becomes complex due to the inherent difficulties of the optimization analytical processes. Metaheuristic algorithms can be employed as optimization methodologies to handle complex engineering problems with minimal computational efforts and high accuracy. However, due to their stochastic nature, only some metaheuristic algorithms are suitable for solving a specific problem. Hence, there is a need to perform a comparative performance analysis of different metaheuristic algorithms in optimizing SAH. The current paper presents a comparative performance analysis of four metaheuristics algorithms, i.e., Firefly algorithm (FA), Particle swarm optimization (PSO), Differential evolution (DE), and Teaching learning-based optimization (TLBO), in optimizing the system and operating parameters of SAH. Two types of artificially roughened SAH absorber plate design patterns have been taken: dimpled plate in a zig-zag pattern and straight-line pattern. Both single and multi-objective optimization techniques are carried out while viewing the maximization of Nusselt number (Nu) and minimization of friction factor (Ff) as two objective functions in single-objective optimization. Results showed that the TLBO algorithm delivered better optimal solutions for single and multi-objective optimization than the other three metaheuristic algorithms. In the single-objective optimization, the maximum improvement in Nu and Ff is 16.81 % and 3.61 %, respectively. In the multi-objective optimization of a zig-zag pattern, the suitable parametric setting is Re = 20000, S/e = 30.83, L/e = 30.83, and d/D = 0.2515 for the optimal value of Nu and Ff as 204.7034 and 0.0134, respectively. For a straight-line pattern, the optimal values for Nu and Ff are 108.6901 and 0.0237, respectively at Re = 12000, p/e = 12, and e/D = 0.0379.

Development of a novel solar dryer with an incorporated heat exchanger

This study analyzes the thermal performance of an indirect-type solar dryer incorporated with a heat exchanger to recover heat from the exhaust. Data were recorded for 8 h from 9:00 to 17:00 from November to January to determine the drying rate for varying airflows from 2 l/s to 12 l/s under the weather conditions of Nepal and Bhutan. The air temperatures in multiple locations in the dryer were recorded and logged for 30-second intervals. The results indicated that incorporating a simple heat exchanger can achieve 78 % and 81 % effectiveness for the lowest tested airflow of 2.5 l/s and 2 l/s in Nepal and Bhutan. The heat transfer effectiveness increases with decreasing flow, resulting in a higher cold side outlet temperature of the heat exchanger for lower airflows. The solar air collector demonstrated efficient performance, achieving 80 % and 90 % efficiencies for the highest tested airflows of 12 l/s and 10 l/s in Nepal and Bhutan, respectively. Due to an increased heat transfer coefficient, the incoming air can effectively remove the accumulated heat from the absorber plate for higher airflows. The drying rates were observed to be the highest for 12 l/s, with a value of 85 g/(h × m2) for apples and 10 l/s, with a value of 56 g/(h × m2) for gingers in Nepal and Bhutan, respectively. From both cases, it can be concluded that the highest tested airflows provide higher air circulation for effective heat and mass transfer from the product to the surrounding air for drying.

Thermal performance improvement in solar air heating: An absorber with continuous and discrete tubular and v-corrugated fins

Solar air heaters (SAHs) are a sustainable and eco-friendly technology that utilizes abundant and free solar energy. Meanwhile, they have poor thermal performance owing to inefficient heat transfer and more heat loss. Efficient heat transfer is achieved by improving absorber area and thermal contact between the absorber plate and air. Thus, the present work uses continuous and discontinuous rectangular tubes and V-corrugated fins on the plain absorber surface to increase absorber area and airflow. An appreciable heat transfer and efficiency improvement is found using the current novel absorber. The SAH with continuous and discrete finned absorbers achievedaverage heat transfer coefficients of 79.2 W/m2K and 67.5 W/m2K, respectively, at a Reynolds number (Re) of 10930, outperforming the plain absorber by87.2 % and 59.3 %, respectively. Nusselt number and friction factorincreased by 100 % and 28.2 % for discrete and 44.6 % and 15.3 % for continuous finned absorbers, respectively. An enhanced heat absorption reduced the heat loss by 6.3–19.5 % and 10.7–23.3 % using a continuous and discrete fin structure. The SAH with discrete and continuous finned absorber reached 82.5 % and 79 % peak energy efficiency at Re of 10930. Though a higher pressure drop, discrete and continuousfinned absorbers have better effective efficiency than plain absorbers, with thermo-hydraulic performance factors of 2.01 and 1.6 at Re 4099. The discrete structure of fins is a vital factor for heat transfer increase in addition to geometry. Therefore, the absorber with combined tubular and v-corrugated discrete fins helps to produce more efficient solar air heaters and promotes sustainable development.

Thermal and effective assessment of solar thermal air collector with roughened absorber surface: an analytical examination

Abstract The current work analyses the thermal (ηth) and effective efficiency (${\eta}_{\mathrm{eff}}$) of a solar thermal air collector (STAC) that has an arc-shaped dimple as a roughness geometry on the absorber plate. Nusselt number (Nu) and friction factor (ff) were computed for roughness geometry during the testing, which was done on STAC. Additionally, for different roughness values, the correlations for Nu and ff were developed and further used in this study. The temperature rise parameter and a parametric design are used to assess these efficiencies. The influence of design variables on STAC performance is analyzed using a numerical model based on thermal and effective evaluations. During the investigation, parameters such as relative roughness height (e/Dh) varied from 0.021 to 0.036, relative roughness pitch (p/e) from 10 to 20, arc angle (α) from 45 to 60°, temperature rise parameter from 0.003 to 0.02 and Reynolds number (Re) from 3000 to 48 000 at a constant solar intensity (I = 1000 W/m2). The ηth and ${\eta}_{\mathrm{eff}}$ are observed to be 85% and 78%, respectively, at the optimum values of roughness parameters, i.e. e/Dh = 0.036, p/e = 10, and α = 60°. The curves have been plotted between each of the roughness parameters and Re in order to evaluate the best ηth and ${\eta}_{\mathrm{eff}}$ . The research emphasizes the usefulness of MATLAB for STAC analysis and optimization, roughness parameters of the suggested collector design, by integrating simulation and experimental data.

Numerical analysis of solar air collector with trapezoidal ribbed absorber plate of indirect solar dryer: estimation of performance parameters with proposed pitch for better performance

Numerical analysis of solar air collector with trapezoidal ribbed absorber plate of indirect solar dryer: estimation of performance parameters with proposed pitch for better performance

Investigation of the Enhancement of Heat Transfer in a Flat Plate Solar Collector With a Corrugated Tube Under Thermosiphon Effect

Abstract The development of new technologies for energy generation and use has been increasing significantly. In this projection, the use of flat solar collectors to convert solar energy into thermal energy through water heating for residential and commercial purposes has grown due to the potential reduction of up to 40% in electrical energy consumption promoted by these devices. A promising but underexplored area in engineering is the study of the intensification of heat transfer in these devices by changing the dimensional and constructive characteristics of the elevation tubes, especially through a numerical approach by passive systems that operate under the thermosiphon effect. Thus, this work aims to investigate, by using computational fluid dynamics (CFD), the heat transfer process in a flat plate solar collector with a concentric plate to the elevation tube, evaluating different diameters, angles of inclination, and slope corrugation profiles subjected to a constant heat flux. The numerical modeling considers a single-phase, incompressible, permanent, three-dimensional, and laminar flow, in addition to the Boussinesq approximation. The results showed that significant increases in the heat transfer rate can be achieved with absorber plates in comparison to those configurations without absorber plates. Moreover, the increase in the tube diameter allowed gains of up to 5.1% in the heat transfer rate, while the increase in the angle of inclination did not promote significant improvements. The triangular profile R10 P20 configuration increased the Nusselt number by 8%, while the R5 P20 configuration promoted a 25% gain in thermo-hydraulic performance.

Energy and exergy analyses of modified solar still with coated hybrid nanomaterial on absorber plate

Energy and exergy analyses of modified solar still with coated hybrid nanomaterial on absorber plate

Enhancing solar air collector performance through optimized entrance flue design: A comparative study

The current study examines the effect of entrance flue conditions on the performance of solar air collectors (SAC) with a single pass channel, focusing on two configurations: a front entrance solar air collector (FESAC) and a side entrance solar air collector (SESAC). The FESAC, introduced to optimise air distribution across the absorber plate, demonstrated higher performance, with higher outlet and lower absorber plate temperatures than the SESAC across various mass flow rates. The absorber plate temperatures for FESAC are 86 °C, 82.9 °C, and 75.1 °C, and for SESAC, 90.4 °C, 85.9 °C, and 79.1 °C for tested air flowrate 0.01118 (Case A), 0.01231 (Case B), and 0.01469 kg/s (Case C) respectively. Additionally, the maximum outlet temperatures for FESAC were 45.2 °C, 42.9 °C, and 39.5 °C for Case A, B, and C, respectively, while for SESAC, they were 43.1 °C, 41.4 °C, and 37.8 °C for the same cases. The study also emphasises a proportional relationship between airflow rate and collector efficiency. The observed daily efficiencies of the FESAC were 37.2 %, 40.4 %, and 44.4 % for the corresponding airflow rates mentioned above, while for the SESAC, they were 39.9 %, 43.4 %, and 47.5 % at these same rates. Additionally, the daily efficiency of the FESAC exhibited an enhancement of 3.1 % to 3.7 % relative to the SESAC, highlighting the effectiveness of entrance flue design in optimising SAC performance. These findings indicate the FESAC's enhanced capability in heat removal from the absorber plate and position the FESAC design as a promising avenue for boosting thermal efficiency in SACs. This study highlights the potential of modifying entrance flue configurations as a complementary approach to existing performance enhancement techniques for solar air collectors.

Experimental assessment of lamination processing method for liquid-based hybrid PV/T modules

Due to the lack of in-depth research on lamination processing methods for PV/T technology, typical flat-plate PV/T modules still face severe lifespan issues that require urgent solutions. Thus, this study proposes a specialized two-stage lamination process method. The efficacy of this process flow in addressing the challenging issue of microscopic hidden cracks in PV cells, which commonly occurred during the processing of PV/T modules, was confirmed through a comprehensive electroluminescence testing procedure. An analysis was conducted to examine the interrelationship between the thermal pressing process, peel strength, and crosslinking degree of the hot-melt adhesive film on both the absorber plate and external surface of the transparent TPT (Tedlar/PET/Tedlar) layer. The results indicated that a high level of peel strength (50 N/cm to 80 N/cm) was achieved between the adhesive film and absorber plate with a selective absorption coating, while ensuring compliance with crosslinking requirements and preventing bubble issues. Therefore, the novel process method proposed in this paper for PV/T modules can effectively address the bottleneck of lifespan issues that have remained unresolved in PV/T technology for years.

Experimental and simulation studies on the no‐load performance assessment of a domestic solar dryer

AbstractSolar dryers have been tested with various simple and complex design modifications for better efficiencies. This article attempts to investigate the effect of a very simple design modification on the no‐load performance of a natural convection domestic solar dryer (NCDSD). A direct‐type domestic solar dryer has been developed with an air cavity surrounding the drying chamber. To compare the effect of air cavity, a domestic solar dryer without air cavity has also been developed and both the dryers were tested simultaneously under the climate of Hisar, India. The values of thermal efficiency were calculated along with convective heat transfer coefficient from absorber plate to the drying air. Both the dryers were also analyzed by developing finite element models in COMSOL multiphysics computer software. The no‐load thermal efficiency for the domestic solar dryer without and with air cavity was found to be 22.68% and 34.08%, respectively. The values of coefficient of correlation for modeled and actual drying tray temperatures for dryer without and with air cavity were 0.980466 and 0.9833917, respectively. The proposed finite element model would be helpful in the design and development of NCDSDs.

Modifying performance of solar still, by using slices absorber plate and new design of glass cover, experimental and numerical study

By utilizing novel techniques on the absorber plates as well as the glass cover, this effort attempts to increase the distilled water productivity of a modified pyramid solar still. Under the climatic conditions of Iraq, the use of basin absorber plates with slices along its length, and a W-shaped glass cover was investigated experimentally and numerically. In this work, two comparable solar stills with basin absorber plates of 1 m2 have been planned and built using regional resources. Two absorber plates made of stainless steel were produced, first one was solid and the second was sliced. Two covers made of glass were produced one has a pyramid-shaped glass cover and the other a W-shape. According to experimental and numerical findings, forming slices and changing the glass cover resulted in a 20 % increase in the amount of distilled water. when compared to a pyramid glass cover and a standard sort of absorber plate.

EFFECTIVE EFFICIENCY ANALYSIS OF ARTIFICIALLY ROUGHED SOLAR AIR HEATER BY DIAGONALLY CHAMFERED CUBOID ARRAY

The solar air heater (SAH) is a very simple and economical device, but its thermal performance is quite poor. Boosting the heat transfer between absorber plates and the airflow can improve the thermal performance of a solar air heater. Applying artificial roughness to the absorber plate is a unique method for improving the thermal performance of solar air heaters compared to other methods. In this study, diagonally chamfered cuboids were utilized as roughness elements to investigate the enhancement of the performance of a solar air heater. This roughness is achieved by attaching diagonally chamfered cuboids to the absorber surface. A thorough experimental investigation was carried out to examine how this roughness affects the performance of solar air heaters. The study considered several parameters, such as relative roughness pitch (RRP) (5 to 8), arm length of cuboid (ALC) (4 to 10 mm), and relative roughness height (RRH) (0.44 to 0.077). To ensure turbulent flow during the experiment, the Reynolds number was kept within the range of 4250 to 18,000, which is considered ideal for solar air heaters operating with a constant heat flux of 1000 W/m<sup>2</sup> on the absorber plate. An overall performance assessment of the artificially roughened solar air heater was conducted, which included analyzing the Nusselt number and friction factor for both roughened and smooth absorber surfaces operating under similar flow conditions. The maximum Nusselt number achieved was 3.68 times higher than that of the smooth absorber plate at Re = 4250, with roughness parameters RRP = 5, RRH = 0.077, and ALC = 10. The analysis also reveals a 2.48-fold improvement in the overall performance of the roughened configuration.

Enhancing Solar Air Heater Performance with Quatrefoil Artificial Roughness: An Adaptive Neuro-Fuzzy System Approach

Solar air Collector is used to transform the solar energy into heat energy. Solar heating technologies use only free, renewable and clean energy. More number of previous studies was done. The roughness element is changed to enhance the airflow’s capacity to absorb heat. In this study Experimental investigates the glazed solar air heater with quatrefoil shaped artificial roughness is placed above the absorber plate in the solar air heater. The solar air heaters (SAH) with quatrefoil shaped artificial roughness and conventional solar air heater are tested. The outcome indicates that the maximum temperatures for conventional SAH and purposely roughened SAH are 670C and 470C, respectively. By the increased of heat transfer area and increased the turbulence lead to higher heat recovery rate of quatrefoil shaped artificial roughness is 47% more compared to conventional type. The solar air heater is predicted by using Adaptive Neuro Fuzzy Inference System (ANFIS) and accuracy is measured as 90%.

Experimental analysis of triangular solar distiller with a new form of absorber

To better improve the evaporation of seawater in solar distillers, and consequently boost the production of distillate, we suggest that the structure of the conventional absorber surface should be modified. The present work aims to study the thermal performance of the Triangular Solar Distiller (Henceforth, TSD) by using a new form of a Trapezoidal Absorber (Henceforth, TA). This new design (Henceforth, TSDTA) proves to reduce the influence of shadow created by the sloped sidewalls and the volume of seawater of the TSD. The experimental results obtained from the TSD are compared to those obtained from a conventional Triangular Solar Distiller equipped with a Plate Absorber (henceforth, TSDPA) under the same weather conditions of Sfax – a central-eastern town Tunisia. The findings show that the trapezoidal structure of the absorber increases the diurnal production of distillate by 22.73% as compared to the plate one. The thermal efficiency reaches a maximum value of 49% for the TSDTA and only 46% for the TSDPA during the daytime.

A numerical study of solar air collectors with corrugated absorber plates featuring diverse wave amplitudes and wavelengths

A numerical study of solar air collectors with corrugated absorber plates featuring diverse wave amplitudes and wavelengths

Effect of displacing the separation plate on the heat exchange effectiveness of unglazed double skin transpired solar collector

Achieving zero-carbon or low-carbon buildings is possible by implementing innovative approaches and incorporating renewable energy sources into the building infrastructure. Thermal energy collection has become critical amid challenges such as climate change, global warming, and environmental pollution. One such thermal energy collection system is Transpired Solar Collector (TSC). TSCs are a well-proven and readily available technology and are a green energy alternative for large space heating. The utilization of Computational Fluid Dynamics (CFD) analysis for the optimization of TSC is a robust and cost-effective approach. A recent variant of TSC, the Double Skin Transpired Solar Collector (DTSC), has been studied for optimisation. The numerical simulations targeted one single parameter: distance of separation plate from the main absorber plate.

Evaluation of fin configurations for an air-cooled hybrid photovoltaic-thermal solar collector

In this work, the examination of an experimental air-cooled photovoltaic-thermal (PV/T) module is introduced. Two different shapes of fin fixed to the copper absorber plate are examined for the classical unit of an air-cooled PV/T collector. Vertical and louver-shaped fins (with the same surface area) are investigated and thermally evaluated in this study. The experiments aimed to increase the temperature difference between inlet and outlet air to reach high thermal performance. The enhancement result showed that the thermal efficiency of the louver fin unit increased by 48% and 54% compared to the vertical fin and unfinned units, respectively. Thus, louver fins are better than vertical fins with the same surface area.

PARAMETRIC CFD STUDY OF SOLAR AIR HEATER HAVING ALTERNATED UPPER AND BOTTOM ABSORBER PLATES IN TURBULENT FLOW

This work presents a computational fluid dynamics (CFD) investigation of a solar air heater (SAH) that features alternating upper and bottom absorber plates to evaluate its thermal behavior and turbulent flow characteristics. Generally, the SAH exhibits low heat transfer characteristics and poor thermal efficiency in turbulent flow. The use of alternating upper and bottom absorber plates facing the turbulent flow would improve heat transfer by producing recirculation zones mainly over these heated plates. The computational fluid dynamics software program, ANSYS Fluent 15.0, along with the renormalization-group (RNG) <i>k-ε</i> turbulence model, was utilized in this analysis to solve the transport equations for turbulent kinetic energy and dissipation rate. The analysis encompassed several geometric and operating parameters, including the relative absorber plate length <i>L<sub>p</sub>/h</i> ranging from 4.375 to 140, the relative absorber plate height <i>h/H</i> ranging from 0.03 to 0.12, and the Reynolds number varying between 3800 and 18,000. The impact of these parameters on heat transfer improvement factors, including the heat transfer amelioration ratio (HTAR), friction loss amelioration ratio (FLAR), and thermohydraulic efficiency factor (THEF), was studied. The optimum computed THEF value was found to be 2.18 for <i>L<sub>p</sub>/h</i> = 4.375, <i>h/H</i> = 0.12, and Re = 3800.