Finned Absorber Plate Research Articles

Performance enhancement of nanofluid-based photovoltaic/thermal system with a novel finned multi-block container of phase change material in the summer season of northern India

This study describes the outdoor experiments conducted on a photovoltaic/thermal (PV/T) system during the summer months of May and June in the year 2023, in northern India. The main goal of this paper is to reduce the temperature of a photovoltaic (PV) module for effective thermal regulation by implementing a hybrid cooling strategy in a PV/T system. This is achieved by integrating two techniques: multi-walled carbon nanotubes (MWCNT)-water nanofluid as the working fluid for active cooling and paraffin wax as the phase change material (PCM) for passive cooling. Therefore, the present study aims to design, fabricate, and test an innovative thermal collector with a multi-block finned absorber plate positioned beneath the PV module to promote uniform heat transfer distribution and mitigate temperature stratification within each PCM block. The proposed PV/T-PCM system's performance is assessed from energetic, exergetic, economic, and environmental standpoints compared to the PV/T system and conventional PV module. The present study also examines the impact of different concentrations (0.1–0.2 %) of MWCNT and volumetric flow rates (0.5–1.5 l/min) of both water and nanofluids as heat transfer fluids. It is shown that a desirable flow rate of 1.5 l/min yields the most favorable outcomes. The PV/T-PCM (0.2 %) system has been found to exhibit the highest levels of energetic and exergetic electrical and thermal efficiencies, with reported values of 13.25 %, 65 %, 12.81 %, and 1.66 %, respectively. The economic assessment demonstrates that the proposed PV/T-PCM system, integrating water and nanofluid, results in cost savings of 17.41 % and 19.63 % compared to a traditional uncooled PV system. In the context of environmental sustainability, the highest net CO2 mitigation is estimated to be 18.01 tons for the nanofluid-based PV/T-PCM system. Thus, the results confirm that the proposed PV/T-PCM (0.2 %) system, incorporating a hybrid cooling technique, achieves optimal performance.

Performance of Finned Absorber Plate Solar Air Heater Having Multiple Triangular Air Flow Passages in Parallel Under Transition to Turbulent Flow Condition

Abstract This paper presents the results of thermal performance study of a solar air heater having absorber plate with inclined fins fitted in equilateral triangular flow passages in parallel using the governing equations under transition to turbulent flow and compares the same with the conventional solar air heater having low aspect ratio rectangular air flow duct at equal pumping power condition. The equal pumping power condition for the equilateral triangular passages of width w and rectangular duct height H has been found to be w = 2.65 H. The finned absorber plate solar air heater has been found to provide 7.3–25.8% better thermal efficiency than the conventional air heater because of the substantial increase in the effective heat transfer surface area due to the fins. The effects of variation of design, ambient, and operating parameters on the performance of the finned solar air heater show that the triangular passage width w must be increased with the increase in the collector length L to satisfy the condition of equal pumping power according to the relation w3/L2.75 = constant. The results of the present study can be utilized for the development of enhanced-performance finned solar air heater with triangular passages.

Performance evaluation of a solar air heater with staggered/longitudinal finned absorber plate integrated with aluminium sponge porous medium

Solar air heaters are used to heat air for drying and space heating applications, however, the low heat transfer between air and absorber plate accounts for its low efficiency. In this paper, an experimental study of a staggered/longitudinal finned plate solar air heater (SLFPSAH) with a built-in aluminium sponge porous media as a sensible heat storage material is presented. The fins with the direction of airflow are arranged in a staggered manner by covering a length of 1.25 m, while the remaining 0.75 m is arranged with longitudinal fins. The parameters influencing the performance of the SLFPSAH are investigated with and without using a porous medium. These parameters include solar irradiance, the temperature difference of air through the heater, air temperature ratio, convective heat transfer coefficient, useful heat gain, daily energy efficiency, and exergy efficiency. Experiments are conducted under different air mass flow rates; namely, 0.0078, 0.01, 0.02, and 0.049 kg/s. The results revealed that the implementation of an aluminium sponge porous media over the absorber plate significantly increases the energetic and exergetic performances of the SLFPSAH. It is found that the average air temperature ratio, daily exergetic efficiency, and daily exergy efficiency of the SLFPSAH integrated aluminium sponge porous medium are about 11.52%, 3.97%, and 45.61% greater than that without the aluminium sponge porous medium, at airflow rate of 0.02, 0.049 kg/s, respectively. Moreover, the maximal increase in the convective heat transfer coefficient of the SLFPSAH integrated with aluminium sponge porous medium is more than 1.62 times that obtained with the SLFPSAH without porous media, at the same conditions. Thus, the SLFPSAH with an integrated aluminium sponge porous medium is an effective way to enhance the exergetic and energetic performances of solar air collectors for solar drying applications.

Thermal performance prediction of a solar air heater with a C-shape finned absorber plate using RF, LR and KNN models of Machine learning

Thermal performance prediction of a solar air heater with a C-shape finned absorber plate using RF, LR and KNN models of Machine learning

Thermo-hydraulic performance of solar air heater with finned absorber plate forming multiple rectangular air flow passages in parallel under laminar flow conditions

The paper presents results of an analysis carried out using the governing equations to compare the heat transfer performance of a uniformly heated flat plate with longitudinal fins, which form multiple rectangular air flow passages in parallel below the plate and cover whole of the passage surface, with that of the low aspect ratio rectangular duct typical of conventional flat plate solar air heater at equal pumping power under laminar flow conditions. The heat transfer rate at equal pumping power for the plate with 1 mm thick steel fins at pitch of 25 mm and 40 mm is found to be about 2.7 and 2.5 times, respectively, over the duct without fins. The heat transfer study is followed by thermo-hydraulic performance study of the solar air heater with absorber plate having longitudinal fins forming multiple rectangular air flow passages in parallel. The finned solar air heater with low air mass flow rates has been found to provide 28–31 % better thermal efficiency than the conventional solar air heater at equal pumping power. The results of the study can be utilized for the development of enhanced performance finned solar air heater operating with low air mass rates to deliver high temperature air.

Enhanced Heat Transfer Performance of Multiple Triangular Air Flow Passages in Parallel With Inclined Fins for Flat Plate Solar Air Heater

Abstract This paper presents results of a study of heat transfer performance of multiple equilateral triangular parallel air flow passages below a uniformly heated flat plate having inclined fins of different thickness, length, and material covering a part of the side walls of the duct for transition to early turbulent regimes using appropriate experimental heat transfer coefficient and friction factor correlations from the literature. The heat transfer performance enhancement at equal pumping power has been measured in terms of a performance parameter (hA/hsAs), where hA is the product of heat transfer coefficient and total heat transfer area for the finned triangular duct, and hsAs is the product for the triangular duct with heated flat plate without fins and adiabatic side walls. The values of the performance parameter for steel fins integral with the heated plate are found to be 1.71–1.78 for 1.0 mm thick fins of 15 mm length and 1.94–2.04 for 1.5 mm thick fins of 20 mm length. For aluminum fins, the performance parameter is 2.36–2.54 for 30 mm long fins of 1–1.5 mm thickness. The results of the presented novel scheme of the finned heated plate can be utilized for the development of enhanced performance solar air heater with the finned absorber plate. Since the presented scheme enhances heat transfer without increased pumping power penalty, the existing smooth rectangular duct solar collectors can be modified for enhanced performance.

Thermo-hydraulic performance of a solar air heater with staggered C-shape finned absorber plate

An experimental investigation has been carried out to study the thermo-hydraulic performance of a solar air heater with staggered multiple C-shape perforated and non-perforated finned absorber plate. The experiments were conducted with a relevant range of flow parameters as Reynolds number from 3000 to 27000 and geometric parameters such as relative pitch to gap ratio from 3.4 to 3.8, relative height ratio 0.3 to 0.7 and relative perforated ratio 1.5 to 3, with focus on their effects on the maximum heat transfer enhancement. The higher thermal performance was achieved at relative pitch to gap ratio, 3.8, relative height ratio, 0.6 and relative perforated ratio, 3. The thermal performance and friction factor for C- shape finned absorber plate without perforated hole for relative pitch to gap ratio, 3.8 and relative height ratio, 0.6 were 2.61 and 5.93 times more than the smooth plate absorber plate, respectively. The perforated fin with the same relative ratios gives the thermal performance and friction factor by 2.67 and 5.34 times higher than the smooth absorber plate solar air heater, respectively. The correlations were developed to match the experimental Nu and f with the deviations of ±9.63% and ±9.44% for non-perforated fin and ±9.53% and ±8.73%for perforated fin respectively.

An experimental investigation of sea water distillation using flat absorber plate and fin absorber plate with PCM storage

The presented study investigates the experiment of the thermal performance of sea water solar distillation system using flat absorber plate and fin absorber plate with phase change material (PCM) storage. The two distillation systems operated simultaneously under the same conditions to study its thermal performances. The experimental investigation shows that the distillation using fin absorber plate with PCM storage achieves better thermal performance than that of using flat absorber plate. The daily water productivity of the distillation using fin absorber plate with PCM is 262.75 mL m−2 in average and the other one is 142.85 mL m−2 in average. The average daily efficiency increases of 48.5 % of the distillation using fin absorber plate with PCM storage compared with the distillation using flat absorber plate. Using absorber plate with fin and PCM storage in the distillation system contributes to increase the thermal performance of the system.

Fe3O4-Water Nanofluid Free Convection within an Inclined 2D Rectangular Enclosure Heated by Solar Energy Using Finned Absorber Plate

This work investigates a hydrodynamic problem involving the Fe3O4-Water nanofluid. The novelty of this investigation lies in the fact that the nanofluid free convection is evaluated within a specific rectangular enclosure having a finned absorber plate as the top wall, heated by solar energy. The fins below the absorber plate permit to enhance heat transfer towards the nanofluid. A numerical simulation is carried out in order to predict the influence of Rayleigh number, nanofluid layer position, enclosure inclination angle, and absorber plate fins height on the nanofluid flow (in terms of streamlines and velocity magnitude) and heat transfer (in terms of temperature and Nusselt number divided by a certain thermal conductivity ratio). Numerical results show a nanofluid buoyancy enhancement and a temperature distribution homogenization, when the Rayleigh number increases, all the more important and pushed to the right area of the enclosure, as the inclination angle of the enclosure is higher. For relatively low fin heights, the nanofluid buoyancy enhancement is all the more important and pushed to the right area of the enclosure as the inclination angle is high. As the fin height increases, the temperature distribution becomes more homogenous.

Numerical thermal performance investigation of phase change material integrated wavy finned single pass solar air heater

The present numerical study comprises thermal performance investigation of double glazed single pass solar air heater exhibiting wavy finned absorber plate integrated with and without PCM. The main objective of the present research work is to design sustained solar air heating systems that can efficiently perform during sunshine, off sunshine and nocturnal hours. In this direction, Design-I (wavy fined solar air heater without PCM) and Design-II (wavy fined solar air heater with PCM) are investigated to obtain the best values of the geometrical and flow parameters. In the present work, first, investigation is carried out to obtain optimum values of geometrical and flow parameters for Design-I, work is then extended to investigate the Design-II exhibiting wavy absorber plate and PCM. MATLAB codes are developed to carry out numerical investigations under transient conditions using an implicit scheme to study the effect of geometrical parameters i.e. amplitude(0.005≤α≤0.015m), wavelength (0.03≤λ≤0.1m) and number of fins (5≤n≤25), and flow parameter i.e. mass flow rate (0.005≤m˙≤0.0128kg/s). The maximum outlet air temperature for Design-I corresponds to optimum values of geometrical parameters obtained at a mass flow rate of 0.005 kg/s, 0.0075 kg/s and 0.01 kg/s is 85.44 ̊C, 73.34 ̊C and 64.9 ̊C, respectively. However, the maximum thermohydraulic efficiency is predicted to be about 47% at the mass flow rate of 0.01 kg/s. Results of Design-II revealed 10 hours thermal backup after sunset at the mass flow rate of 0.0128 kg/s. In addition, investigation for Design-II is extended to present a cold weather condition of an average ambient air temperature of 15oC and an off sunshine hour situation to present possible thermal backup of Design-II. The results of this investigation delineated that using wavy fins on the top and PCM on the bottom side of absorber plate can efficiently provide appreciable instant and high thermal efficiency and thermal energy backup during sunshine, off sunshine and nocturnal hours.

Productivity enhancement of solar still with phase change materials and water-absorbing material

Due to the lower productivity of solar still, researchers from all around the world are continually ensuing to improve distillate output. Hence, there are lots of opportunities and scope of research work on the solar still. Solar desalination is the process of purification saline water to get fresh potable water using direct solar energy. Seawater is available in abundance but the process of desalinating the seawater is very expensive due to enormous energy requirements. Over the years direct solar energy is used as one of the cheapest desalination methods to drive the desalination systems which has no environmental impact also. The solar-based desalination system is referred to as solar still. The basin water depth is inversely proportional to the productivity of potable water. The difference between saline water temperature and glass temperature controls the evaporation rate. The water surface area is directly proportional to the distillation rate. The water surface area has been increased by submerging the wicks in the water, the use of porous materials, fins, sponge, etc. Instead of a single flat horizontal collector, the cascade style still gives more useful results in terms of desalination. The use of phase change materials helped further in the overall increase in the distillation rate. In the present short review paper research works done in this decade have been considered and four primary methods like the effect of the finned absorber plate, cotton wick, and phase change material and nanoparticles have been discussed. It will help future research in the area of solar still to provide an economically viable solution for sustainable potable water.

Solar Air Heater with Finned Absorber Plate and Helical Flow Path: A CFD Analysis

In the present numerical investigation, a unique design of solar air heater with finned absorber plate allowing helical flow of air is considered. The design enhances the heat transfer rate by enhancing the effective heat transfer area as well as by increasing the flow turbulence. The novel design is compared with a conventional single flow single pass design. Computational study of flow dynamics and heat transfer characteristics for both the considered designs is done at different mass flow rates using commercial software ANSYS FLUENT 18.0. Results indicate a maximum thermal performance enhancement of 3.72 times due to the novel absorber plate design as compared to its flat plate counterpart at a mass flow rate of 0.013 kg/s. The rate of enhancement in the heat transfer coefficient with increase in mass flow rate is much higher in case of solar air heater with helical flow as compared to its conventional counterpart. Thermal and hydraulic performance for both the collectors at different mass flow rate is described in details and the results are supported with different contours.

Thermohydraulic performance of double pass solar thermal collector with inline, staggered and hybrid fin configurations

Abstract The present experimental and numerical investigations are aimed to increase the thermal performance of a finned absorber plate solar air heater. A commercial CFD tool is used to perform the numerical investigation and the obtained results are validated with the experimental data. The geometrical parameters such as fin angle (30o ≤ θ ≤ 90o), fin length (0.007 m ≤ L1 ≤ 0.028 m), fin height (0.007 m ≤ L2 ≤ 0.014 m), fin arrangements (inline, staggered, and hybrid), and hydraulic diameter (0.029 m ≤ Dh ≤ 0.057 m) of the heater duct are considered to obtain the optimum values using numerical simulation, while Reynolds number (3000 ≤ Re ≤ 20, 000) as a flow parameter is considered. The obtained CFD results revealed the best thermohydraulic performance for the hybrid staggered fins configuration and found to be about 3.5% and 3.8% in comparison to the staggered and inline fins configuration, respectively. Moreover, CFD investigation revealed the interesting results about the staggered fins configuration, which is the generation of the wavy motion inside the heater duct that confers the significant heat transfer enhancement. Whereas, the experimental thermohydraulic efficiency of the double pass solar air heater design is found to be 79% which is about 13% higher than that of similar design of single air pass.

Numerical investigation of a solar air heater comprising longitudinally finned absorber plate and thermal energy storage system

In the present work, the thermal performance of a double glazed single pass solar air heater consisting of a longitudinally finned absorber plate on its top surface and attached to a phase change material (PCM) with its bottom surface is investigated, theoretically. Paraffin wax (Rubitherm RT42) is used as a PCM. The main idea of this solar air heater design is to use it during nocturnal hours or off sunshine hours. A computational heat transfer and fluid dynamics solution using an implicit scheme has been developed and employed to study the effects of the mass flow rate and number of fins on its thermal performance under transient conditions. The maximum outlet air temperature of the finned type solar air heater with latent heat storage is achieved as 40 °C, 37 °C, and 35 °C for mass flow rates of 0.01, 0.015, and 0.02 kg/s, respectively, and it is predicted that the system can be used for 14, 12, and 10 h after sunset at respective mass flow rates. The maximum daily average thermal efficiency is predicted to be 62.4% at a mass flow rate of 0.02 kg/s which is higher than the other designs considered in the present investigation.

Simulation study of solar air collector with offset strip fin absorber plate for drying agricultural products in a semi-arid climate

Simulation study of solar air collector with offset strip fin absorber plate for drying agricultural products in a semi-arid climate

Experimental study on the performance of double pass and two inlet ports solar air heater (SAH) at different configurations of the absorber plate

Abstract The effect of using different absorber plate configurations on the performance of double pass SAH with two inlet ports is presented. Moreover, the effect of using different air flow percentages through the inlet ports is studied for each studied configuration. Four absorber plate configurations are considered; (i) flat plate (ii) pin finned, (iii) corrugated finned, and (iv) corrugated-perforated finned. Moreover, four percentages of the inlet air are considered: (i) 0% of the air flows through the upper inlet port and 100% through the lower inlet port (0%Up), (ii) 33.3% of the air flows through the upper inlet port and the remainder through the lower inlet port (33.3%Up), (iii) 66.7% of the air flows through the upper inlet port and the remainder through the lower inlet port (66.7 Up), and (iv) 100% of air flows through the upper inlet port (100% Up). These percentages are studied at all absorber plate configurations and for the same total inlet mass flow rate of the air. The measurements are carried out during the day using the solar flux and at night using a solar simulator. The results indicate that increasing the upper air percentage decreases the absorber plate temperature and increases the SAH efficiency for all studied configurations. The efficiency of corrugated-perforated pin fin is the greatest and the flat plate absorber plate is the smallest. The maximum efficiency of the SAH is about 70% for flat plate configuration at (100% Up) and about 79% for the pin finned absorber plate at (100% Up). It is about 82% for the corrugated finned configuration at (100% Up) and about 83% for the corrugated-perforated finned absorber plate at (66.7% Up). The solar simulator analysis provides very near values of the efficiencies which assures the results. The cost analysis indicates that the cost of energy gained by the SAH for the flat plate configuration for 0% UP flow has the maximum cost (0.025 $/kW.h) and the corrugated perforated finned absorber plate of 66.7% has the minimum cost (0.021 $/kW.h).

Thermodynamic performance of forced convection solar air heaters using pin–fin absorber plate packed with latent heat storage materials

In this work, the thermodynamic performance of a forced convection solar air heater (FCSAH) was evaluated using two different absorber plate configurations, namely a flat absorber plate and a pin–fin absorber plate packed with latent heat storage material (paraffin wax). The experiments were carried out under the meteorological conditions of Coimbatore city in India. The parameters such as outlet air temperature, thermo-hydraulic efficiency and exergy efficiency were evaluated with reference to solar intensity, ambient temperature and ambient wind velocity. An artificial neural network (ANN) model was developed to simulate the thermodynamic performance of a FCSAH using flat absorber plate and pin–fin absorber plate packed with paraffin wax to have a realistic performance comparison. The ANN-predicted results are found to be closer to the experimental values with a maximum fraction of absolute variance, minimum root-mean-square errors and minimum coefficient of variance. The results showed that the pin–fin absorber plate packed with paraffin wax has additional heat storage for the period of 3 h with 2–5 °C enhanced outlet air temperature when compared to the flat absorber plate. The FCSAH using pin–fin absorber plate packed with paraffin wax has 3–35 % higher thermo-hydraulic efficiency with 2–15 % higher exergy efficiency when compared to the flat absorber plate. The results confirmed that pin–fin absorber plate packed with paraffin is a good option to enhance the thermodynamic performance of a FCSAH.

Thermal performance characteristics of an absorber plate fin having temperature dependent thermal conductivity and overall loss coefficient

The prime objective of the present numerical study is to analyze the thermal performance characteristics of an absorber plate fin of a sheet and tube type solar flat plate collector of fixed collector area. Considering temperature dependent thermal conductivity and overall loss coefficient and assuming cubic temperature profile along the tube, pseudo-transient form of two-dimensional, highly nonlinear partial differential equation governing the steady state temperature distribution in the absorber plate fin is solved using Alternating Direction Implicit finite difference scheme. Keeping ambient temperature, fluid inlet temperature and number of tubes fixed, numerical results are presented and discussed for wide range of values of aspect ratio of the absorber plate, fluid outlet temperature, overall loss parameter and solar flux. Finally, it is found that there exists an upper limiting value of solar flux beyond which increase in heat transfer rate is insignificant. Further, it is concluded that fin efficiency remains independent of aspect ratio of absorber plate whereas it increases significantly with decrease in overall loss parameter and decreases slightly with increase in fluid outlet temperature.

Effect of thermo-geometric parameters on entropy generation in absorber plate fin of a solar flat plate collector

The prime objective of the present numerical study is to obtain relatively more realistic values of performance parameters of a sheet and tube type solar flat plate collector of fixed collector area and number of tubes. Considering temperature dependent thermal conductivity and overall loss coefficient and assuming cubic temperature profile along the tube, pseudo-transient form of two-dimensional, nonlinear partial differential equation governing the steady state temperature distribution in the absorber plate fin is solved using Alternating Direction Implicit finite difference scheme. Numerical results are presented and discussed for wide range of values of aspect ratio of the absorber plate, overall loss parameter, and dimensionless fluid outlet temperature. On the basis of discussion of these results, it is concluded that assumption of constant thermal conductivity and overall loss coefficient results in overestimation of the total entropy generation rate with substantial error. It is also concluded that for any fixed set of values of dimensionless fluid outlet temperature and overall loss parameter, total entropy generation rate increases linearly with increase in aspect ratio of absorber plate. Further, it is found that total entropy generation rate increases with increase in overall loss parameter, the rate of increase being somewhat higher for lower values of overall loss parameter and a decrease in fluid outlet temperature results in an appreciable increase in total entropy generation rate.

Design and optimization of a solar air heater with offset strip fin absorber plate

Solar air heaters are becoming more and more popular in space heating and industrial processes due to their cost effectiveness and easy maintenance. However, how to increase thermal efficiency of solar air heaters becomes a major challenge. In this paper, the design of a solar air heater with offset strip fins was optimized by numerical modeling. Then, a series of experiments based on ASHRAE Standard 93-2003 was conducted to test the detailed thermal performance of the heater in the light of time constant, thermal efficiency, incident angle modifier and the synthetical resistance coefficient. Results indicate that the instantaneous thermal efficiency exceeded 0.40 even when the heater was running at low airflow rate (100m3h−1) under the typical space heating application where the solar irradiance on the collecting area was 600Wm−2, indoor air temperature 14°C, outdoor air temperature −5°C, and solar incidence angle 20°. Such a design would only require fan power of approximately 20W. The work would be useful for developing energy efficient and cost effective solar air heaters.