Double-pass Solar Air Collector Research Articles

Investigative analysis of the influence of diverse fin configurations on the performance of a dual pass solar air collector

This study conducts a thorough investigation into the thermal performance of the double pass solar air collector, with a specific focus on the effects of three distinct fin configurations: parallel, vertical, and opposed. It is significant as it delves into the realm of solar air heating efficiency, a critical component in the broader application of solar energy technologies. Utilizing the geometric details and experimental findings, this study broadens its scope by examining a range of mass flow rates, specifically 0.0036 kg/s, 0.0110 kg/s, 0.0146 kg/s, and 0.0183 kg/s. Such an approach allows for a comprehensive understanding of the double pass solar air collector’s performance across diverse operational scenarios. The methodology is Computational Fluid Dynamics, which facilitates an in-depth analysis of temperature and velocity contours in both XY and YZ planes of the double pass solar air collector. The results of this study indicate that the parallel fin configuration significantly enhances heat transfer, evidenced by notable temperature increases, especially at the lower end of the mass flow rate spectrum. Conversely, while vertical and opposed fins result in greater pressure drops, they do not proportionally increase the temperature in a similar manner to parallel fins. The study concludes with a strong recommendation for the incorporation of parallel fins in future double pass solar air collector designs, particularly in situations where lower mass flow rates are predominant. This study contributes significantly to both the theoretical and practical aspects of solar collector efficiency, offering valuable insights for the development of more effective solar heating solutions.

A MATLAB simulation-based analytical study of energy, exergy, and cost benefits in jet-impinged protrusion-roughened double pass solar air collector.

This study analyzes the performance and cost-effectiveness of a protrusion-roughened jet-impinged double-pass solar air collector (PRJDPSAC) within a Reynolds number (Re) range of 2500 to 22,500. Examining jet slot parameters, i.e., the jet height ratio (Hjp/Dhd = 0.11-0.44), stream-wise pitch ratio (Xjp/Dhd = 0.44-1.32), and span-wise pitch ratio (Yjp/Dhd = 0.44-1.32), the model demonstrates enhanced energy conversion, minimizes losses, improves efficiency, and brings positive economic impact, making it a promising solution for diverse applications including drying processes, livestock facilities, remote accommodations, and HVAC system pre-heating. The examination incorporates advanced MATLAB simulations to assess energy-exergy performance and cost viability. At lower Re values, both energy ([Formula: see text]) and exergy ([Formula: see text]) efficiencies increase uniformly; however, stabilization and decline occur at higher Re values. The maximum [Formula: see text] for the PRJDPSAC is 4.38% under a temperature rise parameter of 60 × 10-3 Km2/W for obtaining optimum values of Xjp/Dhd = 1.32, Hjp/Dhd = 0.22, and Yjp/Dhd = 1.32, which is 31% higher than that of the smooth double-pass solar air collector (DPSAC). Economic benefits are significant for PRJDPSAC within mair (0.01-0.07kg/s), but above 0.07kg/s, the DPSAC becomes more cost-effective. Integrating simulation and experimental data, the study highlights MATLAB's effectiveness for solar energy system analysis and optimization, reinforcing the practicality of the proposed collector design.

Thermal Performance of Double Pass Solar Air Collector: Numerical and Experimental Investigation

Abstract In this research study, the development of a theoretical model to estimate the efficiency of a double pass solar air heater (DPSAH) was the main objective. The mathematical model was compared to experimental results and found to be in agreement, both qualitatively and quantitatively. The model used energy balance equations to determine the outlet temperature and could solve the temperature equations of each component of the heater simultaneously. A matrix inversion method was used for this purpose. The study found that increasing the Nusselt number led to an increase in energy efficiency, but also caused a drop in outlet temperature at any solar radiation. The mass flow rate (MFR), with larger flow rates resulting in better efficiencies, had a significant impact on the double pass air heater's efficiency. Thus, increasing of DPSAH’s length increases its thermal performances and reach its maximum values for L=9m. These findings could be beneficial in selecting the most efficient design parameters for DPSAH.

Thermal and Thermo-hydraulic Performance of Finned Double-Pass Solar Air Collector Utilizing Cylindrical Capsules Nano-Enhanced PCM

Double-pass solar air collector with a finned absorber and nano-enhanced PCM in the lower channel is one of the significant and attractive designs proposed to improve the performance. This research paper presents a novel mathematical model of steady-state equilibrium equations created and developed for two air streams: the glass cover, absorber plate, fins, nano-enhanced PCM capsules, and back plate. The influence of various operating parameters on thermal and thermo-hydraulic performance was presented and discussed. The simulations were conducted at air mass flow rates from 0.02 kg/s through 0.06 kg/s and solar irradiance levels ranging from 475 W/m2 to 1000 W/m2. The proposed collector has an optimal energy efficiency of 80%, an exergy efficiency of 18.2% at solar irradiance of 1000 W/m2, and a mass flow rate of 0.06 kg/s. The minimum and maximum improvement potentials for solar irradiance levels of 475–1000 W/m2 at an ambient temperature of 298 K are 163–237 W. The proposed collector's best findings in the current study are 1.0 m in length and a width of roughly 0.3 m for air mass flow rates of 0.02-0.06 kg/s.

Design and analysis of new solar‐powered sustainable dryers: Alfalfa crop

AbstractDecreasing carbon emissions is possible with the usage of renewable energy sources. Therefore, the usage of renewable energy has increased in the last decade. Due to the fact that the drying process of agricultural products consumes a significant amount of energy, fossil fuel consumption can be reduced by using the solar dryer. In this study, two novel solar drying systems were designed and tested for alfalfa drying. Experiments were carried out in two different drying systems double‐pass solar air collector (DPSAC) and photovoltaic thermal solar air collector (PVT). In order to increase the heat transfer surface area, unlike the literature, a drying chamber consisting of two intertwined cylinders was designed and manufactured. The aims of this study are to bring the drying kinetics of alfalfa and the performance, energy, and exergy analysis of the designed system to the literature. The effective moisture diffusivity values were found to be in the range of 9.13 × 10−14 to 1.06 × 10−9 and the value for the highest drying rate was determined as 2.53 × 10−2gwater/gdrymatter.min. The highest thermal efficiency was obtained from DPSAC experiment as 73.7%, while the highest COP value was obtained from the PVT experiment as 12.5. The DPSAC dryer has shown the best performance in drying the alfalfa. The outcomes of the present study demonstrate that the use of DPSAC dryer is suitable when only heat energy is required for the drying system and the use of PVT when both heat and electrical energy are required. It is recommended that these systems can be used together in off‐grid agricultural areas.Practical applicationsAlfalfa (Medicago sativa L.), a type of forage crop, is a delicious, high‐energy, and protein food source for dairy cattle. By drying the alfalfa with high nutritional value in a quality method, several beneficial minerals and vitamins are preserved. The drying process is used since ancient times for the protection of the food material and for storage without degradation. Alfalfa is dried in two new solar‐powered sustainable dryers making an important contribution to reducing carbon emissions as well as providing cleaner and more reliable drying methods compared to the conventional solar drying method. This study presents an alternative for the drying process with high energy efficiency for food drying processes, according to the necessity of using both heat and electrical energy. In addition, sustainable solar dryers in this study can be used for drying agricultural products, textile, industry and dewatering municipal waste.

Experimental and thermodynamic analysis of solar air dryer equipped with V-groove double pass collector: Techno-economic and exergetic measures

• Thermodynamic model and experimental validation of v-groove solar dryer. • Optimum flow rate of air within the collector was obtained for maximum efficiency. • SEC was 3.01 kWh/kg at 0.041 kg/s with 59% energy saving for apple drying compared with electricity driven heating. • Sustainability indices of the solar air collector and dryer are 1.50 and 1.047 respectively. • Energy payback period for the system is less than 1 year. Optimised solar air dryers, in terms of efficiency and performance, can solve some major concerns in the agro-industrial processing sector. Solar air dryers can reduce the large share of energy costs of a final product and can provide sustainable energy in rural areas where access to energy is often limited. In this study, a pilot scale v-groove double pass solar air collector has been analysed thermodynamically with real time solar radiation and mass flow rate (0.021-0.061 kg/s) inputs and validated experimentally in terms of first and second law efficiencies. Performance of the process was assessed using experimental drying measures including final moisture content, drying rate and exergy efficiency for drying of Pink Lady apples. Energy payback time and specific energy consumption were calculated to reveal the techno-economic value of the system. The maximum thermal efficiency of the collector was observed to be 88.8% at 0.061 kg/s having exergy efficiency of 6.6% which shows an efficient sourcing for the operation. In terms of the performance of the dryer, mass flow rate of 0.041 kg/s offers a higher moisture removal. Specific energy consumption (SEC) was 3.096 kWh/kg. Thermodynamic model was validated with matching experimentation with acceptable RMSE for the range of investigated measures. Energy payback period time calculated by the embodied energy of the system was obtained to be 0.78 years which implies that the system is capable of addressing a large capacity drying if it is to be scaled-up.

Thermal Performance Analysis of a Double-Pass Solar Air Collector: A CFD Approach

Solar air heaters can reduce climate change by replacing conventional fossil fuel-burning technologies in drying and space heating applications. Concentrating solar technologies, such as compound parabolic concentrators, allow air temperatures up to 120 °C; however, it is desirable to improve their heat transfer to reduce the space requirements for their installation. In this work, a parabolic concentrator composed of a flat receiver designed to recover heat from the cover–receiver–reflectors cavity is analyzed, operating it as a U-shape double pass solar heater. With this operation, first, the air flows through the cavity, and then it is incorporated into the duct, where the dominant heat gain occurs due to the capture of solar radiation. Thus, four input–output configurations in the cavity were modeled through dynamic simulations to determine the influence of the inlet and outlet air flow positions on the solar concentrator outlet temperature. Therefore, the incorporation of the first pass has a contribution of between 36% and 45% in useful energy gain, showing that this appropriate and relatively simple strategy can be implemented to improve the thermal performance of solar air collectors, resulting in instantaneous efficiencies higher than 75%. However, the simulation results demonstrate that the position of the inlets and outlets does not significantly impact the efficiency and outlet temperature.

A comparative study for double pass solar air collector utilizing medial glass panel

A comparative study for double pass solar air collector utilizing medial glass panel

Mathematical Model of the Thermal Performance of Double-Pass Solar Collector for Solar Energy Application in Sierra Leone

The primary aim of this study was to utilize thermal energy for drying applications on March 21 (day of the year, n = 80) for the climatic weather conditions of Freetown, Sierra Leone. We evaluated the heat absorption of a double-pass solar air collector based on its configuration and exterior input variables before it was designed and mounted at the location of interest. This study considered a steady-state heat transfer using the thermal network procedure for thermodynamic modeling of a double-pass solar collector developed for drying and heating purposes. A mathematical model defining the thermophysical collector properties and many heat transfer coefficients is formed and numerically solved for this purpose. Indeed, this helped us generate the hourly temperature of different heat collector components, which aided in the performance evaluation of the system. The impact of the fluid flowing inside the collector on the temperature of the exit air was analyzed. It was observed that a flow rate of 0.02 kg/s produced an output of 91.72°C. The system's thermal efficiency improves with increased flow rate at various solar radiation intensities. It was observed that the thermal efficiency of the collector increases from 29% to 67% at flow rates of 0.01–0.3 kg/s. Collector lengths of 1.4 and 2.4 m are observed to be economically viable. An increase in the flow rate caused an increase on the efficiency. The hourly outputs for the collector components were represented graphically, and the curve patterns were similar to those of previous studies.

Parametric study of a solar dryer system for the development and application of solar energy in Sierra Leone

A transient mathematical model has been evaluated to determine the principle of a solar crop dryer for drying vegetables (onion). Considering the meteorological conditions of Freetown (Latitude 8.4840 N, Longitude -13.2300 W), the model was developed to determine air temperatures and other operational parameters of the drying system for a day of March 21st. However, the investigated system had effectively reduced the drying process of onion. The developed double-pass solar air collector system showed a low-temperature output in the morning hours and displayed high-temperature results in the afternoon hours. From 8:00 to 16:00, the solar collector generates fluid output temperatures above 50 0 C, with a peak value of 96 0 C occurred at 12:00. The influence of the mass flow rate on the system's thermal efficiency was investigated. It was noticed that for a certain solar radiation value, an increased in the mass flow rate caused an exponential increased in the solar air collector thermal efficiency. Findings also revealed that an increased in the solar collector length led to a slightly decreased in the outlet air temperatures at a mass flow rate of 0.02 kg/s. The influence of increasing drying air temperatures and air velocity within the drying chamber reduces drying time significantly. The drying time for products dried in the first tray is lesser than for products dried in the subsequent trays, owing to temperature variations. The computation findings were verified to previous studies in the literature and observed to be strongly comparable.

Thermal Performance of a Finned Double-Pass Solar Air Collector Integrated with a Nanoparticle Enhanced-Pcm Tubular Storage System

Thermal Performance of a Finned Double-Pass Solar Air Collector Integrated with a Nanoparticle Enhanced-Pcm Tubular Storage System

Experimental Performance of Solar Air Heaters for Drying Applications

This paper presents the results of an experimental investigation on an indirect active type of solar dryer, using two distinct solar air collector and their impacts on drying agricultural products. The thermal performance of the proposed collectors has been evaluated using the first and second laws of thermodynamics. Experimental observations were done in climatic conditions Gödöllő, Hungary on the 2nd and 9th of October 2017. The experiments were also carried out to dry 2 kg of sliced apples spread over the drying trays. The mas flow rate of air was maintained as 0.038 kg/s and the dryer was operated from 10:00 a.m. to 3:00 p.m. When a double-pass solar air collector's results are compared to a single-pass solar air collector's, it's evident that the double-pass solar air collector produces much more energy and efficiency. The experimental results showed that single-pass and double-pass collectors have daily efficiencies of 42.77% and 56.10%, respectively, with average exergy efficiency values ranging from 31% to 49% for single-pass and 51% to 67% for double-pass. The most significant aspect determining the collectors' thermal efficiency was the temperature rise between the collector outlet and inlet. The average drying efficiencies of the solar dryer for the single and double-pass collectors were evaluated as 12.16% and 16.45%, respectively. The maximum temperature rise for double-pass was determined to be 20 °C, whereas single-pass was found to be 6.5 °C. Furthermore, the highest drying rate was achieved when sliced apples were dried with a double-pass collector mode. It reduced 52% of the water content in the apple in the same amount of time as single-pass drying, compared to 35% in the case of single-pass drying.

Energy-based performance analysis of a double pass solar air collector integrated to triangular shaped fins

In this paper, the performance of a double pass solar air collector with triangular integrated fins was investigated experimentally at Hungarian University of Agriculture and Life Sciences in Gödöllő, Hungary. The focus of this research is on energy-based performance evaluation. The thermal efficiency of the collector has been compared by testing two collectors that had the same design, with and without fins. The effect of the collector's air mass flow rate on thermal performance was investigated under various environmental situations. The results revealed that the temperature difference is always higher through the finned collector and the higher variation temperature between the inlet and outlet temperature leads to higher useful heat. The daily thermal efficiency of the finned collector was 56.57%, 59.41%, and 61.42%, while for the un-finned collector was 51.04%, 53.28%, and 57.08% for the mass flow rate 0.0081, 0.0101, and 0.0121 kg/s. The finned double pass solar air collector improved the thermal efficiency by 4.3–6.1% over the un-finned one. The efficiency of the finned collector is always higher than the un-finned one regardless of the mass flow rate. The presence of the fins to the top air channels significantly increases collector efficiency, owing to the increased absorbing surface area, which is responsible for increasing the internal thermal convective exchanges. Moreover, it creates a turbulence airflow, meaning that the air will be in good contact with the absorber plate and penetrate all regions, reducing the dead zones contributing to increased heat transfer.

Energetic and exergetic analysis of a new double pass solar air collector with fins and phase change material

Advanced solar air collectors are widely implemented in research for drying purposes. This research study presents a new steady state energy balance and exergy equations for a novel double pass solar air collector with fins and phase change material (PCM) according to first and second law of thermodynamics. The mathematical equations of energy balance were solved using the matrix inversion method. The predictions were observed at mass flow rates ranging from 0.01 kg/sec to 0.15 kg/sec, and solar radiation ranging between 425 W/m2 and 1000 W/m2. The impacts of solar radiation levels and mass air rates on energy efficiency, exergy efficiency and the improvement potential have been estimated and evaluated. The optimum energy efficiency of proposed collector is 73% at mass air rate of 0.15 kg/sec. The exergy efficiency is nearly 2.5–4.2% at maximum solar radiation level of 1000 W/m2 as well as the lowest and highest improvement potential are 980–2287 W for a solar radiation of 425–1000 W/m2.

Energy Analysis of Greenhouse Dryer for Ficus Carica L. Leaves

In this study, a greenhouse solar dryer with double-pass multi-hollow collector for leaf drying was design, constructed, and evaluated. From the result, the double pass solar air collector with multi-hollow tube is capable of increasing air temperature by 5.5℃-10.8℃ compared to ambient air temperature. Thermal efficiency of the dryer was evaluated for passive and active modes, where 47.2% and 50% are recorded respectively. The moisture reduction on mass basis in passive and active dryer recorded was 44% and 74%, respectively. The specific moisture extraction rate (SMER) and specific energy consumption (SEC) of passive dryer was determined to be 0.198 kg per kWh and 5.047 kWh per kg, and active dryer at 0.210 kg per kWh and 4.769 kWh per kg, respectively.

Experimental Investigation of Double Pass Solar Air Collector for Using in Agricultural Applications

In this research, an experimental study has been performed in order to enhance the thermal performance of a double-pass solar air collector by employing extended surfaces. In order to increase the heat transfer area, triangular-shaped fins were mounted on the longitudinal direction of the absorber plate. Four models of the solar air collectors were made of aluminum with different fin configurations. The experiments were carried out at the winter season in the climate of Iraq - Ramadi city with longitude 43.268 and latitude (33.43). The used range of mass flow rate in the experiments was from 0.027 kg/s to 0.037 kg/s. The comparison with previous studies in terms of thermal efficiency showed good agreement where the percentage of error does not exceed 1% between them. The results also provided that the existing of fins was a good technique for enhancing the thermal performance of double-pass solar air collector with a marginal increase in pressure drop. Consequently, it is possible to adopt this kind of solar air collectors for many agricultural applications such as solar dryer.

Experimental and CFD survey of indirect solar dryer modified with low-cost iron mesh

In the present work, double-pass indirect solar dryer (DPISD) and double-pass indirect solar dryer with mesh absorber modification (DPISDMA) have been designed, analyzed, manufactured and tested. The main aim of this study is improving the thermal efficiency of double-pass solar air collector by integrating iron meshes. Pepino fruit (Solanum muricatum L.) samples in two thicknesses have been used in the experimental study. Also, CFD analysis of both solar air collectors and drying chamber and quality metrics such as phenolic, total flavonoid contents and antioxidant activity have been conducted. Numerical simulation and experimental results showed that using mesh modification has positive influence on the performance of the collector. The highest value of the average efficiency of the dryer was obtained in DPISDMA for the thin sample thickness as 23.08%. According to quality analyses, the experiments which done in DPISDMA gave the best results with highest values of TPC, TFC and antioxidant activity values (p < 0.05). Drying data of the pepino fruit for different experiments were modelled according to 8 different most used mathematical models. Accordingly, the best fitted kinetics model was determined as Logarithmic model for all experiments which gave the most accurate statistical values.

Thermal performance enhancement of solar air collector using a novel V-groove absorber plate with pin-fins for drying agricultural products: an experimental study

An experimental investigation of a novel V-groove absorber plate with pin-fins on double-pass solar air collector was made to study the enhancement of thermal performance. The objective of this work is to develop a solar air collector for drying agricultural products with enhanced heat transfer rate by employing pin-fins on V-groove absorber plate under varied configurations. The parameters that influence the instantaneous thermal efficiency of the collector are discussed, and obtained results are compared with a conventional V-groove absorber plate for same mass flow rate values. Energy and exergy analyses were also carried out. The results show that the efficiency of the collector depends strongly on the flow rate. Also, it is noted that for a flow rate of 0.035 kg s−1, the novel V-groove absorber plate with pin-fins installed on both sides exhibits extended heat transfer area, thereby a rise in average thermal efficiency by 17.4%.

Energy-Exergy Analysis of A Novel Multi-Pass Solar Air Collector With Perforated Fins

This work presents performance analysis of a novel multi-pass solar air collector with perforated fins (MPSACF) in winter conditions, Ankara province, Turkey. The aim of this work is to experimentally test and compare the performance of the two different design of solar collectors in the same climatic conditions. In addition, a double-pass solar air collector without fins (DPSAC) at the same absorber area was manufactured and tested as a control group. The total absorber area of both solar collectors is 0.325 m2. Thermal effects for performance improvement of the collectors have been designated. Average thermal efficiency values of DPSAC and MPSACF were calculated as 47.85% and 51.86%, 67.10% and 72.86%, respectively in experiments performed at 0.0069 kg/s (0.7 m/s air velocity) and 0.0087 kg/s (0.9 m/s air velocity) mass flow rates. Exergy efficiency of DPSAC and MPSACF were 2.10-17.12% and 8.74-23.97%, respectively. Coefficient of performance(COP) values were ocomputed 4.63 and 4.94, 3.18 and 3.48 respectively in experiments performed at 0.0069 kg/s and 0.0087 kg/s mass flow rates. Although the MPSACF has high efficiency values, COP values are lower due to the presence of dual fans. Because of their high thermal efficiency, both collectors can be effectively practiced for applications such as preheating, space heating and ventilation, greenhouse heating and product drying©2019. CBIORE-IJRED. All rights reservedArticle History: Received May 16th 2018; Received in revised form October 16th 2018 ; Accepted January 6th 2019; Available onlineHow to Cite This Article: Aktaş, M., Sözen, A., Tuncer, A.D., Arslan, E., Koşan, M., Çürük, O. (2019) Energy-exergy analysis of a novel multi-pass solar air collector with perforated fins. International Journal of Renewable Energy Development, 8(1), 47-55.http://dx.doi.org/10.14710/ijred.8.1.47-55

Drying of grape pomace with a double pass solar collector

ABSTRACTThis study aims to analyze the performance of a novel design of the double pass solar air collector (DPSAC)-assisted drying system and investigate the drying kinetics of grape pomace which is an agricultural by-product. The samples were dried to a moisture content of 0.01 g water/g dry matter between 100 and 250 min depending on the weather conditions. The average thermal efficiencies of DPSAC were calculated as 79.77, 79.85, and 69.46%. Average values of the coefficient of performance of DPSAC were determined as 5.32, 5.13, and 4.32. The highest specific moisture extraction rate value was achieved as 617.18 g water/kWh. Whereas the mass transfer coefficient (hm) values ranged from 9.15E−11 to 1.04E−7 m/s, the effective moisture diffusivity (De) values were obtained between 3.04E−13 and 1.02E−10 m2/s. The qualitative analysis showed that the drying using DPSAC may be an alternative for drying applications in terms of short drying time and energy usage. Nevertheless, these results clearly suggest a complex and effective interplay between thermal performance and drying kinetics.