Flat plate thermal solar collector efficiency: Transient behavior under working conditions part II: Model application and design contributions

Study of rate of heat transfer in a flat-plate solar collector is the main subject of this paper. Measurements of collector and working fluid temperatures were carried out for one year covering the harmattan and rainy seasons in Port Harcourt, Nigeria, which is situated at the latitude of 4.858oN and longitude of 8.372oE. Energy balance equations for heat exchanger were employed to develop a mathematical model which relates the working fluid temperature with the vital collector geometric and physical design parameters. The exit fluid temperature was used to compute the rate of heat transfer to the working fluid and the efficiency of the transfer. The optimum fluid temperatures obtained for the harmattan, rainy and yearly (or combined) seasons were: 317.4, 314.9 and 316.2 [K], respectively. The corresponding insolation utilized were: 83.23, 76.61 and 79.92 [W/m2], respectively, with the corresponding mean collector efficiency of 0.190, 0.205 and 0.197 [-], respectively. The working fluid flowrate, the collector length and the range of time that gave rise to maximum results were: 0.0093 [kg/s], 2.0 [m] and 12PM - 13.00PM, respectively. There was good agreement between the computed and the measured working fluid temperatures. The results obtained are useful for the optimal design of the solar collector and its operations.

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Analysis of Different Techniques for Improving Performance of Flat Plate Solar Collectors for Fruits Drying

Tanzania Journal of Engineering and Technology ◽

10.52339/tjet.v35i1.469 ◽

2014 ◽

Vol 35 (1) ◽

pp. 54-66

Author(s):

Ramadhani Bakari ◽

Rwaichi Minja ◽

Karoli Njau

Keyword(s):

Flat Plate ◽

Rural Areas ◽

Solar Collector ◽

Fruits And Vegetables ◽

Poor Performance ◽

Wire Mesh ◽

Performance Difference ◽

Performance Limits ◽

Counter Flow ◽

Collector Efficiency

Fruits drying had become a broader technology in fruits and vegetables value addition.The technology is reported to be a promising way of drying without incurring higher costbut its adaptation has not been feasible in rural areas. Solar dryers have been developedbut its poor performance limits its applicability. In this study, several techniques formodifications of traditional solar collector were addressed. It was observed that, varyingcollector designs in different techniques, a range of collector performances can bearchived. The research shows that, collector efficiency can be improved by 9.6% whenemploying double duct counter flow compared to conventional collectors. Likewise,performance difference between conventional collectors and studied models were found tobe 8%, 7.2%, 6.1% and 5.2% for model parked with charcoal, 5 mm wire mesh, 4 mmglass thickness and 8 baffles respectively. This study shows that, double duct counter flowsystem is the best option for improving the performance of the collectors, followed bycharcoal and wire mesh. On the hand, using 4 mm glass thickness gave improvedperformance, however, it is recommended for collector size not exceeding 2 m in length.

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Effect of Glass Thickness on Performance of Flat Plate Solar Collectors for Fruits Drying

Journal of Energy ◽

10.1155/2014/247287 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 12

Author(s):

Ramadhani Bakari ◽

Rwaichi J. A. Minja ◽

Karoli N. Njau

Keyword(s):

Flat Plate ◽

Solar Collector ◽

Heat Losses ◽

Solar Collectors ◽

Glass Thickness ◽

North Direction ◽

Clear Glass ◽

Collector Efficiency ◽

Different Thickness

This study aimed at investigating the effect of thickness of glazing material on the performance of flat plate solar collectors. Performance of solar collector is affected by glaze transmittance, absorptance, and reflectance which results into major heat losses in the system. Four solar collector models with different glass thicknesses were designed, constructed, and experimentally tested for their performances. Collectors were both oriented to northsouth direction and tilted to an angle of 10° with the ground toward north direction. The area of each collector model was 0.72 m2with a depth of 0.15 m. Low iron (extra clear) glass of thicknesses 3 mm, 4 mm, 5 mm, and 6 mm was used as glazing materials. As a control, all collector performances were analysed and compared using a glass of 5 mm thickness and then with glass of different thickness. The results showed that change in glass thickness results into variation in collector efficiency. Collector with 4 mm glass thick gave the best efficiency of 35.4% compared to 27.8% for 6 mm glass thick. However, the use of glass of 4 mm thick needs precautions in handling and during placement to the collector to avoid extra costs due to breakage.

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Influence of Obstacles with Wing Delta Shape on Flat-Plate Air Solar Collector Efficiency

Journal of Applied Sciences ◽

10.3923/jas.2007.3302.3306 ◽

2007 ◽

Vol 7 (21) ◽

pp. 3302-3306

Author(s):

P. Gbaha ◽

K. Konan ◽

J.K. Saraka ◽

T.R. Ori ◽

H.Y. Andoh

Keyword(s):

Flat Plate ◽

Solar Collector ◽

Collector Efficiency

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Study of Characteristic of Evacuated Flat Plate Type Solar Collector With Flow Boiling

Volume 6: Energy Systems: Analysis, Thermodynamics and Sustainability ◽

10.1115/imece2007-41720 ◽

2007 ◽

Author(s):

Masahiro Taniguchi ◽

Shigeki Hirasawa ◽

Shunsaku Nakauchi ◽

Tadayoshi Tanaka

Keyword(s):

Flat Plate ◽

Solar Collector ◽

Flow Boiling ◽

Saturation Temperature ◽

Solar Irradiation ◽

Working Fluid ◽

Collector Plate ◽

Collector System ◽

Heat Collector ◽

Collector Efficiency

An evacuated solar collector system with flow boiling in tube has high collector efficiency of solar energy. In this paper, we present experimental and simulation results for characterizing an evacuated flat plate solar collector. By comparing the experiment results with six boiling heat transfer correlation equations, we found that Sani’s correlation is closest to our experimental results. Subsequently, this paper reports on how various factors impact collector efficiency. Collector efficiency decreases with decreasing flow rate of the working fluid, with decreasing solar irradiation, with reduction of thickness and thermal conductivity of the heat collector plate. Collector efficiency increases with decreasing saturation temperature of the working fluid, with decreasing vacuum pressure in the collector, with small bending angle of the heat collector tube. Collector efficiency does not change with change of inside diameter of the heat collection tube, and with change of inlet subcooling temperature of the working fluid.

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Experimental and Theoretical Analysis of Energy Efficiency in a Flat Plate Solar Collector Using Monolayer Graphene Nanofluids

Sustainability ◽

10.3390/su13105416 ◽

2021 ◽

Vol 13 (10) ◽

pp. 5416

Author(s):

Omer A. Alawi ◽

Haslinda Mohamed Kamar ◽

Abdul Rahman Mallah ◽

Hussein A. Mohammed ◽

Mohd Aizad Sazrul Sabrudin ◽

...

Keyword(s):

Flat Plate ◽

Solar Collector ◽

Morphological Properties ◽

Monolayer Graphene ◽

Distilled Water ◽

Maximum Increase ◽

Mass Flow Rates ◽

Temperature Parameter ◽

Collector Efficiency ◽

Flat Plate Solar Collector

Flat-plate solar collectors are one of the cleanest and most efficient heating systems available. Studies on the presence of covalently functionalized graphene (Gr) suspended in distilled water as operating fluids inside an indoor flat-plate solar collector (FPSC) were experimentally and theoretically performed. These examinations were conducted under different testing conditions namely 0.025%-wt., 0.05%-wt., 0.075%-wt., and 0.1%-wt., 0.5, 1, and 1.5 kg/min, 30, 40, and 50 °C, and 500, 750, and 1000 W/m2. Various techniques were used to characterize the functionalized nanofluids’ stability and morphological properties namely UV/Vis spectrophotometry, EDX analysis with a Scanning Electron Microscope (SEM), zeta potential, and nanoparticle size. The results showed that the collected heat improved as the percentage of GrNPs and the fluid mass flow rates increased, although it decreased as the reduced temperature coefficient increased, whereas the maximum increase in collector efficiency at higher concentration was 13% and 12.5% compared with distilled water at 0.025 kg/s. Finally, a new correlation was developed for the base fluid and nanofluids’ thermal efficiency as a function of dropped temperature parameter and weight concentration with 2.758% and 4.232% maximum deviations.

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Parametric Study of a Flat Plate Wick Assisted Heat Pipe Solar Collector

Journal of Solar Energy Engineering ◽

10.1115/1.4023875 ◽

2013 ◽

Vol 135 (3) ◽

Cited By ~ 8

Author(s):

Brahim Taoufik ◽

Mhiri Foued ◽

Jemni Abdelmajid

Keyword(s):

Flat Plate ◽

Heat Pipe ◽

Solar Collector ◽

Solar Collectors ◽

Absorber Plate ◽

Steady State Condition ◽

Collector Efficiency ◽

Evacuated Tube Collectors ◽

Gap Spacing ◽

Evacuated Tube

The use of heat pipes in solar collectors offers several advantages regarding flexibility in operation and application, as they are very efficient in transporting heat even under a small temperature difference. Compared with other systems powered by evacuated tube collectors or flat plate solar collectors using a wickless heat pipe, little attention has been paid to a flat plate solar collectors wick assisted heat pipe. In this paper an analytical model based on energy balance equations assuming a steady state condition was developed to evaluate the thermal efficiency of a flat plate wick assisted heat pipe solar collector. Parameters which affect the collector efficiency are identified, such as tube spacing distance, gap spacing between the absorber plate and the glazing cover, and the emissivity of the absorber plate. The results reflect the contribution and significance of each of these parameters to the collector overall heat loss coefficients. Three heat pipe working fluids are examined and results show that acetone performs better than methanol and ethanol.

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Heat Exchanger Theory Applied to the Design of Water- and Air-Heating Flat-Plate Solar Collectors

Journal of Solar Energy Engineering ◽

10.1115/1.3268243 ◽

1988 ◽

Vol 110 (2) ◽

pp. 132-138 ◽

Cited By ~ 1

Author(s):

Gregory J. Kowalski ◽

Arthur R. Foster

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Flat Plate ◽

Solar Collector ◽

Operating Conditions ◽

Solar Collectors ◽

Heat Transfer Characteristics ◽

Air Heating ◽

Collector Efficiency ◽

The Difference

A general method for the design of flat-plate solar collectors based on solar collector theory has been developed. It can be applied to both liquid- and air-heating solar collectors. The solar collector efficiency is determined by the product of the effectiveness (ε) and the insolation use factor (IUF). The effectiveness describes the heat transfer characteristics of the collector and is shown to be a function of a solar number of transfer units (SNTU) and a parameter ψ. For an air-heating collector, the ψ parameter equals the collector efficiency factor, while for a liquid-heating collector it must account for the difference between the plate and tube heat transfer areas. The effectiveness and SNTU parameters are similar to the effectiveness and NTU parameters used in heat exchanger design methods. The IUF is a measure of the operating conditions of the collector. It represents the difference between the transmittance-absorptance product and the ratio of the minimum heat loss to the insolation on the exterior cover. The relationship between the effectiveness and the SNTU parameter is general for all nonconcentrating collectors. One advantage of this method over the traditional Hottel-Whillier method is that it separates the heat transfer characteristics of the solar collector from its optical properties and the operating conditions.

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Numerical Simulation on V Shaped Solar Flat-Plate Air Collector

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.594-597.2175 ◽

2012 ◽

Vol 594-597 ◽

pp. 2175-2178 ◽

Cited By ~ 1

Author(s):

Ming Dong Chen ◽

Xue Bing Liu

Keyword(s):

Flat Plate ◽

Solar Collector ◽

Theoretical Basis ◽

Transfer Model ◽

Internal Temperature ◽

Solar Radiation Intensity ◽

Collector Efficiency ◽

Working Principle ◽

Height Increase ◽

Solar House

The V-shaped solar flat-plate air collector was design in order to improve the efficiency of solar flat-plate air collector, and the heat transfer model was established on the base of solar collector working principle. Internal temperature distribution of collector and temperature change rule under different sunshine condition is simulated and the relation of collector height, solar radiation intensity and collector efficiency is analyzed. The result showed that internal air temperature of collector increases with collector height increase and gradually achieves a stable value. It will provide a theoretical basis for collector layout of solar house.

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