Comparison of Test Results for Flat-Plate, Transpired Flat-Plate, Corrugated, and Transpired Corrugated Solar Air Heaters

1983 ◽  
Vol 105 (3) ◽  
pp. 231-236 ◽  
Author(s):  
S. J. Rhee ◽  
D. K. Edwards
Keyword(s):  
Flat Plate ◽  
Perforated Plate ◽  
Metal Plate ◽  
Test Results ◽  
Absorber Plate ◽  
Technical Improvement ◽  
Black Metal ◽  
Slotted Plate ◽  
Teflon Film

Five selective-black-metal-plate experimental air heaters with and without transpiration were designed, fabricated, and tested to compare their technical merits. All were 61 cm × 61 cm (2ft × 2ft), double-glazed with low-iron glass, and those with transpiration contained an additional Teflon film to form a plenum above the absorber plate. The configurations were (i) a reference collector with flow on back only, (iia) a transpired slotted plate, (iib) a transpired micro-perforated plate, (iii) a corrugated plate with flow on back, and (iv) a transpired slotted corrugated plate. The results show the magnitude of technical improvement that can be obtained through the slotting, perforating, and corrugating strategems.

Performance Comparison of Flat Plate Collectors Fitted With Non Circular Risers With Integral Fins

2005 ◽  
Author(s):  
V. R. Bhore ◽  
S. B. Thombre
Keyword(s):  
Flat Plate ◽  
Unit Area ◽  
Natural Circulation ◽  
Performance Comparison ◽  
Test Results ◽  
Absorber Plate ◽  
Circulation Mode ◽  
Induced Flow ◽  
Flat Plate Collector ◽  
Buoyancy Induced Flow

The present study deals with comparison of experimentally determined performance characteristics of solar flat plate collectors fitted with novel designs of absorber plate involving non-circular risers with integral fins and operating under natural circulation mode. The main flow passages considered were square, triangular and semicircular in cross section. One standard solar flat plate collector with circular risers was also tested simultaneously for direct comparison. The test results indicate that the absorber fitted with the triangular sectioned risers yields the best performance in terms of the efficiency (63%), and the buoyancy induced flow per unit area (76 kg/hr-m2) from amongst the collectors investigated. It is followed by the absorbers fitted with the semicircular and square sectioned risers respectively. The standard solar flat plate collector is found to yield the lowest values i.e. 46 % and 40 kg/hr-m2 respectively.

Nongray-Radiative and Convective-Conductive Thermal Coupling in Teflon-Glazed, Selective-Black, Flat-Plate Solar Collectors

1984 ◽  
Vol 106 (2) ◽  
pp. 206-211 ◽  
Author(s):  
D. K. Edwards ◽  
S. J. Rhee
Keyword(s):  
Flat Plate ◽  
Solar Collector ◽  
Critical Rayleigh Number ◽  
Thermal Coupling ◽  
Absorber Plate ◽  
Radiation Properties ◽  
Short Circuits ◽  
Flat Plate Solar Collector ◽  
Teflon Film ◽  
Small Spacing

An analysis is presented comparing Teflon film with glass for the inner glazing of a double-glazed selective-black, flat-plate solar collector. The effect of spacing between glazings and between the inner glazing and absorber plate is examined. It is shown that a 12.5-micron Teflon film is superior to glass for the inner glazing of a selective-black collector, because the advantage of its high solar transparency overwhelms the disadvantage of its infrared transparency. A too-small spacing between a selective-black absorber and its inner cover short-circuits the desirable thermal radiation resistance offered by a selective-black absorber plate. Account is taken of spectral variations in the radiation properties of glass, Teflon, and the absorber plate. Allowance is made for the fact that critical Rayleigh number is lower for a plastic film inner glazing than for a glass one.

Energy and Exergy Analysis of Marquise Shaped Channel Flat Plate Solar Collector Using Al2O3–Water Nanofluid and Water

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Sahil Arora ◽  
Geleta Fekadu ◽  
Sudhakar Subudhi
Keyword(s):  
Flat Plate ◽  
Flow Rate ◽  
Volume Fraction ◽  
Pure Water ◽  
Maximum Energy ◽  
Working Fluid ◽  
Absorber Plate ◽  
Energy And Exergy ◽  
Aluminum Plates ◽  
Flat Plate Collector

The present study deals with the experimental performance of a Marquise shaped channel solar flat-plate collector using Al2O3/water nanofluid and base fluid (pure water). The experimental setup comprises a special type of solar flat plate collector, closed working fluid systems, and the measurement devices. The absorber plate is made of two aluminum plates sandwiched together with Marquise-shaped flow channels. The volume fraction of 0.1% of Al2O3/water nanofluid is used for this study. The various parameters used to investigate performance of the collector energy and exergy efficiency are collector inlet and outlet fluid temperatures, mass flow rate of the fluid, solar radiation, and ambient temperature. The flow rate of nanofluid and water varies from 1 to 5 lpm. The maximum energy efficiencies attained are 83.17% and 59.72%, whereas the maximum exergy efficiencies obtained are 18.73% and 12.29% for the 20 nm—Al2O3/water nanofluids and pure water, respectively, at the flow rate of 3 lpm. These higher efficiencies may be due to the use of nanofluids and the sophisticated design of the absorber plate with the Marquise shaped channel.

Polymeric Absorbers for Flat-Plate Collectors: Can Venting Provide Adequate Overheat Protection?

2004 ◽  
Vol 127 (3) ◽  
pp. 421-424 ◽  
Author(s):  
Meghan Kearney ◽  
Jane Davidson ◽  
Susan Mantell
Keyword(s):  
Flat Plate ◽  
Evaporative Cooling ◽  
Polymeric Materials ◽  
Potential Method ◽  
Temperature Limit ◽  
Solar Collectors ◽  
Absorber Plate ◽  
Thermal Index ◽  
Dry Climates ◽  
Material Temperature

Venting and evaporative cooling are modeled as possible techniques for protecting polymer absorbers in single-glazed, flat-plate solar collectors from exceeding the material temperature limit during dry stagnation. Four venting options are considered: (I) venting above the absorber plate, (II) venting below, (III) dual venting, and (IV) venting with evaporative cooling. Results indicate that in hot, sunny conditions, venting may not provide adequate cooling to lower the absorber temperature to the relative thermal index of the polymeric materials currently in use or under consideration for this application. Venting combined with evaporative cooling from a wetted pad directly beneath the absorber plate is identified as a potential method of overheat protection in hot, dry climates.

Optimizing Exergy Efficiency of Flat Plate Solar Collectors Using SQP and Genetic Algorithm

2012 ◽  
Vol 253-255 ◽  
pp. 760-765 ◽  
Author(s):  
Maryam Khademi ◽  
Farzad Jafarkazemi ◽  
Emad Ahmadifard ◽  
Saman Younesnejad
Keyword(s):  
Genetic Algorithm ◽  
Flat Plate ◽  
Solar Collector ◽  
Exergy Efficiency ◽  
Considerable Improvement ◽  
Absorber Plate ◽  
Sqp Method ◽  
Lower Accuracy ◽  
Plate Area ◽  
Flat Plate Solar Collector

An increase in exergy efficiency of flat plate solar collector leads to a considerable improvement in collector’s performance. Different parameters influence the performance of collector. In this paper, Sequential Quadratic Programming (SQP) and Genetic Algorithm (GA) have been employed for optimizing exergy efficiency of the flat plate solar collector. Absorber plate area and mass flow rate of inlet water have been considered as optimization’s variables. The results show the possibility to reach higher exergy efficiency with lower absorber area and consequently lower price. Also it is obvious that SQP method performs optimization process with higher convergence speed but lower accuracy than GA.

scholarly journals Experimental Studies on a Solar Air Heater Having V-Corrugated Absorber Plate with Obstacles Bent Vertically

2014 ◽  
Vol 493 ◽  
pp. 86-92 ◽  
Author(s):  
Ekadewi A. Handoyo ◽  
Djatmiko Ichsani ◽  
Prabowo ◽  
S. Sutardi
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flat Plate ◽  
Air Temperature ◽  
Temperature Rise ◽  
Experimental Studies ◽  
Bottom Plate ◽  
Solar Air Heater ◽  
Absorber Plate ◽  
Air Heater

A solar air heater (SAH) is a simple heater using solar radiation that is useful for drying or space heating. Unfortunately, heat transfer from the absorber plate to the air inside the solar air heater is low. Some researchers reported that obstacles are able to improve the heat transfer in a flat plate solar air collector and others found that a v-corrugated absorber plate gives better heat transfer than a flat plate. Yet, no work of combining these two findings is found.This paper describes the result of experimental study on a SAH with v-corrugated absorber plate and obstacles bent vertically started from 80oto 0owith interval 10oon its bottom plate. Experiments were conducted indoor at five different Reynolds numbers (1447 Re 7237) and three different radiation intensities (430, 573, and 716 W/m2).It is found that the obstacles improve SAH performance. Both the air temperature rise and efficiency increase with inserting obstacles bent at any angle vertically. Unfortunately, the air pressure drop is increasing, too. Obstacles bent vertically at smaller angle (means more straight) give higher air temperature rise and efficiency. However, the optimum angle is found 30o. The air temperature rise and efficiency will be 5.3% lower when the obstacles bent 30oinstead of 0o, but the pressure drop will be 17.2% lower.

Turbulent Flow Over a Flat Plate Downstream of a Finite Height Perforated Plate

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
F. Fouladi ◽  
P. Henshaw ◽  
D. S.-K. Ting
Keyword(s):  
Turbulent Flow ◽  
Flat Plate ◽  
Short Distance ◽  
Free Stream ◽  
Perforated Plate ◽  
Leading Edge ◽  
Grid Turbulence ◽  
Hot Wire ◽  
Velocity Measurements ◽  
Finite Height

An experimental investigation was carried out to study the turbulent flow over a flat plate in a wind tunnel. The turbulence was generated by a plate with diamond-shaped perforations mounted perpendicular to and on the leading edge of the flat plate. Unlike conventional grid turbulence studies, this perforated plate had a finite height, and this height was explored as a key independent parameter. Instantaneous velocity measurements were performed with a 1D hot-wire anemometer to reveal the behavior of the flow a short distance downstream of the perforated plate (X/D = 10–30). Different perforated plate heights (H = 3, 7, 11 cm) and free stream velocities (U = 4.5, 5.5, 6.5 m/s) have been studied.

Using a Windbreak to Improve the Thermal Performance of a Flat Plate Solar Collector: A Feasibility Study

2011 ◽  
Author(s):  
Saeed Moaveni ◽  
Michael C. Watts
Keyword(s):  
Flat Plate ◽  
Heat Loss ◽  
Forced Convection ◽  
Thermal Performance ◽  
Solar Collector ◽  
Large Scale ◽  
Ambient Air ◽  
Absorber Plate ◽  
Wide Range ◽  
Flat Plate Solar Collector

During the past few decades, a wide range of studies have been performed to improve the performance of flat plate solar collectors by either reducing the heat loss from a collector or by increasing the amount of solar radiation absorbed by the absorber plate. Examples of these studies include adding transparent honeycomb to fill the air gap between the glazing and absorber plate to reduce convective heat loss, replacing the air in the gap by other gases such as Argon, Krypton, Xenon and Carbon Dioxide, or adding a chemical coating such as Copper Oxide to increase absorbtance and reduce the emittance of the absorber plate. While these methods improve the collector’s efficiency, they focus primarily on limiting the natural convection that occurs in the collector cavity, or on improving the optical properties of the absorber or glazing. None of these studies have addressed the problem of heat loss due to forced convection to the surrounding ambient air in any detail. Yet, research has shown that forced convection will contribute significantly to the heat loss from a collector. Windbreaks have traditionally been used to direct wind to protect farmland, and to direct wind drifts and sand dunes. Windbreaks also have been shown to provide protection for homes from winter winds which result in reduced heating costs for buildings. While windbreaks have been traditionally used for large scale applications, there is reason to believe that similar benefits can be expected for scaled down applications such as adding a windbreak along side of a flat-plate solar collector. In this paper, we examine the feasibility of using a windbreak to provide a flat plate solar collector protection from the wind in order to improve its performance. A series of experiments were performed wherein the thermal performance of two flat-plate collectors — one without a windbreaker and one with a windbreaker — were measured. The results of these experiments are reported in this paper and the need for further studies to explore different windbreak configurations is discussed.

Relation between Collector Efficiency Factor and the Centre to Centre Distance of Absorber Tubes of Solar Flat-Plate Collector

2014 ◽  
Vol 592-594 ◽  
pp. 2404-2408 ◽  
Author(s):  
Sunita Meena ◽  
Chandan Swaroop Meena ◽  
V.K. Bajpai
Keyword(s):  
Solar Radiation ◽  
Solar Energy ◽  
Flat Plate ◽  
Special Kind ◽  
Radiation Energy ◽  
Efficiency Factor ◽  
Energy Gain ◽  
Absorber Plate ◽  
Collector Efficiency ◽  
Flat Plate Collector

Solar energy collectors are a special kind of heat exchangers that transform solar radiation energy to internal energy of the transport medium. The major component of any solar system is the solar collector. This is a device which absorbs the incoming solar radiation, converts it into heat, and transfers this heat to a fluid (usually air, water, or oil) flowing through the collector. The measurement of the flat plate collector performance is the collector efficiency. The collector efficiency is the ratio of the useful energy gain to the incident solar energy over a particular period of time. The useful energy gain is strongly depends on the collector efficiency factor and this factor directly influenced by few parameters i.e. the centre to centre distance of absorber tubes W , thickness of absorber plate δ and heat loss coefficient UL. This paper has been focused on the relation between W with collector efficiency factor of serpentine tube solar flat-plate collector. This study shows that if we increase the W then Fˈ decreases.

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