Temperature Variation in the Absorber Plate of an Air Heating Flat Plate Solar Collector

1981 ◽  
Vol 103 (2) ◽  
pp. 153-157 ◽  
Author(s):  
L. A. Diaz ◽  
N. V. Suryanarayana

A flat plate solar collector is modelled as a rectangular channel of high width to gap ratio with air entering the collector with a fully developed turbulent velocity profile. One plate of the collector is subjected to a uniform heat flux with the other plate heavily insulated. Experimental values of friction factor and heated plate temperature in the thermal entrance region are presented and compared with analytical predictions. It is shown that there will be significant plate temperature variation in the thermal entrance region particularly at low flow rates. It is also shown that neglecting conduction effects in the absorber plate will not lead to any significant errors in estimating absorber plate temperature variation. Tabulated values of dimensionless plate temperature for different values of the dimensionless distance from the leading edge for several Reynolds number are presented.

2012 ◽  
Vol 253-255 ◽  
pp. 760-765 ◽  
Author(s):  
Maryam Khademi ◽  
Farzad Jafarkazemi ◽  
Emad Ahmadifard ◽  
Saman Younesnejad

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.


Author(s):  
Saeed Moaveni ◽  
Michael C. Watts

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.


Author(s):  
RAMESH C ◽  
SEKAR M

The depletion of conventional energy source, the need for unconventional energy is focused on solar energy as it is avail plentiful. Converting the solar energy in to thermal energy is the effective way of utilization of solar energy rather the conversion of electrical energy. This paper compared the behavior of solar collector at 30º and 45º angles with black chrome coated absorber plate without and with glass reflectors. In the view of performance enhancement of the collector, the reflector was adjusted to maximize the incident ray for every hour. It is found that the collector fixed at 30º with ground heats the water better and again the performance can be increased by the reflector.


1984 ◽  
Vol 106 (2) ◽  
pp. 206-211 ◽  
Author(s):  
D. K. Edwards ◽  
S. J. Rhee

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.


2013 ◽  
Vol 24 (3) ◽  
pp. 8-13 ◽  
Author(s):  
Sunil Chamoli

In this study, exergetic performance analysis of flat plate solar collector has been carried out analytically. A comprehensive mathematical modelling of thermal performance is simulated using MATLAB simulink and optimal geometrical and thermodynamic parameters are predicted pertaining to optimum performance of the system. The optimization procedure was applied to a typical collector and the optimum design points were extracted. The optimum values of collector inlet temperature, mass flow rate, absorber plate area, and fluid outlet temperature for maximum exergy inflow from the system have been obtained.


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