scholarly journals Thermal Resistance Model of a Flat Plate Solar Air Collector for Energy Efficiency Prediction

2021 ◽  
Vol 945 (1) ◽  
pp. 012005
Author(s):  
K. S. Ong ◽  
K. Gobi ◽  
C. H. Lim ◽  
S. Naghavi ◽  
S. Baljit
Keyword(s):  
Flat Plate ◽  
Solar Collector ◽  
Rectangular Cross Section ◽  
Air Flow ◽  
Solution Procedure ◽  
Plate Temperature ◽  
Transfer Resistance ◽  
Pv Panel ◽  
Resistance Model ◽  
Air Flow Velocity

Abstract The temperature of a PV panel rises during operation which affects its power output. A PV panel is similar to a flat plate solar collector. This paper presents a simple theoretical heat transfer resistance model and a solution procedure to predict the absorber plate surface temperature of the solar collector. The model consisted of a rectangular cross-section steel duct placed inclined at an angle to the horizontal and exposed to solar radiation. The heat absorbed on the top surface of the plate is transmitted by conduction through the plate and heats the air in the duct. This creates a natural buoyancy effect which induces a natural convection air flow rate. A simple one-dimensional theoretical model of the solar collector with the thermal resistances of the various components is proposed. Simulated results of plate temperature and induced air flow velocity are presented.

scholarly journals Experimental Study of Forced- Convection from Horizontal Rectangular Fins Array into Air Duct

2019 ◽  
Vol 15 (1) ◽  
pp. 35-45
Author(s):  
Saad Najeeb Shehab
Keyword(s):  
Experimental Study ◽  
Heat Flux ◽  
Flow Velocity ◽  
Forced Convection ◽  
Surface Heat Flux ◽  
Rectangular Cross Section ◽  
Air Flow ◽  
Surface Heat ◽  
Wide Range ◽  
Air Flow Velocity

    In this work, an experimental study has been done to expect the heat characteristics and performance of the forced-convection from a heated horizontal rectangular fins array to air inside a rectangular cross-section duct. Three several configurations of rectangular fins array have been employed. One configuration without notches and perforations (solid) and two configurations with combination of rectangular-notches and circular-perforations for two various area removal percentages from fins namely 18% notches-9% perforations and 9% notches-18% perforations are utilized.  The rectangular fins dimensions and fins number are kept constant. The fins array is heated electrically from the base plate with five different magnitudes of power-inputs. Five several air flow velocity into a duct are utilized. The influence of fin geometry, air flow velocity, Reynolds number and the surface heat flux on the heat-performance of forced heat convection have been simulated and studied experimentally. The experimental data indicates that the combination of 18% rectangular-notched and 9% circular-perforated rectangular fins array gave best forced heat performance in terms of average heat transfer coefficient about (25% - 45%) and (7% - 20%) compared than solid and 9% notches with18% perforations fins array respectively. Five empirical correlations to predict the average Nusselt number for the 18% notches with 9% perforations rectangular fins array at wide range of surface heat flux are deduced. The present data are compared with previous works and a good closeness in behavior is noticed.

scholarly journals Energy and exergy analysis of air based photovoltaic thermal (PVT) collector: a review

2019 ◽  
Vol 9 (1) ◽  
pp. 109 ◽  
Author(s):  
Ahmad Fudholi ◽  
Mariyam Fazleena Musthafa ◽  
Abrar Ridwan ◽  
Rado Yendra ◽  
Ari Pani Desvina ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Flat Plate ◽  
Solar Collector ◽  
Exergy Analysis ◽  
Exergy Efficiency ◽  
Pv Panel ◽  
Energy And Exergy ◽  
Energy And Exergy Analysis ◽  
Flat Plate Solar Collector

<span lang="EN-US">Photovoltaic thermal (PVT) collectors convert solar radiation directly to both electrical and thermal energies. A PVT collector basiccaly combines the functions of a flat plate solar collector and those of a PV panel. This review presents thermodinamics fundamentals, descriptions, and previous works conducted on energy and exergy analysis of air based PVT collector. Studies in 2010 to 2018 of the energy and exergy analysis of air based PVT collectors are summarized. The energy and exergy efficiency of air based PVT collector ranges from 31% to 94% and 8.7% to 18%, respectively. In addition, flat plate solar collector is presented. Studies conducted on air based PVT collectors are reviewed.</span>

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
Keyword(s):  
Flat Plate ◽  
Temperature Variation ◽  
Solar Collector ◽  
Entrance Region ◽  
Low Flow ◽  
Absorber Plate ◽  
Plate Temperature ◽  
Thermal Entrance Region ◽  
Flat Plate Solar Collector ◽  
Thermal Entrance

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.

Numerical Studies on Heat Transfer over a Flat Plate with Triangular Rib-Groove Geometry at Laminar Flow Conditions

2017 ◽  
Vol 374 ◽  
pp. 121-130 ◽  
Author(s):  
T.S. Ravikumar ◽  
Sivamani Seralathan ◽  
Venkatesan Hariram ◽  
Hemanth Kumar Guntamadugu
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Laminar Flow ◽  
Flat Plate ◽  
Flow Velocity ◽  
Air Flow ◽  
Heated Plate ◽  
Flow Conditions ◽  
Air Flow Velocity ◽  
Laminar Flow Conditions

In this present study, periodically positioned triangular shaped ribs having a round top corner at the bottom with groove positioned on the top side of the plate is analyzed at laminar flow conditions. The numerical results obtained for the heated plate with rib-groove geometry are compared with that of the flat plate kept under similar conditions. At lower air flow velocity, the Nusselt number of the flat plate improved from 400 to 1407 with the provision of triangular ribs-groove arrangement in it. Similarly, it improved from 850 to 6420 at higher air flow velocity with triangular ribs-groove arrangement. Higher Nusselt number values leads to a higher heat transfer coefficient values. Therefore, the triangular ribs-groove geometry gives an enhanced rate of heat transfer with minimum pressure drop. The study shows that irrespective of geometry, the rate of heat transfer is relying on fluid (air in this present case) flow velocity over heated plate, fluid flow contact with the heated plate and surface area of the heated plate.

EXPERIMENTAL AND ANALYTICAL STUDIES OF VERTICAL AXIS WIND TURBINES

2018 ◽  
pp. 51-58
Author(s):  
B. P. Khozyainov
Keyword(s):  
Wind Turbine ◽  
Flow Velocity ◽  
Wind Power ◽  
Wind Turbines ◽  
Power Efficiency ◽  
Air Flow ◽  
Geometrical Parameters ◽  
Wind Speeds ◽  
Analytical Studies ◽  
Air Flow Velocity

The article carries out the experimental and analytical studies of three-blade wind power installation and gives the technique for measurements of angular rate of wind turbine rotation depending on the wind speeds, the rotating moment and its power. We have made the comparison of the calculation results according to the formulas offered with the indicators of the wind turbine tests executed in natural conditions. The tests were carried out at wind speeds from 0.709 m/s to 6.427 m/s. The wind power efficiency (WPE) for ideal traditional installation is known to be 0.45. According to the analytical calculations, wind power efficiency of the wind turbine with 3-bladed and 6 wind guide screens at wind speedsfrom 0.709 to 6.427 is equal to 0.317, and in the range of speed from 0.709 to 4.5 m/s – 0.351, but the experimental coefficient is much higher. The analysis of WPE variations shows that the work with the wind guide screens at insignificant average air flow velocity during the set period of time appears to be more effective, than the work without them. If the air flow velocity increases, the wind power efficiency gradually decreases. Such a good fit between experimental data and analytical calculations is confirmed by comparison of F-test design criterion with its tabular values. In the design of wind turbines, it allows determining the wind turbine power, setting the geometrical parameters and mass of all details for their efficient performance.

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