06-04-2012, 05:02 PM
Performance analysis for flat plate collector with and without porous media
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Introduction
Energy is a vital need in all aspects and due to the
increasing demand for energy coupled with its inefficient
consumption, the environment has been polluted
either directly or indirectly. To prevent this
from becoming a global disaster, it is inevitable to
strengthen efforts of energy generation and utilization
using sustainable means and progressively substituting
the fossil fuels for renewable sources of
energy.
Theoretical analysis
Figure 1 shows schematically the cross sectional
views and the thermal network of the solar air
heaters investigated in the present work. In all
types, the air heaters are composed of three plates,
i.e. the cover, the absorber and the rear or back
plate. The air flows in the upper channel depth
between the cover and the absorber plate in type
1(i.e. Single flow), but it is turned to continue flowing
in the lower duct between the absorber and the
rear plate in type 2, 3 (i.e. Double flow).
Results and discussion
Numerical values of different parameters such as
outlet temperature, efficiency and the pressure drop
were computed corresponding to an ambient temperature
33oC, solar radiation 500W/m2, air velocity
1.5 m/s, inlet temperature of 35oC and different
values of mass flow rate. The detailed specifications
of the data for all types of solar air heaters considered
in this study are given in Table 1 overleaf.
Validation
Validation and verification focus on the comparison
between the predicted output and the experimental
results for each solar air heater type. The experimental
results has been done by Karim and
Hawlader, (2004) for flat plate collector in single
and double pass mode, while El-Radi, (2001) has
done an experiment on the double pass flat plate
collector with porous media in the lower duct.