scholarly journals Thermal Investigations of Double Pass Solar Air Heater with Two Types of Porous Media of Different Thermal Conductivity

2021 ◽  
Vol 39 (1A) ◽  
pp. 79-88
Author(s):  
Jalal M. Jalil ◽  
Shrooq J. Ali
Keyword(s):  
Thermal Conductivity ◽  
Porous Medium ◽  
Stainless Steel ◽  
Porous Media ◽  
Thermal Efficiency ◽  
Wire Mesh ◽  
Solar Air Heater ◽  
Steel Wool ◽  
Double Pass ◽  
Air Heater

This study describes an experimental investigation of the thermal efficiency of stainless steel mesh and steel wool as a porous medium in the lower channel of a double pass solar air heater. An experimental setup was planned and developed. Various types of porous media with high thermal conductivity and with different porosities have been tested. The effects of the porosity of wire mesh, the thermal conductivity of porous media, mass flow rate, and the intensity of radiation have been studied. Experimental results show that thermal efficiency with using porous media is greater than without using porous media. When used steel wool as a porous medium, the thermal efficiency reached 79.82 percent while it can be achieved 76.  The percent by using stainless mesh as porous material. The reduction in porosity increasing thermal efficiency. The thermal efficiency of multi-pass solar air collector when used steel wool as porous media is 6, 12.6 and31.7percent higher than without porous media at porosity 98.75, 97.5, and 96.25percent. While it can increase 8.1 and 28.5 percent at porosity 97.875 and 95.75 percent when using stainless steel as porous media.

scholarly journals Thermal Evaluation of a Double-Pass Unglazed Solar Air Heater with Perforated Plate and Wire Mesh Layers

2020 ◽  
Vol 12 (9) ◽  
pp. 3619
Author(s):  
Afaq Jasim Mahmood
Keyword(s):  
Flow Rate ◽  
Thermal Efficiency ◽  
Air Flow ◽  
Wire Mesh ◽  
Inlet Temperature ◽  
Solar Air Heater ◽  
Outlet Temperature ◽  
Air Flow Rate ◽  
Double Pass ◽  
Air Heater

In this study, an experimental outdoor investigation of the thermal efficiency and outlet air temperature was conducted on an unglazed, double-pass, solar air heater with a perforated absorber plate and packing wire mesh layers as a supplemental absorbent area. This was done to observe their effects on the thermal performance of the solar air heater. The double-pass collector was constructed with a bed height of 0.05 m, and a collection area of 1.5 m2. The height of the upper channel was fixed at 0.015 m to improve the thermal efficiency, and the outlet temperature at air flow rates between 0.003 and 0.018 kg/s. The collector was mounted with a slope of 42° facing south, to maximize the intensity of solar irradiance during winter. The effects of the air flow rate, ambient temperature, inlet temperature, outlet temperature, and solar intensity were experimentally investigated. The results showed that thermal efficiency could be improved by increasing the air flow rate, where the highest thermal efficiency achieved was 86% at 0.018 kg/s. However, the temperature difference was increased to a maximum value of 38.6 °C, when the air flow rate was decreased to 0.003 kg/s. Furthermore, the results demonstrated a significant improvement in the thermal efficiency and outlet temperature; and when compared with previous research, the experimental results and the predictions for the outlet temperature using the theoretical model agreed.

scholarly journals Performances of packed bed double pass solar air heater with different inclinations and transverse wire mesh with different intervals

2016 ◽  
Vol 20 (1) ◽  
pp. 175-183 ◽  
Author(s):  
Gnanadurai Sugantharaj ◽  
Kumar Vijay ◽  
Kalidasa Kulundaivel
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Packed Bed ◽  
Wire Mesh ◽  
Solar Air Heater ◽  
Double Pass ◽  
Air Heater ◽  
Collector Efficiency

Solar air heating is a technology in which the solar energy from the sun is captured by an absorbing medium and used to heat the air flowing through the heater. In this study, thermal performance of a double pass solar air heater has been investigated experimentally at different conditions. The experiments were conducted with different inclinations of the collector, with and without wire mesh vertically fixed at the second pass in transverse direction and with different mass flow rates. The effect of air mass flow rate, wire mesh pitch and collector inclination on temperature rise and thermal efficiency have been studied. Results show that efficiency increases with mass flow rate. For the same mass flow rate, the thermal efficiency increases with the decrease in the wire mesh pitch. The maximum daily average efficiency of air heater was 79.8% at 0.025 kg/s mass flow rate, 10 cm wire mesh gap and 9? collector inclination facing south. The highest collector efficiency was observed in solar air heaters with 10 cm wire mesh gap.

The effect of using transverse fins on a double pass flow solar air heater using wire mesh as an absorber

Solar Energy ◽  
2011 ◽  
Vol 85 (7) ◽  
pp. 1479-1487 ◽  
Author(s):  
M.F. El-khawajah ◽  
L.B.Y. Aldabbagh ◽  
F. Egelioglu
Keyword(s):  
Wire Mesh ◽  
Solar Air Heater ◽  
Double Pass ◽  
Air Heater

scholarly journals Various Designs of Solar Collectors for Enhancement of Thermal Performance

2011 ◽  
Vol 8 (1) ◽  
pp. 101-105
Author(s):  
M. K. Lalji ◽  
R. M. Sarviya ◽  
J. L. Bhagoria
Keyword(s):  
Thermal Performance ◽  
Thermal Efficiency ◽  
Energy Demand ◽  
Packed Bed ◽  
Wire Mesh ◽  
Solar Air Heater ◽  
Air Heater ◽  
The Matrix ◽  
Solar Heater ◽  
Economical Alternative

Solar energy is an economical alternative to the today's energy demand. Solar air heater is used for heating the air economically but produces low thermal efficiency. In this paper, an attempt has been made to study the design of solar heaters to increase the thermal efficiency. The matrix solar air heater with a wire mesh produces higher thermal efficiency over the conventional flat plate solar air heater. The evaluation of different methods for increasing efficiency of packed bed solar air heater has been done . Effect of different parameters on thermal efficiency of solar heater has also been studied.

Enhanced Double-Pass Solar Air Heater With and Without Porous Medium

2011 ◽  
Vol 8 (6) ◽  
pp. 643-654 ◽  
Author(s):  
Ehsan Mohseni Languri ◽  
Hessam Taherian ◽  
Kamel Hooman ◽  
John Reisel
Keyword(s):  
Porous Medium ◽  
Solar Air Heater ◽  
Double Pass ◽  
Air Heater

Experimental Study of a Solar Air Heater With a New Arrangement of Transverse Longitudinal Baffles

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Afaq Jasim Mahmood
Keyword(s):  
Heat Transfer ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
Air Flow ◽  
Maximum Temperature ◽  
Maximum Efficiency ◽  
Solar Air Heater ◽  
Air Flow Rate ◽  
Double Pass ◽  
Air Heater

This study presents a new design for improving the convection heat transfer coefficients of double-pass solar air heater. Three cases were described by using a different number of transverse baffles (three, five, and seven) in the lower channel of the collectors; steel mesh sheets were also used to enlarge the heat transfer area. All collectors have a space of 25 mm between its glass covers and a 50 mm depth of air channel. Furthermore, this work examined the effect of air flow rate and baffles number on device's thermal efficiency and outlet temperature. The experimental results indicate raises in the thermal efficiency as the air flow rate goes from 0.011 kg/s to 0.038 kg/s. A maximum efficiency of 68% was obtained from the case of seven baffles at the air flow rate of 0.038 kg/s. Moreover, the difference between collector's inlet and outlet temperatures, ΔT, indicated an inverse relationship with air flow rate. Thus, the results show ΔT increases as the air flow rate reduced. The maximum temperature difference recorded was 54 °C, which achieved using seven baffled solar air heater at 0.011 kg/s air flow rate in the middle of the day. It has also been found that thermal efficiency of double-pass solar air heater is greater than single-pass solar air heater, using same air flow rate and number of baffles. Finally, the pressure drop associated with increasing the number of baffles and air flow rate was deliberated.

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