performance analysis of solar chimney

1. Performance Analysis of Solar Chimney
Submitted to - Presented by-
Mechanical Engg. Dept. Robin Jain
MNIT 2014PTE5059
M.Tech Thermal Engineering
MALAVIYA NATIONAL INSTITUTE OF TECHNOLOGY,
JAIPUR

2. Introduction
Solar chimney (SC) is a passive element that make
use of the solar energy to induce buoyancy-driven
airflow and naturally ventilate the building.
Solar Chimney is a passive device that
 Enables heating of air in the tower.
 As air heated in the tower, it rises up and create
upward draught
Source: Rakesh
et. al. (2011)

3. Working Principle of Solar Chimney
 The system uses the solar energy.
 The temperature difference between the outdoor temperature
air in the chimney and the air temperature in the attached
room promotes movement of air
 The rate at which air is drawn through the room depends upon
the buoyancy-force experienced, (i.e. dependent upon the
temperature differential), the resistance to flow through the
chimney, and the resistance to the entry of fresh air into the
room.
Source: D. J. Harris
et. al. (2007)

4. Solar Chimney

5. Types of Solar Chimney
There are four general types of solar chimney:
1. Open loop system
2. Closed loop system

6. Types of Solar Chimney
Type 1 Type 2

7. Types of Solar Chimney
Type 3 Type 4

8. Advantages and Disadvantages of Solar Chimney
Advantages:
1. simple to use and easy to maintain.
2. low maintenance cost and the electricity cost saving
3. no harmful impact on the environment.
Disadvantages:
1. High initial investment cost.
2. Recommended for new houses which has excellent insulation and air-tightness.
3. Space requirement is the major hindrance.
4. Skilled man power required for well designing of system.

9. Applications of Solar Chimney
Solar Chimney can be used in a vast variety of fields:
 In the generation of electricity
 Integrated in buildings as a natural ventilation device
 Sunrooms can also be designed to function like solar
chimneys
 Integrated in buildings as a heating device

11. Physical Model

12. Thermal Network
Mean air temperature 𝑇𝑓 can be find out using above equations

13. Modelling of Solar Chimney (cont.)
Air flow rate can be find out using given equation
Heat transfer from glass cover to ambient can be find out using given equation

14. Modelling of Solar Chimney (cont.)
Heat transfer between wall and glass cover can be find out using given equation
Conduction heat transfer from vertical wall to room can be find out using given equation
Solar radiation heat flux normal to and absorbed by the glass cover is given by
Solar radiation heat flux absorbed by the blackened wall is given by

15. Modelling of Solar Chimney (cont.)
The instantaneous efficiency of heat collection by the solar chimney is given by
Physical properties of air is given by

16. Experimental Setup
Rectangular box
2.00 m highX0.48 m wide
X1.02 m deep.
Top, base and side wall were
fabricated from
22 mm thick rigid polyurethane sheets
laminated both sides with 1 mm
thick steel sheet.
4 mm thick glass glazing
50 mm thick rigid polyurethane sheet
For heat absorbing wall
Width of air gap is 0.45m
Orientation of solar chimney towards
south

18. Location of Thermocouple Points

19. Air Temperature Distribution
Temperature distribution across air gap depth (d = 0.1 m)

20. Mean Wall, Air and Glass Temperature
Typical air, glass and wall temperature distributions along the chimney
10:24 am
16 January 2002
H = 670 W 𝑚−2
d = 0.1 m

21. Effect of Incident Solar Radiation
Variation of mean glass, wall and air temperatures, air volumetric and mass flow rates, and
instantaneous efficiency with solar radiation (d = 0.1 m)

22. Effect of Incident Solar Radiation
(cont.)
Variation of mean glass, wall and air temperatures, air volumetric and mass flow rates, and
instantaneous efficiency with solar radiation (d = 0.2 m)

23. Effect of Incident Solar Radiation
(cont.)
Variation of mean glass, wall and air temperatures, air volumetric and mass flow rates, and
instantaneous efficiency with solar radiation (d = 0.3 m)

24. Effect on Inlet Air Flow Velocity
Mea Inlet air flow velocity variation with air gap depth and incident solar radiation

25. Effect on Instantaneous Efficiency
Instantaneous efficiency variation with air gap depth and incident solar radiation

27. Experimental v/s Theoretical Results
Experimental and predicted mean glass, wall and air temperatures (H = 650 W 𝑚−2)

28. Experimental v/s Theoretical Results
Experimental and predicted mean glass, wall and air temperatures (H = 200 W 𝑚−2)

29. Experimental v/s Theoretical Results
Experimental and predicted mean air temperature rise, inlet air flow velocity,
And instantaneous efficiency (H = 650 W 𝑚−2
)

30. Experimental v/s Theoretical Results
Experimental and predicted mean air temperature rise, inlet air flow velocity,
And instantaneous efficiency (H = 200 W 𝑚−2
)

34. Building Description

36. Conclusion
 No reverse flow was observed up to 0.3 m gap
 The experimental and theoretical results have more satisfactory agreement
for large air gap.

37. References
 [1] K.S. Ong*, C. C. Chow, Performance of a Solar Chimney.