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Solar chimney

performance analysis of solar chimney

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Solar chimney

  1. 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. 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. 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. 4. Solar Chimney
  5. 5. Types of Solar Chimney There are four general types of solar chimney: 1. Open loop system 2. Closed loop system
  6. 6. Types of Solar Chimney Type 1 Type 2
  7. 7. Types of Solar Chimney Type 3 Type 4
  8. 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. 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
  10. 10. Physical Model
  11. 11. Thermal Network Mean air temperature 𝑇𝑓 can be find out using above equations
  12. 12. 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
  13. 13. 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
  14. 14. 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
  15. 15. 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
  16. 16. Location of Thermocouple Points
  17. 17. Air Temperature Distribution Temperature distribution across air gap depth (d = 0.1 m)
  18. 18. 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
  19. 19. 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)
  20. 20. 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)
  21. 21. 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)
  22. 22. Effect on Inlet Air Flow Velocity Mea Inlet air flow velocity variation with air gap depth and incident solar radiation
  23. 23. Effect on Instantaneous Efficiency Instantaneous efficiency variation with air gap depth and incident solar radiation
  24. 24. Experimental v/s Theoretical Results Experimental and predicted mean glass, wall and air temperatures (H = 650 W 𝑚−2)
  25. 25. Experimental v/s Theoretical Results Experimental and predicted mean glass, wall and air temperatures (H = 200 W 𝑚−2)
  26. 26. Experimental v/s Theoretical Results Experimental and predicted mean air temperature rise, inlet air flow velocity, And instantaneous efficiency (H = 650 W 𝑚−2 )
  27. 27. Experimental v/s Theoretical Results Experimental and predicted mean air temperature rise, inlet air flow velocity, And instantaneous efficiency (H = 200 W 𝑚−2 )
  28. 28. Building Description
  29. 29. 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.
  30. 30. References  [1] K.S. Ong*, C. C. Chow, Performance of a Solar Chimney.

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