Iranian Journal of Mechanical Engineering Transactions of ISME

Iranian Journal of Mechanical Engineering Transactions of ISME

Numerical analysis of air flow specification in solar chimneys with vegetation layer

Authors
Arash Miradollah Lavasni 1
Mehrdad Mohammadi 2
Ramin Mehdipour 3
1 Assistant professor, Department of Mechanical Engineering, Islamic Azad University, Central Tehran Branch
2 Msc. Student, Department of Mechanical Engineering, Islamic Azad University, Central Tehran Branch
3 Assistant professor, Department of Mechanical Engineering, Tafresh University
Abstract
Nowadays, the ever increasing demand to provide energy and the constant decrease of fossil fuels resources has made the usage of renewable energy resources vital. Solar chimneys are considered a significant approach to supply electricity. They are of particular interest due to the high absorption level of solar energy and also because of the advantages of using air as an absorber. However, these systems do not provide enough economic efficiency. Plant breeding in the collector’s section of a solar chimney was presented in this study as a mean to overcome the economical obstacles. Also possible geometrical and physical effects on air flow parameters were investigated by means of numerical simulation. Our simulation results were validated with comparison to the experimental model in Manzanares, Spain. Velocity as well as the temperature gradient at collector’s outlet was calculated. Our results showed excellent affinity to those of Spanish prototype as the error percentage was lesser than 5%. Vegetation layer was modeled as a porous media at the bottom of the collector and its possible effects was investigated on the air flow parameters at Ra = 1010. It was observed that due to the vegetation layer the velocity and temperature gradient at collector’s outlet were decreased 2.5% and 2%, respectively. These slight reductions show that plant breeding in large areas of collector’s bottom could be served as an outstanding idea to enhance the costefficiency challenges of solar chimneys while producing only negligible negative effects on air flow parameters.
Keywords
Solar Energy
Solar chimney
Porous media
numerical simulation
Heat Transfer

Subjects

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Iranian Journal of Mechanical Engineering Transactions of ISME
Volume 17, Issue 4 - Serial Number 41
Heat Transfer and Fluid Mechanics
Winter 2016
Pages 6-22

  • Receive Date 11 August 2014
  • Revise Date 25 October 2015
  • Accept Date 24 November 2015