Journal of Thermal Analysis and Calorimetry

, Volume 133, Issue 2, pp 1001–1013 | Cite as

Energy- and exergy-based thermal analyses of a solar bakery unit

  • Iqra Ayub
  • Anjum MunirEmail author
  • Waseem Amjad
  • Abdul Ghafoor
  • Muhammad Salman Nasir


The use of solar concentrating technique for cooking purpose has been widely reported rather than for the baking process which is rigidly precise and requires process controlled conditions. Secondly, the energy and exergy analyses are rarely made for the baking process. In this paper, an energy- and exergy-based thermal analysis of an innovative solar bakery unit powered by Scheffler reflector has been presented. The system comprised of primary reflector (Scheffler reflector), secondary reflector, receiver and baking chamber. The baking experiments were conducted using four product samples (cakes) at 180 °C. The entire bakery unit was divided into two main parts, i.e. fan–receiver and baking chamber to find out the inefficiencies of bakery unit and its components. It was found that fan–receiver component handled major portion of solar energy and showed energy losses. It possessed high improvement potential (IP) rate (0.153 kW), high exergetic factor (f) value (59.26%) and low exergy efficiency (15%). Thermal analysis of baking process in the baking chamber showed variations in rate of energy utilization, energy utilization ratio, exergy losses and exergy efficiency in range of 0.01–0.07 kW, 25–75%, 0.19–1.08 kW and 6.62–56.46%, respectively. The overall exergy efficiency of system was found to be 59.26%. The study provides a detailed and sequential procedure to perform the thermal analysis of a solar concentrated technology-based bakery unit.


Solar baking Thermal analysis Scheffler reflector Exergy 

List of symbols


Rate of energy utilization/kJ s−1


Net available energy/kJ s−1




Receiver efficiency/%


Air flow rate/kg s−1


Specific humidity/g of water kg of dry air−1


Enthalpy/kJ kg−1


Relative humidity/%


Air velocity/m s−1


Specific heat/kJ kg−1 k−1


Heat given by receiver to air as output/kW


Heat received by zigzag receiver/kW


Beam radiations/W m−2


Aperture area of Scheffler reflector/m2


Surface area of Scheffler reflector/m2


Solar declination


Energy utilization ratio/%


Exergy/kJ kg−1


Exergy rate/kJ s−1


Exergetic efficiency/%


Exergetic factor/%


Improvement potential/kJ s−1



The authors wish to acknowledge the Department of Energy Systems Engineering, University of Agriculture Faisalabad, Pakistan, and International Centre for Development and Decent Work (ICDD), Germany, for the financial support.


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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2018

Authors and Affiliations

  • Iqra Ayub
    • 1
  • Anjum Munir
    • 1
    Email author
  • Waseem Amjad
    • 1
  • Abdul Ghafoor
    • 2
  • Muhammad Salman Nasir
    • 3
  1. 1.Department of Energy Systems EngineeringUniversity of Agriculture FaisalabadFaisalabadPakistan
  2. 2.Department of Farm Machinery and PowerUniversity of Agriculture FaisalabadFaisalabadPakistan
  3. 3.Department of Structures and Environmental EngineeringUniversity of Agriculture FaisalabadFaisalabadPakistan

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