ABSTRACT
Present work investigates a noble approach toward the heat loss analysis of parabolic dish type solar cooker. Various experiments have been done on cooking pot to get the input parameter for calculation purposes. Cooking pot was kept at the focus of a parabolic dish type concentrator and repeated experiments have been done to measure solar radiation intensity (direct and Indirect) using a pyrometer, temperature at the focus of parabolic dish using a thermocouple and air velocity using hot wire anemometer to investigate the heat losses from the cooking pot. In the present article, a numerical approach has been performed to define the new parameter called performance index of the cooking pot which decides how the useful energy of working fluid inside the cooking pot approaches concentration ratio of the parabolic dish type solar cooker. The present analysis shows that the performance index varies from 15.45 to 17.66 and efficiency varies from 85.83% to 98.10% with the time of the day.
Acknowledgment
The authors gratefully acknowledge the MHRD New Delhi for financial support for conducting this study.
Nomenclature
Optical concentration ratio
Geometrical concentration ratio
Intensity of radiation falling on dish concentrator
Intensity of radiation falling on cooker
Area of dish collector
Area of section of cooker containing air (steam)
Area of cooker
Area of top surface of cooker
Heat received by receiver (cooker)
Heat received by cooking fluid
Heat transfer from receiver to air (steam) in cooking pot
Heat transfer due to radiation from side (cylindrical surface)
Heat lost from cooker
Mass of the receiver (cooker)
Mass of air in cooker
Specific heat capacity of receiver
Temperature of receiver
Time
Absorptivity of receiving surface
Heat collected by dish concentrator
Heat lost from bottom of cooker
Reflectivity of dish surface
Shading factor for the cooker
Optical efficiency of dish concentrator
Cylindrical surface area of cooking pot (cooker)
Temperature of air (steam) above fluid in cooker
Heat transfer between fluid to air (steam) above fluid in cooker
Mass of fluid in cooking pot (cooker)
Specific heat capacity of fluid
Temperature of fluid
Temperature of receiver (cooker)
Heat lost from top surface of cooker
Specific heat capacity of air in cooker
Ambient temperature
Thickness of cooker
Thermal conductivity of cooker material
V= Wind velocity
Stefan Boltzmann constant
Emissivity of black matt paint
Emissivity of aluminum
Sky temperature
Radius of cooking pot
Length of cooking pot
Base area of cooking pot (cooker)
Heat transfer coefficient of air above fluid in cooker
Convection heat transfer coefficient for cylindrical (side) surface
Convection heat transfer coefficient for bottom surface of cooker
Convection heat transfer coefficient for top surface of cooker
Radiation heat transfer coefficient for cylindrical (side) surface
Radiation heat transfer coefficient for bottom surface
Radiation heat transfer coefficient for top surface