Numerical Investigation of Convective Heat Loss from Upward Facing Cavity Receivers of Different Shapes at Different Inclinations and Temperatures

Shivam Kumar; Dadasaheb Jagannath Shendage; Prafulla Doke; Shireesh Balwant Kedare; Shridhar Laxman Bapat

Authors

Shivam Kumar Department of Energy Science and Engineering, Indian Institute of Technology-Bombay, Mumbai, Maharashtra 400076, India
Dadasaheb Jagannath Shendage Department of Mechanical Engineering, Indian Institute of Technology-Bombay, Mumbai, Maharashtra 400076, India
Prafulla Doke Department of Mechanical Engineering, Indian Institute of Technology-Bombay, Mumbai, Maharashtra 400076, India
Shireesh Balwant Kedare Department of Energy Science and Engineering, Indian Institute of Technology-Bombay, Mumbai, Maharashtra 400076, India
Shridhar Laxman Bapat Department of Mechanical Engineering, Indian Institute of Technology-Bombay, Mumbai, Maharashtra 400076, India

Keywords:

Upward facing cavity, Solar receiver, Natural convection heat loss, Receiver design

Abstract

Scheffler solar concentrator system is commonly used system in India. It is used for industrial process heat, cooking and power generation. It utilizes an upward facing cavity receiver fixed at local latitude. In the present work, upward facing cavity receivers are analysed numerically to study the heat loss by natural convection for six different shapes (cylindrical, cubical, spherical, hemispherical, dome-cylindrical and cone-cylindrical) having equal aperture dimension and cavity depth. CFD analysis is carried out on these different cavity receiversfor isothermal wall temperatures (600 K, 725 K, 850 K and 950 K) at varied inclinations (θ=00 to -900 with 100 interval). The heat loss is observed to increase linearly with increase in surface temperature. Moreover, for a fixed wall temperature, the convective heat loss increases with angle up to a certain inclination angle and then decreases. It is observed that a) cone-ylindrical
shaped cavity receiver is the most efficientin terms of solar flux utilization, b) and the hemispherical cavity has the highest convective heat loss (up to 3.23 times that of cone-cylindrical shape).