Estimation of convective heat losses from conical cavity receiver of solar parabolic dish collector under wind conditions and receiver orientations

Abhinav Rajan,K S Reddy

doi:10.1051/e3sconf/202131311001

Abstract

The parabolic dish collector is one of the recognized concentrated solar power systems based on point focusing, which provides high-temperature heat, high concentration ratio, and low heat loss. This system consists of a parabolic reflector and a cavity receiver situated in the focus line. In this work, the conical cavity receiver with an aperture diameter of 0.5 m is considered for a 100 m2 parabolic reflector having a focal to diameter ratio of 0.48. Due to the complexity of flow and temperature profile, the estimation of convective heat loss is a difficult task in a cavity receiver. More heat losses are associated with high temperature obtained in the cavity receiver of the parabolic dish collector. Due to diverse wind effect, the convective heat losses ramp up, which significantly influences the thermal performance of the concentrating power system. The present work aims to investigate the heat losses due to convection from the conical cavity receiver. The numerical investigation was performed using ANSYS Fluent 20R1 to calculate the convective heat losses from the conical cavity receiver of varying diameter to height ratio for varying wind speed, receiver orientation in head-on, and back-on wind flow directions. The considered influential parameters are varying from 0.5 to 1.5 for diameter to height ratio (d/h), 0° to 90° for receiver orientation (γ), 0 to 10 m/s for wind speed (V). The heat losses are highest at 60° and 75° receiver orientation for d/h = 0.5 and d/h = 1-1.5, respectively, at high wind speed in head-on condition, whereas in back-on wind condition, 30° receiver orientation has more heat losses among all the d/h values at high wind speed. The heat loss at 90° receiver orientation is low for 4-10 m/s. The trends of heat loss curve at receiver orientations for given wind conditions are similar for velocity more than 2 m/s. The result reveals that the considered influential parameters have a remarkable effect on convective heat losses from the cavity receiver.

Highlights

The parabolic dish collector is one of the concentrated solar power systems used for hightemperature industrial applications by absorbing the incoming solar energy under varying weather conditions [1]
The numerical investigation is carried out in this present work to inspect the effect of wind speeds, wind conditions, receiver orientations, and receiver configuration on convective heat loss from conical cavity receiver of parabolic dish collector
The wind effect caused the flow separation and adverse pressure gradient, due to which the receiver was subjected to heat loss

Summary

Introduction

The parabolic dish collector is one of the concentrated solar power systems used for hightemperature industrial applications by absorbing the incoming solar energy under varying weather conditions [1]. The numerical investigation is carried out in this present work to inspect the effect of wind speeds, wind conditions, receiver orientations, and receiver configuration on convective heat loss from conical cavity receiver of parabolic dish collector. This model can be assumed to be helpful in the estimation of convective heat loss from cavity receivers for process heat applications of medium and high temperatures. The numerical investigation is performed to evaluate heat loss due to convection with the variation in influential parameters such as receiver orientation (γ) from 0° to 90°, wind speed (V) from 0 to 10 m/s. Due to the unavailability of experimental data of this cavity receiver, the present model is validated with data from a numerical investigation [17] and is found the deviation of ± 9% between the models

Result and discussions

Findings

Conclusion