Electromagnetic modelling of light trapping by a micro-textured solar absorber

Description

Solar energy is a vast and largely untapped resource in Australia, which has the highest solar radiation per square metre of any continent. Recently, central tower Concentrating Solar Power (CSP) technology has received significant attention due to its ability to cheaply store energy and produce electricity in a 24-hour cycle. Vital to the efficiency of central tower CSP technology is the effectiveness of light absorption at the solar receiver.

The central aim of this project is to develop highly efficient, durable, and economical competitive absorber coatings to help transform the CSP industry, which has the potential of becoming an essential part of the renewable energy sector in Australia and worldwide. To achieve the main objective, a multi-scale engineering approach composed of optics modelling, materials science, and ageing testing will be performed. In this project, three main goals are set. The first goal is to model and understand the light trapping mechanism of a micro-textured coating to find the best morphology that optimises light absorption (position 1). The second goal is to improve the durability and light absorption of solar thermal absorbers by developing micro-texturing and multi-layer deposition techniques as well as introducing new materials (position 2). The third goal is to develop and validate accelerated ageing tests that reproduce the extreme conditions of high temperature, radiative fluxes, thermal stresses and fatigue of CSP receivers (position 3).

The objective of this HDR project is to understand the light absorption mechanism in a micro-textured absorber coating and determine the best morphology to optimise light trapping and reduce thermal emission. For the characteristic lengths larger than the wavelength of incident light, a Monte Carlo ray tracing approach will be taken to estimate the absorptance and thermal emission of the coating. For characteristic lengths similar to the wavelength of incoming light, computational electromagnetics methods such as Rigorous Coupled-Wave Analysis (RCWA) and Finite-Difference Time-Domain (FDTD) method will be used to solve Maxwell’s equations and model light-trapping effects, while a solution of the radiative transfer equation (RTE) will be sought to determine thermal emission properties. RCWA is a widely-used technique in the semiconductor industry for analysing periodic structures, providing an approximation of the pore (lattice) size dependence on optical and thermal properties. FDTD can be used to model more light-matter interaction for irregular shapes, as the micro-textured coatings, including the impact of backscattering. The RTE can be used to understand the near-field radiative heat transfer phenomena in aperiodic structures and participating media.

Requirements

  • Strong fundamental knowledge of thermal radiation and electromagnetism.
  • Knowledge of numerical methods for solving partial differential equations.
  • Experience with Monte Carlo ray tracing tools.
  • Ability to interpret experimental results and compare with simulated data.
  • Excellent scientific writing skills.

Keywords

Optical modelling, light trapping,absorber coating, solar thermal, concentrating solar power

Updated:  1 November 2018/Responsible Officer:  Dean, CECS/Page Contact:  CECS Marketing