Systems and methods for direct thermal receivers using near blackbody configurations
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Solution Overview
Problem
Concentrating solar power systems face low thermal efficiencies due to radiant and convective heat losses from high-temperature thermal receivers, limiting their ability to operate effectively at temperatures above 650°C.
Innovation Solution
A receiver design featuring external and internal panels configured to form an internal cavity with an open face, where the heat transfer medium is distributed through channels, and radiation is absorbed and reflected multiple times to minimize energy loss, with angled portions to intercept radiation and reduce direct impingement on the back panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high temperature operation (above 650°C) is implemented in thermal receivers, then the system can operate at higher temperatures suitable for supercritical CO2 cycles, but thermal efficiency decreases due to increased radiant and convective heat losses
Solution Approach 1:
The patent implements a nested cavity structure where an internal cavity is positioned within an external cavity. The internal cavity contains the heat transfer medium channels and absorbs solar radiation, while the external cavity provides an additional thermal barrier. This nested configuration reduces radiant and convective heat losses to the environment, enabling high-temperature operation above 650°C while maintaining thermal efficiency above 90%.
Solution Approach 2:
The patent employs selective surface coatings on the cavity walls with controlled emissivity properties. These coatings are designed to absorb solar radiation effectively while minimizing thermal radiation losses at high temperatures. The use of such surface treatments allows the system to operate at elevated temperatures without proportionally increasing heat losses, thus maintaining high thermal efficiency.
2Loss of energy
If conventional receiver designs are used, then the structure is simpler, but thermal efficiency remains low due to direct heat loss from hot surfaces to the environment
Solution Approach 1:
The patent implements a nested cavity structure where an internal cavity is positioned within an external cavity. The internal cavity contains the heat transfer medium channels and absorbs solar radiation, while the external cavity provides an additional thermal barrier. This nested configuration reduces radiant and convective heat losses to the environment, enabling high-temperature operation above 650°C while maintaining thermal efficiency above 90%.
Solution Approach 2:
The patent introduces a heat transfer medium (such as air, CO2, or particulate matter) as an intermediary between the absorbed solar radiation and the working fluid. This medium circulates through channels in the cavity walls, absorbing thermal energy and transferring it efficiently to the working fluid. This intermediary approach enhances heat transfer effectiveness and reduces direct thermal losses.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances thermal efficiency by maximizing radiation absorption and minimizing losses, allowing the system to operate at temperatures exceeding 650°C with thermal efficiencies above 90%.
Implementation Method 1
radiation is absorbed and reflected multiple times to minimize energy loss
Implementation Method 2
radiant and convective heat losses from the receivers' various hot surfaces to the environment
Implementation Method 3
convective heat losses from the receivers' various hot surfaces to the environment
Data Source
AI summary
An aspect of the present disclosure is a receiver for receiving radiation from a heliostat array that includes at least one external panel configured to form an internal cavity and an open face. The open face is positioned substantially perpendicular to a longitudinal axis and forms an entrance to the internal cavity. The receiver also includes at least one internal panel positioned within the cavity and aligned substantially parallel to the longitudinal axis, and the at least one internal panel includes at least one channel configured to distribute a heat transfer medium.