Efficiently Optimizing Solar Dish Receiver Designs

Caty Fairclough May 29, 2017
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When designing a solar dish receiver, you may need to rerun your simulation multiple times to find an optimized design iteration. To save time, you can build an app that enables you to rapidly test different geometries and more easily create improved designs. Let’s explore a new simulation app in COMSOL Multiphysics® version 5.3, the Solar Dish Receiver Designer, which you can use as inspiration for building apps of your own.

Designing Efficient Devices for Collecting Solar Energy

For solar energy to reach Earth, it has to travel millions of miles through the vacuum of space. After a long journey, most of the energy reflects back into space or is absorbed by the atmosphere, leaving less than half to be absorbed by Earth’s surface.

A photograph of a sunset on a beach, illustrating the concept of solar radiation.
Solar radiation hitting Earth.

A portion of the solar radiation absorbed by the earth’s surface reaches devices that can use this energy. Paraboloidal solar dish collectors, for example, focus incident solar radiation into a small region (the cavity receiver). This region generates intense heat that can be transformed into chemical or electrical energy, which can power electronic devices.

A photograph of a paraboloidal dish.
A schematic of solar radiation entering a paraboloidal dish concentrator.

Left: A paraboloidal dish. Image by Thennicke — Own work. Licensed under CC BY-SA 4.0, via Wikimedia Commons. Right: Schematic depiction of a simple paraboloidal dish concentrator with solar radiation entering from the right.

When designing solar dishes, it’s important to maximize their efficiency so that they use as much of the available solar energy as possible. While this can be achieved by rerunning simulations to analyze small design variations, there is an easier way. By turning a model into an app, you can enable colleagues and coworkers to quickly test different geometries. Meanwhile, you can spend your time working on other projects instead of continuously running simulation tests for design changes.

Let’s examine an example app that can help you analyze solar dish receiver designs.

Simplifying the Solar Dish Receiver Design Process with an App

The Solar Dish Receiver Designer supports six different cavity geometries:

  1. Cylindrical
  2. Dome
  3. Heteroconical
  4. Elliptical
  5. Spherical
  6. Conical

App users select a cavity type by simply clicking on the appropriate icon in the Cavity Settings section on the app’s left side.

To view the updated geometry, users click on the Update/Show Geometry button in the ribbon. The resulting geometry then appears on the right side of the app, as shown below.

A screenshot of the Solar Cavity Receiver Designer.
The user interface for the Solar Cavity Receiver Designer with the heteroconical geometry selected.

If further changes to the geometry or physics are needed, it’s easy to make them by specifying values in the Geometry Settings, Cylindrical Cavity Settings, and Physics Settings sections. Here, app users can alter the focal length and rim angle of the dish, cavity radius and height, absorption coefficient of the cavity walls, solar irradiance, and more. You can choose different inputs and outputs for your own app to customize it for your organization’s needs.

In this case, the chosen fields enable us to investigate different perturbations and deviations from an ideal design: a perfectly smooth dish reflecting a collimated beam. For instance, by altering the solar disc angle parameter, users can account for sunshape — which covers perturbations in incident ray directions and the solar limb darkening phenomenon.

If app users want to account for surface roughness of the dish instead, they enter a surface slope error. It’s also possible to specify the absorption coefficients for both the cavity and dish surfaces. All of this can be performed without the assistance of a simulation expert because the complicated physics are hidden underneath a simplified user interface.

Simulation Results for the Solar Dish Receiver

After choosing a preferred geometry and entering the desired parameters, users can click on the Compute button in the app ribbon to find the flux distribution. In this example, a parabolic dish reflects incident solar radiation and a small cavity receiver collects the concentrated energy. As such, the app traces the reflected solar rays as they travel from the paraboloidal dish to the cavity receiver that is positioned at the focal plane.

The number of rays analyzed within this study can be altered within this same ribbon via the Advanced Settings button. By default, the app releases rays from 1000 distinct points. The app’s users can increase this number to achieve a better statistical convergence and more accurate flux distribution, but it uses more memory and time.

 

Video showing the Solar Dish Receiver Designer.

The user interface of the demo app provides the ability to create three different plots to display results. The plots are generated by selecting one of the following buttons in the ribbon:

  1. The Flux Distribution in the Focal Plane button creates a plot that shows the focal plane’s incident solar flux.
  2. The Radial Concentration Ratio in the Focal Plane button plots the concentration ratio as a function of the focal plane’s radial position. (The concentration ratio is a key element in the performance of solar thermal power systems.)
  3. The Flux Distribution on the Side Walls button generates a plot that visualizes the incident heat flux on the cavity receiver’s side walls.

After receiving the desired data for the customized set of parameters, app users can click on the Generate Report button in the ribbon to export their findings. This also functions as a convenient way to keep track of the parameters that they tested.

Improve the Design of Solar Dish Receivers with an App

The Solar Dish Receiver Designer highlights how apps provide users with a great deal of flexibility. From start to finish, the straightforward user interface simplifies the process of analyzing designs and sharing findings — clearing the way for an optimized solar dish receiver design.

Click the button below to try out this app. We hope that it will inspire you to create apps of your own.

Further Resources


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