physics

Particle receiver

Particle receiver is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Particle receiver rather than just read about it. In short: A particle receiver is an object placed on the top of a solar tower on which surface solar energy is concentrated by means of a solar field composed of large number of mirrors, called heliostats. The goal is to transform solar energy into thermal energy that can be used in a heat process, thermochemical process, or in a heat engine to produce electricity in a solar tower power plant.

Key takeaways

Particle receiver belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Particle receiver to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Particle receiver from memory before moving on to harder problems.

Reference excerpt

A particle receiver is an object placed on the top of a solar tower on which surface solar energy is concentrated by means of a solar field composed of large number of mirrors, called heliostats. The goal is to transform solar energy into thermal energy that can be used in a heat process, thermochemical process, or in a heat engine to produce electricity in a solar tower power plant. To accomplish this, it is necessary to introduce certain material, called heat transfer medium, to the receiver that is then heated up, either directly or indirectly, by the concentrated solar energy before leaving the receiver at a higher temperature. Unlike receivers used in conventional concentrated solar power (CSP), power plants which employ molten salts as a heat transfer medium that is heated indirectly by flowing through the metal tubes that are exposed to the concentrated solar energy, particle receivers adopt solid particles which then can be heated either directly or indirectly, depending on the technology considered. One of the main advantages of adopting particles as a heat transfer medium is the possibility of direct heating, where particles are exposed directly to the incoming solar radiation, thus avoiding issues related to non-uniform heating of receiver tubes. Also, the possibility to reach temperatures above 1000 °C allows for the adoption of Brayton cycle with supercritical CO2 as the working fluid which can achieve higher thermal efficiency compared to the steam Rankine cycle which is used in the conventional CSP power plants that have a maximum temperature limit of 565 °C due to issues related with the thermal stability of the molten salts.

Directly heated particle receiver

Free-falling receiver

This technology is based on a free-falling particle curtain inside the receiver cavity that absorbs concentrated solar radiation. The idea of using falling solid particles in a concentrated solar power facility to supply high-temperature heat to the power cycle or chemical process was introduced in a pioneering work carried out by Martin and Vitko during the beginning of the 1980s at Sandia National Laboratories. However, the first step towards demonstrating the concept at the larger scale was carried out in 2009 at National Solar Thermal Test Facility in Albuquerque, New Mexico, where prototype particle receiver was placed atop the 61-meter-tall (200 ft) solar tower with a solar field able to provide 5 MWth. These tests resulted in receiver thermal efficiency of around 50% and maximum temperature increase of the particles of around 250 °C. More comprehensive tests were carried out in 2015 using a 1 MWth receiver having a 1 by 1 meter aperture through which concentrated sun radiation enters the cavity. Receiver thermal efficiency ranged from 50% to 80%, and the temperature of the particles at the bottom of the receiver reached 700 °C in some cases. Limit on the maximum temperature of molten salts used in the conventional solar tower power plants led to a workshop organized by United States Department of Energy (DOE) in August 2016 which identified three possible pathways for the next generation CSP power plants based on the following heat transfer carriers: molten salts, solid particles, and gaseous fluids. This further led to the Generation 3 Concentrating Solar Power Systems funding program that started on May 15 of 2018 when DOE announced its intention to provide $72 million to the project where three teams are going to compete in building a system integrated with a thermal energy storage that is able to efficiently capture solar energy and provide it to the working fluid of the power cycle at temperatures above 700 °C. On March 25, 2021 DOE announced that the pathway adopting falling solid particles is the most promising one for achieving 2030 cost targets of 0.05$/kWh and awarded Sandia National Laboratories with $25 million for building, testing, and operating pilot plant adopting particle receiver at National Solar Thermal Test Facility which is expected to be completed by the end of 2024.

Obstructed-flow receiver Idea of obstructing the flow of particles while retaining the concept of direct heating is motivated by the fact that by slowing down the flow of particles, it is possible to increase thermal efficiency of the receiver by increasing the opacity of the particle curtain and reduce their loss through the aperture. Early tests of this concept were carried out at Sandia during the 1980s, but no analytical nor experimental studies were published until the 2010s. Experiments carried out at Sandia in 2015 using chevron-shaped porous structures managed to improve heating of the particles and reduce their loss through the receiver aperture. However, there were problems related to the direct exposure of the stainless steel 316, used for constructing these porous structures, to concentrated solar radiation, and its wear due to particle flow over it. Another design proposes to use a spiral ramp over which particles flow due to the combined effect of the gravitational force and mechanically induced vibrations. Tests showed that it is possible to reach particle temperature of 650 °C and thermal efficiency of around 60%. However, this design requires beam-down optics that would result in additional optical losses, and significant particle flow could be difficult to obtain using the proposed design.

Centrifugal receiver

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Particle receiver

Start with the simplest possible case. Write down what Particle receiver claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Particle receiver before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Particle receiver ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Particle receiver

In research: Particle receiver appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Particle receiver in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Particle receiver is common in secondary-school and first-year university syllabi. It links to neighbouring topics Solar energy, Solar thermal energy, so understanding it makes those chapters shorter.
In everyday life: Look for Particle receiver outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Particle receiver in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Particle receiver means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Particle receiver out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Particle receiver in simple terms?

Why does Particle receiver matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Particle receiver?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Particle receiver.