physics

Trompe

Trompe 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 Trompe rather than just read about it. In short: A trompe is a water-powered air compressor, commonly used before the advent of the electric-powered compressor. A trompe is somewhat like an airlift pump working in reverse.

Key takeaways

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

Reference excerpt

A trompe is a water-powered air compressor, commonly used before the advent of the electric-powered compressor. A trompe is somewhat like an airlift pump working in reverse. Trompes were used to provide compressed air for bloomery furnaces in Catalonia and the United States. The presence of a trompe is a signature attribute of a Catalan forge, a type of bloomery furnace. Trompes can be enormous. At Canadian Hydro Developers' Ragged Chute facility in New Liskeard, Ontario, water falls down a shaft 351 feet (107 m) deep and 9 ft (2.7 m) across to generate compressed air for mining equipment and ventilation.

Operation Trompes are very simple devices. They consist of four main parts: a water-supply pipe or shaft with an air-inlet inside it, a water outflow pipe, a separation chamber, and a takeoff air-pipe. The vertical pipe or shaft goes down from higher point to a separation chamber; a pipe, that is typically narrower than previous one, coming away from that chamber, allows the water to exit at a lower level, and another pipe (air-pipe) coming from the chamber allows the compressed air to exit as needed.

Water rushing down the vertical pipe falls through a constriction. The constriction produces a lower pressure because of the venturi effect, and an external port allows air to be sucked in thus creating a constant air supply. The air forms bubbles in the pipe. As the bubbles go down the pipe they are pressurized proportionally to the hydraulic head, which is the height of the column of water in the pipe. The compressed air rises to the top of the separation chamber (wind box). The separation chamber has a compressed-air takeoff pipe, and the compressed air can be used as a power source. The energy of the falling water creates a partial vacuum inside the pipe that is compensated by the air from the outside atmosphere provided through inlet. The air is compressed by surrounding water pressure (which increases under a column due to the discharge to atmospheric pressure). The pressure of the air delivered cannot exceed the hydraulic head of the discharge pipe of the separation chamber. Large trompes were often situated at high waterfalls so that ample head was available. (However, trompes can raise the water, via siphon-effect, nearly to 70% of its initial elevation.) The Ragged Chute plant on the Montreal River near the town of Cobalt, Ontario, is a trompe and tourist attraction. It is now owned by TransAlta (formerly by Canadian Hydro Developers), and while the structures of the trompe still exist, it no longer functions as a compressed air plant and currently exists next to a functioning modern hydroelectric plant. Compressed air from a trompe is at the temperature of the water, and its partial pressure of water vapor is that of the dewpoint of the water's temperature. If the water is cool, the compressed air can be made very dry by passing it through pipes that are warmer than the water. Often, ordinary outside air can warm the pipes enough to produce dry, cool compressed air. Today, trompes constructed of plastic pipe are being used to provide aeration for mine drainage treatment. In this application, mine water is used to drive the trompe and the compressed air that is generated is used to oxygenate the mine water and to drive off excess dissolved carbon dioxide that may be present thus raising the pH of the water being treated. The trompe is closely related to the Sprengel vacuum pump which uses mercury falling through a tube to create a vacuum instead of pressure.

See also Bloomery (Catalan forge) Hydraulic ram Pulser pump

References

External links

Farga Rossell a catalan furnace in Andorra (retrieved April 2, 2011) Article in Mother Earth News (retrieved October 15, 2011) Ragged Chutes in Cobalt Ontario. Uses a 107-meter head. (previously retrieved August 27, 2009, as of May 19, 2010 cobalt.ca no longer has technical details of the chute) Cobalt Mining Legacy Archived 2010-08-05 at the Wayback Machine Ragged Chutes technical details (retrieved August 6, 2010) C. H. Taylor pioneer hydraulic compressor designer including Ragged Chutes in Cobalt Ontario (retrieved August 6, 2010) Illustrated Book by C.H. Taylor: Taylor Hydraulic Air Compressor (1897) (retrieved October 16, 2011) Trompe Catalan Furnace in San Juan Capistrano, California

Illustrations

Worked examples

Example 1 — a first encounter with Trompe

Start with the simplest possible case. Write down what Trompe 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 Trompe 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 Trompe 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 Trompe

In research: Trompe 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 Trompe 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: Trompe is common in secondary-school and first-year university syllabi. It links to neighbouring topics Compressors, Energy conversion, Industrial furnaces, so understanding it makes those chapters shorter.
In everyday life: Look for Trompe 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 Trompe in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Trompe 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 Trompe out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Trompe in simple terms?

A trompe is a water-powered air compressor, commonly used before the advent of the electric-powered compressor. A trompe is somewhat like an airlift pump working in reverse.

Why does Trompe 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 Trompe?

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 Trompe.