A compressor is such a standard piece of equipment that we no longer think about it and it is used everywhere from pumps to air conditioners. If we can improve the design then it can lead to a huge power savings. A California company (Carnot) has come up with a new design that reduces the noise output, lasts longer and reduces the cost of ownership by 20 percent while using no oil. The new design uses a Trompe and combines it with a centrifuge to get it to work more efficiently.
A Trompe is an ancient technology which uses falling water to compress air. It was used extensively till fossil fuels made it less desirable by producing more power. Historically, miners have used large-scale trompes to power their mining equipment and provided ventilation. In fact a 350-feet-deep trompe was setup in Michigan which was able to produce 5,000 horsepower.
A trompe, often placed in a river, has a simple design. Flowing water falls into an intake pipe which has an air cone (or some other aerating device) on top. The water falling around the cone creates suction, pulling the air down with it. Air bubbles travel down the pipe with the water until reaching an air chamber.
At the air chamber (also called a plenum or reservoir), the bubbles escape from the water. In the process, the air has been compressed, dehumidified, and cooled to the same temperature as the water. The pressurized air can now be put to use.
Meanwhile, the water leaves through the outtake pipe. Air pressure from the reservoir pushes the water upwards, nearly to the same height it originally fell from, and the water returns to the river.
The issue with Trompe is that it needs a large setup if we want to generate enough compression and that is obviously not possible in all places. So the Carnot team explored options to accelerate the water movement and arrived at using a centrifuge. In their setup the compressor sucks in air through a filter at the top and mixes it with water on top of a fast moving drum, this outward force compresses the air and the mixture of air & water is forced out at that bottom where they are separated into air and water as they pass through the exit channel. The image below gives a good overview of how the technology would work:
Model of Carnot compressor
The resultant compressor is very quiet since the only moving parts are the spinning drum powered by an electric motor and an exhaust fan. In lab tests the system was found to operate indoors at below 70 dB. Obviously the technology is still quite new and needs to mature a lot before bulk deployment, but it is very interesting and I see a great future for it if it works as advertised.
Source: Carnot puts a centrifugal spin on a 500-year-old air compressor design
The Trompe: A Basic Overview
– Suramya