Ericsson cycle

[2] The following is a list of the four processes that occur between the four stages of the ideal Ericsson cycle: The ideal Otto and Diesel cycles are not totally reversible because they involve heat transfer through a finite temperature difference during the irreversible isochoric/isobaric heat-addition and isochoric heat-rejection processes.

The aforementioned irreversibility renders the thermal efficiency of these cycles less than that of a Carnot engine operating within the same limits of temperature.

Ericsson coined the term "regenerator" for his independent invention of the mixed-flow counter-current heat exchanger.

Stirling called it an "economiser" or "economizer", because it increased the fuel economy of various types of heat processes.

When heat is recovered from exhaust gases and used to preheat combustion air, typically the term recuperator is used, because the two flows are separate.

Ericsson invented and patented his first engine using an external version of the Brayton cycle in 1833 (number 6409/1833 British).

Ericsson's engine can easily be modified to operate in a closed-cycle mode, using a second, lower-pressure, cooled container between the original exhaust and intake.

Because of the higher pressure difference between the upward and downward movement of the work-piston, specific output can be greater than of a valveless Stirling engine.

Ericsson was also responsible for an early use of the screw propeller for ship propulsion, in the USS Princeton, built in 1842–43.

It had a combination of four dual-piston engines; the larger expansion piston/cylinder, at 14 feet (4.3 m) in diameter, was perhaps the largest piston ever built.

The ship was wrecked when blown aground in November 1892 at the entrance to Barkley Sound, British Columbia, Canada.

An important advantage of the Ericsson cycle over the widely known Stirling engine is often not recognized : the volume of the heat exchanger does not adversely affect the efficiency.

With high temperature hydraulic fluid, both the compressor and the expander can be liquid-ring pumps even up to 400 °C, with rotating casing for best efficiency.

Rendering of an Ericsson engine. A cold gaseous working fluid, such as atmospheric air (shown in blue), enters the cylinder via a non-return valve at the top-right. The air is compressed by the piston (black) as the piston moves upward. The compressed air is stored in the pneumatic tank (at left). A two-way valve (gray) moves downward to allow pressurized air to pass through the regenerator where it is preheated. The air then enters the space below the piston, which is an externally heated expansion-chamber . The air expands and does work on the piston as it moves upward. After the expansion stroke, the two-way valve moves upward, thus closing off the tank and opening the exhaust port . As the piston moves back downward in the exhaust stroke, hot air is pushed back through the regenerator , which reclaims most of the heat, before passing out the exhaust port (left) as cool air.
Ideal Ericsson cycle
Ericsson Caloric engine
Ericsson Caloric Engine