Brayton cycle

[1] An engine using the cycle was originally proposed and patented by Englishman John Barber in 1791, using a reciprocating compressor and a turbine expander.

In 1872, George Brayton applied for a patent for his "Ready Motor", a reciprocating heat engine operating on a gas power cycle.

[3] The fuel / air was contained in a reservoir / tank and then it was admitted to the expansion cylinder and burned.

[4] Brayton produced and sold "Ready Motors" to perform a variety of tasks like water pumping, mill operation, running generators, and marine propulsion.

[6] Inspired by the internal combustion engine invented by Brayton displayed at the Centennial Exposition in Philadelphia in 1876, Selden patented a four-wheel car working on a smaller, lighter, multicylinder version.

He then filed a series of amendments to his application which stretched out the legal process, resulting in a delay of 16 years before the patent[6] was granted on November 5, 1895.

Selden had never actually produced a working car, so during the trial, two machines were constructed according to the patent drawings.

The liquid was forced through a spring-loaded, relief-type valve (injector) which caused the fuel to become divided into small droplets.

Brayton describes the invention as: “I have discovered that heavy oils can be mechanically converted into a finely divided condition within a firing portion of the cylinder, or in a communicating firing chamber.” Another part reads, “I have for the first time, so far as my knowledge extends, regulated speed by variably controlling the direct discharge of liquid fuel into the combustion chamber or cylinder into a finely divided condition highly favorable to immediate combustion.” This was likely the first engine to use a lean-burn system to regulate engine speed and output.

In this manner, the engine fired on every power stroke and speed and output were controlled solely by the quantity of fuel injected.

A variable-quantity injection pump provided the fuel to an injector where it was mixed with air as it entered the cylinder.

Rudolf Diesel originally proposed a very high compression, constant-temperature cycle where the heat of compression would exceed the heat of combustion, but after several years of experiments, he realized that the constant-temperature cycle would not work in a piston engine.

[10] (velox burner, aerodynamics by Stodola) A Brayton-type engine consists of three components: a compressor, a mixing chamber, and an expander.

In the original 19th-century Brayton engine, ambient air is drawn into a piston compressor, where it is compressed; ideally an isentropic process.

The compressed air then passes through a mixing chamber where fuel is added, an isobaric process.

Figure 2 indicates how the specific power output changes with an increase in the gas turbine inlet temperature for two different pressure ratio values.

The highest gas temperature in the cycle occurs where work transfer to the high pressure turbine (rotor inlet) takes place.

The closed Brayton cycle is used, for example, in closed-cycle gas turbine and space power generation.

[remove or clarification needed] In 2002, a hybrid open solar Brayton cycle was operated for the first time consistently and effectively with relevant papers published, in the frame of the EU SOLGATE program.

[dubious – discuss][citation needed] This is an open Brayton cycle which also generates work from heat, but with a different order of the stages.

Incoming air is first heated at atmospheric pressure, and then passes through the turbine, generating work.