Condensing Steam Engine

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Group Design Project
Designing an engine to be powered by low grade waste heat with electronic control which can be further developed to generate electricity
Group Members
S. Brizzi, E. Fraser, M. Hamdis, M. O’Hara, W. Porter, M. Thonduparampil

Supervisors
Dr. Gerald Muller, Professor Andrew Cruden

The aim of this project was to design, build and test a condensing steam engine using ideas taken from the 18th century machine built by James Watt. This would then be brought into the 21st century by including an electronic control system for testing forced expansion giving higher efficiencies.

The low theoretical efficiency of these engines caused their wide spread use to come to an end during the 19th century. However, the modernisation of the engine and the forced expansion of steam, with a view to obtaining efficiencies of over 10%, have once again made this engine a viable technology.

One cubic metre of steam per second at 100 °C contains 1.6 MW of energy. The recovery of this energy, with an efficiency of 10%, would provide 160 kW of electricity, enough to power 160 households, saving up to £806 a day.

The condensation of steam creates an area of low pressure on one side of the piston. The pressure difference between that and the atmospheric steam on the other side of the piston causes a force on the piston that drives the engine.

As part of modernising the engine, electronically operated valves control the steam flow through the machine. Using a MyRio Data Acquisition system together with LabVIEW software allows for observation of pressures within the machine and precise manipulation of valve timings.

The forced expansion cycle allows the steam to expand past atmospheric pressure by preventing the inlet of steam during the latter part of the stroke. This allows for a greater power output from the same amount of steam and so a higher efficiency.

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