The design of a prototype Otto-Atkinson engine and evaluation of the part load fuel efficiency

This thesis is an investigation into the application of the hybrid Otto-Atkinson cycle, as a means of improving the part load fuel efficiency of spark-ignition engines. The primary objective of this thesis was to investigate the technical feasibility of the modified Atkinson cycle as a spark-ignition engine concept and thus to quantify the associated potential for greater fuel efficiency. The modified Atkinson cycle is a hybrid cycle which approximates the Otto cycle at full load but tends to emulate the Atkinson cycle at part load, and therefore it is referred to as the Otto-Atkinson cycle. In order to fulfil this objective, a single cylinder engine which operated on the Otto-Atkinson cycle, was designed and constructed. This unusual cycle was achieved by a crank linkage which allowed the power output to be controlled by varying the inlet and compression strokes rather than by the more conventional method of throttling the induced fuel-air mixture. Thus the pumping losses associated with throttled part-load operation are eliminated. Furthermore, the expansion stroke is always greater than the compression stroke, the difference being greatest at part loads. This results in a cycle which approximates the Atkinson cycle for part-load operation. A simplified thermodynamic simulation of the cycle was formulated. Theoretical predictions were made based on this simulation.

Grantor dc:publisher.institution

Department of Mechanical Engineering

Year dc:date.issued

1992

Author dc:creator

• Van Binsbergen, Peter J

Advisor dc:contributor.advisor

• Yates, Andrew

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/17351

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/17351