Graduation date: 2008
Driven by the need for high energy-density power sources, demand has
stimulated the development of small-scale engines. A small-scale engine
with a fuel supply could replace batteries and utilize higher energy-density
liquid hydrocarbon fuels; such an advance could deliver a new age of
portable devices. Currently, operable small-scale engines exist; yet their
efficiencies are poor. One possible alternative for improving efficiency is
the incorporation of thermal regeneration. This thesis develops a concept
for an efficient miniature reciprocating engine for portable power production
that is based upon the regenerated atmospheric cycle and uses a
magnet-actuated in-cylinder regenerator. As part of the development of
the proposed engine, a dynamic model of the regenerator was developed
concurrently with an engine simulator. The dynamic model was validated
using the engine simulator and can now be used to develop a model to
study the thermal aspects of regeneration. The engine simulator was also
used to study a unique lubrication-free low-friction piston-cylinder set
that utilizes a graphite-glass clearance seal. The piston cylinder set was
subjected to several pressure tests, including one with a 26 h duration. It
was found that with the addition of aspiration slots, the piston cylinder
set with the engine simulator operating at 1800 rpm could reach a peak
pressure of approximately 370 kPa with a pressure ratio of approximately
4.2. For the 26 h long-duration test, it was found that the graphite piston
did not show any significant wear. However, elastomer cups that were
part the ball-joint supports for the piston did exhibit wear that lead to a
decrease in peak cycle pressure with time.