الفهرس 
Stirling engineOnly 14 pages are availabe for public view
 |  | from | 204 |  |  |
| | | from | 204 | | |
Abstract
According to the objective of this research, an investigation
of the performance of transposed-fluids heat exchangers to be
used in Stirling engine design, eight simple heat exchangers were
designed, manufactured, and tested experimentally to be used as a
heater and a cooler in the alpha type Stirling engine.
Each specimen was a shell-and-tube, air-to-water, and
elbow bend heat exchanger. As a first step a number of five heat
exchangers were designed, manufactured, and tested. Each
specimen of this group has a different tube bank arrangement and
geometrical configuration. The specimen which has minimum dead
volume, low pressure DROP and high rate of heat transfer was
selected as the best one to be improved in the second step. From
the discussion of the first step experimental results, it was found
that a specimen of (quadrant cross-section) and circular tube
arrangement can be selected as the best one.
Three specimens were manufactured similar to the best one.
These specimens have the same geometrical configuration and
tube bank arrangement, but have different tube spacing. So they
have different number of tubes consequently different dead
”
volumes. from the discussion of the second step experimental
results, it was found that the specimen of the least number of tubes
has the minimum pressure drop, but does not have the minimum
dead volume, while it has a reasonably high rate of heat transfer Each one of the eight tested specimens was employed
individually as a heater and a cooler in a computer program (Excel
program) to study the engine performance analytically. Based on
the Schmidt analysis the engine work space was divided into three
isothermal regions. This program considers the friction losses and
consequently the pressure DROP due to the working fluid flow
through each part of the engine.
The dimensions of the engine parts were optimized
analytically according to two schemes to get a maximum output
power. In the first scheme, different strokes of the expansion and
compression were assumed. In the second scheme, they were
assumed to be equal. For all calculations the optimum performance
was calculated at a charging pressure, which insures 40 bar
maximum pressure inside the machine. The cooling water mass
flow rate and its inlet temperature to the cooler were assumed
constant. Also the hot gasses mass flow rate and its inlet
temperature to the heater were assumed constant. The inner
diameter of the expansion and compression spaces was assumed
to be equal. The optimum dimensions of the engine were found.
The optimum engine power was found for a specimen which has
square cross-section, in-line tube bank arrangement.