Abstract
The objective of this thesis work has been to investigate the potential for positive displacement (or volumetric) types of expansion machines for the application in small scale cogeneration as alternatives to conventional turbo expanders. Major design parameters have been identified, and fairly generalized relation between design parameters and operational, application-specific, parameters have been established for various types of volumetric expanders. Rotary displacement expanders and the Lysholm twin-screw type in particular, as well as piston type expanders have been analyzed. This study has been concentrated on thermodynamic performance related to design parameters, and also on mechanical design aspects and constraints. The possibilities for direct drive of high-speed, high frequency generators, have also been considered. Analytical expressions for performance evaluation, based on major design parameters, have been derived. For the screw expander, also a more detailed model for computer simulation has been developed. Simulation results have been used for a generalized performance prediction for screw expanders, independent of machine size. Due to mechanical limitations and increased internal leakage at higher pressures, the screw expander should be limited to roughly 40 bar. For low/medium temperature expander applications, the screw machine application should then be straight-forward. In a 40 bar saturated steam cycle, the
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Platell, P
[1]
- Royal Inst. of Tech., Stockholm (Sweden). Dept. of Machine Design
Citation Formats
Platell, P.
Displacement expanders for small scale cogeneration.
Sweden: N. p.,
1993.
Web.
Platell, P.
Displacement expanders for small scale cogeneration.
Sweden.
Platell, P.
1993.
"Displacement expanders for small scale cogeneration."
Sweden.
@misc{etde_10117125,
title = {Displacement expanders for small scale cogeneration}
author = {Platell, P}
abstractNote = {The objective of this thesis work has been to investigate the potential for positive displacement (or volumetric) types of expansion machines for the application in small scale cogeneration as alternatives to conventional turbo expanders. Major design parameters have been identified, and fairly generalized relation between design parameters and operational, application-specific, parameters have been established for various types of volumetric expanders. Rotary displacement expanders and the Lysholm twin-screw type in particular, as well as piston type expanders have been analyzed. This study has been concentrated on thermodynamic performance related to design parameters, and also on mechanical design aspects and constraints. The possibilities for direct drive of high-speed, high frequency generators, have also been considered. Analytical expressions for performance evaluation, based on major design parameters, have been derived. For the screw expander, also a more detailed model for computer simulation has been developed. Simulation results have been used for a generalized performance prediction for screw expanders, independent of machine size. Due to mechanical limitations and increased internal leakage at higher pressures, the screw expander should be limited to roughly 40 bar. For low/medium temperature expander applications, the screw machine application should then be straight-forward. In a 40 bar saturated steam cycle, the total efficiency should be limited to roughly 15-20%. Piston machines have a potential for high-pressure applications and improved efficiency particularly at part load. For expansion of steam, with 200 bar, 500 centigrade admission, a total efficiency of roughly 30% should be possible at part load. However, several problems remain to be solved, e.g. concerning tribology and lubrication, valve design, materials selection, etc. 35 refs, 70 figs, 3 tabs}
place = {Sweden}
year = {1993}
month = {Dec}
}
title = {Displacement expanders for small scale cogeneration}
author = {Platell, P}
abstractNote = {The objective of this thesis work has been to investigate the potential for positive displacement (or volumetric) types of expansion machines for the application in small scale cogeneration as alternatives to conventional turbo expanders. Major design parameters have been identified, and fairly generalized relation between design parameters and operational, application-specific, parameters have been established for various types of volumetric expanders. Rotary displacement expanders and the Lysholm twin-screw type in particular, as well as piston type expanders have been analyzed. This study has been concentrated on thermodynamic performance related to design parameters, and also on mechanical design aspects and constraints. The possibilities for direct drive of high-speed, high frequency generators, have also been considered. Analytical expressions for performance evaluation, based on major design parameters, have been derived. For the screw expander, also a more detailed model for computer simulation has been developed. Simulation results have been used for a generalized performance prediction for screw expanders, independent of machine size. Due to mechanical limitations and increased internal leakage at higher pressures, the screw expander should be limited to roughly 40 bar. For low/medium temperature expander applications, the screw machine application should then be straight-forward. In a 40 bar saturated steam cycle, the total efficiency should be limited to roughly 15-20%. Piston machines have a potential for high-pressure applications and improved efficiency particularly at part load. For expansion of steam, with 200 bar, 500 centigrade admission, a total efficiency of roughly 30% should be possible at part load. However, several problems remain to be solved, e.g. concerning tribology and lubrication, valve design, materials selection, etc. 35 refs, 70 figs, 3 tabs}
place = {Sweden}
year = {1993}
month = {Dec}
}