Performance comparison of a novel thermofluidic organic-fluid heat converter and an organic rankine cycle heat engine
File(s)ASMEORC2015_KirmseetalPaper.pdf (402.42 KB)
Accepted version
Author(s)
Kirmse, C
Taleb, AJ
Oyewunmi, OA
Haslam, AJ
Markides, CN
Type
Conference Paper
Abstract
The Up-THERM engine is a novel two-phase heat engine with a single moving part–a vertical solid
piston–that relies on the phase change of a suitable working fluid to produce a reciprocating displacement
and sustained thermodynamic oscillations of pressure and flow rate that can be converted to useful work.
A model of the Up-THERM engine is developed via lumped dynamic descriptions of the various engine
sub-components and electrical analogies founded on previously developed thermoacoustic principles.
These are extended here to include a description of phase change and non-linear descriptions of selected
processes. The predicted first and second law efficiencies and the power output of a particular Up-
THERM engine design aimed for operation in a specified CHP application with heat source and sink
temperatures of 360 ○C and 10 ○C, are compared theoretically to those of equivalent sub-critical, nonregenerative
organic Rankine cycle (ORC) engines. Five alkanes (from n-pentane to n-nonane) are being
considered as possible working fluids for the aforementioned Up-THERM application, and these are
also used for the accompanying ORC thermodynamic analyses. Owing to its mode of operation, lack
of moving parts and dynamic seals, the Up-THERM engine promises a simpler and more cost-effective
solution than an ORC engine, although the Up-THERM is expected to be less efficient than its ORC
counterpart. These expectations are confirmed in the present work, with the Up-THERM engine showing
lower efficiencies and power outputs than equivalent ORC engines, but which actually approach ORC
performance at low temperatures. Therefore, it is suggested that the Up-THERM can be a competitive
alternative in terms of cost per unit power in low-power/temperature applications, especially in remote,
off-grid settings, such as in developing countries where minimising upfront costs is crucial.
piston–that relies on the phase change of a suitable working fluid to produce a reciprocating displacement
and sustained thermodynamic oscillations of pressure and flow rate that can be converted to useful work.
A model of the Up-THERM engine is developed via lumped dynamic descriptions of the various engine
sub-components and electrical analogies founded on previously developed thermoacoustic principles.
These are extended here to include a description of phase change and non-linear descriptions of selected
processes. The predicted first and second law efficiencies and the power output of a particular Up-
THERM engine design aimed for operation in a specified CHP application with heat source and sink
temperatures of 360 ○C and 10 ○C, are compared theoretically to those of equivalent sub-critical, nonregenerative
organic Rankine cycle (ORC) engines. Five alkanes (from n-pentane to n-nonane) are being
considered as possible working fluids for the aforementioned Up-THERM application, and these are
also used for the accompanying ORC thermodynamic analyses. Owing to its mode of operation, lack
of moving parts and dynamic seals, the Up-THERM engine promises a simpler and more cost-effective
solution than an ORC engine, although the Up-THERM is expected to be less efficient than its ORC
counterpart. These expectations are confirmed in the present work, with the Up-THERM engine showing
lower efficiencies and power outputs than equivalent ORC engines, but which actually approach ORC
performance at low temperatures. Therefore, it is suggested that the Up-THERM can be a competitive
alternative in terms of cost per unit power in low-power/temperature applications, especially in remote,
off-grid settings, such as in developing countries where minimising upfront costs is crucial.
Date Issued
2015-10-12
Date Acceptance
2015-05-01
Copyright Statement
© 2015 the Authors.
Source
3rd International Seminar on ORC Power Systems (ASME ORC 2015)
Start Date
2015-10-12
Finish Date
2015-10-14
Coverage Spatial
Brussels, Belgium