Liquid-metal Rankine power conversion systems (PCS) coupled with a fission reactor
remain an attractive option for space power applications because system specific power
and efficiency is very favorable for plant designs of 100 kW(e) or higher. Potential
drawbacks to the technology in a reduced gravity environment include two-phase fluid
management processes such as liquid-vapor phase separation. The most critical location
for phase separation is at the boiler exit where only vapor must be sent to the turbine
because blade erosion occurs from high velocity liquid droplets entrained by vapor flow.
Previous studies have proposed that rotary separators be used to separate the liquid and
vapor from a two phase mixture. However these devices have complex turbo machinery,
require kilowatts of power and are untested for high vapor flow conditions. The
Interphase Transport Phenomena (ITP) laboratory has developed a low-power, passive
microgravity vortex phase separator (MVS) which has already proven to be an essential
component of two-phase systems operating in low gravity environments.
This thesis presents results from flight experiments where a Rankine cycle was operated
in a reduced gravity environment for the first time by utilizing the MVS for liquid and
vapor phase separation. The MVS was able to operate under saturated conditions and
adjust to system transients as it would in the Rankine cycle by controlling the amount of
liquid and vapor within the device. A new model is developed for the MVS to predict
separation performance at high vapor flow conditions for sizing the separator at the boiler, condenser, and turbine locations within the cycle by using a volume limiting
method. This model factors in the following separator characteristics: mass, pumping
power, and available buffer volume for system transients. The study is concluded with
overall Rankine efficiency and performance changes due to adding vortex phase
separation and a schematic of the Rankine cycle with the integration of the MVS is
presented. The results from this thesis indicate the thermal to electric efficiency and
specific mass of the cycle can be improved by using the MVS to separate the two phases
instead of a rotary separator.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/85858 |
| Date | 10 October 2008 |
| Creators | Supak, Kevin Robert |
| Contributors | Best, Fred R. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, born digital |
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