Performance issues in solar thermal energy transport systems
Pacific Northwest Laboratory, sponsored by the US Department of Energy through Sandia National Laboratories, is performing an assessment of three solar thermal electricity generating concepts; central receivers, dishes, and troughs. Concepts are being studied over a range of system sizes 0.5 MWe to 100 MWe with solar multiples from 1.0 to 2.8. Central receiver systems using molten salt, sodium, and water-steam working fluids are studied. The dish system selected for study uses a kinematic Stirling engine at the focal point, and the trough system is based on Accurex designed collectors heating a heat transfer oil. Of the three concepts studied, the central receiver and trough systems utilize thermal transport systems. A thermal transport system is the piping and fluid required to transfer thermal energy between receiver, and storage and between storage and steam generator. The literature contains many transport system designs, most of which are optimized with regard to cost and performance. We used the parameters specified from the optimizations to design our systems and scale the designs over the 0.5 MWe to 100 MWe size range. From these designs, thermal losses and pump sizes are derived then combined in a system model to obtain total annual averaged efficiency as a function of plant field size. We found that central receiver transport efficiency improves with field size whereas trough transport efficiency degrades with field size. We found that overnight cooldown accounts for roughly 50% of the total thermal losses for all transport systems. Trough performance is substantially degraded because the receiver tubes are not drained which allows a large overnight heat loss. Trough transport performance was found to be sensitive to fluid velocity.
- Research Organization:
- Pacific Northwest Lab., Richland, WA (USA)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 6446226
- Report Number(s):
- PNL-SA-14022; CONF-870307-22; ON: DE87011336
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
140700* -- Solar Thermal Power Systems
CENTRAL RECEIVERS
CONCENTRATING COLLECTORS
ENERGY LOSSES
ENGINES
EQUIPMENT
HEAT ENGINES
HEAT LOSSES
LOSSES
PARABOLIC COLLECTORS
PARABOLIC DISH COLLECTORS
PARABOLIC TROUGH COLLECTORS
PIPES
POWER PLANTS
SOLAR COLLECTORS
SOLAR EQUIPMENT
SOLAR POWER PLANTS
SOLAR RECEIVERS
SOLAR THERMAL POWER PLANTS
STIRLING ENGINES
THERMAL POWER PLANTS