Evaluation of the evacuated solar annular receivers used at the midtemperature solar systems test facility (MSSTF)
Experimental studies at the Sandia/DOE Midtemperature Solar Systems Test Facility (MSSTF) using the parabolic-cylindrical collector field subsystem are described. Tests evaluated vacuum integrity characteristics of ten glass-to-metal sealed concentric-cylinder receivers installed at the MSSTF in May 1977. Additional testing measured heat-loss reductions and related collector performance gains possible by annulus gas evacuation. Structural defects in four receivers and gas desorption from the receiver tubes at temperatures > 470/sup 0/K necessitated continuous annulus gas evacuation. Pressure rises of 1.8 x 10/sup -4/ Pa/s and 2.2 x 10/sup -2/ Pa/s, measured with receiver tube surfaces at 443/sup 0/K and 578/sup 0/K, respectively, are indicative of the outgassing. One-sun heat-loss and collector efficiency tests were performed with air-filled annular spaces maintained at 8.379 x 10/sup 4/ Pa (atmospheric pressure) and at pressures < 10 Pa. Overall collector efficiency improved by 3.5 to 9% and one-sun heat losses were reduced by 20 to 50%, depending upon operating temperature, annulus pressures, and insolation. Failure of the receiver assemblies to maintain annulus pressures below 1 Pa precluded expected overall efficiency improvements of 11 to 12%. Further, onsite vacuum maintenance was proved unfeasible because of the extensive pumpout manifolding and the additional manpower, parasitic energy, and capital equipment costs required.
- Research Organization:
- Sandia Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- EY-76-C-04-0789
- OSTI ID:
- 6082886
- Report Number(s):
- SAND-78-0983
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
EVACUATED TUBE COLLECTORS
TESTING
PARABOLIC TROUGH COLLECTORS
PERFORMANCE TESTING
SOLAR RECEIVERS
COMPUTERIZED SIMULATION
COST
DEFECTS
DEGASSING
EFFICIENCY
HEAT LOSSES
INSOLATION
MATHEMATICAL MODELS
MEDIUM VACUUM
PERFORMANCE
PRESSURE MEASUREMENT
SIMULATION
SOLAR ABSORBERS
TEST FACILITIES
TUBES
CONCENTRATING COLLECTORS
ENERGY LOSSES
EVACUATED COLLECTORS
LOSSES
PARABOLIC COLLECTORS
SOLAR COLLECTORS
141000* - Solar Collectors & Concentrators