Non-tracking Solar Thermal Technology and Its Applications Bruce Johnston UC Solar University of...
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Transcript of Non-tracking Solar Thermal Technology and Its Applications Bruce Johnston UC Solar University of...
Non-tracking Solar Thermal Non-tracking Solar Thermal Technology and Its Technology and Its
ApplicationsApplications
Bruce JohnstonBruce JohnstonUC SolarUC Solar
University of California, MercedUniversity of California, [email protected]@sbcglobal.net
ObjectivesObjectives
The objective was to develop a non-The objective was to develop a non-tracking solar thermal system that tracking solar thermal system that would:would:– Operate at relatively high temperaturesOperate at relatively high temperatures– Be easily adapted for practical useBe easily adapted for practical use– Have a fairly low manufacturing costHave a fairly low manufacturing cost
ResultResult
XCPC design using MGVTXCPC design using MGVT Relies on non-imaging opticsRelies on non-imaging optics 60 degree acceptance angle60 degree acceptance angle Consistently operates at 200CConsistently operates at 200C Has the potential to operate at even Has the potential to operate at even
higher temperatures (approaching higher temperatures (approaching 400C)400C)
Significance of a Non-tracking Significance of a Non-tracking SystemSystem
CostCost– Trackers are priced in the thousands of Trackers are priced in the thousands of
dollarsdollars– Each tracker requires a power supplyEach tracker requires a power supply
Ease of MaintenanceEase of Maintenance– Few moving partsFew moving parts– Easier to keep cleanEasier to keep clean
StabilityStability– Sturdy, well anchored frameSturdy, well anchored frame
55
slider
R
Collector ShapeCollector Shape
2R/sin
Tube DesignTube Design
Standard Tube-in-tube designStandard Tube-in-tube design– Commercially availableCommercially available– ReliableReliable– Replacement rate is 2%-4% per yearReplacement rate is 2%-4% per year
U-tube designU-tube design– Designed by our groupDesigned by our group– Slightly better performance than the Slightly better performance than the
tube-in-tube designtube-in-tube design
Tube-in-tube ConfigurationTube-in-tube Configuration
1 Outer Glass1 Outer Glass 2 Absorber2 Absorber 3 Seal3 Seal 4 Outlet Channel4 Outlet Channel 5 Inlet Channel5 Inlet Channel
U-tube ConfigurationU-tube Configuration
Collector OrientationCollector Orientation
East WestEast West– Collectors are arranged horizontally or Collectors are arranged horizontally or
left to rightleft to right– Better performing than North South Better performing than North South
configuration at higher temperaturesconfiguration at higher temperatures North SouthNorth South
– Collectors are arranged vertically or up Collectors are arranged vertically or up and downand down
– Easy maintenance is a trade off for Easy maintenance is a trade off for slightly lower performanceslightly lower performance
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
-80.000 -60.000 -40.000 -20.000 0.000 20.000 40.000 60.000 80.000
Azimuth Angle
Effi ciency (PSolRad)
Efficiency with 60 degree Efficiency with 60 degree Acceptance AngleAcceptance Angle
Parabolic Trough Parabolic Trough ImprovementsImprovements
Angular tolerance could be increased from 0.5° to 2.0°
Thermodynamic efficiency could improve significantly
Overall system costs will be reduced
Vacuum Tube Vacuum Tube ImprovementsImprovements
Improve tube designImprove tube designBetter flow path designBetter flow path design
Better selective coatingsBetter selective coatings
Better vacuum sealsBetter vacuum seals
Selective Coating Selective Coating ImprovementImprovement
Low Emissivity (< 0.07 at 400C)Low Emissivity (< 0.07 at 400C) High Absorptivity (> 0.96)High Absorptivity (> 0.96) Low reflectance (Low reflectance (≈0) at wavelengths <= ≈0) at wavelengths <=
2 microns2 microns High reflectance (High reflectance (≈1) and wavelengths > ≈1) and wavelengths >
2 microns2 microns Stability in a vacuum at 400CStability in a vacuum at 400C
ApplicationsApplications
Process heat (e.g. to dry fruit)Process heat (e.g. to dry fruit) Desalination processesDesalination processes Heating and cooling of structuresHeating and cooling of structures
– Absorption chillersAbsorption chillers Single effectSingle effect Double effectDouble effect
Solar Cooling Demonstration Solar Cooling Demonstration ProjectProject
UC Solar ProjectUC Solar Project First of its kind in the USAFirst of its kind in the USA Student designedStudent designed 23.5 KW system23.5 KW system 6.5 ton double effect absorption 6.5 ton double effect absorption
chillerchiller Cools a 700 sq. ft. structureCools a 700 sq. ft. structure
UC Solar Absorption ChillerUC Solar Absorption Chiller
Broad 6.5 ton unitBroad 6.5 ton unit Hot water or gas Hot water or gas
drivendriven COP approx. 1.2COP approx. 1.2 Made in ChinaMade in China
Hot Water or Steam Hot Water or Steam Absorption ChillersAbsorption Chillers
COPCOP
Single-effect chiller..............0.60 to 0.75Single-effect chiller..............0.60 to 0.75
– 90C-150C90C-150C
Double-effect chiller.............1.19 to 1.35Double-effect chiller.............1.19 to 1.35– > 150C > 150C
23.5 KW Collector Array 23.5 KW Collector Array
Building and ArrayBuilding and Array
12’x57’ Office (approx 700 sq. ft.)12’x57’ Office (approx 700 sq. ft.) 23.5 KW array (52 sq. meters)23.5 KW array (52 sq. meters)
Key Project MembersKey Project Members
Dr. Roland WinstonDr. Roland Winston Kevin BalkowskiKevin Balkowski Heather PoiryHeather Poiry
QuestionsQuestions
Bruce JohnstonBruce Johnston [email protected]@sbcglobal.net [email protected]@ucmerced.edu 209-228-2907209-228-2907