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Solar Thermal Systems. Trends and Technology. Contents. 1) Introduction 2) Evacuated Tube Technology 3) Evacuated Tube Projects 4) Design Consideration 5) Control Systems. 1) Introduction. Solar Thermal has been around a long time
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Solar Thermal Systems Trends and Technology
Contents • 1) Introduction • 2) Evacuated Tube Technology • 3) Evacuated Tube Projects • 4) Design Consideration • 5) Control Systems
1) Introduction • Solar Thermal has been around a long time • Solar Thermal technology is quite mature – far more efficient than PV – over 90% • Flat Plate and Evacuated Tube both Developed Technology • Payback 10-15 years with no rebates and at current energy prices.
Applications • Domestic Hot Water • Hotels, Apartments, Condos, Restaurants • Industrial Hot Water • Parts washing, Process heat • Agricultural Hot Water • Dairy, Bottling • A/C Reheat – Dehumidification • Space Heating • Chillers • Swimming Pools
2) Evacuated Tube Technology • Two most important parts: vacuum insulation and heat pipe technology • Vacuum – the best insulator • Heat pipe – takes advantage of the latent heat of steam • Styles • Flow through • Sealed pipe • Temperature limiting
2) Evacuated Tube Technology Evacuated Tube vs Flat Plate
2) Evacuated Tube Technology • Efficiency Curve Comparison:
2) Evacuated Tube Technology • Output of Selected Solar Panels (SRCC Data):
4) Design Considerations • Facility BTU usage • Existing Facilities vs New • Flow meters, BTU meters • Watt meter or Gas meter • Recirculation • Collectors • 35,000-40,000 BTU/day • Storage • Use Profile • 40 -80- gallons per collector
4) Design Considerations • Freezing • Freezing is biggest problem with solar thermal - up till now solution has been: • Glycol – heat capacity, double wall, glycolic acid • Drainback – practical limitations • Evacuated Tube • Direct water • Simple • Fewer components • Lower maintenance
5) Control Systems • Size of System • Few intermediate Delta T controllers • RESOL DeltaSol M – 12 inputs, 6 outputs, pre-programmed • Temperature compensating valves • Data Acquisition • Additional data for efficiency and service Temperature alarms Low Flow/Pressure alarms • Real time $$ Savings Reports • PLC considerations • Flexibility, scalability • Remote logging • Building management interface