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Energy & Its Impact on Global Society. Jerome K. Williams, Ph.D. Saint Leo University Dept. Mathematics & Sciences. Chapter 6: Solar Energy. Active vs. Passive Solar Heating Solar Systems: Cost-Benefit Analysis Energy Conservation (DHW) Passive & Active Solar Space Heating
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Energy & Its Impact on Global Society Jerome K. Williams, Ph.D. Saint Leo University Dept. Mathematics & Sciences
Chapter 6: Solar Energy • Active vs. Passive Solar Heating • Solar Systems: Cost-Benefit Analysis • Energy Conservation (DHW) • Passive & Active Solar Space Heating • Thermal Energy Storage Materials
Active vs. Passive Solar Heating • Core components of System • Collection Device • Storage Facility • Distribution System
Active vs. Passive Solar Heating • Active solar heating system uses pump or fan to circulate fluid (water or air) that Sun heats • Passive solar heating system does not use external power but allows fluid (water or air) that Sun heats to circulate by natural means
Active vs. Passive Solar Heating • Active solar heating system: heat swimming pools & hot water heaters • Passive solar heating system: space heating home. • System can save up to 50% heating costs for 1-5% increase in construction costs: drawback is you must incorporate system when house is built
Solar Systems: Cost-Benefit Analysis • Three Types of Solar Domestic Hot Water (DHW) Systems • Flat-plate collector (FPC) • Batch Water Heaters (Bread box) • Passive (Thermosiphoning)
Solar Systems: Cost-Benefit Analysis • Flat Plate Collector (FPC) Systems • Most common system for DHW & pools • Expensive system ($3000 - $5000) • Payback (Break Even Point) 15-30 years • Time interval dependent upon variables (rebates, tax credits, net metering, etc.)
Solar Systems: Cost-Benefit Analysis • Batch Water Heater (Figure 6.25) • Commonly called bread box heater • Inexpensive system ($500 - $1000) • Older technology; been around over a century • Break even point: 5-10 years
Solar Water Heater: Do It Yourself • http://www.youtube.com/watch?v=RGQXqZOMTL4
Solar Systems: Cost-Benefit Analysis • Thermosiphon Method • Passive Solar System • Water flows from collector to tank under natural circulation • Storage tank situated above collector • Commonly used in Asia, particularly China
Energy Conservation (DHW) • To further reduce water heating bill: • Reduce thermostat temperature to 120 F • Insulate water heater (R-19 fiberglass) • Use reduced flow shower heads and low flow aerators for sinks
Passive & Active Solar Space Heating • Passive solar space heating system: House acts as solar collector and storage facility • Object: let sunlight enter (large windows; south side) and store energy inside structure using material of house itself
Passive & Active Solar Space Heating • Essential elements passive solar system • Excellent insulation • Solar collection (large South-facing windows) • Thermal storage facilities
Passive & Active Solar Space Heating • Passive Systems: Three Categories • Direct Gain • Indirect Gain • Attached solar greenhouse
Passive & Active Solar Space Heating • Direct Gain System • Sunlight enters house (South side; large windows) • Thermal storage material placed inside house to absorb solar radiation (daytime) & radiate it outward at night • Concrete, slate, stone, brick
Passive & Active Solar Space Heating • Indirect Gain System • Sunlight enters house (South side; large windows) • Thermal storage material placed near window. • Idea: Collect & store absorbed solar energy inside material. Use heat transfer (convection/radiation) to distribute heat • Trombe wall
Passive & Active Solar Space Heating • Attached Greenhouse • Sunlight enters greenhouse (South side) • Entire structure acts like “large thermal storage wall” • Serves dual function: food and heat production • Concrete floors & water filled drums common energy storage devices
Passive & Active Solar Space Heating • Active Solar Space Heating • Been around for long time; not commonly seen in US due to cost issues
Thermal Energy Storage Materials • Recall heat energy absorbed or released is governed by equation • Q = mcΔT • See Table 6.5 for Thermal Energy Storage Data
Problems • 3, 5, 24, 25