Post on 16-Aug-2020
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Mechanical EngineeringME217 Energy, Environment & Society
ME 217: Energy, Environment & Society Fall 2015
Solar fundamentalsand direct applications
Mechanical EngineeringME217 Energy, Environment & Society
Your opinion on solar
A) it's a toy for greenies
B) it is a major resource
C) it is part of the solution
D) it is too expensive
E) it is impractical
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What happens in the Sun
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Blackbody radiation
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The electromagnetic spectrum
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The solar spectrum
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How much energy on Earth?
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Average solar energy in U.S.
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The solar engineer's questions
Where is the Sun as a function of time? Position of sun defined by solar angles
How much stuff is there between my solar device and the sun? How much atmosphere?
what's in the atmosphere, including haze, aerosols, etc.
Weather (clouds)
Why do I care about this? To optimize the design of my solar device / system and to predict
its performance
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Earth-Sun relative motion
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Fundamental orientation angles
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The Sun's path viewed from Earth
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Sun path charts (L=28o)
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What happens to solar photons
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Atmospheric thickness
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To track or not to track?
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Availability vs. complexity
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A typical set of measurements
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Typical Meteorological Year data
http://rredc.nrel.gov/solar/pubs/tmy2/data.html
global radiation measurement
beam radiation measurement
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Season-specific data - summer
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Season-specific data - winter
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Ok so how do we use this energy?
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Where could we use this energy?
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how much heat do we need?
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degree-days for various locationscity heating degree days per year
(ºF) (ºC)
Miami FL 155 86
San Francisco CA 2614 1452
New York NY 4735 2635
Philadelphia PA 4759 2644
Vancouver BC 5267 2926
Boston MA 5630 3128
Denver CO 6127 3404
Toronto ON 7319 4066
Minneapolis MN 7882 4379
Winnipeg MB 10,399 5777
Anchorage AK 10,471 5817
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how well materials transfer heat
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Ballpark calculation for a house
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Options for heat storage
water turns out to be a pretty good choice!
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The passive solar heating ideal
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Basics of active solar collector
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Options for active collectors
unglazed evacuated tubeglazed flat plate
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how materials absorb / emit heat
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A typical low-temp collector
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Medium temperature collector
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High temperatures – vacuum tubes
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Efficiency vs. technology & use
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How to size an array
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A typical residential configuration
glazing
DHW use
solar circuit
space heating HX
circulation pumps
insulationsolar absorber
radiator
backup heatinsulated tanksolar heat exchangercold water inlet
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How to turn heat into cool