solar thermal Flashcards
solar thermal history
first for burning ants; 17-1800s solar cookers; 1900s solar buildings/furnaces
solar resource size
> 1600EJ/year
where are best US resources
southwest
passive solar building design
daylighting(illumination from sun not lighting), control(window shade), aperture(window), absorber(tile floor), distribution, thermal mass
direct solar gain
most common passive solar design–sunlight penetrates directly into building
indirect solar gain
insulating space collects/distributes the heat, but no light gets in; called a trombe wall (that sounds like “trombone” chad do you play the trombone?)
daylighting
not really solar thermal; maximizing use of natural light in building design
china & solar thermal
china is leader in installed capacity and expansion
two types of solar hot water heating
passive and active!
active solar water heaters
use pumps to circulate water through heat-absorbing solar thermal collectors
passive solar water heaters
simpler than active. thermosiphon principle–when collector heats the water, it rises to be stored; then when needed, sinks and is reheated
two types of thermosiphons
open loop, closed loop
open loop thermosiphon
water circulates through solar collector–good for hot climates
closed loop thermosiphon
working fluid circulates and warms a storage tank of water–good for climates where it freezes
evacuated tube collectors
more insulated than flat collectors–vacuum between inner and outer tubes; can achieve much higher temperatures; good for cold climates or hot temp applications–57% of capacity, 78% new installs
solar air heating collectors
absorbing medium captures energy from sun and heats air, which is circulated through building; <1% of solar thermal; glazed and unglazed
solar salt ponds
if hot water is needed on a super large scale, use salt gradient pond–heat collects in dense, salty bottom
US solar heating trends
more people are using solar to heat their swimming pools..
solar cooking
trapping heat of sun to cook food–don_t need wood! No smoke! Portable! But weird culturally, and can only use when the sun is out.
solar thermal electric gen types (four)?
point focus, line focus, continuous, segmented; examples: dish, trough, tower, linear fresnel
solar thermal electric is also known as..
concentrated solar power
parabolic trough/linear fresnel
concentrates solar energy onto a long receiver tube positioned along line focus of reflector
central receiver (tower)
uses heliostats (sun tracking mirrors) that reflect solar energy to receiver atop a tower; this energy heats molten salt, which powers generator–salt can store heat for a while before generating
parabolic dish
parabolic two-axis tracking concentrator to focus rays into a receiver at dish’s focal point
