A runaway greenhouse effect is causing global warming, but did you know greenhouse energy can also be used to reverse global warming. We have many alternatives to choose but we are still far from going green. The GREEN TRAIN is simple social networking tool designed to help us get started in the right direction. As my Dad once said we all have to start someplace. If these simple videos help us get started they will have acomplished their task and wake our sleeping lions.
Friday, March 25, 2011
Hot Air Collector
Hot Air solar collectors can supplement the heating requirements of a house in a cold climate. As long as the house is well insulated and one side of the house has adequate sunlight exposure a home made solar hot air heating system could be a good investment. The price of oil will continue to rise, but the wise use of sunlight energy may be used to reduce the consumption fossil fuel concentrates. Hydronic solar collectors have the advantage of supplying heat and hot water all year long, but the simplicity of hot air collectors has a special appeal to home owners with limited time for projects. Hot air collectors do not require storage tanks to store heat or radiant floors to distribute heat. Instead household furnishings and interior walls are used to store daytime solar heat and release it gradually at night
Data Analysis: T1 is the temperature of air at the top of the heat storage chamber and T2 is the temperature of air toward the bottom of the heat storage chamber. When the fan is off T1 reaches 135*F by 3:30PM and T2 remains at 50*F. This is what we would expect since heated air from the collector in not circulating through the heat storage chamber. After the fan comes on the T1 (temperature of air from collector) drops and T2( temperature of air returning to collector ) increases. By 4 PM the the temperature differential between incoming and outgoing air stabilizes at 22*F. This differential temperature is used to measure the heat gain of the collector. To estimate the efficiency of heat collection we will need to know: the vertical sunlight intensity at 4 PM, the surface area of the glazing surface and the flow rate of the circulated air. GLAZING SURFACE 7 sq ft
FLOW RATE OF FAN 20 CFM
SOLAR FLUX 200 BTU/sq ft
MASS OF AIR (m) .075 lbs/ft^3
HEAT CAPACITY OF AIR (Cp) .24 BTU/*F
Qc = heat gain/hr from collector
Qs = heat energy available from sunlight ( assumption 200 BTU/sq ft)
Qc = 20 CFM x 60 min x .075lbs./ft^3 x .24 BTU/*F x (T1-T2)
Qc = 475 BTU/hr Qs = 200BTU/sq ft x 7 sq ft. = 1,400 BTU/hr
Efficiency = Qc/Qs = 475/1400 = 34%
This is just one of many solar hot air collector designs. Now that you understand the basic concept you can design your own solar hot air heating system. let me know what you come up with..
This is just one of many solar hot air collector designs. Now that you understand the basic concept you can design your own solar hot air heating system. let me know what you come up with..
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