The story of traping the sun’s heat energy might begin with a cave man choosing a south facing cave or an Anasizi Indian laying mud brick against a south facing canyon wall. But we shall begin this solar heating story with Horace de Saussure, a noted Swiss naturalist, who invented the “Hot Box”. Horace was born in Switzerland and spent much of his time mountain climbing throughout the Alps and into France. For this reason many people believed him to be French. At any rate the “Hot Box” concept is basic to understanding the nature of a solar collector. No one seemed to care much about “Hot Boxes” back in 1767. France was in debt and the peasants of France were more concerned with making bread than warming themselves with sunlight.
Horace would tell you the heating effect of sunlight passing through glass was known for some time and that is true, but Horace brought this phenomena to the publics attention in 1767 when he recorded a temperature of 230*F inside his home made “Hot Box”. Unfortunately, the people of France were on the verge of a revolution, and a box that trapped the sun’s was of little interest at that time. More than a century passed before some clever technicians began to apply Saussure’s invention.
De Saussure, Herschel, and Langley all demonstrated that temperatures exceeding the boiling point of water could be produced in a glass-covered box. De Saussure stated almost self-effacingly, "Someday some usefulness might be drawn from this device for it is actually quite small, inexpensive, and easy to make." Indeed, his modest hope was more than fulfilled: the hot box became the prototype for the solar collectors of the late nineteenth and twentieth centuries—collectors that were able to supply hot water and heat for homes. Unfortunately conventional solar collectors are still not as cost effective as they could be due to the high initial investment.
The Modified Trickle Down solar heating system was specially developed for do it yourselfers with carpentry skills, interested in saving money. This system makes use of commonly available, low-cost materials and recycled materials. MTD works best when flush mounted on a properly oriented roof. Once the concept is understood it may be incorporated into the design of an energy independent MTD house.
Have you looked at max flow rates? Presumably this would be a function of length and width of the panel and permeability and thickness of the trickle material (felt).
ReplyDeleteWhat kind of transit times for the water? One could put some food coloring in the water at the top and look at the time it takes for exiting water to become colored.
The reason I am interested in transit times, is because there is should be an ideal length of collector. One could make the length (or height) or the collector 20 feet long and it would result in the water being a little bit hotter than, say, an 8 foot collector but the transit time would much longer (presumably 2.5 times longer) resulting in a much decreased maximal flow rate.
In fact, my gut feeling is that you have the collector oriented wrong and that the collector should have the oriented opposite so that the width is rather large and length or height relatively shorter.
Your thoughts would be most welcome.