Kyle Noe wrote: Up by the greenhouse, I've got the second handle done and I'm working on a solution to sealing up the gap around the handle shaft. Felt like the hours flew by and I was working at a snail's pace. I put the handles on and tried the latch out. The handles are so heavy they are making the latch slow to close. I'm going to have to increase the tension on the spring arms tomorrow.
Jim Siefert wrote:Interesting passive heat transfer solution I thought could be implemented in a wofati...
They are great for moving heat up. The problem is they only work to move heat up or at a very limited down. You need another system to move the heat down. The limit for the down is the wicking height of the refrigerant used in the tube. If the tube is lined with a wicking material they can be made to move heat down very limited distances but then you need lots of tubes and lots of transitions to make down work and the transitions from one tube to the next kill you. Think of them like an electric diode that only works one way.
They could be great for doing a freezer wofati or building a walk in cooler in a basement that ran without power for say 6 months of the year in northern climates. But the greenhouse needs a way to put the heat back down into the ground after it pull is out. So they are non ideal for it.
I read this book about the construction of China's railway line to Tibet. "Methods included using pipes called thermosiphons along the sides of the tracks to refrigerate vulnerable parts of the soil along the highest parts of the plateau, an area that comprises the largest continuous sub-Arctic permafrost region on the planet. These cooling sticks are 7.6-meter-long steel tubes drilled into the soil; they contain ammonia, which draws latent heat out of the soil as it evaporates. " Might this be an alternative to that hole/trench? It has no moving parts.
Bob, I believe it would require finding the exact pressure to ensure evaporation/condensation happens at the proper temperature, based on the subsurface soil temps. Say it's always 50*F 10 feet down, then the pressure would need to be adjusted so the liquid turns to a gas at 50.x*F, and as it rises up to the colder end it condenses and gives off that phase change heat. Then the pipe would need to be sturdy enough to withstand the increased pressure during the warmer months when the top of the pipe is much hotter, heating up the entire pipe above that evaporation point.
I'm not quite a lumberjack, but that's OK, I sleep all night and I dream all day; I'll coppice trees, I'll grow my food, and compost poo and pee! With a well and off-grid solar, it's a permies life for me! https://www.youtube.com/watch?v=FshU58nI0Ts
I visited the first wofati greenhouse project site today. It was so beautiful, I couldn't take pictures of portions that were in construction... it would have been impolite. The thing is sooooo beautiful.