Good Photos
That is a big heatex allright. I have been experimenting with a smaller $98 brazed plate heat exchanger(5" X 12" 10 plate 1"NPT ports) on my 6/1. The brazed flat plate I have thermosiphons very well. I started off my testing with my original small test cooling tank on the secondary loop. Since I knew the temp rise info and available runtime of this small tank under a 2K load with the tank connected directly to the engine, I thought it would be a good test base. With the tank directly connected to the engine, I get just shy of an hours run at around 2KW of electrical load. With the engine thermosiponing to the heatex and the heatex thermosiphoning to the tank, I got just slightly over an hours run time under the same load and basically the same atmospheric conditions. I attribute the extra time to the water added to the system whenI added the additional hoses and heatex.
I am on to my next stage now which replaces the test tank with a 12" X 12" liquid to air heatex(radiator) rated for domestic water pressure and designed to go into a furnace duct. I still thermosiphon the primary loop from engine to heatex. I use a small Taco pump on the secondary loop as the 4 pass radiator would not thermosiphon well. Under my test setup, this configuration works great and I have done several multi hour test runs between 2-3KW of electrical load. At the 65-70F ambient air temps in my garage with an ex auto radiator fan drawing air thru the radiator, the 12X12 radiator is right at it's limit to dissipate enough heat at a full 3KW electrical load. At my maximum test load of 3070W(13.2A @228VAC + 60W lightbulb) the engine outlet temps gradually rise from the upper 190's at a 2KW load till they reach boiling point. This takes about 10-15 minutes to reach boiling from the time the full 3KW is switched on. A 16X16 radiator would probably work well under these conditions.
My ultimate goal will be to loop water from my hot water tank thru the radiator(inside a insulated/louvered fan box) to the heatex and back to the tank. A good outlet temp from the heatex with the engine under load just happens to be 120F. I will feed this water to the tank to maintain it's temp. As the 50 gal tank saturates and the outlet water temp from the bottom of the tank tank begins to rise, a thermal switch wll engage the fan to begin dissipating the engine heat into the house via the radiator. Using hot water from the tank and lowering the tank temp with 55-60F makup water from the well, will shutoff the fan untill the tank heat builds back up. With the 50 Gal to buffer the temp and the added losses from the tank and plumbing, the 12 X 12 radiator should work fine once the system is completed. I don't expect it to have to sustain 3KW for extended periods of time in operation, it will only ever see 3KW rarely and then only then for short durations.
One thing I was reading about on a brewers website that might help with your coil in the pool is to add a piece of wire or a smaller pipe inside the pipe coil. If left to it's own, the fluid flowing inside of the pipe will develop into layers due to laminar flow. The layer closest to the skin will give up it's heat and then serve as an insulating layer, like the layer of water in a wetsuit. What the brewers who make their own heatexchangers out of copper pipe do, is add a solid copper wire inside the copper tube before they form their coil. This causes the water to turbulate and breakes up the laminar flow along the inner tube skin, increasing transfer efficiency. It is the herringbone pattern stamped into the plates of these brazed heatexchangers that make them so efficient thru high turbulence, even at low flow speeds. The same theory applies to submerged coils.
Ron
