Liquid Thermal Mass

A Liquid Thermal Mass is a system that combines the volume of Soap Solution, which can be smaller, with larger volumes of water that can provide a large thermal mass. The roof/wall cavity space per square foot of greenhouse floor area might be 2 to 4 cubic feet - so if you had a thousand square foot greenhouse you might need to make 2000 to 4000 cubic feet in volume of high expansion bubbles to fill the roof and wall cavities. The "high expansion" bubbles are 200 to 400 parts air to one part Soap Solution. Therefore you would want to have 10 to 20 cubic feet of liquid at a minimum in the soap liquid system. In actual fact you need about twice that amount since all the liquid cannot possibly be made into bubbles. There is always some Soap Solution draining back while the bubbles are made and you main tank where the pump will draw must always have a reasonable reserve of liquid in it. So I would recommend that you have twice the Soap Solutionthat? is the calculated minimum.

But the Soap Solution is not only used for keeping heat in by making Bubble Insulation? at night or in north facing walls and roof cavities on Cold Winter Days?. It is also used for keeping heat out on Hot Summer Days? by making Bubble Shading in south facing walls and roof cavities. Additionally, the Soap Solution is used during sunny days for Liquid Cooling by using a Thin Liquid Film Cooling? process. This process uses more flow of Soap Solution and therefore the Soap Solution Tank will need

But your system will function more effectively if you can store more solar gain in a larger liquid thermal mass system. This additional liquid can be water that is used for irrigation, fish tanks and pools and any water reservoirs and even "dry" soil beds that you can couple to the soap liquid system by laying flexible pipe into these other thermal mass components. Then the soap liquid will give or take thermal energy from this larger thermal mass as the liquid is circulated.

The lowest part of the wall cavity is then treated like a collector gutter to bring the drain-down soap liquid back to the soap liquid tank + pipe. You can have quite a lot of the volume of the soap liquid in the pipe and the Soap Solution Tank is used for the "surge" that is needed during the bubble generation. In larger projects that have Wide Span flat Sola Roof areas the roof cavities drain to a "tower tank" that is the main soap liquid reservoir for a large system. The wall cavities drain separately from the knee wall hieght to a smaller on grade "sump" tank where there is a sump pump that sends the soap liquid back into the main tower tank. From the bottom of the tower tank there is a line of pipe that runs through the floatation (nutrient solution beds) or soil growing beds before going to the supply lines to the bubble generators. The liquid going to the generators for the 3 to 5 minute generating cycle is therefore identical to the temperature of this larger thermal mass.

There is also a by-pass valve that lets the soap liquid pump draw directly from the Soap Solution Tank and by-pass the pipe system. This gives the possibility of de-coupling the soap liquid and the other liquid (water based) thermal mass systems. It is clear that these various liquids are not being mixed they are just thermally coupled.