Introduction: "Delta" Solar Heat Collector and Soil Warmer for the Greenhouse
This project is at proof of concept stage. In my experiment, water at 8 degrees to 10 degrees C is dumped on the top of the dripwall and drips to the bottom. On its way down it collects heat from the material and the water temperature increases by 2 to 15 degrees C. (depending on if the sunshine is on the This warmed water drips into the soil and takes its heat to the bottom of the container, The water returns to the bucket usually a few degrees warmer than when it left it. Water is continuously pumped out of the bucket and onto the dripwall during sun hours. The Dripwall collects solar heat, it transmits this heat quickly to the water. The original idea was that it would collect heat from the air of an over heated greenhouse and transmit it to the water, thus cooling the air and storing the heat at the same time. Most people just open a vent when their greenhouse overheats but this involves serious energy loss. Some greenhouses can overheat in the winter and then later in the day, they need the power on to maintain the temp! But if we stored instead of vented, it would be more logical. However my greenhouse will not get hot until April or May and it is serving primarily now as a solar heat collector and to move that heat down under the plants to make them grow. This is an attempt to cheaply solve some difficult greenhouse problems and to use solar energy effectively. It is not a finished product but it is several steps in the right direction. (And it works!). Soil has rotten thermal conductivity, you can heat the top of the soil and it will take ages for the heat to transmit down into the soil. But if you drip warm water on the soil, the problem is solved, the water takes its heat with it down and in. Also, water has really high heat capacity about twice that of soil so it is like little heat "bullets" going down into the soil. Water has over 3000 times the volumetric heat capacity of air and this means that 3 liters of water has the same heat capacity as all the air in a little 6 by 8 greenhouse!