- Green Belt
- Posts: 234
- Joined: Tue Dec 29, 2009 4:10 pm
I thought of doing something very similar to this some time ago...probably for the same reasons too. I'm not a fan of plumbing so it never made it to the "write it down" stage. I don't know of a specific solution that would meet your needs...but it is very possible to make the item you described.
What you need is an inline heater with a different control system from those found in circulating systems. For example, 1) in a hot tub the water would be heated and pass into the main "pool" of water. 2) A thermostat would turn the heater on or off based upon the temperature of the water. Your problem is more interesting...
You will be dealing with variable rates of water flow. The amount of time you have to heat the water will be based upon the length of your heated pipe section and the flux of the water.
There are two equivalent ways of looking at this problem:
A) The amount of power needed to heat the water will depend upon the time it is exposed to heat, and the volume that passes through the heated section in that time.
B) This is equivalent to saying the amount of power needed to heat the water will depend upon the 1) flux (speed) of the water, 2) diameter of the pipe, 3) desired temperature 4) incoming temperature and 5) the length of the pipe.
The 2nd and 5th data points however will be constant so they can be ignored and you would only have to look at 1) the speed of the water and 3) desired/starting temp. As the water speed doubles the amount of energy required to bring the water to the same temperature also doubles...if you assume that the pipe acts as a null insulator.
As for the design...you could either have an engineer/math type calculate the amount of energy needed to heat the water...or you could build the device, measure the results and calibrate the device accordingly. If I were doing this for a large company I'd go the engineer route...personal prototype, I'd go the prototype route.