Milestone-Proposal talk:Self-regulating Trace Heater
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Self-Regulating Trace Heater revolutionized Electrical Trace Heating -- Chetsandberg (talk) 23:23, 28 March 2018 (UTC)
Hundreds of millions meters of electrical trace heating is installed yearly, most of it being self-regulating. Trace heating is installed on pipe systems to prevent water freezing, to reduce viscosity for easy pumping, to melt snow in critical pavements and to keep roofs clear of ice and snow. Having a distributed heater is not revolutionary, but having an infinite distributed thermostat at each infinitely small distributed section surely is. To make a self-regulating heater, the base polymer (polyolefin, PVDF, or PRA) is infused with carbon black providing a parallel heating resistance between two parallel 16 gauge wires with circuit lengths up to 200 meters long. A hot pipe “expands the core, “pulling” the carbon chains apart raising the resistance and causing the power to reduce (voltage squared /resistance). The key is that the polymer has been radiation cross-linked, and when the core cools, the cross linking returns the polymer crystalline structure to the original matrix position, thus returning that section of heater to the original resistance.
The local temperature determines the expansion of the polymer and the polymer type (polyolefin, PVDF, or PRA) determines the crystalline melt temperature where the polymer matrix disappears and the polymer expands. Another critical attribute, is the cut to length nature of the self-regulating heater. Historically electrical trace heaters were constant wattage series circuit and the resistance had to be factory determined and fabricated. Cutting the heater changed the resistance and thus the heat output. Now the piping didn’t have to be pre measured and many fewer heater sets were sent back to the factory for remanufacturing. No wonder by 2007, over a Billion feet of the self-regulating heater was manufactured in the building proposed for the IEEE Milestone Plaque!