February 2017 Archives

Thermodynamics or Thermonuclear War

Law I: You can't win, you can only lose.
Law II: The only way to win is not to play.

In thermodynamics and energy conversion systems, the rules of thermodynamics are immutable. The only variables to implementation are 1) cost of design, 2) labor cost of design implementation, and 3) materials cost of design implementation. These variables all support one equation to calculate a single value: return on investment (ROI), less maintenance cost.

In converting from AC to DC or DC to DC, the fewer the steps, the greater the efficiency. The more transistors act like switches and less like variable resistors, the higher the efficiency. The lower the loss in the transformer or inductor stages, the greater the efficiency. A 90% (0.9) efficient inverter connected in series with another 90% (0.9) efficient inverter results in an overall efficiency of (0.9 x 0.9 = 0.81) 81%. Thus it is most important to make sure that any conversation stage is as efficient as possible to eliminate losses which will invariably appear as heat. This is true of electrical distribution systems, backup power supplies, line-shaft power systems, and belt-powered systems as well.

In a belt-based transmission system, losses can be as high as 5% per stage. Similarly, gear-based transmission systems and hydraulic systems also suffer from losses due to realistic implementation concerns. Multiple stages, lubricants or lack thereof, and turbulence further lower overall efficiency. Thus, while it may be possible to store energy from a solar collector by raising a rail car full of concrete to twice it's height, much energy may be wasted in mechanical gear trains unless a mechanically large gear is used and a small pinion. Even then, one would need a considerable motor/generator to convert from electrical to mechanical.

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