I read an experiment which demonstrated that metal filings fired at a surface using air blasts charges the particles, surface and airstream. I understand this is triboelectricity, resulting from friction.
Experiments show that the charge increases if
- airstream is faster
- airstream is hotter
- particles are finer (greater surface area)
- particles are shot at surface obliquely
What if we use concentrated sunlight to heat air (e.g. to 300° C) and blow that air at high speeds to fire fine sand on some surface and continuously do so to generate electricity? Why isn't this feasible? Is there some physical limit that comes into play which makes this idea irrelevant?
EDIT 1: I'm frustrated as to why someone is assuming I meant to make some perpetual mumbo jumbo machine. It's not! This is a conversion of heat (in solar) to electricity. The device being so simple, I think it should be useful for charging cell phones and such, with lack of efficiency being a non-issue, since solar is mostly wasted anyway!
I am using the concentrated sunlight to generate a temperature (and thus, pressure) gradient in the setup, so that airflow is generated. There is no "pump" in my modified system. I am trying to heat air to generate "chimney" effect airflow.
Note: Generally I don't like talk about efficiency when it comes to simple easy to make, use and maintain devices like this. Unless it's too low, don't bring it up.