I plan to add a hydrogen fuel cell in my smart car and i want to know if it would be safer to run a secondary fuel line using a fuel tee and running a hose from the hydrogen fuel cell output straight to the tee input. Or run a small hollow needle right into the air intake from the hydroxy fuel cell.
niether. both are dangeous to your wallet. You'll spend a fortune and waste energy.
fuel will fill up your cell if you tap into the fuel line. You want your Hydrogen to go straight into the intake. The Vacuum greatly increases hydrogen production.
hydrogen fuel cell - I don't think that means what you think it means. A real hydrogen fuel cell takes hydrogen you already have, plus air, and turns it into electricity that you use to run an electric car. You are thinking of an HHO generator, which aims to make hydrogen and oxygen from water using electrictity. cell, typically made of some probes stuck in a rubbermaid container full of water, with the vapor from that (mostly water vapor) fed into your gasoline engine. And some idiots think this improves MPG. Water vapor injection might improve MPG. HHO definitely does not, because it takes 10 watts of energy to make 1 watt worth of HHO. It's an over unity scam (google that) which violates the first law of thermodynamics (google that).
I don't know why you would want to void your warranty with something that can't and won't work. The whole add hydrogen to your engine is a CON and yes I can prove it. But to answer your question, with the tiny amount of hydrogen that you'll be adding the needle would be the safest way and it would be the easiest one to undo.