Temperature pressure volume!

Jon D London "T1 P1 V1"

The equation is (P1 x V1)/T1 = (p2 x v2)/t2 ! Now you can run the numbers to answer your question.

The Combined Form of Boyle's and Charle's Laws, I believe. Good answer.

Many thanks！I will have to find out what ambient air pressure is at 15 and 85 degrees first to slot figures in. Jon.. UK

"ambient air pressure is at 15 and 85 degrees "

Ambient air is the general atmospheric or barometric pressure and is usually used as 14.7 psi absolute. Any computed pressure is also in psi abs. Altitude and temperature neglected.

I think Stirling Stan is right but here's some more info. You have to make sure you use the correct units or the formula doesn't work. Also, the ideal gas equation is for an ideal gas so you'll be more accurate finding the exact value for the gas constant when air is used; link below for that. I think you should come up with the exact same value as Stirling Stan but not positive. Ideal gas equation when you let nR=constant is the same formula as Stirling Stan's and the nR constant cancels out of the equation but you may still find this useful.

http://en.wikipedia.org/wiki/Ideal_gas_law

http://www.engineeringtoolbox.com/individual-universal-gas-constant-d_588.html

Hello Jon D. - I'd only add to other posts - there's no direct reason why air at 15°C will be higher than at 85°C (or 100°C). If it's at 100°C it's clearly not coming straight from the atmosphere (turbocharger perhaps?) so pressure could be higher, but that's another matter.

If pressure is same, required volume increase is x (273 + 100)/(273 + 15) = 1.295

Cheers.....Codey

Many thanks! As you may know it no easy getting advice concerning new inventions without giving the whole concept away. I'll do some thinking and working out and maybe post again soon. J;)

Hi, umm re read your reply... pressure will only remain constant if the volume increases. That is to say the expansion due to heat increases the volume to maintain a constant pressure. This could actually be desireable for heat transfer reasons allowing more than half the exhaust heat to be recaptured [with my cunning engine design ;) ]. Regards, Jon

Hi Jon, that's correct, it gives required volume increase if the pressure is constant. If pressure is changed from P₁ to P₂ also need to x it by P₁/P₂ to keep mass of air constant (P absolute of course)

But I believe heat recovery from exhaust gas to induction air has been tried before and not been made to work. Heating the induction air gives lower air mass (for a given engine capacity) and lower power, along with other problems. Cooler air is better, hence use of intercoolers (which are really aftercoolers) with turbochargers.

But the best of luck!

Cheers......Codey

Have you ever thought what if the intuction volume was over double the volume of the power piston or rotor chamber... tinkering with one aspect of existing designs at a time achives little. A full system re-design may just change everything. Thanks for your help. Jon