tok-tokkie wrote:But is that not why F1 is going to force the teams to use Heat & Kinetic energy recovery? To make the devices small and implementable on production cars thereby doing something about the 60% odd lost. I favour a fuel limit for the race & any engine & recovery system the teams choose. MYT is not addressing the fundamental problem of using the energy presently wasted.
This is the problem with using the word efficiency for different things. People see a 35%-40% efficiency and think CHRIST! we are wasting over half of the energy available. This is true from an input - output perspective.
Due to the 2nd law of Thermodynamics. A certain percentage of the heat potential from the engine simply isn't available to do work. It cannot be used or recovered. This is a stone cold fact and can't be got round as it's a fundamental principle of physics.
A better way of looking at this is % utilisation of energy that is thermodynamically available to do work. This can be found by the ideal otto cycle for SI engines and the Diesel cycle for CI engines.
Calculate the thermal efficiency of an SI engine with compression ratio 10:1. Using the ideal Otto cycle we can calculate the maximum possible thermal efficiency. This calculation applies to any configuration of engine that uses the Otto cycle.
Method of reaching the efficiency calculation:http://web.mit.edu/16.unified/www/SPRIN ... ode25.html
nmax = maximum possible thermal efficiency.
nmax = 1-(1/CR^(gamma-1))
nmax = 1-(1/10^(1.3-1))
nmax = 1-(1/10^(0.3))
nmax = 0.498812766So for any SI engine using the Otto cycle (4 strokes) with a CR of 10:1. The maximum efficiency is 50%.
So out figure of 40% total efficiency is acutally 40/50 = 80% of maximum.
Leaving 20% available for recovery.
Still quite a lot, but only a third of what is commonly thought to be available for recovery.PLEASE NOTE THAT MANY TEXTBOOKS WILL USE A GAMMA VALUE OF 1.4. WHICH INDICATES A CYCLE OF AIR ONLY. Leading to a maximum theoretical efficiency of 60%.