I'm in my last session of classes, and the textbook we currently have is

Advanced Fitness Assessement and Exercise Prescription by Vivian H. Heyward

I can't remember offhand the name of my Exercise Physiology book, but when I get the chance I'll post that .....

It takes time, which is cool, if you are at about 60-70% or yor MHR.
which is exactly why a target fat burning workout is at least 20 mins of moderate (60-70%) intensity .... the oxidative system kicks in after 2/3 minutes of continual exercies ... the ATP-PC system is only 5-8 seconds, and the glycolitic system is roughly a minute to a minute and a half ....

and actually the Acetyl-CoA goes to the Kreb's cycle where it is broken into CO2 and H+ ..... The ETC (electron transport chain) then takes that H+ and combines it with O2 to make water and prevent acidification ... That's when Oxidative Phosphorylation kicks in and uses the electrons from the ETC to reform ATP (energy), and it is here that Lipolysis (break down of fat) occurs .. from the fat you get your glycerol which is then sent back to the Kreb's cycle to start all over again ....

that is why you want to keep your HR in that "target range" .. if you do, you are most effeciently using the Kreb's cycle, ETC, and OP to burn fat ...