It seems like every time we buy a new car the fuel efficiency does not significantly increase. It has been 30 years! Why can't scientists make a breakthrough?! #HeatEngines #Explained #ChemE (1/31)

Today’s passenger cars have an average gas mileage of about 31 MPG while cars built 30 years ago still get 27 MPG.

Yup this is only a 15% increase in 30 years. But why? (2/31)

In this thread we will explain why engines have struggled to advance in their efficiency using the Second Law of Thermodynamics. (3/31)

Now I know many of you may be saying, “How will I ever understand the Laws of Thermodynamics, I’m not a rocket scientist.” Well fear not, because by the end of these tweets you will be able to say you know rocket science (Or at least why an engine cannot be 100% efficient). 4/31

Cars are powered by internal combustion engines. Sounds complicated, yuck! But these engines can be more generally classified as heat engines. (5/31)

A heat engine relies on heat transfer to do work. Heat transfer occurs spontaneously from a hot reservoir (Qh) to a cold one (Qc). A heat engine then uses part of the heat transfer to do work (W). (6/31)