**Disclosure: I've never taken a Thermodynamics class either. Although, I own both of the books below and wouldn't hesitate to recommend them to anyone. With this said, the reviews at Amazon concur with my findings. So, I hope this is of some help.
I've got two recommendations. They're both dover books and they're sold as a pair (under 'Better Together') at Amazon.
The first book is the best 'little' book on Thermodynamics. It's based on a series of 4 lectures given by an expert chemical engineer to a group of underclassman ChemE students at RPI.
It contains some 'descriptive calculus' and is definitely at a level above a pop-sci book. Still, it's not a formal text. Just a quick intro course. You can probably plow through it in a weekend.
The second book is more technical than the first and almost as slim! In fact, I've been told it's comprehensive and even covers some physical chemistry! It's by Fermi -- Feynman wasn't the only good physics expositor you know! With that said, it's another good, more technical book. It's also a slim 160 pages! It's cheap, concise, and written by a legend.
Frankly, I wish there were more books like this for other areas of physics as well.