Thermodynamics by Michael A. Boles, Yunus A. Cengel (2001, Hardcover, Illustrated)

For engineering textbooks, Cengel has got to be one of the best authors. All the concepts are clearly explained, and the examples show the necessary steps that can be applied to any problem. I sold this book back initially and then bought it again as a reference when I had to take thermo 2.

I'm not really a big fan of textbooks, but if you are an engineer or someone who works with thermo - related stuff, it's always good to have some sort of reference material. For those situations where you may not be sure how something works, this is where you want to look. Cengel - one of the authors - is a well-respected professor in the mechanical engineering department at penn state, an accredited engineering school.