Hi enginej! Welcome to PF!
Have you already taken the basic courses on engineering thermodynamics and heat transfer? These will cover the fundamentals on how basic heat exchangers work, especially (and obviously) heat transfer. I suppose these courses are required for your major anyway, so you'll take them eventually. Also, find out if your department offers a thermo-fluids specialization for your major and look for courses on advanced heat transfer, preferably focused on heat exchanger design.
I can also recommend you some textbooks.
Thermodynamics: An engineering approach by Çengel. I've personally used it in my engineering thermodynamics class and I find it a great textbook. Includes some concepts of heat transfer in one of the first chapters, however, these are mostly conceptual.
Also, Transport Phenomena by BSL, and Fundamentals of heat and mass transfer by Incropera and DeWitt. I haven't used these personally, however, they are used in my school for transport phenomena and heat transfer courses, which I'm about to take next semester, and I've heard great things of both texts.