ikarga,
Your endeavour is commanding;- that's the only way to learn and do a good job. Don't be afraid to make mistakes, I have learn most of my trade from my own mistakes.
However, the thermal design has to start with the understanding of the heat transfer principles, ie from the books. I don't want to recommend any particular one, because I don't know your financial resources and nothing is cheap. Start reading the free downloads from the web, just type in "heat transfer". There are many resources, read everything. Then start learning the principles of pressure vessel design. Buy an old copy of TEMA and read it three times until you can recite it backwards. Try to apply the ASME BPV code to the available designs and see how do you stack up to those rules. ASK MANY QUESTION ON THIS FORUM, specific question each time. Remember, only the smart one can learn from the smart and dumb one, only the dumb knows everything so he doesn't have to learn. I don't want to discourage you, but this trade takes hard work, sometimes decades to understand "why" is it so. I, for myself, I got today to understand now how little I know.
best of luck,
gr2vessels