Consider some materials from below. A detailed study should be based on more specific data, with respect to design/operating conditions, nature of the fluids, hydraulic requirements, impurities, available footprint etc. etc.
elbadi,
I see that you are new here and I'll give you some unsolicited advice. Ask yourself "why are these guys hanging around eng-tips.com just waiting to give me millions (OK hundreds) of dollars worth of free consulting?" The answer is different for every single one of us, but it is reasonably common for the answer to be "to stretch our minds around unusual or interesting problems". Read your post and see if you think it will engender this interest.
If you had described a problem and discussed what you see as the merits and limitations of shell and tube heat exchangers vs. "block" heat exchangers (whatever that is) then maybe you would have ignited some discussion. Your post as it stands is unlikely to get much response.