Solidworks would be a good package to design and test your heat exchanger, you can 'build' your design and run simulations on it to analyse your design with differing parameters.
I am designing a flat plate heat exchanger for a project and I am not sure where to start with the hand calculations, specifically the LMTD and E-NTU methods, also how to work out the parameters which i will need to complete these methods such as area and number of plates. My deadline is soon...