I have been reading about PHEs, however I have not come across any methods for calculating the number of plates required in PHEs. Can someone please explain how the number of plates are calculated.

In design of STHE, you assume a value of U and perform iterations to see if the assumed value meets/exceeds HT or pressure drop requirements. I have some knowledge about the Bell-Delaware method for STHE calculations by hand and would like to be able to do similar calculations for PHEs.

All the calculation methods I have come across involve specifying the number of plates (rating calculations) but I am more interested in designing for a specific plate configuration, say I have a plate and would like to use those to determine the size (number of plates) for the required heat duties.

I have access to Aspen EDR (in college) but I don't have a real problem. I just want to be able to understand how the number of plates are calculated.

From Hewwit's Process Heat Transfer

Mass flow rate, m = 2*M / N + 1

where, M = Total mass flow of the system

Once I know the number of plates (N) to use here, I should be able to proceed to

S = b*W

S = Surface area of passage

b = Channel width

W = Plate width

onto velocity v = m /rho * S

Re = vD*rho/mu onto Nusselt number and HT coefficients to eventually overall HT coefficient

Any help on this would be greatly appreciated.