VERIFY: the heat exchanger is characterized in all its parts, then the user enters all the geometric parameters, then defines an EXCHANGE AREA.
The user then, VERIFIES, the behavior of the heat exchanger of which he has inserted the geometric parameters, to vary the thermal conditions: temperatures, flow rates, dirt.

DESIGN: the user does not know yet how the heat exchanger will be characterized. Therefore, it does not know its geometric characteristics. It does not know its exchange area.
But the user knows the thermal conditions to which he wants to operate the heat exchanger or what performance must have.
In this case it will be the software in question that will suggest the construction of the heat exchanger, and therefore the exchange surface, which is closer to the thermal performance required by the user.

In SHELL there are two ways to design an exchanger:

1. DESIGN, WITHOUT selecting "Automatic": the user only defines:
a. Shell internal diameter
b. Baffles diameter
c. Outer most diameter
d. Tube model
e. Holes in the baffles

This feature provides only 1 possible solution, as the user has already defined the Shell internal diameter.

2. DESIGN, WITH select "Automatic": the user DOES NOT define any geometric parameters.
Therefore, since the user has not imposed any constraint, the software proposes multiple solutions, varying the Shell internal diameter, which try to meet the thermal demands made by the user.
The various solutions can be viewed by clicking on the BLUE arrows at the top of the mask.