Refer to THEMA handbook and find two choices for shell and tube exchangers. Choose in ASPEN HYSYS either two shells to avoid the cross, or a longitudinal baffle making two passes in one shell. The two shells are preferred technically and by operators, but are more costly.

Longitudinal baffles often leak, require more maintenance, are harder to clean, and more difficult to control, but are an economical choice in many applications.

If the shell needs an expansion joint for large temperature differences, then a longitudinal baffle cannot operate in that part of the shell. For that reason TEMA offers a variety of standard configurations that cover these cases.

If you proceed to the ASPEN exchanger design program from HYSYS, then the advantage of two shells may become more important in the startup conditions and cleaning conditions.

Many failures of equipment do not occur in normal operation. More often they occur in abnormal operation and startup or cleaning operations where unusually large temperature changes occur. I routinely specify all of these conditions to the mechanical designer which results in longer service life and better operation.

Other engineers prefer the lower first cost and earlier replacement or redesign with stronger alloys.

Similar examples apply to plate exchangers, and spiral exchangers.

firstly check you simulation data to ensure they are entered correctly. if the problem still exists, maybe that situation is not feasible. to remove the error, you can use multi pass shell and tube and/or using different utility and also ................

If you have a temperature cross in your simulation you most likely accidentally specified it that way. You could remove one of the specified temperatures and put in UA instead,  You probably need to do some trouble shooting tracing the origin of the bogus temperature input.

I've solved the problem by adjusting the flow rate.

Thank you all,

Unfortunately most temp cross flow issues occur due to poor or bad specifications but I have found the commonest issue relating to awkward flowrates. Start your adjustments from there