Process Integration has been applied in several industrial processes mainly using standard shell and tube heat exchangers (1-1 or 1-2). The flow arrangement in 1-2 multiple shell and tube heat exchangers involves part counter-current flow and part co-current flow. This fact is accounted for in the design by introducing a $FT$ correction factor into the 1-1 heat exchanger design equation. To avoid some steep regions in the feasible space of heat exchangers design some authors introduce other parameters like $XP$ or G. Until now it was not possible to have an overall map to give some guidelines of how to choose between the several $XP$ approaches established in the literature. This paper summarizes the current existing criteria in a general design algorithm $DeAl12$ to show a path for the calculations of the main design variables of the heat exchanger. Also a new strategy design algorithm $StratDeAl12$ is introduced in this paper to allow the best choice between the existing $XP$ approaches based on the heat exchanger cost minimisation. Several examples illustrate the advantage of using the developed algorithm and the deviations obtained in the heat exchanger cost if a wrong approach was chosen.

1.
Smith, R., 1995, Chemical Process Design, McGraw-Hill, New York, Chap. 7.
2.
,
S.
,
Linnhoff
,
B.
, and
Smith
,
R.
,
1988
, “
Design of Multipass Heat Exchangers: An Alternative Approach
,”
ASME J. Heat Transfer
,
110
, pp.
304
309
.
3.
Shenoy, U. V., 1995, Heat Exchanger Network Synthesis—Process Optimization by Energy and Resources Analysis, Gulf Publishing Company, Houston, pp. 255–264, Chap. 6.
4.
Gulyani
,
B. B.
,
2000
, “
Estimating Number of Shells in Shell and Tube Heat Exchangers: A New Approach Based on Temperature Cross
,”
ASME J. Heat Transfer
,
122
, pp.
566
571
.
5.
Wales
,
R. E.
,
1981
, “
Mean Temperature Difference in Heat Exchangers
,”
Chem. Eng.
,
88
(
4
), pp.
77
81
.
6.
Santos
,
L. C.
, and
Zemp
,
R. J.
,
2000
, “
Energy and Capital Targets for Constrained Heat Exchanger Networks
,”
Braz. J. Chem. Eng.
,
17
(
4–7
), pp.
659
669
.
7.
Floudas, C. A., 1995, Nonlinear and Mixed-Integer Optimization—Fundamentals and Applications, Oxford University Press, Oxford, UK, pp. 314–315.