The paper presents the results the simulation of the shell-and-tube bundle heat exchangers. The paper is structured on fourth parts. The first part presents the process structure and the input and output variables of the heat exchanger. The second part presents a summary of the mathematical model of the shell-and-tube bundle heat exchanger. The next part there is presented the stage of the model adaptation to a particular heat exchanger. In the fourth part there are presented the obtained numerical results. The mathematical model, the solving algorithm and the calculus program have been validated by comparing the obtained numerical results for the output variables with the values presented in literature.