Using multiple tube passes – what about temperature differences? Change in shell side flow rate?

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By using a multi-tube heat exchanger to increase the flow velocity of the fluid inside the tubes and thereby raise the convective heat transfer coefficient, the flow resistance inside the tubes increases. So what happens to the average temperature difference? Some believe that \"when using multiple tubes or shells, it is necessary to take into account the temperature difference correction factor, so the temperature difference decreases.\" Association P357 states the following: It mainly depends on the allowable pressure drop across the tubes and the range of temperature variations of the hot fluid. As the number of tubes increases, the flow velocity within the tubes increases. For the cooling process, the liquid flow rate inside the tube is between 0.5 and 1.0 m/s, while the gas mass flow rate is around 5–10 kg/l(m2•s). For the condensation process, a single-pass design is generally used, with the temperature difference correction factor Ft