2.13 Bathes. As presented in Section l.5.1.1. baffles nay be classified as either longitudinal or transverse type. Longitudinal baffles are used to control the overall flow direction of the shell fluid. Transverse baffles may be classified as plate baffles or grid baffles. Plate baffles are used to support the tubes, to direct the fluid in the tube bundle at approximately right angles to the tubes, and to increase the turbulence and hence the heat transfer coefficient of the shell fluid. However, the window section created by the plate baffles results in excessive pressure drop with insignificant contri- bution to heat transfer; flow normal to the tubes in crossflow section may create flow- induced vibration problems. The rod baffles, a most common type of grid baffles, shown in Fig. l. l, are used to support the tubes and to increase the turbulence.