Depending upon type, some plates employ diagonal flow while others are designed for vertical flow . Plates are pressed in thicknesses between 0.5 to 0.9 mm and the degree of mechanical loading is important. The most severe case occurs when one process liquid is operating at the highest working pressure, and the other is at zero pressure.
The maximum pressure differential is applied across the plate and results in a considerable unbalanced load that tends to close the typical 0.1 to 0.2 inch gap.
It’s essential, therefore, that some form of interplate support is provided to maintain the gap and two different plate forms do this. One method is to press pips into a plate with deep washboard corrugations to provide contact points for about every 1 to 3 square inch of heat transfer surface. Another is the chevron plate of relatively shallow corrugations with support maintained by peak/peak contact.
Alternate plates are arranged so that corrugations cross to provide a contact point for every 0.2 to 1 square inch of area. The plate then can handle a large differential pressure and the cross pattern forms a tortuous path that promotes substantial liquid turbulence, and thus, a very high heat transfer coefficient.
