Graphical Solution for Shells in Series

When calculating weighted MTD s it is important to remember the following points  

If curves bow out (convex), the MTD factor will be greater than a straight line. 

The correction factor will be less than a stra ht line if the curves bow in (concave). 

If the normal method of determining the correction factor is used, it will give too high an MTD. Unless the unit had a safety factor, it would be underdesigned. 

Line T2 is the hot fluid line. Line t2 is the cold fluid line. Draw a horizontal dashed line through temperature point 2 until it intersects the Ti T2 line. This intersection is shown as temperature. From this point drop down vertically and intersect the cold fluid line. This is shown as ta. 

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