Countercurrent exchange - Wikipedia, the free encyclopedia
Here is a very basic diagram on the difference between the two. Showing that counter current exchange is the more efficient. This of course will only apply if the lube oil bypass on the FOHE is closed. If it is open then little heat is transferred to the fuel. As the lube oil flow through the shell side of the FOHE is a torturous path across the many tubes and around the baffle plates, it would be interesting to know how far the bypass needs to be open before there is no flow on the shell side of the exchanger and therefore no heat input to the fuel. Are we sure that this exchanger arrangement is counter current flow? If it is concurrent then less heat transferred to the fuel even when it is fully in service.