prq123
Chemical
- Jan 4, 2006
- 41
We have a shell and tube exchanger which has gas on the shell side and liquid on the tube side. On the gas side, the exchanger has one inlet nozzle on the top side and two outlet nozzles. One gas outlet nozzle (say Nozzle A) is at the bottom while the other gas outlet nozzle (say Nozzle B) is at the side of the exchanger (at the mid point of the exchanger). During normal operation the flow is out Nozzle A only (design case). During another mode of operation (rating case) the flow is out through Nozzle B only (no flow through Nozzle A).
I suspect that when the outlet flow is only through Nozzle B the U*A will be less than the design case U*A as there would be a "dead spot" in the exchanger where there is no forward flow, which results in lower velocities and hence lower U. I understand that HTRI can not be used to calculated the reduction in U*A when the flow is out Nozzle B. HTRI can not distinguish whether the flow is out Nozzle B or Nozzle A with regards to U*A. Is this correct? If so, is there any way to estimate the reduction in U*A when the flow is out Nozzle B.
Thanks.
I suspect that when the outlet flow is only through Nozzle B the U*A will be less than the design case U*A as there would be a "dead spot" in the exchanger where there is no forward flow, which results in lower velocities and hence lower U. I understand that HTRI can not be used to calculated the reduction in U*A when the flow is out Nozzle B. HTRI can not distinguish whether the flow is out Nozzle B or Nozzle A with regards to U*A. Is this correct? If so, is there any way to estimate the reduction in U*A when the flow is out Nozzle B.
Thanks.