Close Loop

Problem Statement:
An existing closed-loop cooling system is to be modeled. The flow path includes parallel pumps, parallel heat exchangers, and multiple parallel cooling loads. The fluid is water, nominally at 60 degrees Fahrenheit and 50 PSIA. The pump suction pressure (at the connection from a surge tank) is approximately 20 PSIA.

The combined supply header is 4 inch schedule 40. This header then supplies two 2 inch lines as well as a 1 inch line. The question is whether flow velocities throughout the system are maintained less than the desired limit of 8 feet per second (this limit being an arbitrary design limit based on the sound characteristics of the system).

Solution:
The first step is to build the network layout and define all system hardware. Next the fluid information is entered. Finally, the pressure at the suction of the pumps is defined. The system will then solve for all system flow rates, pressures, and velocities. By displaying velocities, it is easily seen whether the desired criteria is met. If not, "what if" scenarios can be readily analyzed to determine the best way to meet the desired criteria.

Other Considerations:
In the above case, nominal conditions were modeled. Further analysis could include off-normal conditions and casualty situations (e.g., failure of one pump, loss of surge tank level, et cetera).