Hi all,
Thanks for all the responses.
Georgeverghese,
The pump with the re-circulation will run at 16l/s at 5 psid.
e43u8,
Yes, the pump is centrifugal and the back pressure is high. I re-run the hydraulics by trial and error to get the 5 psi differential pressure, but the pump is at the...
Hi,
I am performing a temporary modification to create a tie-in to an existing cooling water system (150 psig, 100C) involving adding a small booster pump (operating point at 20 psi, 11 L/s) in a branch circuit (3" line). I plan to use the existing system design pressure and temperature for...
Hi,
Correction. The room is about 1500m3.
If I were to size tempoeary acu, I would need to include the 50kw as cooling load if the fan were to turn on.
Bill,
The fan with ductwork recirculates air inside the room.
Hi,
Thank you for the responses.
Energyprofessional,
I have a fan that takes electrical input of about 50 kW. The fan, fan motor and the duct work are all inside a conditioned space. It is a huge fan and blow air through a cooling coil downstream. I suggest not to run the fan when the...
Hi,
Use the example above, the 9W that produces the pressure rise at a given flow is to overcome the friction in the ductwork. The friction, which is an irreversible pressure loss through the duct, eventually results to heat and transfer to the air stream and the space. If I have an ACU with...
Hi,
Thanks. When I tried to break it down mathematically, I run into the problem that
Pelect = Qloss (motor+fan) + (diff. pressure)*flow
The (diff. pressure)*flow is the work done by the fan to move the air, say 9W. However, we are also counting this same amount of energy (9W) as heat...
Hi,
I read about that when a fan + motor runs inside an air stream, the fan heat into the conditional space is equal to the electrical power input. I am trying to understand this concept. If the electrical power input is 10W, then
say, 1 W goes to heat as motor loss, and
9 W goes to produce...
Hi all,
Thanks for the discussions.
The pump capacity is 167 L/s. It is a horizontal centrifugal pump. The pump draws water from a sump located in a high elevation. The NPSHr curve from the manufacture show when the flow rate is 15% above the BEP, the NPSHr starts to increase substantially...
Hi,
Thanks.
This pump is required to work for at least 3 months following an accident. In the first day the water temperature goes to 100C, and its vapour pressure increased substantially. It is this period where the NPSH margin is the lowest.
For that 1 day period, I wonder if a pump can...
Hi,
I would like to ask what is an acceptable NPSH margin in the industry. I have a pump in an open system that is for accident mitigation purpose. Therefore, should I specify a higher NPSH margin like 50% above the NPSH required.
What will happen if the pump runs below the NPSH required...
Hi,
If the pump suction pipe diamater is different than pump discharge pipe diameter, then I need to account for the difference in velocity head?
thanks
Hi all,
I have two pressure indicators; one in the suction and the other in the discharge sides of the pump. I would like to find out the flow rate of the system. The questions that I have are:
1. Does the DP measurement across the pump reflect accurately to the overall system pressure...
Hi,
I would like to acquire information on the selection of N2 cylinder (size,pressure rating, temperature etc) and the necessary components such as pressure regulator.
The application that I am dealing with is to use N2 to pressurize an accumalator up to 70 psig (N2 on one side; water on the...
Hi all,
This HX was designed 30 years ago. The HX is for water cooling application. About 3% of the tubes are to be plugged to fix a FIV problem. During commissioning dated back 30 yrs, it was found the HX has a FIV problem when the secondary side flow reaches to 100%.
The uncertainty that...
