ASHRAE and SNAME T&R 4-16 (2015) use a formula for sensible heat gain from equipment operated by electric motors as follows: q_em = 2545*(P/E_M)*F_UM*F_LM
where
q_em = heat equivalent of equipment operation, Btu/h
P = motor power rating, hp
E_M = motor efficiency, decimal fraction <1.0
F_UM =...
Sandcounter,
I apologize as my question may not have been clear. I am not referring to any nozzle reduction on the pump body itself as it is understood those loses should be accounted for in the pump curve. I am referring to reductions made immediately upstream of the pump casing in order to...
I have reviewed a number of forum discussions and posted guidelines regarding pump selection and pump nozzle sizing, and most appear to indicate that pump nozzle sizing is solely a product of the pump manufacturer's design and need not be considered in the system design and/or calculations for...
A colleague of mine says ASHRAE duct design analysis cannot be relied upon for air velocities in excess of 12,000 fpm. As evidence he references ASHRAE's Friction Chart for Round Duct (See 21.8, Figure 9 in 2009 ASHRAE Handbook-Fundamentals) which only goes up to 12,000 fpm. Is it true that a...
The expansion tank is connected to the pump suction in order to create a point of zero pressure, or at least near zero pressure.
I thought there would be a requirement for the expansion tank to be a certain distance above the highest point of the system but haven't been able to find this...
I work for a marine engineering company and we use ASTM F708 as a pipe support standard for most of piping applications. Not sure if this is what you are asking because I didn't fully understand the question.
I am designing a closed loop cooling system for multiple consumers at varying heights above baseline. The system will include a vented (open top) expansion tank to account for fluid expansion due to temperature differentials. The bottom of the expansion tank will connect to the suction side of...
Looking for a standard or publication stating maximum inlet velocity recommendations/restrictions for heat exchangers or different varieties. I am designing a cooling water system where one of the consumers specifies 185 GPM and DN 50 connections to the heat exchanger. Inlet velocity is in...
In my situation the pump is a 3196 Goulds with discharge nozzle size of 1.5" compared with 3" for the discharge piping. Difference in velocity is significant, 36 fps compared with 10 fps. The velocity head is either 20.4 ft or 1.5 ft depending on which velocity is used.
Also, if the velocity head at the pump discharge nozzle is required for calculation of pump TDH, why isn't velocity head considered at the pump suction nozzle?
I need some direction on velocity head for calculation of centrifugal pump TDH. Is the velocity to be used that measured at the pump discharge nozzle or at the pipe connected to the nozzle (usually larger than the pump nozzle)? Isn't the velocity head at the pump nozzle included by the...
Thank you for your comments and analysis. This is a difficult problem... I don't have a dynamic simulator.. Will have to do this the hard way with excel :)
There is a sump at the tank bottom where the suction bellmouth is located so yes the static head of the tank is the full 25%.
The cargo tanks are entirely separated structurally. They would only be connected through the cargo piping however I expect with continuous suction from the pumps...
The marine vessel being designed has multiple cargo tanks and multiple cargo pumps. Initially during unload all pumps unload one tank (same tank) until level of tank is low then operators open second tank. These cargo pumps will cavitate (NPSHr>NPSHa) when pumping from single tank at low cargo...
We have a customer who wants to use a plate heat exchanger to cool marine diesel oil. In my experience shell and tube heat exchangers have been used for MDO cooling. A plate heat exchanger seems to be more prone to leakage than shell and tube. Does anyone have any experience with plate heat...
A system my company is designing requires a heat exchanger for cooling #2 diesel fuel returning from a marine engine. The Owner preference is to use a plate heat exchanger for the application which Alfa Laval has quoted model M6-FG. Our company has designed similar engines arrangements in the...
