Concepts
NPSHa < NPSHr is acceptable from pump operation (T/F)
False: a pump requires a certain amount of head at the inlet to operate, so if the actual in the system is lower, the pump will cavitate
The Equation for calculating brake horsepower for a pump
BHP = (hydraulic hp)/(pump efficiency)
Determine the overall outer heat transfer coefficient given:
pipe: 15 [m]
ri = 5[cm] t = 3 [cm]
hi = 2500 [W/m2 C] ho = 7 [W/m2 C]
ksteel = 43 [W/m C]
1.722 [W/m2 C]
temperature inlet/outlet diagram for an AFU where:
T,tube, in = 377 [F]
T,tube,out = 200 [F]
Tshell, in = 160 [F]
Tshell, out = 275 [F]
*SoMe DrAwInG ReQuIrEd*
Delta P equation as a function of hydraulic head
delta P = (head [ft] * specific gravity)/2.31
The methods and mediums of convection and conduction in a system
Convection: what is fluid flow across a solid in the boundary layer
Conduction: What is molecular interactions throughout a solid
Equation for annual operating cost
annual operating cost = (utility amount)(cost per amount)
NPSHa acceptable for the system provided for propane at its bubble point at 100 [F] given: specific gravity = 0.485, NPSHr = 10 [ft]
losses:
check valve = 1.0 [psi] valves = 0.2 [psi]
orifice = 1.2 [psi] control valve = 9 [psi]
line losses = 0.75 [psi]
NPSHa = 24.04 [ft], Yes
The graphical representation of co-current and counter-current H.E (w' no phase change) and their thermodynamically impossible graphs
*insert drawings of pretty graphs here*
The point at which the max. flowrate occurs for compressed flow
when is the choked point/in choked flow
The effect of relative roughness on the friction factor within laminar flow
(see Moody diagram)
equation for radiative heat transfer
q1-2 = (sigma)A(F12)((T1^4)-(T2^4))
hydraulic hp required for a pump moving liquid propane
specific gravity = 0.485
Q = 375 [gpm]
Psuction = 175 [psig] Pdischarge = 260 [psia]
15.4 [hp]
Illustrate heat transfer from a 80 [F] space through a layer of steel sandwiched between layers of insulation to a freezer at -20[F]
show the pretty picture with all labels and visual aids
Moody and Fanning friction factor are equivalent and completely interchangeable (T/F)
They can be used in the same scenario but Fanning = 1/4 Moody and have different equations and graphs
type of convection with largest heat transfer coefficient
forced convection
Equation for flowrate through nozzle
Q = Cn*An*SQRT((2(p1-p2))/(density(1-beta^4))))
q/L for pipe w' Ts = 176[F], ro = 1.35 [in] with air @ velocity = 70 [ft/s], Patm and 110 [F] flowing across it given:
viscosity air = 0.021 [lbm/ft h]
density air = 0.0613 [lbm/ft^3]
air thermal conductivity = 0.0181 [Btu/(h ft F)]
q/L = 45.03 [Btu/h ft]
Find q subcooled based on graph given:
mh = 10 [lbm/h] mc = 15 [lbm/h]
Cp,h = 6.65 [Btu/lbm F] Cp,c = 1 [Btu /lbm F]
hfg,h (or lambda,h) = -812 [Btu/lbm]
hfg, c (or lamba,c) = -615 [Btu/lbm]
q subcooled = 1915 [Btu/h]
heat removed during phase change
what is latent heat?
the two assumptions inherent to assuming isentropic nozzle compressed flow
what are reversible and adiabatic
Demonstrate whether heat flux is conserved in cylindrical and planar conduction geometries
This is a bit *DiFfIcUlT* to type; see board
Using the Lockhart-Martinelli Method, the delta P(two-phase) over 347[ft] of 5[in] inner diameter pipe assuming plug flow regime:
Vapor Liquid
density [lbm/ft^3] 2.43 29.49
viscosity [cP] 1.021*10^-2 5.365*10^-2
surface tension [dyne/cm] 4.62
mass flowrate [lbm/h] 2500 2000
1159 [psi]
Given the pump curve shown, what is the pressure added by the pump handling a flowrate of 500[gpm] and 11[in] impeller if the fluid has a specific gravity of 0.847.
18.33 [psi]
Given the wall shown with the specifications, what is the temperature at the interface between wall 2 and 3?
T = 286.3 [K]