Concepts
The two types of convection
What are forced and natural convection?
See card 14
Demonstrates two relationships of h and x where x is the length of the boundary layer
what are h(0) = infinity, h(infinity)=0
what is q"=6.192[Btu/(ft^2 F
What is q = deltaT/R
Where delta T is the change in Temperature over the Resistance R present towards heat transfer
Definition of heat exchanger fouling
What is the buildup (i.e minerals etc.) on pipe walls that hinder heat transfer
The heat associated with a phase change
What is latent heat?
See card 13
The identities of m, n, x, y, z
m = fully turbulent region
n= viscous sub-layer
x = laminar
y = transition
z = turbulent
The resistance against heat transfer for steam (h internal = 500 [W/m^2 K]) in a 12 [cm] inner diameter pipe that is 12 [m] long and k=60[W/m K] to the outside air (h outside = 25 [W/m^2 K] if t=4[cm].
What is 0.00586 [K/W]
The Delta T LMTD equation
What is
DeltaT = (DeltaT1 - DeltaT2)/ln(DeltaT1/DeltaT2)
The possible range of values for any "h-bar"
what is h(0) > "h-bar" > h(x)
where x is the full length of boundary layer
The flow pattern that has less mixing with different components and why.
What is turbulent flow due to its flat velocity front?
This temperature (see card 3)
What is the approach temperature? The minimum temperature difference between the hot and cold streams in a H.E.
The length of 4" schedule 40 pipe required for air at 28[C] and h=20[W/m^2 C] to only have a heat loss of 2.149[kW] with its surface temperature at 43[C]
What is L = 10[m]?
The Heat Exchanger Design Equation
What is
q = UA(DeltaT LMTD)
The methods and mediums of convection and conduction within a system
Convection: What is fluid flow across a solid in the boundary layer?
Conduction: What are molecular interactions throughout a solid?
This flow has higher convective heat transfer, all other factors being equal
What is turbulent flow?
Illustration of the key feature of the boundary layer for convection over a flat plate.
What is heat transfer only occurs within the boundary layer? See card 18
The overall heat transfer coefficient __
See card 20
What is Uo = 1.722[W/m^2 C]?
The equation for overall system heat transfer if wall thickness is negligible
What is
U = 1/((1/hi)+(1/ho))
The equation that relates between h and the temperature gradient over a flat plate
h = (-kf (partial T/partial y)evaluated at y=0)/(Ts - T_infinity)
Card 4
The main metric for sizing/costing a heat exchanger
What is the required surface area?
DOUBLE JEOPARDY!
The graphical representation of co-current and counter-current H.E (w' no phase change) and their thermodynamically impossible graphs
See board for drawing and walk through (card 2)
Given this graph and values (see card 19), qsubcooled is ___
What is -1995 [Btu/h]
DOUBLE JEOPARDY!
Depiction of T v. q graph for counter-current Heat Exchanger where cooling water stays is only sensibly heated and the process fluid goes from superheated to subcooled marking in/out temperatures and indicating equation separation regions and their q's
What is the graph on card 12