WorksheetsHeat transfer concepts until NTU
Total questions: 10
Worksheet time: 14mins
Which are the units of lobal heat transfer coefficient?
W/m2°C
m2°C/W
J/m2°C
Ninguna de las anteriores
Heat transfer rate is directly proportional to
overall transfer coefficient
resistance
When heat capacity ratios of two streams are equal, it is true that these are equal
individual heat transfer coefficients
Reynolds and Prandtl numbers
temperature differences
thermal resistance
One of the next are dimensional
Heat transfer rate
thermal effectiveness
NTU
C*
The equation for the "Heat Capacity Ratio" is (the ° sign is to represent flow)
C=°m⋅Cp
C=Cp°m
R=tCp
R=Cp⋅t
The correction factor for multi-pass heat exchangers is
F
R
U
C*
What dimensionless number is directly related to the area of the heat exchanger?
NTU
C*
ϵ
Euler
Which method is preferred, because of its simplicity, to calculate the area of a heat exchanger?
LMTD
NTU-Efectiveness
None of these ones
If NTU is 2, U is 200 W/m2°C, and Cmin is 2 W/°C, what is the area in square meters?
0,02
2
0,2
20
Calculate the thermal efectiveness for a heat exchanger with the following data: 1. Cold fluid: mass flow= 2 kg/s; Cp=1 kJ/kg°C; Tc,1=10 °C
Hot fluid: mass flow= 2 kg/s; Cp=2 kJ/kg°C; Th,1=100 °C; Th2=60 °C
0,89
0,5
1,2
Ninguna de las anteriores
