Heat transfer concepts until NTU

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)

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*

• 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