ISH 202 E, Introduction To Heat Transfer Spring 2021 Questions June 10, 2021 (Session 9)
ISH 202 E, Introduction To Heat Transfer Spring 2021 Questions June 10, 2021 (Session 9)
ISH 202 E, Introduction To Heat Transfer Spring 2021 Questions June 10, 2021 (Session 9)
Spring 2021
Questions
June 10, 2021 (Session 9)
1. Engine oil (Cp=2100 J/kg°C) is to be heated from 20°C to 60°C at a rate of 0.3 kg/s in a 2
cm diameter thin-walled copper tube by condensing steam outside at a temperature of
130°C (hf=2174 kJ/kg) . For an oveall heat transfer coefficient of 650 W/m2.°C, determine
the rate of heat transfer and the length of the tube required to achieve it.
2. Cold water (Cp=4.18 kJ/kg°C) enters a cross-flow heat exchanger at 14°C at a rate 0f 0.35
kg/s where it is heated by hot air (Cp=1.0 kJ/kg°C) that enters the heat exchanger at 65°C
at a rate of 0.8 kg/s and leaves at 25°C. Determine the maximum outlet temperature of the
cold water and the effectiveness of the heat exchanger
3. A shell and tube heat exchanger with 2-shell passes and 8-tube passes is used to heat
ethyl alcohol (Cp=2670 J/kg°C) in the tubes from 25°C to 70°C at a rate of 2.1 kg/s. The
heating is to be done by water (Cp=4190 J/kg°C) that enters the shell side at 95°C and
leaves at 45°C. If the overall heat transfer coefficient is 950 W/m2.°C, determine the heat
transfer surface area of the heat exchanger.