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GATE ME 2021 || Heat-Transfer quiz 3

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Question 1

The peak wavelength of radiation emitted by a black body at a temperature of 2000 K is 1.45 μm. If the peak wavelength of emitted radiation changes to 2.90 μm, then the temperature (in K) of the black body is___.

Question 2

A heat exchanger is used to heat cold water (CP = 4.18 kJ/kg-K) entering at 15 °C at a rate of 1.2 kg/s by hot air (CP = 1.005 kJ/kg-K) entering at 90 °C at a rate of 2.5 kg/s. The highest rate of heat transfer in the heat exchanger is _____ kW.

Question 3

For a glass plate transmissivity and reflectivity are specified as 0.76 and 0.08 respectively, the absorptivity of the glass plate is ___________.

Question 4

For the parallel flow heat exchange the effectiveness is 0.4 and capacity ratio is unity, then NTU is___.

Question 5

In the counter flow heat exchange, for the hot fluid the specific heat is 3 kJ/kg K, mass flow rate is 6 kg/s, inlet temperature is 150 °C and outlet temperature is 100 °C. For the cold fluid, the  specific heat is 3 kJ/kg K, mass flow rate is 8 kg/s, inlet temperature is 20 °C . Neglecting the heat transfer to surrounding, the outlet temperature of the cold fluid in °C is ________.

Question 6

The emissive power of a blackbody is P. If its absolute temperature is doubled, the emissive power becomes.
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Mar 26ESE & GATE ME