Chemical Engineering
2019 · Paper 1
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Complete GATE CH 2019 Paper 1 overview, original pages and practice · Timed previous-paper practice
Questions 52–54 of 65. Imported answers require review unless explicitly marked reviewed.
Question 42
Open questionCHNAT2 marksNeeds review
A solid sphere of radius 1 cm and initial temperature of 25 °C is exposed to a gas stream at 100 °C. For the solid sphere, the density is 10⁴ kg/m³ and the specific heat capacity is 500 J/(kg K). The density of the gas is 0.6 kg/m³ and its specific heat capacity is 10³ J/(kg K). The solid sphere is approximated as a lumped system (Biot number<< 1) and all specific heats are constant. If the heat transfer coefficient between the solid and gas is 50 W/(m² K), the time (in seconds) needed for the sphere to reach 95 °C is __________ (rounded off to the nearest integer).
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Open questionCHNAT2 marksNeeds review
Stream A with specific heat capacity
J/(kg K) is cooled from 90 °C to 45 °C in a concentric double pipe counter current heat exchanger having a heat transfer area of 8 m². The cold stream B of specific heat capacity
J/(kg K) enters the exchanger at a flow rate of 1 kg/s and 40 °C. The overall heat transfer coefficient
W/(m² K). Assume that the mean driving force is based on the arithmetic mean temperature difference, that is
where
and
refer to the temperature of the
stream (
) at the inlet and exit, respectively. The mass flow rate of stream A (in kg/s), is __________ (rounded off to two decimal places).Log in to check the answer
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A 20 cm diameter cylindrical solid pellet of a nuclear fuel with density 600 kg/m³ and conductivity of 300 W/(m K) generates heat by nuclear fission at a spatially uniform rate of 10⁴ W/kg. The heat from the fuel pellet is transferred to the surrounding coolant by convection such that the pellet wall temperature remains constant at 300 °C. Neglecting the axial and azimuthal dependence, the maximum temperature (in °C) in the pellet at steady state is __________ (rounded off to the nearest integer).
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