Problem 1
HT-HW #1 - In-Class Assignment
Monday, February 03, 2020 @ 8:00 AM, MY 136
Liquid ethanol is a flammable fluid and can release vapors that form explosive mixtures at
temperatures above its flash point at 16.6°C. In a chemical plant, liquid ethanol ($c_p$=2.44 kJ/kg K,
$\rho$ = 789 kg/m³) is being transported in a pipe with an inside diameter of 5 cm. The pipe is located
in a hot area with the presence of an ignition source, where an estimated 20 kW of heat is added
to the ethanol. Your task as an engineer is to design a pumping system to transport the ethanol
safely and to prevent fire hazard. If the inlet temperature of the ethanol is 10°C, determine the
volume flow rate that is necessary to keep the temperature of the ethanol in the pipe below its flash
point.
Liquid ethanol
$T_{in}$ = 10°C
$\dot{Q}$ = 20 kW
$T_{out}$
Problem 2
Water is heated in an insulated, constant diameter tube by a 7-kW electric resistance heater. If the
water enters the heater steadily at 15°C and leaves at 70°C, determine the mass flow rate of the
water.
Water
15°C
Resistance
heater, 7 kW
70°C