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Energy Analysis of Control Volumes at Steady
Chapter 4, Problem 24P(choose chapter or problem)
Refrigerant 134 a enters a horizontal pipe operating at steady state at \(40^{\circ} \mathrm{C}, 300 \mathrm{kPa}\) and a velocity of \(40 \mathrm{~m} / \mathrm{s}\). At the exit, the temperature is \(50^{\circ} \mathrm{C}\) and the pressure is \(240 \mathrm{kPa}\). The pipe diameter is \(0.04 \mathrm{~m}\). Determine (a) the mass flow rate of the refrigerant, in \(\mathrm{kg} / \mathrm{s}\), (b) the velocity at the exit, in \(\mathrm{m} / \mathrm{s}\), and (c) the rate of heat transfer between the pipe and its surroundings, in kW.
Questions & Answers
QUESTION:
Refrigerant 134 a enters a horizontal pipe operating at steady state at \(40^{\circ} \mathrm{C}, 300 \mathrm{kPa}\) and a velocity of \(40 \mathrm{~m} / \mathrm{s}\). At the exit, the temperature is \(50^{\circ} \mathrm{C}\) and the pressure is \(240 \mathrm{kPa}\). The pipe diameter is \(0.04 \mathrm{~m}\). Determine (a) the mass flow rate of the refrigerant, in \(\mathrm{kg} / \mathrm{s}\), (b) the velocity at the exit, in \(\mathrm{m} / \mathrm{s}\), and (c) the rate of heat transfer between the pipe and its surroundings, in kW.
ANSWER:Step 1 of 4
Part a
We are required to calculate the refrigerant’s mass flow rate.
The mass flow rate has a mathematical expression of,
Where, A is the area of cross section, is the velocity of refrigerant’s flow,
is the specific volume of the refrigerant.