Air flows from a regulated pressure source at 100 bara through a \(100-\mathrm{m}\)-long pipe into the atmosphere at \(1 \mathrm{~atm}\) pressure and \(25^{\circ} \mathrm{C}\). The pipe is new commercial steel pipe with an actual inside diameter of \(0.5 \mathrm{~cm}\). The pipe is horizontal. Neglect entrance and exit effects.

a. Determine if the flow is choked for both the adiabatic and isothermal cases.

b. Estimate the mass flow in \(\mathrm{kg} / \mathrm{s}\) for the adiabatic case.

For air, the molecular weight is 29 .
Problems 4-5 through 4-7 involve liquid cyclohexane, \(\mathrm{C}_{6} \mathrm{H}_{12}\). For liquid cyclohexane at \(25^{\circ} \mathrm{C}\), the density is \(778.1 \mathrm{~kg} / \mathrm{m}^{3}\) and the viscosity is \(0.00102 \mathrm{~Pa}\)-s. The molecular weight is 84.16 .

Problems 4-5

Cyclohexane liquid at 10 barg flows through a \(1-\mathrm{cm}\)-diameter hole to atmospheric pressure. Estimate the discharge rate if the ambient pressure is \(1 \mathrm{~atm}\).

Problems 4-6

A vertical cylindrical storage vessel is \(10 \mathrm{~m}\) high and \(2 \mathrm{~m}\) in diameter. The vessel contains liquid cyclohexane currently at a liquid level of \(8 \mathrm{~m}\). The vessel is vented to the atmosphere. A 1-cm-diameter hole develops in the bottom of the vessel. Calculate and plot the discharge rate of cyclohexane as a function of time until the vessel is completely empty. Show that the time to empty is the same as the time calculated using Equation 4-21.

Problems 4-7

Cyclohexane flows through \(100 \mathrm{~m}\) of horizontal pipe. The pipe is \(3-\mathrm{cm}\) ID commercial steel pipe with light rust. The upstream supply pressure is 7 barg and the downstream pressure is 1 atm. Estimate the flow rate, in \(\mathrm{kg} / \mathrm{s}\), through the pipe.

Transcribed Image Text:

te 1 At Cog A 2gh (4-21)