Problem 94
Saturated ammonia vapor flows inside a horizontal tube with a length and an inner diameter of \(1 \mathrm{~m}\) and \(25 \mathrm{~mm}\), respectively. The tube is made of ASTM A268 TP443 stainless steel. The ammonia vapor enters the tube at a flow rate of \(5 \mathrm{~g} / \mathrm{s}\), and condensation occurs inside the tube at \(190 \mathrm{kPa}\). The minimum temperature suitable for ASTM A268 TP443 stainless steel tube is \(-30^{\circ} \mathrm{C}\) (ASME Code for Process Piping, ASME B31.3-2014, Table A-1M). If the flow rate of ammonia vapor at the tube exit is \(0.5 \mathrm{~g} / \mathrm{s}\), would the temperature of the tube wall comply with the ASME Code?
Problem 98
Steam is being condensed at \(60^{\circ} \mathrm{C}\) by a 15 -m-long horizontal copper tube with a diameter of \(25 \mathrm{~mm}\). The tube surface temperature is maintained at \(40^{\circ} \mathrm{C}\). Determine the condensation rate of the steam during \((a)\) film condensation, and (b) dropwise condensation. Compare and discuss the results.
Problem 99
Consider a non-boiling gas-liquid two-phase flow in a tube, where the ratio of the mass flow rate is \(\dot{m}_{l} / \dot{m}_{g}=300\). Determine the flow quality \((x)\) of this non-boiling two-phase flow.
Problem 100
Consider a non-boiling gas-liquid two-phase flow in a \(102-\mathrm{mm}\) diameter tube, where the superficial gas velocity is one-third that of the liquid. If the densities of the gas and liquid are $\rho_{g}=8.5 \mathrm{~kg} / \mathrm{m}^{3}\( and \)\rho_{l}=855 \mathrm{~kg} / \mathrm{m}^{3}$, respectively, determine the flow quality and the mass flow rates of the gas and the liquid when the gas superficial velocity is $0.8 \mathrm{~m} / \mathrm{s}$.
Problem 101
A non-boiling two-phase flow of air and engine oil in a 25 -mm-diameter tube has a bulk mean temperature of \(140^{\circ} \mathrm{C}\). If the flow quality is \(2.1 \times 10^{-3}\) and the mass flow rate of the engine oil is $0.9 \mathrm{~kg} / \mathrm{s}$, determine the mass flow rate of air and the superficial velocities of air and engine oil.
Problem 103
An air-water slug flows through a 25.4-mm-diameter horizontal tube in microgravity conditions (less than 1 percent of earth's normal gravity). The liquid phase consists of water with dynamic viscosity of $\mu_{l}=85.5 \times 10^{-5} \mathrm{~kg} / \mathrm{m} \cdot \mathrm{s}\(, density of \)\rho_{l}=997 \mathrm{~kg} / \mathrm{m}^{3}\(, thermal conductivity of \)k_{l}=0.613 \mathrm{~W} / \mathrm{m} \cdot \mathrm{K}$, and Prandtl number of \(\operatorname{Pr}_{l}=5.0\). The gas phase consists of air with dynamic viscosity of $\mu_{g}=18.5 \times 10^{-6} \mathrm{~kg} / \mathrm{m} \cdot \mathrm{s}\(, density \)\rho_{g}=1.16 \mathrm{~kg} / \mathrm{m}^{3}$, and Prandtl number \(\operatorname{Pr}_{\mathrm{g}}=0.71\). At a superficial gas velocity of \(V_{s g}=0.3 \mathrm{~m} / \mathrm{s}\), a superficial liquid velocity of \(V_{s l}=0.544 \mathrm{~m} / \mathrm{s}\), and a void fraction of \(\alpha=0.27\), estimate the two-phase heat transfer coefficient \(h_{t p}\). Assume the dynamic viscosity of water evaluated at the tube surface temperature to be $73.9 \times 10^{-5} \mathrm{~kg} / \mathrm{m} \cdot \mathrm{s}$.
Problem 105
An air-water mixture is flowing in a \(5^{\circ}\) inclined tube that has a diameter of \(25.4 \mathrm{~mm}\). The two-phase mixture enters the tube at \(25^{\circ} \mathrm{C}\) and exits at \(65^{\circ} \mathrm{C}\), while the tube surface temperature is maintained at \(80^{\circ} \mathrm{C}\). If the superficial gas and liquid velocities are \(1 \mathrm{~m} / \mathrm{s}\) and $2 \mathrm{~m} / \mathrm{s}$, respectively, determine the two-phase heat transfer coefficient \(h_{t p}\). Assume the surface tension is $\sigma=0.068 \mathrm{~N} / \mathrm{m}\( and the void fraction is \)\alpha=0.33$.
Problem 106
A mixture of petroleum and natural gas is being transported in a pipeline with a diameter of \(102 \mathrm{~mm}\). The pipeline is located in a terrain that caused it to have an average inclination angle of \(\theta=10^{\circ}\). The liquid phase consists of petroleum with dynamic viscosity of $\mu_{l}=297.5 \times 10^{-4} \mathrm{~kg} / \mathrm{m} \cdot \mathrm{s}$, density of \(\rho_{l}=853 \mathrm{~kg} / \mathrm{m}^{3}\), thermal conductivity of \(k_{l}=0.163\) \(\mathrm{W} / \mathrm{m} \cdot \mathrm{K}\), surface tension of \(\sigma=0.020 \mathrm{~N} / \mathrm{m}\), and Prandtl number of \(\operatorname{Pr}_{l}=405\). The gas phase consists of natural gas with dynamic viscosity of $\mu_{g}=9.225 \times 10^{-6} \mathrm{~kg} / \mathrm{m}-\mathrm{s}\(, density of \)\rho_{g}=9.0 \mathrm{~kg} / \mathrm{m}^{3}\(, and Prandtl number of \)\operatorname{Pr}_{\mathrm{g}}=0.80$. The liquid is flowing at a flow rate of \(16 \mathrm{~kg} / \mathrm{s}\), while the gas is flowing at \(0.055 \mathrm{~kg} / \mathrm{s}\). If the void fraction is \(\alpha=0.22\), determine the two-phase heat transfer coefficient \(h_{t p}\). Assume the dynamic viscosity of liquid petroleum evaluated at the tube surface temperature to be $238 \times 10^{-4} \mathrm{~kg} / \mathrm{m} \cdot \mathrm{s}$.
Problem 108
Consider a two-phase flow of air-water in a vertical upward stainless steel pipe with an inside diameter of \(0.0254\) \(\mathrm{m}\). The two-phase mixture enters the pipe at \(25^{\circ} \mathrm{C}\) at a system pressure of $201 \mathrm{kPa}\(. The superficial velocities of the water and air are \)0.3 \mathrm{~m} / \mathrm{s}\( and \)23 \mathrm{~m} / \mathrm{s}$, respectively. The differential pressure transducer connected across the pressure taps set $1 \mathrm{~m}\( apart records a pressure drop of \)2700 \mathrm{~Pa}$, and the measured value of the void fraction is \(0.86\). Using the concept of the Reynolds analogy, determine the two-phase convective heat transfer coefficient. Use the following thermophysical properties for water and air: $\rho_{l}=997.1 \mathrm{~kg} / \mathrm{m}^{3}, \mu_{l}=8.9 \times 10^{-4} \mathrm{~kg} / \mathrm{m} \cdot \mathrm{s}, \mu_{s}=4.66 \times\( \)10^{-4} \mathrm{~kg} / \mathrm{m} \cdot \mathrm{s}, \operatorname{Pr}_{l}=6.26, k_{l}=0.595 \mathrm{~W} / \mathrm{m} \cdot \mathrm{K}, \sigma=0.0719 \mathrm{~N} / \mathrm{m}\(, \)\rho_{g}=2.35 \mathrm{~kg} / \mathrm{m}^{3}$, and \(\mu_{g}=1.84 \times 10^{-5} \mathrm{~kg} / \mathrm{m} \cdot \mathrm{s}\).
Problem 109
Water is boiled at \(120^{\circ} \mathrm{C}\) in a mechanically polished stainless steel pressure cooker placed on top of a heating unit. The inner surface of the bottom of the cooker is maintained at \(130^{\circ} \mathrm{C}\). The cooker that has a diameter of \(20 \mathrm{~cm}\) and a height of $30 \mathrm{~cm}$ is half filled with water. Determine the time it will take for the tank to empty. Answer: \(22.8 \mathrm{~min}\)
