Steam at 250 psia and 700°F steadily enters a nozzle whose inlet area is 0.2 ft2. The mass flow rate of steam through the nozzle is 10 lbmys. Steam leaves the nozzle at 200 psia with a velocity of 900 ft/s. Heat losses from the nozzle per unit mass of the steam are estimated to be 1.2 Btu/lbm. Determine (a) the inlet velocity and (b) the exit temperature of the steam.

Steam at 250 psia and 700°F steadily enters a nozzle whose inlet area is 0.2 ft2. The mass flow rate of steam through the nozzle is 10 lbmys. Steam leaves the nozzle at 200 psia with a velocity of 900 ft/s. Heat losses from the nozzle per unit mass of the steam are estimated to be 1.2 Btu/lbm. Determine (a) the inlet velocity and (b) the exit temperature of the steam.

University Physics Volume 2

18th Edition

ISBN:9781938168161

Author:OpenStax

Publisher:OpenStax

Chapter3: The First Law Of Thermodynamics

Section: Chapter Questions

Problem 62P: For a temperature increase of 10 at constant volume, what is the heat absorbed by (a) 3.0 mol of a...

See similar textbooks

Similar questions

For a temperature increase of 10 at constant volume, what is the heat absorbed by (a) 3.0 mol of a dilute monatomic gas; (b) 0.50 mol of a dilute diatomic gas; and (c) 15 mol of a dilute polyatomic gas?
A test is conducted to determine the overall heat transfer coefficient in a shell-and-tube oil-to-water heat exchanger that has 24 tubes of internal diameter 1.2 cm and length 2 m in a single shell. Cold water (cp = 4180 J/kg·K) enters the tubes at 20°C at a rate of 3 kg/s and leaves at 55°C. Oil (cp = 2150 J/kg·K) flows through the shell and is cooled from 120°C to 45°C. Determine the overall heat transfer coefficient Ui of this heat exchanger based on the inner surface area of the tubes.
A 1.0 m * 1.5 m double-pane window consists of two 4-mm-thick layers of glass (k = 0.78 W/m·K) that are separated by a 5-mm air gap (kair = 0.025 W/m·K). The heat flow through the air gap is assumed to be by conduction. The inside and outside air temperatures are 20°C and 220°C, respectively, and the inside and outside heat transfer coefficients are 40 and 20 W/m2·K. Determine (a) the daily rate of heat loss through the window in steady operation and (b) the temperature difference across the largest thermal resistance.
Cold water (cp = 4180 J/kg·K) enters the tubes of a heat exchanger with 2-shell passes and 20-tube passes at 20°C at a rate of 3 kg/s, while hot oil (cp = 2200 J/kg·K) enters the shell at 130°C at the same mass flow rate and leaves at 60°C. If the overall heat transfer coefficient based on the outer surface of the tube is 220 W/m2·K, determine (a) the rate of heat transfer and (b) the heat transfer surface area on the outer side of the tube.
Two concentric spheres of diameters 15 cm and 25 cm are separated by air at 1 atm pressure. The surface temperatures of the two spheres enclosing the air are T1 = 350 K and T2 = 275 K, respectively. Determine the rate of heat transfer from the inner sphere to the outer sphere by natural convection.
A one-shell and two-tube type heat exchanger has an overall heat transfer coefficient of 300 Btu/h·ft2·°F. The shell side fluid has a heat capacity rate of 20,000 Btu/h·°F, while the tube side fluid has a heat capacity rate of 40,000 Btu/h·°F. The inlet temperatures on the shell side and tube side are 200°F and 90°F, respectively. If the total heat transfer area is 100 ft2, determine (a) the heat transfer effectiveness and (b) the actual heat transfer rate in the heat exchanger.
Steam in a heating system flows through tubes whose outer diameter is 3 cm and whose walls are maintained at a temperature of 120°C. Circular aluminum alloy fins (k = 180 W/m·K) of outer diameter 6 cm and constant thickness t = 2 mm are attached to the tube. The space between the fins is 3 mm, and thus there are 200 fins per meter length of the tube. Heat is transferred to the surrounding air at 25°C, with a combined heat transfer coefficient of 60 W/m2·K. Determine the increase in heat transfer from the tube per meter of its length as a result of adding fins.
Two 5-cm-diameter, 15-cm-long aluminum bars (k = 176 W/m·K) with ground surfaces are pressed against each other with a pressure of 20 atm. The bars are enclosed in an insulation sleeve and, thus, heat transfer from the lateral surfaces is negligible. If the top and bottom surfaces of the two-bar system are maintained at temperatures of 150°C and 20°C, respectively, determine (a) the rate of heat transfer along the cylinders under steady conditions and (b) the temperature drop at the interface.
The exhaust duct from a heater has an inside diameter of 114.3 mm with ceramic walls 6.4 mm thick. The average k = 1.52 W/mK. Outside this wall, an insulation of rock wool 102 mm thick is installed. The thermal conductivity of the rock wool is k = 0.046+1.56*10-4T (°C) (W/mK). The inside surface temperature of the ceramic is T1= 588.7 K, and the outside surface temperature of the insulation is T3= 311 K. Calculate the heat loss for 1.5 m of duct and the interface temperature T2between the ceramic and the insulation.Assumesteady heat transfer.Hint: The correct value of km for insulation is that evaluated at the mean temperature of T2+T3/2. Hence, for the first trial assume a mean temperature of, say, 448 K. Then, calculate the heat loss and T2. Using this new T2, calculate a new mean temperature and proceed as before.
The tube in a heat exchanger has a 2-in inner diameter and a 3-in outer diameter. The thermal conductivity of the tube material is 0.5 Btu/h·ft·°F, while the inner surface heat transfer coefficient is 50 Btu/h·ft2·°F and the outer surface heat transfer coefficient is 10 Btu/h·ft2·°F. Determine the overall heat transfer coefficients based on the outer and inner surfaces.
Consider a well-insulated horizontal rigid cylinder that is divided into two compartments by a piston that is free to move, but does not allow either gas to leak into the other side. Initially, one side of the piston contains 1 m3 of N2 gas at 500 kPa and 120°C while the other side contains 1 m3 of He gas at 500 kPa and 40°C. Now thermal equilibrium is established in the cylinder as a result of heat transfer through the piston. Using constant specific heats at room temperature, determine the final equilibrium temperature in the cylinder. What would your answer be if the piston were not free to move?
For a certain gas, R=0.267 kJ/kg∙K and k=1.384. (a) What is the value of specific heat at constant pressure in kJ/kg∙K?