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Cylindrical dry-bulb and wet-bulb thermometers are installed in a large-diameter duct to obtain the temperature
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Fundamentals of Heat and Mass Transfer
- Weather balloons are high-altitude balloons that are capable of reaching an altitude of 40 km (or 25 miles). They are usually filled with hydrogen or helium gas. One such balloon is filled with air that is initially at a temperature of 304 K and at atmospheric pressure. This particular balloon can expand to a maximum diameter of 28 m when it reaches an altitude where the pressure and temperature are 0.028 atm and 190 K respectively. Determine the diameter of the balloon at lift off. ____________________marrow_forwardNutrients dissolved in water are carried to upper parts of plants by tiny tubes partly because of the capillary effect. Determine how high (in meters) the water solution will rise in a tree in a 0.005-mm-diameter tube as a result of the capillary effect. Treat the solution as water at 20°C with a contact angle of 15°. Surface tension of some fluids in air at 1 atm and 20°C (unless otherwise stated) Surface Tension Fluid , N/m* Water: 0°C 0.076 0.073 20°C 100°C 300°C Glycerin SAE 30 oil 0.059 0.014 0.063 Mercury Ethyl alcohol Blood, 37°C Gasoline Ammonia 0.035 0.440 0.023 0.058 0.022 0.021 Soap solution Kerosene 0.025 0.028arrow_forwardInclude a brief description and the diagram of the system. Dry air at 25◦C and atmospheric pressure flows inside a 5-cm-diameter pipe at a velocity of 3 m/s. The wall is coated with a thin film of water, and the wall temperature is 25◦C. Calculate the water-vapor concentration in the air at exit of a 3-m length of the pipe.arrow_forward
- Carbon dioxide flows steadily through a varying cross- sectional-area duct such as a nozzle at a mass flow rate of 3 kg/s. The carbon dioxide enters the duct at a pressure of 1400 kPa and 200°C with a low velocity, and it expands in the nozzle to a pressure of 200 kPa. The duct is designed so that the flow can be approximated as isentropic. Determine the following parameters at each location along the duct that corresponds to a pressure drop of 200 kPa: (i) density; (ii) velocity: (iii) flow area; (iv) mach number. You may assume: • Carbon dioxide is an ideal gas with constant specific heats at room temperature; • Flow through the duct is steady, one-dimensional and isentropic. Use c, 0 846 kJ/kgk andk = 1.289 throughout the calculations, which are the constant-pressure specific heat and specific heat ratio values of carbon dioxide at room temperature. The gas constant of carbon dioxide is R = 0.1889 kJ/kg K.arrow_forwardThe diagram shows a schematic for a thermometer based on the expansion of some fluid. There is a spherical reservoir of the fluid, with radius R, which is connected via a tube to a vertical section, with a circular cross section, radius r. a. assuming r << R, show that the change in fluid level in the tube is given by: 4 BR³ AT AL = 3 p² Where AT is the change in temperature and is the volumetric expansion coefficient of the fluid b. what properties should the system have to be most sensitive?arrow_forwardA vertical cylindrical shell storage tank of 4 m inside diameter and 6 m high is filled with three liquids having specific gravities of 3, 1 and 0.8. Each liquid has heights of 2 m inside the tank. A sharp edge orifice 120 mm diameter with C = 0.65 is located at the lowest point Determine the time to empty one half of its contents through orifice. Determine the time to empty the whole tank through the orifice.arrow_forward
- Consider a spherical instrument pod of diameter 100 mm that is used to make soundings and measure conditions in water. If the pod dissipates 400 W into the water which is at 15°C with a current of 1 m/s, find the surface temperature of the pod, in °C. Assume constant properties. °℃arrow_forwardCylindrical vessel of 1m diameter and 4 m length has hydrogen gas at pressure of 100 kpa and 27 °C. Determine the amount of heat to be supplied so as to increase gas pressure to 125 kPa. For hydrogen take Cp= 14.307 kJ/kg K, Cv= 10.183 kJ/kg K.arrow_forwardMethanol (SG=0.792) is contained in a large tank under a pressure of 350000 Pa absolute. When a valve on the bottom of the tank is opened, the methanol drains freely though a 0.02 m ID tube whose outlet is 7.00 m below the surface of the methanol. The pressure at the outlet of the discharge pipe is 101325 Pa. Some useful constants and conversions: g = 9.8 m/s2 , Pref = 1000 kg/m3 . a. Draw the system. Label points I and 2 (where you will define A= 2-1) and label the variables with values b Write the general form of the energy balance. Cancel out negligible terms, and state the keyword/assumption to justify. Simplify to the resultant energy balance. c.) Assume the diameter of the tank is very big compared to the drain tube velocity, which make the velocity of liquid in the tank equal to zero. Estimate the methanol discharge velocity in the drain tube in m/s. *hint: divide your EB by m to eliminate m and V. Recall, n = pV = pvA and = v/m=1/parrow_forward
- People buying food in sealed bags at high elevations often notice that the bags are puffed up because the air inside has expanded. A bag of pretzels was packed at a pressure of 0.98 atm and a temperature of 21.0°C. When opened at a summer picnic in Santa Fe, New Mexico, at a temperature of 30.0°C, the volume of the air in the bag is 1.32 times its original volume. What is the pressure of the air (in atm)? atmarrow_forwardSTELIA Aerospace are planning to design a spherical cryogenic tank to be stored with liquid hydrogen. It is also designed with a system that if the tank reaches maximum capacity all entry and exit nozzles will automatically be closed. The specific gravity of this fluid is approximately seven hundredths the density of water. The tank is designed to have two-entry filtration system and an exit nozzle located at the bottom. The liquid hydrogen flows into the cryogenic tank at a rate of 0.85 kilograms per second and 0.75 kilograms per second. At the same time the exit nozzle is opened with a rate of 0.005 kilograms per second. (a)The shutoff valves were closed after 35 minutes, what is the volume and radius of the spherical tank? (b) Using your answers on item a, how full is the tank (in percentage) after 27.15 minutes?arrow_forwardThe actual velocity of a gas entering in a chimney is 8 m/sec the gas temperature is 25 C and pressure of 98 Kpa with a gas of 0.287 KJ.kg-K . Determine the chimney diameter in meter if mass of gas is 50000 kg/hr.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning