To a good approximation, the dynamic viscosity the thermal conductivity k, and the specific heat cp are independent of pressure. In what manner do the kinematic viscosity and thermal diffusivity vary with pressure for an incompressible liquid and an ideal gas? Determine
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Fundamentals of Heat and Mass Transfer
- 9:25 G令. View Recordings PROBLEM SET A (4 problems) Problem 1 The sliding plate viscometer shown below is used to mensture the viscosity of a fluid. The top plate is movmg to the right with a coustant velocity of 10 m's in re stationary. What is the viscosity of the fluid? Assume a linear velocity distribution e to a force of 3 N. The bottom plate is to m 1 mm Problem 2 Calculate the density and specific weight of carbou dioxide at a pressure of 300 kN'm“ absolute and 60°C. Problem 3 A 10 m' oxygen tank is at 15°C and 800 kPa. The valve is opened, and some oxygen is released until the pressure in the tank drops to 600 kPa. Calculate the mass of oxygen that has been released from the tank if the temperature in the tank does not change during the process. 40:45 59:06 C ||arrow_forwardA thin plate of very large area is placed in a gap of height h with oils of Еxample viscosities u' and u" on the two sides of the plate. The plate is pulled at a constant velocity V. Calculate the position of plate so that : The shear force on the two sides of the plate is equal (i) The force required to drag the plate is minimum. Assume viscous flow and neglect all end effects. SO Position of the plate, y: Thin platearrow_forwardConsider a thin-walled, fi xed-volume container of volume V that holds an ideal gas at constant temperature T. It can be shown by dimensional analysis that the number of particles striking the walls of the container per unit area per unit time is given by nv-/4, where as usual n is the particle number density. The container has a small hole of area A in its surface through which the gas can leak slowly. Assume that A is much less than the surface area of the container. (a) Assuming that the pressure inside the container is much greater than the outside pressure (so that no gas will leak from the outside back in), estimate the time it will take for the pressure inside to drop to half the initial value. Your answer should contain A, V, and the mean molecular speed v-. (b) Obtain a numerical result for a spherical container with a diameter of 40 cm containing air at 293 K, if there is a circular hole of diameter 1.0 mm in the surface.arrow_forward
- Air flows over a flat plate at 38 m/s, 25°C and 1 atm pressure. The kinematic viscosity of air at 25°C is v= 1.562 × m/s. 10-5 What platé length should be used to achieve a Reynolds number of 1 x 108 at the end of the plate? (Round the final answer to two decimal places.) The iength of the plate is m.arrow_forwardThe torque T necessary to rotate a disc of radius R a distance h from a flat plate depends on the rotational speed w and the fluid viscosity mu. Relate T to the appropriate variables to include fluid density (rho).arrow_forwardA rod of diameter 0,08 m and length 0,13 m is inside a concentric cylindrical casing. The rod and its casing are vertically located. A liquid of density 900 kg/m3 and viscosity 0.9 Pa.s is used as a lubrication medium between rod and its casing. The rod is rotated at a speed of 46 rad/s. Due to the narrow clearance 0,03 m between rod and casing gravitational effects and surface curvature effects are ignored . Assume liquid flow in clearance as laminar steady and incompressible and use pi number, π = 3.14 a) What is the magnitude of shearing stress over the rod (in Pa)? b) What is the magnitude of frictional torque on rod (in N m)? c) What is the magnitude of Reynolds Number of flow ? Use clearence as dimensional characteristics in Reynolds Number calculationarrow_forward
- A chromel–constantan thermocouple measuring the temperature of a fluid is connected by mistake with copper–constantan extension leads (such that the two constantan wires are connected together and the copper extension lead wire is connected to the chromel thermocouple wire). If the fluid temperature was actually 250 C and the junction between the thermocouple and extension leads was at 90 C, what e.m.f. would be measured at the open ends of the extension leads if the reference junction is maintained at 0 C? What fluid temperature would be deduced from this (assuming that the connection error was not known)?arrow_forwardDetermine the dynamic viscosity (Pa-sec) and kinematic viscosi ty (m2/s) of vater with a specific weight of 9.81 kN/m3, if a Falling Sphere Viscosimeter test is conducted using an alumi num sphere that has a diameter of 10 mm and a specific weight of 28.06 kN/m3. The theoretical terminal velocity of the sphere is 0.650 m/s www.arrow_forwardFigure 1 shows a layer of oil (8.95 kN/m3), the thickness of 0.3 mm, between two parallel [8] flat plates. The upper plate is pulled across the bottom plate with a cable connected to a winch. The upper plate moves with a velocity of 0.05 m/s. The area of contact between the upper plate and the oil is 1.5 m2. Determine the kinematic viscosity of the oil if the torque acting on the winch drum should not exceed 24.5 x 10-3 Nm. Take the drum diameter as 50 mm.arrow_forward
- ASAParrow_forwardThe erythrocyte sedimentation rate (heaviness) test of a blood sample is often used as a diagnosis of immune disorders and some other diseases. Assuming that the red blood cells are about a sphere with a diameter of (approximately 5 um) and a density (g/ml 1.125), and the density and viscosity of the plasma in which the red blood cells are settled (Pa.s), (1025 kg/m3 10-3 x 1.5) On arrangement and acceleration m/s2 9.81 Calculate the erythrocyte sedimentation rate (settlement rate). 9:40 73% * "l Asiacell 90 x 10-6 m/s 1 0.9 x 10-6 m/min 90 x 10-6 m/minarrow_forwarda) First, let's start with the steady-state analysis for the cable. What is the steady-state temperature of the wire surface if this current has been passing through the cable for a long period of time in these underwater conditions? Enter only a numeric value (with no units entered) and express your answer in ∘C. b) Now, let's think about the transient case. Assume that the cable starts at the same uniform temperature as the water and then the electrical current is passed through the cable. We're now interested in the amount of time it takes to heat up. Start by calculating the Biot number for this scenario. Enter only a numeric value (your answer should be unitless). c)arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning