PROBLEM: 1VB-29 FROM THE BOOK: ENGINEERING THERMOFLUIDS, M. MASSOUD. 28. For flow over a flat plate, the average temperature difference (i.e., T, – Tf)when the plate temperature is kept constant is readily calculated. This is not thecase if a constant heat flux to or from the surface is imposed. Use the averagingscheme over the plate length as given by:f(T, – Ts-T, kdxT, -Tf6 dxto find the average temperature difference. [Hint: Substitute for AT in the nu-merator from the Nu number and for Nu number from Equation IVb.2.11 and in-tegrate].29. Obtain the average temperature difference for the laminar flow of fluids overa heated plate (L × b), for constant heat flux boundary condition, in terms of theRe and the Pr numbers. For this purpose, use the result of Problem 28 and the lo-cal Nu, number for constant heat flux boundary condition given as:1/2.1/3Nuy = 0.453 Re2² Pr'-(4 = constant )where in this relation properties are developed at the film temperature.-1/2[Ans.: T, -Tf = 1.47 Re7"2 Pr-/3 4, (LIk)].

Write the expression of Nusselt number. Nux=0.453Rex1/2Pr1/3Nu=0.680ReL1/2Pr1/3

29. Obtain the average temperature difference for the laminar flow of fluids over a heated plate (L × b), for constant heat flux boundary condition, in terms of the Re and the Pr numbers. For this purpose, use the result of Problem 28 and the lo- cal Nu, number for constant heat flux boundary condition given as: 1/2 Nuy = 0.453 Re2 Pr/3 (4 = constant ) where in this relation properties are developed at the film temperature. -1/2 -1/3 [Ans.: T, -Tf =1.47 Re7"² Pr %D

29. Obtain the average temperature difference for the laminar flow of fluids over a heated plate (L × b), for constant heat flux boundary condition, in terms of the Re and the Pr numbers. For this purpose, use the result of Problem 28 and the lo- cal Nu, number for constant heat flux boundary condition given as: 1/2 Nuy = 0.453 Re2 Pr/3 (4 = constant ) where in this relation properties are developed at the film temperature. -1/2 -1/3 [Ans.: T, -Tf =1.47 Re7"² Pr %D

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.23P: Using the information in Problem 1.22, estimate the ambient air temperature that could cause...

See similar textbooks

Similar questions

Heat transfer Question Please explain how to write an excel spreadsheet that will calculate the temperature at any time and any location for a cylinder that is being cooled by convection using the first 4 terms of the Fourier expansion that is a solution to the PDE. Input variables are to be Tj, Too, h, k, p, D.t Try this over a variety of Fourier numbers, some less than .2, some near 0.2, and some much greater than 0.2
Estimate the Celsius equivalent of Absolute temperature (a) and standard Temperature (b). 19 put of BI三|に Paragraph question Path: p Maximum file size: 100MB, maximum number of files: 1 hp
The heat transfer between a solid body and a fluid medium is determined by the equation Q=h·A·(Ts-Tf). Here; Q is the amount of heat transferred, h is the heat transfer coefficient, A is the heat transfer surface area, Ts is the temperature of the surface and Tf is the temperature of the fluid. These parameters were measured as h=250±1.75 W/m2ºC, A=20±0.75 m2, Ts =100±0.75ºC and Tf =25±0.75ºC, including error levels. What is the total uncertainty in the amount of heat transferred, in ±%? a. 3.98 b. 4.07 c. 2.73 d. 2.95 e. 3.88
7) Give two disadvantages of empirical thermometers. 8) Consider two liquids, A and B. with temperatures Te > TA. The two objects are put into thermal contact for a time period. Without just saying 'heat flows from hot to cold' how would you prove to someone that a quantity of heat flowed from B to A. (think of James Joule's experiments) 9) If the temperature of the sun were to suddenly double, by what multiplicative factor would the thermal radiation change ? Show Work
The temperature of an exotic liquid in a pipe of length L = 2 can be described by the following PDE Ꭷ2Ꭲ . ər² ƏT Ət ƏT ?х + D (2) with time t, temperature T, u a constant velocity, and D a constant thermal diffusivity. For a grid of M+ 1 equally spaced points along the pipe and Ar the spacing between points, write the equation for the right-hand-side fi of Eq. (2) at mesh point with second order accurate central finite differences.
The Reynolds number is a dimensionless group defined for a fluid flowing in a pipe as Re = Duplu where Dis pipe diameter, u is fluid velocity, p is fluid density, and u is fluid viscosity. When the value of the Reynolds number is less than about 2100, the flow is laminarthat is, the fluid flows in smooth streamlines. For Reynolds numbers above 2100, the flow is turbulent, characterized by a great deal of agitation. Liquid methyl ethylketone (MEK) flows through a pipe with an inner diameter of 2.067 inches at an average velocity of 0.48 ft/s. At the fluid temperature of 20°C the density of liquid MEK is 0.805 g/cm? and the viscosity is 0.43 centipoise [1 cP = 1.00 x 10-³ kg/(m-s)]. Without using a calculator, determine whether the flow is laminar or turbulent. Show your calculations.
When fluid flows over a surface, the Reynolds number will output whether the flow is laminar (smooth), transitional, or turbulent. Determine the dimension for the Reynolds number using the SI. The Reynolds number is expressed as pVD R = where p is the density of the fluid, V is the free stream fluid velocity, Dis the characteristic length of the surface, and u is the fluid viscosity. The units of fluid viscosity are kg/(m - s). O a.s1 O b. m O c. m/s O d. Dimensionless
Newtons laws of cooling proposes that the rate of change of temperature is proportional to the temperature difference to the ambient (room) temperature. And can be modelled using the equation: dT/dt = -k (T-Ta)It can also be written as dT/T-Ta = -k dtWhere:T = Temperature of materialTa = Ambient (room) temperaturek = A cooling constanta) integrate both sides of the equation and show that the temperature difference is given by:(T-Ta) = CoE^-kt(Co is a constant for this problem)B) calculate Co if the initial temperature is 70 degrees C and Ta = 20 degrees C?
According to the Newton's cooling law, the temperature of any substance is directly related to the distinction between the substance temperature and its environment (ambient) temperature dT =-k(T – T,)k(T-T) dt where Tis the substance temperature (C) T is the time (minute) k is constant T. is environmental temperature A casting ladle of molten metal has 290 °C, By using Euler methodology, evaluate the temperature from t=0 to 35 min with a step size of 2 min. If, T, is 25°C and k is 0,009/min.
A K- type thermocouple is used to measure the temperature in a heating process. The length of the bare material is 100mm and thickness is 1.5mm. Find the time constant of the bare material. Турe of Thermo-Material couple K ( Q W/m- (kg/m³)| k) |(J/Kg- oc) J Iron- Constantan 46 8535 345 Kromel- Alumel 35 8738 380 T Copper- Constantan 160 8902 316 Cromel - Contantan 33 8825 336 IN Nicrocil- Nisil 34 8702 376 Pt(30%)Rhodium - B 19 15718 56 Pt(6%)Rhodium Platinum(13%)Rodium 55 16628 99 Platinum Platinum(10%)Rodium - Platinum IS 52.9 16745 99 Time constant of the bare material is, T=
Orange JO A O X 91|4 2:26 ch1_introductio.. Shear stress (t) is the resistance per unit area of the upper plate t = R/A=T/A Water responds to shear stress by continuously yielding in angular deformation in the direction of the shear. IThe rate of angular deformation in the fluid, d(8)/dt ,is proportional to the shear Istress, as shown in Figure 1.1. do dt dx ,and v = dy dx Angular deformation (Shear strain), 0 = dt do Rate of shear strain = dt dx dv (Velocity gradient) dy dy dt dv Therefore, to dv T = constant dy dv T = - dy The proportionally constant, u, is called the absolute viscosity of the flyid Example A flat plate of 50 cm² is being pulled over a fixed flat surface at a constant velocity of 45 cm/sec (Figure 1.1). An oil film of unknown viscosity separates the plate and the fixed surface by a distance of 0.1 cm. The force (T) required to pull the plate is measured to be 31.7 N, and the viscosity E of the fluid is constant. Determine the viscosity (absolute). 22 Example A flat…
Specific Heat, Cp Water Thermal Thermal Content, Temperature, T Density, p Conductivity, k Ibm/ft3 Diffusivity, a ft2/s Food %(mass) °F Btu/h-ft.°F Btu/lbm-R Fruits/Vegetables Apple juice Apples Apples, dried Apricots, dried Bananas, fresh 1.51 x 10-6 1.47 x 10-6 87 68 62.4 0.323 0.922 85 32-86 52.4 0.242 0.910 41.6 73 53.4 0.127 1.03 x 10-6 0.650 1.22 x 10-6 1.51 × 10-6 43.6 73 82.4 0.217 0.662 76 41 61.2 0.278 0.856 Broccoli 21 35.0 0.223 | 1.42 x 10-6 Cherries, fresh Figs Grape juice 92 32-86 65.5 0.315 0.952 40.4 73 77.5 0.179 1.03 x 10-6 0.642 1.51 × 10-6 1.51 × 10-6 89 68 62.4 0.328 0.934 Peaches 36-90 2-32 59.9 0.304 0.934 Plums 3 38.1 0.143 | Potatoes 32-158 0-70 65.7 0.288 1.40 x 10-6 0.868 Raisins 32 73 86.2 0.217 1.18 x 10-6 0.592 Meats Beef, ground Beef, lean 67 43 59.3 0.235 1.40 x 10-6 0.802 74 37 68.0 0.272 1.40 x 10-6 0.844 Beef fat 95 50.5 0.110 72 95 73 Beef liver 0.259 0.832 1.18 x 10-6 1.40 x 10-6 Cat food 39.7 71.2 0.188 0.638 Chicken breast 75 32 65.5 0.275 0.850