Fundamentals of Heat and Mass Transfer
7th Edition
ISBN: 9780470917855
Author: Bergman, Theodore L./
Publisher: John Wiley & Sons Inc
expand_more
expand_more
format_list_bulleted
Videos
Textbook Question
Chapter 6, Problem 6.39P
Forced air at
Estimate the surface temperature of the chip if it is dissipating 30 mW.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
Forced air at T0 = 25°C and V = 17 m/s is used to cool electronic elements on a circuit board. One such element is a chip, 4 mm x 4 mm, located 129 mm from the leading edge of
the board. Experiments have revealed that flow over the board is disturbed by the elements and that convection heat transfer is correlated by an expression of the form
Nuz = 0.04RE0.85 Pr3
V, T.
Chip
Board
L
mm
Estimate the surface temperature of the chip if it is dissipating 38 mW.
Forced air at T∞ = 25°C and V = 12 m/s is used to cool electronic elements on a circuit board. One such element is a chip, 4 mm × 4 mm, located 153 mm from the leading edge of the board. Experiments have revealed that flow over the board is disturbed by the elements and that convection heat transfer is correlated by an expression of the form
Nu_x=0.04Re_x^{0.85}\Pr^{\frac{1}{3}}Nux=0.04Rex0.85Pr31
Estimate the surface temperature of the chip if it is dissipating 32 mW.
Consider two cases involving parallel flow of dry air at V=V= 2.5 m/s, T∞=45°C, and atmospheric pressure over an isothermal plate at Ts=20°C. In the first case, Rex,c=Rex,c=5 × 105, while in the second case the flow is tripped to a turbulent state at x=0 m.
a. At what x‐location, in m, are the thermal boundary layer thicknesses of the two cases equal? in m
b. what is the q'' lam at W / m^2
c. what is the q'' turb at W / m^2
Chapter 6 Solutions
Fundamentals of Heat and Mass Transfer
Ch. 6 - The temperature distribution within a laminar...Ch. 6 - In flow over a surface, velocity and temperature...Ch. 6 - In a particular application involving airflow over...Ch. 6 - Water at a temperature of T=25C flows over one of...Ch. 6 - For laminar flow over a flat plate, the local heat...Ch. 6 - A flat plate is of planar dimension 1m0.75m. For...Ch. 6 - Parallel flow of atmospheric air over a flat plate...Ch. 6 - For laminar free convection from a heated vertical...Ch. 6 - A circular. hot gas jet at T is directed normal to...Ch. 6 - Experiments have been conducted to determine local...
Ch. 6 - A concentrating solar collector consists of a...Ch. 6 - Air at a free stream temperature of T=20C is in...Ch. 6 - The heat transfer rate per unit width (normal to...Ch. 6 - Experiments to determine the local convection heat...Ch. 6 - An experimental procedure for validating results...Ch. 6 - If laminar flow is induced at the surface of a...Ch. 6 - Consider the rotating disk of Problem 6.16. A...Ch. 6 - Consider airflow over a flat plate of length L=1m...Ch. 6 - A fan that can provide air speeds up to 50 m/s is...Ch. 6 - Consider the flow conditions of Example 6.4 for...Ch. 6 - Assuming a transition Reynolds number of 5105,...Ch. 6 - To a good approximation, the dynamic viscosity the...Ch. 6 - Prob. 6.23PCh. 6 - Consider a laminar boundary layer developing over...Ch. 6 - Consider a laminar boundary layer developing over...Ch. 6 - Experiments have shown that the transition from...Ch. 6 - An object of irregular shape has a characteristic...Ch. 6 - Experiments have shown that, for airflow at T=35C...Ch. 6 - Experimental measurements of the convection heat...Ch. 6 - To assess the efficacy of different liquids for...Ch. 6 - Gases are often used instead of liquids to cool...Ch. 6 - Experimental results for heat transfer over a flat...Ch. 6 - Consider conditions for which a fluid with a free...Ch. 6 - Consider the nanofluid of Example 2.2. Calculate...Ch. 6 - For flow over a flat plate of length L, the local...Ch. 6 - For laminar boundary layer flow over a flat plate...Ch. 6 - Sketch the variation of the velocity and thermal...Ch. 6 - Consider parallel flow over a flat plate for air...Ch. 6 - Forced air at T=25C and V=10m/s is used to cool...Ch. 6 - Consider the electronic elements that are cooled...Ch. 6 - Consider the chip on the circuit board of Problem...Ch. 6 - A major contributor to product defects in...Ch. 6 - A microscale detector monitors a steady flow...Ch. 6 - A thin, flat plate that is 0.2m0.2m on a side is...Ch. 6 - Atmospheric air is in parallel flow...Ch. 6 - Determine the drag force imparted to the top...Ch. 6 - For flow over a flat plate with an extremely rough...Ch. 6 - A thin, flat plate that is 0.2m0.2m on a side with...Ch. 6 - As a means of preventing ice formation on the...Ch. 6 - A circuit board with a dense distribution of...Ch. 6 - On a summer day the air temperature is 27C and the...Ch. 6 - It is observed that a 230-mm-diameter pan of water...Ch. 6 - The rate at which water is lost because of...Ch. 6 - Photosynthesis, as it occurs in the leaves of a...Ch. 6 - Species A is evaporating from a flat surface into...Ch. 6 - Prob. 6.57PCh. 6 - Prob. 6.58PCh. 6 - An object of irregular shape has a characteristic...Ch. 6 - Prob. 6.60PCh. 6 - An object of irregular shape 1 m long maintained...Ch. 6 - Prob. 6.62PCh. 6 - Prob. 6.63PCh. 6 - Prob. 6.64PCh. 6 - Prob. 6.65PCh. 6 - A streamlined strut supporting a bearing housing...Ch. 6 - Prob. 6.67PCh. 6 - Consider the conditions of Problem 6.7, for which...Ch. 6 - Using the naphthalene sublimation technique. the...Ch. 6 - Prob. 6.70PCh. 6 - Prob. 6.71PCh. 6 - Prob. 6.72PCh. 6 - Dry air at 32C flows over a wetted (water) plate...Ch. 6 - Dry air at 32C flows over a wetted plate of length...Ch. 6 - Prob. 6.75PCh. 6 - Prob. 6.76PCh. 6 - Prob. 6.77PCh. 6 - An expression for the actual water vapor partial...Ch. 6 - A mist cooler is used to provide relief for a...Ch. 6 - A wet-bulb thermometer consists of a...Ch. 6 - Prob. 6.81PCh. 6 - Prob. 6.83PCh. 6 - An experiment is conducted to determine the...Ch. 6 - Prob. 6.85PCh. 6 - Consider the control volume shown for the special...Ch. 6 - Prob. 6S.2PCh. 6 - Prob. 6S.3PCh. 6 - Consider two large (infinite) parallel plates, 5...Ch. 6 - Prob. 6S.5PCh. 6 - Consider Couette flow for which the moving plate...Ch. 6 - A shaft with a diameter of 100 mm rotates at 9000...Ch. 6 - Consider the problem of steady, incompressible...Ch. 6 - Prob. 6S.11PCh. 6 - A simple scheme for desalination involves...Ch. 6 - Consider the conservation equations (6S.24) and...
Additional Engineering Textbook Solutions
Find more solutions based on key concepts
Determine the normal stress in each member of the truss structure. All joints are ball joint, and the material ...
Introduction To Finite Element Analysis And Design
Calculate magnitude and location of the resultant force of water on this annular gate.
Fox and McDonald's Introduction to Fluid Mechanics
The two identical boards are bolted together to form the beam. Determine the maximum spacing s of the bolts to ...
Statics and Mechanics of Materials (5th Edition)
The rate of heat addition and the magnitude of kinetic and potential energy change.
Introduction to Heat Transfer
The pendulum bob B has a weight of 5 lb and is released from rest in the position shown, = 0. Determine the te...
Engineering Mechanics: Dynamics (14th Edition)
The force in each member of truss and the state of members are in tension or compression.
Engineering Mechanics: Statics & Dynamics (14th Edition)
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- Air flows inside a tube 60 mm in diameter (d) and 2.1 m long (l) at a velocity w = 5 m/sec. Find the heat-transfer coefficient α if the mean air temperature tf = 100oC. Note: Write your answer in space provided without the unit (the answer is in kcal/m2-hr-oC, one decimal places)arrow_forwardA 1-in-diameter (D = 1 inch) rotating machined shaft has a groove 0.1-in deep with a 0.1-in radius machined into it. The shaft is subjected to a pulsating (i.e. R = 0) torque and bending moment of following values. Based on laboratory experiments at 550°F, Sut = 150 ksi, Sy = 120 ksi, and S'e = 90 ksi are measured. Using mod-Goodman equation and for operating temperature of 550°F and 90% reliability, determine the factor of safety for yielding and fatigue of this shaft. Tmax = 2000 Ib-in Mmax = 1600 lb-in Mmin = -1200 Ib-in D - -d- M T M Tarrow_forwardConsider parallel flow over a flat plate for air at 300 K and engine oil at 380 K. The free stream velocity is u temperature difference between the surface and the free stream is the same in both cases, with Ts > T (a) Determine the location, in m, where transition to turbulence occurs, xc, for both fluids. 8 X (b) For laminar flow over a flat plate, the velocity boundary layer thickness is given by = layer thickness 6, in m, for x = 1 for each fluid. Part A Determine the location, in m, where transition to turbulence occurs, xc, for both fluids. (c) Determine the thermal boundary layer thickness 6₁, in m, for x = 1 for each fluid. At an x-location where both fluids experience laminar flow conditions, which fluid has the largest temperature gradient at the plate surface, — dT/ dy|y_o? Which fluid is associated with the largest local Nusselt number Nu? Which fluid is associated with the largest local heat transfer coefficient h? y=0 Xc,air = Xc,eo = i m 5 Rex m = 1.6 m/s. The Determine…arrow_forward
- A nuclear reactor is cooled by liquid sodium. The liquid sodium has the following properties: dynamic viscosity = 0.41 mPa·s, specific heat capacity = 1.2 kJ/kgK, thermal conductivity 82 W/mK. Which of the following statements is correct for this scenario? please explain A The thermal boundary layer is thicker than the hydraulic boundary layer. B Heat is transferred through the fluid more easily than momentum. C The velocity varies significantly from the surface to the thickness of the thermal boundary layer. D The hydraulic boundary layer is thicker than the thermal boundary layer.arrow_forwardConsider two cases involving the parallel flow of dry air at V= 1.5 m/s, T∞=45°C, and atmospheric pressure over an isothermal plate at Ts=20°C. In the first case, Rex,c=R5 × 105, while in the second case the flow is tripped to a turbulent state at x=0 m. At what x‐location, in m, are the thermal boundary layer thicknesses of the two cases equal? What are the local heat fluxes, in W/m2, at this location for the two cases?arrow_forwardAir at 22˚C and at atmospheric pressure flows over a flat plate at a velocity of 1.65 m/s. If the length of the plate is 2.179 m and its temperature is 98 ˚C, Calculate Heat rate by using exact and approximate methods both. What is the %age difference of the heat transfer rate values by these methods? Take width of the plate as unity. Properties given at 60˚C are as follows: Density: 1.058 kg/m3 , cp = 1.005 kJ/kg˚C, k= 0.02897 w/m˚C, Kinematic viscosity is 18.97 × 10-6 m2 /sarrow_forward
- The liquid food is flowed through an uninsulated pipe at 90 ° C. The product flow rate is 0.3 kg / s and has a density of 1000 kg / m³, specific heat 4 kJ / (kg K), a viscosity of 8 x 10-6 Pa s, and a thermal conductivity of 0.55 W / (m) K). Assume that the change in viscosity is negligible. The internal diameter of the pipe is 30 mm with a thickness of 3 mm made of stainless steel (k = 15 W / [m ° C]). The outside temperature is 15 ° C. If the outer convective heat transfer coefficient is 18 W / (m² K), calculate the heat loss at steady state per meter pipe length. a. Find the convection coefficient in pipe = W / m² ° C. b. Calculate heat loss per meter pipe length = wattsarrow_forwardAir at 20 ◦ C flows inside a pipe 18-mm-ID having a uniform heat flux of 150 W/m 2 on the surface, the average flow velocity at entry being 1.0 m/s. The air pressure is 2 bar. Determine the value of convection coefficient. If the pipe is 2.5 m long, determine the air exit temperature and the wall temperature at the exit. Assume fully developed hydrodynamic boundary layer.arrow_forwardThe liquid food is flowed through an uninsulated pipe at 90 ° C. The product flow rate is 0.4 kg / s and has a density of 1000 kg / m³, specific heat 4 kJ / (kg K), a viscosity of 8 x 10-6 Pa s, and a thermal conductivity of 0.55 W / (m) K). Assume that the change in viscosity is negligible. The internal diameter of the pipe is 20 mm with a thickness of 3 mm made of stainless steel (k = 15 W / [m ° C]). The outside temperature is 15 ° C. If the outer convective heat transfer coefficient is 18 W / (m² K), calculate the heat loss at steady state per meter of pipe length. a.Find the convection coefficient in the pipe = AnswerW / m² ° C. b. Calculate heat loss per meter pipe length = Answerwatt.arrow_forward
- A 2-cm diameter, 10-m long tube transports water at an average flow velocity of 8 m/s. The water enters at 20°C and leaves at 30°C. To compute for the Nusselt number of the water flow, what is the exact value of the temperature in °C on which the water properties should be based?arrow_forwardConsider two cases involving parallel flow of dry air at V = 4m/s, T, = 45°C, and atmospheric pressure over an isothermal plate at T, = 20°C. In the first case, Re = 5 x 105, while in the second case the flow is tripped to a turbulent state at x = 0m. At what x -location, in m, are the thermal boundary layer thicknesses of the two cases equal? What are the local heat fluxes, in W/m?, at this location for the two cases? X = i W/m? urb W/m? iarrow_forwardIn mechanical fluidarrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning
Principles of Heat Transfer (Activate Learning wi...
Mechanical Engineering
ISBN:9781305387102
Author:Kreith, Frank; Manglik, Raj M.
Publisher:Cengage Learning
Intro to Compressible Flows — Lesson 1; Author: Ansys Learning;https://www.youtube.com/watch?v=OgR6j8TzA5Y;License: Standard Youtube License