Question

A long 10 cm × 20 cm rectangular cross section steel bar ݇ k= 63.9 W/mK...

A long 10 cm × 20 cm rectangular cross section steel bar ݇ k= 63.9 W/mK and alpha=18.8*10^-6 m^2 /s was heated to an initial temperature of 450°C. The steel bar is allowed to cool in a room with a temperature of 25°C and convection heat transfer coefficient of 25 W/m^2 K. The bottom surface of the bar is insulated while the other surfaces are exposed to convection. With a uniform nodal spacing of 5 cm, determine the duration required to cool the center of the bar to 100°C.

Engineering   Mechanical-Engineering   
0 0
Add a commentTranscribed image text
Next >

Homework Answers

Answer #1

0 0
Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Log In

Sign Up

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
In a steel spherical reactor with a heat transmission coefficient (10 + X) W / mK,...
In a steel spherical reactor with a heat transmission coefficient (10 + X) W / mK, water is boiled at 350 oC. The inner diameter of the tank is 80 cm and the wall thickness is (5+ (X / 2)) cm. This tank is insulated with (X) cm thick concrete (k = 2.5 W / mK). Outdoor heat transfer coefficient (10+ (X)) W / m2K, indoor heat transfer coefficient is 500 W / m2K. Calculate both surface temperatures of the...
Consider a large uranium plate of thickness 5 cm and thermal conductivity k = 28 W/m...
Consider a large uranium plate of thickness 5 cm and thermal conductivity k = 28 W/m K in which heat is generated uniformly at a constant rate of q˙ = 6 × 10^5 W/m^3 . One side of the plate is insulated while the other side is subjected to convection in an environment at 30◦C with a heat transfer coefficient of h = 60 W/m2 K. Considering six equally spaced nodes with a nodal spacing of 1 cm, (a) Sketch...
A stainless-steel fin (k = 16 W/m. °C) has a length of 15 cm and a...
A stainless-steel fin (k = 16 W/m. °C) has a length of 15 cm and a square cross section 12.5 by 12.5 mm attached to a wall maintained at 250 °C. The heat-transfer coefficient is 40 W/m. °C, and the environment temperature is 90 °C. Calculate the percentage increase in heat transfer after attaching the fin.
It's a heat transfer question. A stainless steel fin with a constant base temperature (900K) and...
It's a heat transfer question. A stainless steel fin with a constant base temperature (900K) and with an insulated end. Apply convection at all cylindrical surfaces except the base and the tip. The convection coefficient, h = 50 W/(m2·K), and fluid temperature of T∞ = 300K. Plot the temperature distribution along the center axis line (T vs x). Include a contour plot across the cross section of the fin. Assume zero contact resistance between the sections. K=19.8W/m-k Cp=557J/Kg-K Rho= 7900Kg/m^3...
800 W/m3 of heat is generated within a 10 cm diameter nickel- steel sphere for which...
800 W/m3 of heat is generated within a 10 cm diameter nickel- steel sphere for which k = 10 W/m·K. The environment is at 20◦C and there is a natural convection heat transfer coefficient of 10 W/m2K around the outside of the sphere. What is its center temperature at the steady state? [21.37◦C.]
A spherical object (50 cm diameter, c=0.46 kJ/kg*C, k = 42 W/m*C, density = 7800 kg/m3...
A spherical object (50 cm diameter, c=0.46 kJ/kg*C, k = 42 W/m*C, density = 7800 kg/m3 ) is initially at a uniform temperature of 450 C. It is suddenly placed in a constant temperature environment of 100 C. The convection transfer coefficient is 500 W/m2*C. How long would it take for temperature in the center of the sphere to cool down to 150 C? Note: Bi for a sphere is (hD)/(6k).Suggestion: First calculate Biot number, then determine if T is...
Consider an aluminum pin fin (k = 240 W/m·K) with a 2 mm by 2 mm...
Consider an aluminum pin fin (k = 240 W/m·K) with a 2 mm by 2 mm square cross-section and a length of 4 cm that is attached to a surface at 100o C. The fin is exposed to air at 25o C with a convection heat transfer coefficient of 20 W/m2 · o C. Determine the rate of heat transfer and the tip temperature of the fin for the following cases: (a) Convection from the fin tip. (b) Adiabatic tip...
a) A 12 mm diameter mild steel sphere (k = 42.5 W/m K) is exposed to...
a) A 12 mm diameter mild steel sphere (k = 42.5 W/m K) is exposed to cooling airflow at 27 0C resulting in the convective coefficient, h = 114 W/ m2 K. The relevant properties of mild steel are given as follows: Density , /7850 2 mkg  Specific heat K kgJc p / 475 and thermal diffusivity hr m /043.0 2  Determine: (i) Time required to cool the sphere (lumped parameter system) from 540 0C to 950C. [7...
1. An oven chimney is made of brick with a heat transmission coefficient 1.1 W/mK 10...
1. An oven chimney is made of brick with a heat transmission coefficient 1.1 W/mK 10 cm thick. Since the shaft exterior radiation beam coefficient is 0.8 and the flue gas temperature is 350°C, the external ambient temperature is 25°C and the outer ambient heat transport coefficient is 20 W/m2K; a) Calculate the shaft exterior temperature. b) In order to reduce the risk of burn injury that may occur in the body, the shaft is asked to be below 55°Cve...
A freshly baked loaf of bread (30cm long, 15cm high, 10 cm wide) is removed from...
A freshly baked loaf of bread (30cm long, 15cm high, 10 cm wide) is removed from an oven and set on the counter (assumed insulated) to cool. The bread is at 125°C initially (assume uniform) and the room is at 25°C. Thermal conductivity and diffusivity for bread are k=0.05 W/m•K and α=5x10-7 m2/s, and the convective heat transfer coefficient is h=10 W/m2K. (a) Write down the governing differential equation in three-dimension representing this problem. (b) Write down the boundary conditions...
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT