1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
ira [324]
3 years ago
10

A thick aluminum block initially at 26.5°C is subjected to constant heat flux of 4000 W/m2 by an electric resistance heater whos

e top surface is insulated. Determine how much the surface temperature of the block will rise after 2112 seconds. Consider the diffusivity of pure aluminum to be 9.71 × 10−5 m2/s and conductivity of pure aluminum to be 237 W/m·k.
Determine how much the surface temperature of the block will rise after 30 minutes.
Engineering
1 answer:
Yanka [14]3 years ago
5 0

Given Information:

Initial temperature of aluminum block = 26.5°C

Heat flux = 4000 w/m²

Time = 2112 seconds

Time = 30 minutes = 30*60 = 1800 seconds

Required Information:

Rise in surface temperature = ?

Answer:

Rise in surface temperature = 8.6 °C after 2112 seconds

Rise in surface temperature = 8 °C after 30 minutes

Explanation:

The surface temperature of the aluminum block is given by

T_{surface} = T_{initial} + \frac{q}{k} \sqrt{\frac{4\alpha t}{\pi} }

Where q is the heat flux supplied to aluminum block, k is the conductivity of pure aluminum and α is the diffusivity of pure aluminum.

After t = 2112 sec:

T_{surface} = 26.5 + \frac{4000}{237} \sqrt{\frac{4(9.71\times 10^{-5}) (2112)}{\pi} }\\\\T_{surface} = 26.5 + \frac{4000}{237} (0.51098)\\\\T_{surface} = 26.5 + 8.6\\\\T_{surface} = 35.1\\\\

The rise in the surface temperature is

Rise = 35.1 - 26.5 = 8.6 °C

Therefore, the surface temperature of the block will rise by 8.6 °C after 2112 seconds.

After t = 30 mins:

T_{surface} = 26.5 + \frac{4000}{237} \sqrt{\frac{4(9.71\times 10^{-5}) (1800)}{\pi} }\\\\T_{surface} = 26.5 + \frac{4000}{237} (0.4717)\\\\T_{surface} = 26.5 + 7.96\\\\T_{surface} = 34.5\\\\

The rise in the surface temperature is

Rise = 34.5 - 26.5 = 8 °C

Therefore, the surface temperature of the block will rise by 8 °C after 30 minutes.

You might be interested in
Which two is right about febuary 14
igor_vitrenko [27]

Answer:A and B

Explanation:

3 0
3 years ago
Read 2 more answers
In the High Low Logic Index low levels are bearish and high levels are bullish, generally True False
Irina-Kira [14]

Answer:

True

Explanation:

Logic index is selection of values based on the logical streams. The values appear on the logical array. The levels are determined on the market investment performance. If there are many buyers available in the market the index will be high and the market will be bullish. If there are few or no investors available the market index will be low which means the market is bearish.

8 0
3 years ago
Steam enters a turbine at 120 bar, 508oC. At the exit, the pressure and quality are 50 kPa and 0.912, respectively. Determine th
Archy [21]

Answer:

The turbine produces <u>955.53 KW</u> power.

Explanation:

Taking the turbine as a system. Applying Law of Conservation of Energy:

m(h₁ - h₂) - Heat Loss = P

where,

m = mass flow rate of steam = 1.31 kg/s

h₁ = enthalpy at state 1 (120 bar and 508°C)

h₂ = enthalpy at state 2 (50 KPa and x = 0.912)

Heat Loss = 225 KW

P = Power generated by turbine = ?

First, we find h₁ from super steam tables:

At,

T = 508°C

P = 120 bar = 12000 KPa = 12 MPa

we find that steam is in super-heated state with enthalpy:

Due to unavailibility of values in chart we approximate the state to 500° C and 12.5 MPa:

h₁ = 3343.6 KJ/kg

Now, for state 2, we have:

P = 50 KPa and x = 0.912

From saturated steam table:

h₂ = hf₂ + x(hfg₂) = 340.54 KJ/kg + (0.912)(2304.7 KJ/kg)

h₂ = 2442.4 KJ/kg

Now, using values in the conservation equation:

(1.31 kg/s)(3343.6 KJ/kg - 2442.4 KJ/kg) - 225 KW = P

<u>P = 955.53 KW</u>

5 0
3 years ago
A cylindrical aluminum core is surrounded by a titanium sleeve, and both are attached at each end to a rigid end-plate. Set up t
NeX [460]

Complete Question

The complete question is shown on the first uploaded image

Answer:

a) The elongation of the composite bar is given as δ = 0.072 in

b) The axial stress induced in each material is = 5485.7 psi

Explanation:

The explanation to the answer above is shown on the second uploaded image

3 0
3 years ago
14. The top plate of the bearing partition
aliina [53]

Answer:

d. is applied after the ceiling joists are

installed.

7 0
3 years ago
Other questions:
  • A solid titanium alloy [G 114 GPa] shaft that is 720 mm long will be subjected to a pure torque of T 155 N m. Determine the mini
    5·1 answer
  • What’s a pnp transitor?
    5·2 answers
  • If you owned a business, what are some of the ways you could follow green computing recommendations with regards to recycling an
    13·1 answer
  • Problem: design the following rectangular floor beam for a building.
    15·2 answers
  • Unitate de masura in SI pt F​
    11·1 answer
  • Consider a circuit element, with terminals a and b, that has vab= -12V and iab= 3A. Over a period of 2 seconds, how much charge
    8·1 answer
  • calculate force and moment reactions at bolted base O of overhead traffic signal assembly. each traffic signal has a mass 36kg,
    6·1 answer
  • The Web and Digital Communications pathway is broken down into four main categories of technology. Which category BEST describes
    13·1 answer
  • Select the correct answer.
    11·1 answer
  • I need help with this question
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!