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
koban [17]
3 years ago
9

The convection coefficient for flow over a solid sphere may be determined by submerging the sphere, which is initially at 25 °C,

into the flow, which is at 75 °C, and measuring its surface temperature at some time during the transient heating process. If the sphere has a diameter of 0.1 m, a thermal conductivity of 22 W/(m·K), and a thermal diffusivity of 0.40 ×10-5 m2/s, at what time will a surface temperature of 60 ºC be recorded if the convection coefficient is 300 W/(m2·K)?
Engineering
1 answer:
sashaice [31]3 years ago
7 0

Answer:

t = 59.37 s

Explanation:

Given data:

thermal diffusivity = \alpha = \frac{k}{\rho c_p} =0.40\times 10^{-0.5}

theraml conductivity = k = 22 W/m.K

h = 300 W/ m^2.K

T_i = 25 degree C = 298 k

T_o = 60 degree C = 333 k

T_{\infty}= 75 degree C =  348 L

diameter d = 0.1 m

characteristics length Lc = r/3 = = 0.0166

Bi = \frac{hLc}{K} = \frac{300\times 0.0166}{22} = 0.226

\tau = \frac{\alpha t}{lc^2} = \frac{0.4\times 10^{-5}\times t}{0.0166^2}

\tau = 0.036 t

\frac{T_o -T_{\infty}}{T_i -T_{\infty}} = Ae^[\lambda^2 \tau}

at Bi = 0.226

Ai = 0.982

\lambda = 0.876

\frac{333348}{298-348} = 0.982e^{-0.879^2 0.036t}

0.3 = 0.982 e^{-0.2t}

0.305 = e^{-0.2t}

-1.187 = - 0.02t

t = 59.37 s

You might be interested in
Which of the following are true about the American Wire Gauge?
harina [27]

Answer:

A. smallest wire is No. 12

7 0
3 years ago
I = 48 mA, R = 1125 2. What is Vs ?
german
54 volts

Ohms law. E= I x R
6 0
3 years ago
Engine oil flows through a 25‐mm‐diameter tube at a rate of 0.5 kg/s. The oil enters the tube at a temperature of 25°C, while th
Elodia [21]

Answer:

a) the log mean temperature difference (Approx. 64.5 deg C)

b) the rate of heat addition into the oil.

The above have been solved for in the below workings

Explanation:

3 0
3 years ago
*3–32. The rubber block is subjected to an elongation of 0.03 in. along the x axis, and its vertical faces are given a tilt so t
riadik2000 [5.3K]

Rubber block is not shown. I have attached an image of it.

Answer:

A) ε_x = 0.0075

B) ε_y = 0.00375

C) γ_xy = 0.0122 rad

Explanation:

We are given;

δ = 0.03 in

L = 4 in

ν_r = 0.5

θ = 89.3° = 89.3π/180 rad

Let's calculate ε_x in the direction of axis x

Thus, ε_x = δ/L = 0.03/4 = 0.0075

Let's calculate ε_y in the direction of axis y;

ε_y = v•ε_x = 0.5 x 0.0075 = 0.00375

Now, shear strain is angle between π/2 rad surfaces at that point.

Thus,

γ_xy =  π/2 - θ = π/2 - 89.3π/180

γ_xy = π(0.003889) = 0.0122 rad

3 0
3 years ago
An inventor claims to have devised a cyclical power engine that operates with a fuel whose temperature is 750 °C and radiates wa
Phantasy [73]

Answer:

Yes

Explanation:

Given Data

Temprature of source=750°c=1023k

Temprature of sink =0°c=273k

Work produced=3.3KW

Heat Rejected=4.4KW

Efficiency of heat engine(η)=\frac{Work produced}{Heat supplied}

and

Heat Supplied {\left (Q_s\right)}=Work Produced(W)+Heat rejected\left ( Q_r \right )

{Q_s}=3.3+4.4=7.7KW

η=\frac{3.3}{7.7}

η=42.85%

Also the maximum efficiency of a heat engine operating between two different Tempratures i.e. Source & Sink

η=1-\frac{T_ {sink}}{T_ {source}}

η=1-\frac{273}{1023}

η=73.31%

Therefore our Engine Efficiency is less than the maximum efficiency hence the given claim is valid.

5 0
3 years ago
Other questions:
  • There are 20 forging presses in the forge shop of a small company. The shop produces batches of forgings requiring a setup time
    10·1 answer
  • Main technologies used in atms vending machines game consoles and microwave ovens
    6·1 answer
  • This is a new technology meant to reduce vehicle roll-overs A. Lane-departure warning B. Anti-lock brakes C. Inspection reports
    7·1 answer
  • A large prime number isP = 232582657 - 1
    8·1 answer
  • Se requiere un permiso aprobación o restricción contaminante para todos los métodos comerciales de descarga de aguas residuales
    13·1 answer
  • When we utilize a visualization on paper/screen, that visualization is limited to exploring: Group of answer choices Relationshi
    9·1 answer
  • Please write the following code in Python 3. Also please show all output(s) and share your code.
    10·1 answer
  • Realize the function f(a, b, c, d, e) = Σ m(6, 7, 9, 11, 12, 13, 16, 17, 18, 20, 21, 23, 25, 28)using a 16-to-1 MUX with control
    13·1 answer
  • The typical Canadian worker is able to produce 100 board feet (a unit of measure) of lumber or 1000 light bulbs per year. The wo
    12·1 answer
  • An American architect whose principles of building included consonance with the landscape was ____________________________.
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!