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irga5000 [103]
3 years ago
8

Thick fluids such as asphalt and waxes and the pipes in which they flow are often heated in order to reduce the viscosity of the

fluids and thus to reduce the pumping costs. Consider the flow of such a fluid through a 100-m-long pipe of outer diameter 30 cm in calm ambient air at 0°C. The pipe is heated electrically, and a thermostat keeps the outer surface temperature of the pipe constant at 25°C. The emissivity of the outer surface of the pipe is 0.8, and the effective sky temperature is -30°C.
Required:
Determine the power rating of the electric resistance heater, in kW, that needs to be used.
Engineering
1 answer:
Gala2k [10]3 years ago
7 0

Answer:

what id the answer

Explanation:

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Un material determinado tiene un espesor de 30 cm y una conductividad térmica (K) de 0,04 w/m°C. En un instante dado la distribu
aksik [14]

Answer:

Para x=0:

\phi=1.2 W/m^{2}  

Para x=30 cm:

\phi=-2.4 W/m^{2}  

Explanation

Podemos utilizar la ley de Fourier par determinar el flujo de calor:

\phi=-k\frac{dT}{dx}(1)

Por lo tanto debemos encontrar la derivada de T(x) con respecto a x primero.

Usando la ley de potencia para la derivda, tenemos:

\frac{dT(x)}{dx}=300x-30

Remplezando esta derivada en (1):

\phi=-0.04(300x-30)

Para x=0:

\phi=0.04(30)

\phi=1.2 W/m^{2}  

Para x=30 cm:

\phi=-0.04(300*0.3-30)

\phi=-2.4 W/m^{2}    

Espero que te haya ayudado!

4 0
3 years ago
Technician A says if the input signal turn-on time is too fast for the input circuit, your program may operate as though the inp
ASHA 777 [7]

Answer:

b. Technician B only

Explanation:

A watchdog timer is a circuit that automatically monitors the MCU (Microcontroller Unit) for any anomaly, detects it and helps the MCU to recover from the malfunction it has detected.

If the input signal turn-on time is too fast for the input circuit, that is a malfunction and this activates the watchdog timer circuit to correct this malfunction immediately. So Technician B only is correct as the watchdog timer is activated immediately once there is a malfunction.

7 0
3 years ago
A ballistic pendulum consists of a 3.60 kg wooden block on the end of a long string. From the pivot point to the center‐of‐mass
Pavel [41]

Answer:

17.799°

Explanation:

When the bullet hits the block at that time the momentum is conserved

So, initial momentum = final momentum

P_i=P_f

So 28\times 10^{-3}\times 210=(3.6+0.028)v_f

v_f=1.6207\ m/sec

Now energy is also conserved

So \frac{1}{2}\times (3.6+0.028)\times 1.6207^2=(3.6+0.028)\times 9.81\times 2.8(1-cos\Theta )

cos\Theta =0.8521So\ \Theta =17.799^{\circ}

3 0
2 years ago
Q10: Technician A says that nearly all brands of scan tools will pull DTCs from the ABS
Llana [10]

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7 0
3 years ago
Ignoring any losses, estimate how much energy (in units of Btu) is required to raise the temperature of water in a 90-gallon hot
Rudik [331]

Answer:

Q=36444.11 Btu

Explanation:

Given that

Initial temperature = 60° F

Final temperature = 110° F

Specific heat of water = 0.999 Btu/lbm.R

Volume of water = 90 gallon

Mass = Volume x density

1\ gallon = 0.13ft^3

Mass ,m= 90 x 0.13 x 62.36 lbm

m=729.62 lbm

We know that sensible heat given as

Q= m Cp ΔT

Now by putting the values

Q= 729.62 x 0.999 x (110-60) Btu

Q=36444.11 Btu

5 0
2 years ago
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