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ss7ja [257]
3 years ago
12

The temperature controller for a clothes dryer consists of a bimetallic switch mounted on an electrical heater attached to a wal

l-mounted insulation pad. The switch is set to open at 70 °C, the maximum dryer air temperature. In order to operate the dryer at a lower air temperature, sufficient power is supplied to the heater such that the switch reaches 70 °C (Tset) when the air temperature T is less than Tset. If the convection heat transfer coefficient between the air and the exposed switch surface of 30 mm2 is 25 W/m2 ꞏ K.
Required:

How much heater power Pe is required when the desired dryer air temperature is T[infinity]=50°C?
Engineering
1 answer:
Naddika [18.5K]3 years ago
6 0

Answer:

0.015\ \text{W}

Explanation:

T_{set} = Set temperature = 70^{\circ}\text{C}

T_\infty = Air temperature = 50^{\circ}\text{C}

A = Surface area = 30\ \text{mm}^2=30\times 10^{-6}\ \text{m}^2

h = Convection heat transfer coefficient = 25\ \text{W/m}^2\text{K}

Heater power is given by

P_e=hA(T_{set}-T_\infty)\\\Rightarrow P_e=25\times 30\times 10^{-6}(70-50)\\\Rightarrow P_e=0.015\ \text{W}

The required heater power is 0.015\ \text{W}

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Compressed Air In a piston-cylinder device, 10 gr of air is compressed isentropically. The air is initially at 27 °C and 110 kPa
Helen [10]

Answer:

(a) 2.39 MPa (b) 3.03 kJ (c) 3.035 kJ

Explanation:

Solution

Recall that:

A 10 gr of air is compressed isentropically

The initial air is at = 27 °C, 110 kPa

After compression air is at = a450 °C

For air,  R=287 J/kg.K

cv = 716.5 J/kg.K

y = 1.4

Now,

(a) W efind the pressure on [MPa]

Thus,

T₂/T₁ = (p₂/p₁)^r-1/r

=(450 + 273)/27 + 273) =

=(p₂/110) ^0.4/1.4

p₂ becomes  2390.3 kPa

So, p₂ = 2.39 MPa

(b) For the increase in total internal energy, is given below:

ΔU = mCv (T₂ - T₁)

=(10/100) (716.5) (450 -27)

ΔU =3030 J

ΔU =3.03 kJ

(c) The next step is to find the total work needed in kJ

ΔW = mR ( (T₂ - T₁) / k- 1

(10/100) (287) (450 -27)/1.4 -1

ΔW = 3035 J

Hence, the total work required is = 3.035 kJ

4 0
3 years ago
What would be the structure for the body points for a persuasive presentation?.
Nataliya [291]
A persuasive speech is structured like an informative speech. It has an introduction with an attention-getter and a clear thesis statement. It also has a body where the speaker presents their main points and it ends with a conclusion that sums up the main point of the speech.
5 0
2 years ago
Fluid power is a. The technology that deals with the generation, control, and transmission of power-using pressurized fluids b.
snow_tiger [21]

Answer:  a) The technology that deals with the generation, control and transmission of power using pressurized fluids

Explanation: Fluid power is defined as the fluids which are under pressure and then are used for generation,control and transmit the power. Fluid power systems produces high forces as well as power in small amount . These systems usually tend to have better life if maintained properly. The force that are applied on this system can be monitored by gauges as well as meter.

8 0
3 years ago
When a variable is stored in memory, it is associated with an address. To obtain the address of a variable, the & operator c
liubo4ka [24]

Answer:

Explanation:

1) C program file addressOfScalar.c

#include <stdio.h>

int main()

{

//intialize a char variable, print its address and the next address

char charvar = 'a';

printf("address of charvar = %p\n", (void *)(&charvar));

printf("address of charvar - 1 = %p\n", (void *)(&charvar - 1));

printf("address of charvar + 1 = %p\n", (void *)(&charvar + 1));

//intialize a int variable, print its address and the next address

int intvar = 1;

printf("address of intvar = %p\n", (void *)(&intvar));

printf("address of intvar - 1 = %p\n", (void *)(&intvar - 1));

printf("address of intvar + 1 = %p\n", (void *)(&intvar + 1));

}

In C programming language, an int variable takes 4 bytes of memory. So any arithmetic on integer address, always considers it as 4 bytes of data. So intvar-1 refers to a location 4 bytes before intvar's address and intvar+1 refers to 4 bytes after intvar's address.

3 0
3 years ago
- WHEN YOU ARE TOWING A TRAILER:
zheka24 [161]

Answer:

And Im still going with B..

7 0
3 years ago
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