11. Which of these is NOT true when dealing with refrigerants?

Air at 80 kPa and 10Â°C enters an adiabatic diffuser steadily with a velocity of 150 m/s and leaves with a low velocity at a pre

il63 [147K]

Answer:

The exit temperature is 293.74 K.

Explanation:

Given that

At inlet condition(1)

P =80 KPa

V=150 m/s

T=10 C

Exit area is 5 times the inlet area

Now

$A_2=5A_1$

If consider that density of air is not changing from inlet to exit then by using continuity equation

$A_1V_1=A_2V_2$

So $A_1\times 150=5A_1V_2$

$V_2=30$ m/s

Now from first law for open system

$h_1+\dfrac{V_1^2}{2}+Q=h_2+\dfrac{V_2^2}{2}+w$

Here Q=0 and w=0

$h_1+\dfrac{V_1^2}{2}=h_2+\dfrac{V_2^2}{2}$

When air is treating as ideal gas

$h=C_pT$

Noe by putting the values

$h_1+\dfrac{V_1^2}{2}=h_2+\dfrac{V_2^2}{2}$

$1.005\times 283+\dfrac{150^2}{2000}=1.005\times T_2+\dfrac{30^2}{2000}$

$T_2=293.74K$

So the exit temperature is 293.74 K.

7 0

3 years ago

Describe the medium/long-range transportation options available to people prior

lakkis [162]

Answer:

answer below:

Explanation:

Before the Industrial Revolution, transportation relied on animals (like horses pulling a cart) and boats. Travel was slow and difficult. It could take months to travel across the United States in the early 1800s before industrial revolution

The Industrial Revolution completely changed the way people traveled and how goods were transported.

the problem of traveling upstream was solved during the industrial revolution by the steam engine. in order to make better use of water transportation, canals were build to connect rivers, lakes and oceans. the invention of the railroad and the steam powered locomotive opened up a whole new world in transportation. even with steamboats and railroads, people still needed a better wat to travel between rivers and train stations. a new process called the "macadam " process was used to create smooth gravel roads

I hope this helps a bit.

3 0

2 years ago

A long, circular aluminum rod is attached at one end to a heated wall and transfers heat by convection to a cold fluid.

Trava [24]

Answer:

a. Heat removal rate will increase

b. Heat removal rate will decrease

Explanation:

Given that

One end of rod is connected to the furnace and rod is long.So this rod can be treated as infinite long fin.

We know that heat transfer in fin given as follows

$Q_{fin}=\sqrt{hPKA}\ \Delta T$

We know that area

$A=\dfrac{\pi}{4}d^2$

Now when diameter will triples then :

$A_f=\dfrac{\pi}{4}{\left (3d \right )}^2$

$A_f=9A$

$Q'_{fin}=\sqrt{9hPKA}\ \Delta T$

$Q'_{fin}=3\sqrt{hPKA}\ \Delta T$

$Q'_{fin}=3Q$

So the new heat transfer will increase by 3 times.

Now when copper rod will replace by aluminium rod :

As we know that thermal conductivity(K) of Aluminium is low as compare to Copper .It means that heat transfer will decreases.

3 0

2 years ago

A 14-lb crate is pulled up a frictionless 40° ramp with an initial velocity of v1=0.4 ft/s. It is pulled 0.3 ft from location #1

Morgarella [4.7K]

Answer:

3.25 ft/s

Explanation:

The crate is of =14-lb=m₁

The angle of inclination is = 40°=Ф

The initial velocity = 0.4 ft/s= v₁

Distance the crate will move is= 0.3 ft =d

The load pulling downwards is = 36 lb= m₂

Acceleration of the pulley, a= m₂g - m₁gsinФ / m₁+m₂ where g= 32.17 ft/s^2

a= 36*32.17 - 14*32.17*sin 40° / 14+36

a=17.37 ft/s^2

Apply the formula for final velocity

V₂²=V₁²+2ad

V₂²=0.4²+ 2*17.37*0.3

V₂²=10.582

V₂ =√10.582 = 3.25 ft/s

6 0

3 years ago

The Acme threading tool forms an inc luded angle of how many degrees? A. 30 B. 55 C. 29 D. 60

Schach [20]

Answer:

(C) 29°

Explanation:

ACME THREAD ANGLE : it is the angle measured between the thread axis and thread the thread flanks, with the help of thread angle we calculate the shape of screw thread it is the mean of v thread and square thread the acme thread angle is denoted by β every thread has its own charactersistics which depends on the pitch and diameter of the thread

4 0

3 years ago