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3 years ago

Which basic principle influences how all HVACR systems work?

Engineering

1 answer:

bezimeni [28]3 years ago

6 0

Answer:

B) An increase in pressure can lower the boiling point of a liquid and change the temperature at which it turns to a gas.

Explanation:

B) An increase in pressure can lower the boiling point of a liquid and change the temperature at which it turns to a gas.

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What is the best reason a scientist might use a model to represent the solar system?

uranmaximum [27]

So they can grasp a better understanding! good luck

3 0

4 years ago

The product second moment of area Ixy is found by multiplying Ix and Iy. a)True b)- False

Kamila [148]

Answer:

(b)False

Explanation:

$I_{xy}$ defined as

$I_{xy}$ = $\int \left (x\cdot y\right )dA$

Where x is the distance from centroidal x-axis

y is the distance from centroidal y-axis

dA is the elemental area.

The product of x and y can be positive or negative ,so the value of $I_{xy}$ can be positive as well as negative .

So from the above expressions we can say that the product of $I_{x},I_y$ is different from $I_{xy}$ .

7 0

3 years ago

A power of 100 kW (105 W) is delivered to the other side of a city by a pair of power lines, between which the voltage is 12,000

OLga [1]

Answer:

I = 8.3 Amp

potential drop = 83 V

Explanation:

Power = 100 KW

V = 12,000 V

R = 10 ohms

Calculate current I in each wire:

P = I*V

I = P / V

I = 100 / 12 = 8.333 A

Calculate potential drop in each wire:

V = I*R

V = (8.3) * (10)

V = 83 V

4 0

3 years ago

A heated plate is built into the wall of a large room. The room is maintained at 300 K. The exposed surface of the plate is main

myrzilka [38]

Answer:

Explanation:

7 0

3 years ago

A sphere is assumed to have the properties of water and has an initial heat generation 46480 W/m^3 How much should the heat gene

Verdich [7]

Answer:

Resulting heat generation, Q = 77.638 kcal/h

Given:

Initial heat generation of the sphere, $Q_{Gi} = 46480 W/m^{3}$

Maximum temperature, $T_{m} = 360 K$

Radius of the sphere, r = 0.1 m

Ambient air temperature, $T = 25^{\circ}C$ = 298 K

Solution:

Now, maximum heat generation, $Q_{m}$ is given by:

$T_{m} = \frac{Q_{m}r^{2}}{6K} + T$ (1)

where

K = Thermal conductivity of water at $T_{m} = 360 K = 0.67 W/m^{\circ}C$

Now, using eqn (1):

$360 = \frac{Q_{m}\times 0.1^{2}}{6\times 0.67} + 298$

$Q_{m} = 24924 W/m^{3}$

max. heat generation at maintained max. temperature of 360 K is 24924 $W/m^{3}$

For excess heat generation, Q:

$Q = (Q_{Gi} - Q_{m})\times volume of sphere, V$

where

$V = \frac{4}{3}\pi r^{3}$

$Q = (46480 - 24924)\times \frac{4}{3}\pi\0.1^{3} = 21556\times \frac{4}{3}\pi\0.1^{3} W/m^{3}$

$Q = 90.294 W$

Now, 1 kcal/h = 1.163 W

Therefore,

$Q = \frac{90.294}{1.163} = 77.638 kcal/h$

3 0

3 years ago