BRIGHT HEADLIGHTS
AND SEVERE WEATHER CONDITIONS
Answer: valving the pump discharge to reduce the flow will only result in an increase in the water velocity according to the laws of continuity of flow.
Q = AV = constant.
The pump speed of 150 gpm is, and will remain constant. Valving simply reduces flow area A, which is balanced out by increased velocity V of water through the pipe.
This does not affect the pump speed Q (flow rate) and hence it remains the same.
Given:
Temperature of water, 
= 
=273 +(-6) =267 K
Temperature surrounding refrigerator, 
= 
=273 + 21 =294 K
Specific heat given for water, 
= 4.19 KJ/kg/K
Specific heat given for ice, 
= 2.1 KJ/kg/K
Latent heat of fusion, 
= 335KJ/kg
Solution:
Coefficient of Performance (COP) for refrigerator is given by:
Max 
= 
= 
= 9.89
Coefficient of Performance (COP) for heat pump is given by:
Max 
= 
= 10.89
Answer:
24.72 kwh
Explanation:
Electric energy=potential energy=mgz where m is mass, g is acceleration due to gravity and z is the elevation.
Substituting the given values while taking g as 9.81 and dividing by 3600 to convert to per hour we obtain
PE=(108*9.81*84)/3600=24.72 kWh
