Question

An engineer is developing an electric water heater to provide acontinuous ("on demand") supply of hot water. One trial design isshown in the figure. Water is flowing at the rate F, the inlet thermometer registers
T_1, the voltmeter reads V, and the ammeter reads current I. Then the power (i.e., the heat generated perunit time by the heating element) is VI.
Assume that the heat capacity of water is C and that the heat capacity of the heater apparatus is C_h.




Part A
When a steady state is finally reached, what is the temperature reading T_2 of the outlet thermometer?
Express the outlet temperature interms of T_1, F, C, and any other given quantities.





Imagine that the input temperature ofthe water is T_1=18 degrees C, the ammeter reads I=15.0 A, the voltmeter reads V=120V, and the flow rate is F=0.500 kg/min . The heat capacity of water C=4200 J/(kg*K).
Part C
What is the power P at which the heater operates?

Answer 1

A:   (VI/FC)+T_1

B: In steady state the temperature of the apparatus doesn't change. Hence its heat capacity is irrelevant.

C:1800W

D: 69 deg C

E: 163A