A domestic hot water tank contains 200 kg at 20°C. How much energy must be supplied to heat this water to 70°C?(Specific heat capacity of water=4200J/(kg°C))
Answers
Answer:
Basics of Thermodynamics:
* First law of thermodynamics:
The first law of thermodynamics states that the cyclic integral of the net heat transfer is equal to the cyclic integral of the net work tranfer. Mathematically,
∮
2
1
δ
Q
=
∮
2
1
δ
W
Q
1
−
2
=
W
1
−
2
+
Δ
E
1
−
2
Where,
Q
1
−
2
is the heat transfer during the process 1 to 2.
W
1
−
2
is the work transfer during the process 1 to 2.
Δ
E
1
−
2
is the total change in energy during the process 1 to 2.
If we neglect the change in potential anergy and change in kinetic energy, then
Q
1
−
2
=
W
1
−
2
+
Δ
U
1
−
2
Δ
U
1
−
2
is the change in internal energy during the process 1 to 2.
* Stages of Steam:
Steam or vapour is a gaseous phase of water. Steam is widely used for the power generation through steam engines and steam turbines. The following are the three stages of steam:
1. Wet steam
2. Dry steam or dry saturated steam
3. Superheated steam
* Constant Volume Process (V=Const.):
During this process, the volume remains constant. The workdone is zero.