Answer:
Heat gain of 142 kJ
Explanation:
We can see that job done by compressing the He gas is negative, it means that the sign convention we are going to use is negative for all the work done by the gas and positive for all the job done to the gas. With that being said, the first law of thermodynamics equation will help us to solve this problem.
Δ ⇒
Δ
Therefore, the gas gained heat by an amount of 142 kJ.
Answer:
maximum value of the power delivered to the circuit =3.75W
energy delivered to the element = 3750e^{ -IOOOt} - 7000e ^{-2OOOt} -3750
Explanation:
V =75 - 75e-1000t V
l = 50e -IOOOt mA
power = IV = 50 * 10^-3 e -IOOOt * (75 - 75e-1000t)
=50 * 10^-3 e -IOOOt *75 (1 - e-1000t)
=
maximum value of the power delivered to the circuit =3.75W
the total energy delivered to the element =
Answer:
A) ΔS_refrigerant = 0.70754 Kj/K
B) ΔS_space = -0.68441 Kj/K
C) ΔS_total = 0.02313 Kj/K
Explanation:
A) From he table attached, at Pressure of 140 KPa, and by interpolation, we get, Temperature of T = -18.77°C
Converting to degree kelvin yields;
T = -18.77 + 273 = 255.23 K
Formula for entropy change of refrigerant is given as;
ΔS_refrigerant = Q_in/T_refrigerant
We are given Q = 180 KJ
Thus, ΔS_refrigerant = 180/255.23 = 0.70754 Kj/K
B) Formula for entropy change of cooled space is given as;
ΔS_space = Q_out/T_s pace
T_space = -10°C = 273 - 10 = 263K
Thus, ΔS_space = -180/263 = -0.68441 Kj/K
C) the total entropy change would be;
ΔS_total = ΔS_refrigerant + ΔS_space
Thus,
ΔS_total = 0.70754 - 0.68441 = 0.02313 Kj/K
