Thermodynamic Processes

Question 1

What is thermal efficiency ?

Answer 1

Thermal efficiency is the fraction of input heat energy converted into useful work.

Question 2

Define thermal equilibrium.

Answer 2

Thermal equilibrium is when two systems in contact have the same temperature, so there is no net flow of heat energy between them.

Question 3

What is the formula for maximum theoretical thermal efficiency (Carnot efficiency)?

Answer 3

ηmax​= 1 − Th​ / Tc​​

Question 4

What is the formula for work in terms of heat?

Answer 4

W = Qh - Qc

Question 5

The First Law of Thermodynamics:

Answer 5

ΔU = Q - W

AKA = Formula for change in internal energy

Question 6

What does 𝑇ℎ represent?

Answer 6

The temperature of the hot reservoir (in Kelvin).

Question 7

What does 𝑇𝑐 represent?

Answer 7

The temperature of the cold reservoir (in Kelvin).

Question 8

What does 𝑄ℎ represent?

Answer 8

The heat energy absorbed from the hot reservoir (in Joules).

Question 9

What does 𝑄𝑐 represent?

Answer 9

The heat energy released/rejected to the cold reservoir (in Joules).

Question 10

Are 𝑇ℎ and 𝑇𝑐 about energy or temperature?

Answer 10

Temperature.

Question 11

Are 𝑄𝑐 and 𝑄ℎ about energy or temperature?

Answer 11

Energy.

Question 12

Which equation uses 𝑇ℎ and 𝑇𝑐?

Answer 12

Maximum theoretical (Carnot) efficiency:
η = 1 − 𝑇𝑐 / 𝑇ℎ

Question 13

What is the equation for thermal efficiency in general?

Answer 13

η = 1 - Q out / Q in