CTD Topic 3 Part 3 Review

Which of the following statements is True?

• In heat engines, the work associated with the system is positive.

• Heat engine is a device that converts heat energy into mechanical energy

• Impossible heat engines have efficiency < than Carnot efficiency

• Carnot cycle is a irreversible heat engine working between 2 temp limits.

A heat pump is another name for a heat engine, there's no difference in its function

• True

• False

Second law of thermodynamics states: It is impossible to transfer heat from a cooler body to a hotter body.

• True

• False

Which of the following terms is used to assess the efficiency (n) of a heat engine?

• n = -W*Q1

• n = -(W+Q1)/Q2

• n = -W/Q1

• n=Q1-Q2-W

A heat engine becomes more efficient as the temperature difference between the hot and cold reservoir increase.

• True

• False

A refrigerator needs external energy to transport heat from the cold reservoir to the hot reservoir.

• True

• False

A heat engine takes in heat from low temp reservoir, does work using this energy, expels the rest to the high heat reservoir.

• True

• False

The COP of a heat pump and refrigerator are the same and differs only by the negative sign.

• True

• False