Heat engines and heat pumps

How does your refrigerator (Jääkaappi) work?

• Moves heat from inside the fridge to the room

• Blows cold air into the fridge

• Uses convection cells

• It generates cold air

In a fridge the condenser coils are

• inside the fridge

• outside the fridge

In a fridge the evaporator coils are

• inside the fridge

• outside the fridge

The temperature of the gas coming into the condenser coils is

• the same as the surroundings

• greater than the surroundings

• less than the surroundings

The expansion device on a fridge

• decreases the temperature of the refrigerant liquid leaving the condenser

• increases the temperature of the refrigerant liquid leaving the condenser

• decreases the temperature of the refrigerant gas leaving the condenser

• increases the temperature of the refrigerant gas leaving the condenser

The main purpose of any heat engine is ........................................... . 

• To convert heat energy into movement, W.

• To convert heat energy into internal energy, W.

• To convert heat energy into work, W.

No engine can transfer all the input heat energy into useful work. Some energy is transferred to the surroundings. Which thermodynamic law is this?

• 1st Law

• 2nd Law

The mode or cycle of the heat pump that removes ice from the outdoor coil is known as the ____________________ mode.

• heating

• defrost

• cooling

• off-cycle

A Carnot engine function between two reservoir between 527 ⁰C and 127 ⁰C . Calculate the carnot efficiency for the engine.

• 50 %

• 60 %

• 65 %

• 75 %

• 80 %

The four strokes of an internal combustion engine are

• in, out, combustion, exhaust

• intake, out take, compression, power

• intake, compression, combustion, exhaust

• in, out, power, compression