Refrigeration Cycle Steps

Refrigeration Cycle

• Heat is rejected by the refrigerant in the condenser.
• The refrigerant expands and its pressure and temperature decrease as it passes through the nozzle.

Thermodynamics

• The second law of thermodynamics deals with the direction of spontaneous processes.
• The coefficient of performance (COP) of a refrigerator measures its efficiency in transferring heat from the cold reservoir to the hot reservoir.

Energy Efficiency

• If the COP of a refrigerator is 5, 20% of the energy is extracted from the cold reservoir, and 80% is used as external work.
• The efficiency of a heat engine is 25% if it absorbs 3000 J from the hot reservoir and 2250 J are wasted per cycle.

Refrigeration Process

• The refrigerant absorbs heat at constant pressure in the evaporator.
• A refrigerator releases heat to the air outside through the condenser.

Magnetic Materials

• Diamagnetic materials are repelled by a uniform magnetic field.

Laws of Thermodynamics

• The first law of thermodynamics states that energy is conserved.
• The second law of thermodynamics relates to the extraction of energy from the cold reservoir in a refrigerator.

Thermodynamic Processes

• If dW = 0 and dQ = 0, the process is an isometric and adiabatic process.
• The COP of a refrigerator measures the ratio of heat transferred from the cold reservoir to the work input.

Compressor Function

• The purpose of a compressor in a refrigeration cycle is to increase the pressure and temperature of the refrigerant.

Work and Energy

• If 20% of the energy is extracted from the cold reservoir, 80% is used as external work.

Refrigerator Performance

• If the condenser temperature decreases, the refrigeration process becomes more efficient.
• The efficiency of a heat engine is inversely proportional to the COP of a refrigerator.