Intro to Refrigeration Systems: An Elementary Refrigerator

Elementary Refrigeration System:

1. Setup and Equilibrium:

   • Tank of refrigerant (R22) inside a closed box.
   • Initial state: temperature equilibrium at 80°F, pressure at 144 PSIG.

2. System Description:

   • Cylinder contains a mixture of liquid and vapor refrigerant.
   • In equilibrium, no heat transfer occurs as temperatures are the same.

3. Theoretical Process:

   • Releasing Refrigerant:
     • Imagine releasing refrigerant (not practically done).
     • Pressure decreases, lowering the boiling point and temperature of the refrigerant.
     • As refrigerant boils, it absorbs heat, cooling the box from 80°F to 70°F.
   • Pressure and Boiling Point:
     • Lower pressure = lower boiling point.
     • 102 PSIG pressure correlates with a lower boiling point and 60°F refrigerant temperature.

4. Capturing Refrigerant:

   • Sustainable Solution:
     • Use a separate capture tank with a check valve.
     • Refrigerant vapor fills the capture tank, picking up heat and increasing pressure back to 144 PSIG.
   • Pressure-Temperature Relationship:
     • Use a pressure-temperature chart to understand the relationship.

5. Condensation Process:

   • Raising Pressure:
     • Increase pressure to 226 PSIG to raise temperature to 110°F.
     • Cooler ambient air condenses vapor into a liquid.
   • Transferring Liquid:
     • Use a hose (acting as a metering device) to maintain pressure differences.
     • Liquid refrigerant re-enters the original tank at a lower pressure and temperature, restoring initial conditions.

6. Basic Components and Function:

   • System demonstrates fundamental refrigeration components and principles.
   • Future steps include optimizing cylinder design for efficient heat transfer.

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Key Concepts:

• Equilibrium: No heat transfer when temperatures are equal.
• Pressure-Temperature Relationship: Direct correlation, shown in a pressure-temperature chart.
• Sustainable Practices: Importance of capturing and reusing refrigerant.
• Condensation and Compression: Techniques to convert vapor back into liquid by increasing pressure and controlling temperature.