Understanding Ice and Air Conditioning

Jan 6, 2025

Lecture on Ice and Air Conditioning Concepts

Heat Transfer with Ice

  • Cooling with Ice: Air blown across ice results in heat transfer, cooling the air.
    • Example: Air at 70°F blown over ice cools to 50°F.
    • Ice remains at 32°F until fully melted.
  • Melting Ice: Takes 144 BTUs of heat energy to melt 1 pound of ice.

John Gorey and Ice Machines

  • Background: John Gorey, a Florida physician, used ice to cool patients, noting better treatment responses in cooler conditions.
  • Ice supply issues: 1800s Florida required ice shipment from the north, which was expensive.
  • Invention of Ice Machine: Gorey utilized scientific principles to invent an ice machine.
    • Faced opposition from ice shipping companies.
    • Died in poverty despite the invention's significance.

Refrigeration and Air Conditioning

  • YouTube Example: Demonstrates cooling air with ice and fan; refrigerant cycle re-freezes melted ice.
  • BTUs and Ice:
    • 1 ton of ice = 2,000 pounds.
    • 288,000 BTUs to melt 1 ton of ice in 24 hours.
    • 12,000 BTUs per hour = 1 ton of air conditioning.

Air Conditioners and Tonnage

  • Sizing Air Conditioners:
    • Air conditioners rated by tons, based on ice cooling capacity.
    • Typical AC: 3-ton unit, equal to melting 3 tons of ice in 24 hours.
  • Conversions:
    • 1 ton = 12,000 BTUs/hr
    • 2 tons = 24,000 BTUs/hr
    • 3 tons = 36,000 BTUs/hr
    • 4 tons = 48,000 BTUs/hr
    • 5 tons = 60,000 BTUs/hr
  • Model Numbers: Often indicate tonnage.

Latent Heat and Cooling Efficiency

  • Ice vs. Water Heating:
    • Ice absorbs heat without temperature increase until fully melted (latent heat).
    • Example: Ice chest retains cooler temperature compared to water under same conditions.
  • Practical Application: Latent heat concept critical in HVAC applications.
    • Tonnage of air conditioning tied back to ice cooling methods by John Gorey.

Conclusion: Understanding heat transfer, latent heat, and historical developments in ice machines and air conditioning helps grasp modern HVAC principles.