Pressure-Temperature Relationships


Description:

The key terms—saturation, superheat, and subcooling, and how they relate to the functioning of an air conditioning system, the various temperature and pressure scales used in the HVAC industry and the concept of a pressure-temperature chart

Learning Outcome:

Upon completion of this module you will be able to:

  1. Define "temperature."
  2. Discuss the various temperature scales used in the HVAC industry.
  3. Define "pressure."
  4. Discuss the various pressure scales used in the HVAC industry.
  5. Describe the basic relationship between temperature and pressure, and how it affects the operation of an air conditioning system.
  6. Explain saturation.
  7. Define superheat, and demonstrate how to calculate it with the aid of a pressure-temperature chart.
  8. Define subcooling, and demonstrate how to calculate it with the aid of a pressure-temperature chart.

Topic 1: Temperature

  • Topic Introduction and Objectives
  • A Definition for Temperature
  • A Definition for Absolute Zero
  • Check-Point Question: Absolute Zero
  • Motion of Molecules in the Three States of Matter
  • Check-Point Question: Motion of Molecules in the States of Matter
  • Thermometer
  • Checking the Accuracy of a Thermometer
  • Check-Point Question: Thermometer
  • Temperature Scales
  • Topic Summary

Topic 2: Pressure

  • Topic Introduction and Objectives
  • Atmospheric Pressure
  • Pressure and the Boiling Point
  • Pressure Scales
  • Pressure Scales Used in Air Conditioning Systems
  • "Inches of Mercury Vacuum"
  • Topic Summary

Topic 3: Saturation, Superheat, and Subcooling

  • Topic Introduction and Objectives
  • Saturation
  • Saturation Points in Air Conditioning Systems
  • Temperature-Pressure Relationships for Different Refrigerants
  • Superheat
  • Calculating Superheat
  • Subcooling
  • Calculating Subcooling
  • Summary
  • Topic Summary