Figure 6-12. - Condensation of moisture on a glass of cold water.

Figure 6-10. - Normal surface evaporation.

Figure 6-11. - Evaporation by pressure reduction.

Figure 6-13. - Pressure causes a vapor to condense.

Q3. What is the difference between "sensible heat" and "latent heat"?

Q4. What is the atmospheric pressure at 4,686 feet?

Q5. Exertion of pressure on a substance with a constant pressure does what to the substance?

Q4. Removal of heat from a vapor causes what change to occur?

MECHANICAL REFRIGERATION SYSTEMS

Learning Objective: Identify and understand different types of refrigeration system components and their operation.

Mechanical refrigeration systems are an arrangement of components in a system that puts the theory of gases into practice to provide artificial cooling. To do this, you must provide the following: (1) a metered supply of relatively cool liquid under pressure; (2) a device in the space to be cooled that operates at reduced pressure so that when the cool, pressurized liquid enters, it will expand, evaporate, and take heat from the space to be cooled; (3) a means of repressurizing (compressing) the vapor; and (4) a means of condensing it back into a liquid, removing its