Q24. What type of cooling tower is installed indoors?

Q25. Forced draft underflow towers retain the advantages of what other type of cooling tower?

Q26. Air intake louvers and fill are made of what material?

Q27. Cooling towers evaporate approximately how much water every hour for each ton of refrigeration?

Q28. Rotary compressors are used in what type of units?

Q29. Semisealed and sealed compressors have reduced service requirements because of the elimination of what part?

Q30. What control is temperature sensitive and controls the operation of the cooling unit?

Q31. What device maintains humidity at a predetermined point?

Q32. What causes a motor to shut down when a motor is too hot?

AUTOMOTIVE AIR CONDITIONING

Learning Objective: Understand the basic principles of operation, maintenance, and repair of automotive air conditioning.

Vehicle air conditioning is the cooling (refrigeration) of air within a passenger compartment. Refrigeration is accomplished by making practical use of three laws of nature - heat transfer, latent heat of vaporization, and the effects of pressure on boiling or condensation. The first two laws are discussed in chapter 6 of this TRAMAN; the practical application of the third is outlined below.

EFFECT OF PRESSURE ON BOILING OR CONDENSATION

The saturation temperature (the temperature where boiling or condensation occurs) of a liquid or vapor increases or decreases according to the pressure exerted on it.

In the fixed orifice tube refrigerant system, liquid refrigerant is stored in the condenser under high pressure (fig. 7-35). When the liquid refrigerant is released into the evaporator by the fixed orifice tube,

Figure 7-35. - Air-conditioning refrigeration system-fixed orifice.