HOW A REFRIGERATOR DOES ITS COOLING JOB

The pressure-temperature relationship for various refrigerants point out the importance of this differential. As the liquid spills from the metering device back into the low-pressure area in the refrigerator evaporator, the cycle is complete. In practice, this is it continuous effect as long as the refrigerator compressor is running. The compressor used in these systems is basically a pump. It is often a piston-type pump, especially in the larger air-conditioning and refrigerator units. Most refrigerators, freezers, and small air conditioners it is often a .101ary compressor. In these, a rotor is mounted off center within a cylinder. As it spins at high speeds, vanes attached to the rotor wipe the cylinder walls. Centrifugal force adds to the effectiveness of the heat between wall and vane. A system of valves, usually of the reed type, allows the refrigerant vapor to enter at the low-pressure area. As valve turns, the section which encompasses the refrigerant lit-conies smaller and smaller, and the refrigerant exits at another high pressure. Regardless of the type of refrigerator compressor that you have in your refrigerator, you ll see only a black steel cylinder or ball if you look for it. The reason for this is that the pump and motor are combined into one assembly and then sealed into a refrigerator steel housing. The only components accessible are the electrical terminals. We use the term hermclic compressor to describe such compressors. They are used exclusively in small (less than 10 horsepower) refrigeration systems. They greatly reduce refrigerator service problems and add years to the 11tv of a refrigeration system. It has been said that rotary hermetic compressors don t wear out, they wear in. There s a great deal in that statement. The home refrigerator and freezer is a basic application of the refrigeration principle. Fundamental components evaporator, refrigerator condenser, compressor, and refrigerator capillary tube are sized and matched to limit a particular temperature level. Most refrigerators of recent years utilizing high-speed rotary compressors maintain their temperatures at approximately 70 percent running time. A refrigerator thermostat cycles the compressor on and off to maintain the level. It has a single pair of contacts and its sensing virulent is clamped to the evaporator. The demand upon the system of running time required will vary the load, the amount oil, age, and the ambient temperature. The simplest refrigerator of all is the one many of us grew up with these standard refrigerators, the evaporator forms a freezer, always it the very top of the appliance. The rest of the refrigerator is cooled by the chilled air currents that flow from the evaporator above. Most refrigerators purpose is the natural ail currents within tile Many such trays have a flapper for restricting air flow, this should he closed in winter the load on the refrigerator compartment is light, and open in summer for increased cooling capacity. Don t remove the tray this can causes freezer temperatures to raise sharply and may induce tile efficiency of the entire system. (Condensers used on home refrigerators and freezers are classified as Antic and forced air. A static condenser, found on standard refrigerators, is one mounted on the back of the refrigerator or freezer, consisting of tubing with fins or wires to help dissipate heat. Air flows around it easily and heat is given off into this air within the room. There are no moving parts. Another type of static is used on some freezers. In this application, the condenser 1uhing is attached to the inside of the cabinet. The warming effect in tile cabinet helps reduce condensation. The forced-air con ¬denser, however, has come into wide use in recent years. In this design water from refrigerators and frostless freezers is carried to evaporation loon under cabinet, where heat from condenser and room air evaporates it. It must be cleaned every three to six months to eliminate odors from food which may find their way into defrost water. Pan placement is critical in refrigerators, since it acts as air baffle in addition to its duty for defrost water. Recreational vehicles make wide use of such designs.