Figure 9-81 shows how the spiral-shaped members fit together. Abetter view is shown in Fig. 9-82. The two members fit together forming crescent-shaped gas pockets. One member remains stationary, while the second member is allowed to orbit relative to the stationary member. This movement draws gas into the outer pocket created by the two members, […]
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The scroll compressor (Fig. 9-80) is being used by the industry in response to the need to increase the efficiency of air-conditioning equipment. This is done in order to meet the U.S. Department of Energy Standards of 1992. The standards apply to all air conditioners. All equipment must have a Seasonal Energy Efficiency Ratio (SEER) […]
Read More…The twin screw is the most common type of screw compressor used today. It uses a double set of rotors (male and female) to compress the refrigerant gas. The male rotor usually has four lobes. The female rotor consists of six lobes. Normally, this is referred to as a 4 + 6 arrangement. However, some […]
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A single screw compressor is shown in Fig. 9-77. The compression process starts with the rotors meshed at the inlet port of the compressor. The rotors turn. The lobes separate at the inlet port, increasing the volume between the lobes. This increased volume causes a reduction in pressure. Thus, drawing in the refrigerant gas. The […]
Read More…Screw compressors operate more or less like pumps, and have continuous flow refrigerant compared to reciprocals. Reciprocal have pulsations. This results in smooth compression with little vibration. Reciprocals, on the other hand, make pulsating sounds and vibrate. They can be very noisy. Screw compressors have almost linear capacity-control mechanisms. That results in excellent part-load performance. […]
Read More…The rotating blade rotary compressor has its roller centered on a shaft that is eccentric to the center of the cylinder. Two spring-loaded roller blades are mounted 180° apart. They sweep the sides of the cylinder. The roller is mounted so that it touches the cylinder at a point between the intake and the discharge […]
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The only moving parts in a stationary blade rotary compressor are a steel ring, an eccentric or cam, and a sliding barrier (see Fig. 9-71). Figure 9-72 shows how the rotation of the off-center cam compresses the gas refrigerant in the cylinder of the rotary compressor. The cam is rotated by an electric motor. As […]
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Process tubes are installed in compressor housings at the factory as an aid in factory dehydration and charging. These can be used in place of the suction tube if they are of the same diameter and wall thickness as the suction tube. Standard discharge tubing arrangements for Tecumseh hermetic compressors are shown in Fig. 9-67. […]
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Tecumseh, like other compressor manufacturers, made compressors for many manufacturers of refrigerators, air-conditioning systems, and coolers. Because of this, the same compressor model may be found in the field in many suction and discharge variations. Each variation depends upon the specific application for which the compressor was designed. Suction connections can usually be identified as […]
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There are four general types of single-phase motors. Each has distinctly different characteristics. Compressor motors are designed for specific requirements regarding starting torque and running efficiency. These are two of the reasons why different types of motors are required to meet various demands. Resistance-start induction-run The resistance-start induction-run (RSIR) motor is used on many small […]
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