Category Archives for Multistage Systems

Reciprocating Compressors Performance Review

The refrigeration professional who selects and operates compressors should have a clear understanding of how the evaporating and condensing temperatures affect the refrigerating capacity and power requirements of the compressor. The compressor is often called the heart of the refrigeration … Continue reading

30. April 2018 by Jim
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The Role Of Reciprocating Compressors

In the early 1970s the builder of a large refrigeration facility would install a row of reciprocating compressors in the machine room to provide the compression requirements. Today, the same owner would choose one or two screw compressors to achieve … Continue reading

30. April 2018 by Jim
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Deciding Between Single And Two-Stage Compression

The designer of a low-temperature refrigeration system must decide whether to choose a single- or a two-stage arrangement. It is hard to imagine any facility where the first cost of the two-stage system is not greater than a single stage … Continue reading

30. April 2018 by Jim
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Side Port Of A Screw Compressor For Liquid Subcooling

One of the options available on a screw compressor is a side port which provides an entry into the gas spaces during the compression process. This feature allows gas to be compressed from the intermediate to the discharge pressure, avoiding … Continue reading

30. April 2018 by Jim
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Multistage Systems – Compressor Selection And Control

For a given temperature of the low-temperature evaporator and a given condensing temperature, the intermediate pressure is controlled by the relative pumping rates of the low- and high-stage compressors. The basic rules for controlling pressures, and thus the saturation temperatures, … Continue reading

30. April 2018 by Jim
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Shortcuts In Multistage System Design Calculations

This chapter has explained how to compute capacity requirements of the lowand high-stage compressors in two-stage systems. The precise method requires the application of mass and energy balances around the intermediate-pressure devices. Repeated two-stage calculations are tedious, although design and … Continue reading

30. April 2018 by Jim
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Multistage Systems – Two-Stage Compression With Two Temperature Levels Of Evaporation

Many plants serve evaporators at several different temperature levels. Examples are particularly frequent in the food refrigeration industry where a facility maintains some space at, for example, -23°C (-10°F) for storing frozen food and another space at 2°C (36°F) for … Continue reading

30. April 2018 by Jim
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Multistage Systems – Optimum Intermediate Pressure

When the intermediate pressure in a two-stage system is selected at a very high value or a very low value, the benefits are reduced. In fact, if the intermediate pressure is the same as either the condensing or the evaporating … Continue reading

30. April 2018 by Jim
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Multistage Systems – Refrigerant Flows In A Flash Tank/Intercooler

Figure 3.17 shows another way to visualize the processes that take place in the flash-tank/intercooler of a two-stage system. A stream that is 100% liquid enters at the left from the condenser. A large portion of this liquid is cooled … Continue reading

30. April 2018 by Jim
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Multistage Systems – Refrigerant Flows In A Flash Tank/Intercooler

Figure 3.17 shows another way to visualize the processes that take place in the flash-tank/intercooler of a two-stage system. A stream that is 100% liquid enters at the left from the condenser. A large portion of this liquid is cooled … Continue reading

26. April 2018 by Jim
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