Refrigeration system, mechanical-compression

For example, in a simple mechanical-compression refrigeration system, the refrigeration is the desired product, so the numerator in... 

Several types of fluids are used as refrigerants in mechanical compression systems ammonia, halocarbon compounds, hydrocarbons, carbon dioxide, sulfur dioxide, and cryogenic fluids. A wide temperature range therefore is afforded. These fluids boil and condense isotherm ally. The optimum temperature or pressure at which each can be used can be deterrnined from the economics of the system. The optimum refrigerant can be deterrnined only... 

Refrigerant temperatures greater than 32°F suggest the steam jet or lithium bromide absorption system. Between 30°F and —40°F, the ammonia-water absorption or a mechanical compression system is indicated. At less than —40°F, a mechanical compression is used, except in special desiccant situations. The economics of temperature level selection will depend on utility (steam, power) costs at the point of installation and the type of pay-out required, because in some tonnage ranges, the various systems are competitive based on first costs. 

There are two common refrigeration systems, mechanical and thermal compression. In the mechanical system work is done in compressing a gas, the refrigerant. The energy thus added plus the amount of refrigeration required must be removed in a condenser, usually by cooling water. The calculations necessary and some typical values are given in references 20 and 21. 

Volume 3/Second Edition, which covers heat transfer, refrigeration systems, compression surge drums, and mechanical drivers. 

Steam jet refrigeration may be used for process cooling between 2 and 25°C when excess steam is readily available. Steam jet systems generally provide between 10 and 100 tons of refrigeration capacity per unit. Steam jet refrigeration systems are similar to mechanical systems in that an evaporator, compression device, condenser, and refrigerant are the basic system components. A... 

Used in both absorption- and compression-type systems, ammonia is the oldest, most efficient and economical mechanical refrigerant... 

In this the refrigerant vapor is compressed mechanically. Two-stage motor compressors are used mostly in freeze-drying systems. This compressor is installed in a screwed-on housing together with an electric motor. 

Steam-Jet (Ejector) Systems These systems substitute an ejector for a mechanical compressor in a vapor compression system. Since refigerant is water, maintaining temperatures lower than the environment requires that the pressure of water in the evaporator must be below atmospheric. A typical arrangement for the steam-jet refrigeration cycle is shown in Fig. 11-104. 

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