Refrigeration systems components

To meet the 1993 Energy Standards, the industry undertook, at considerable cost, the optimization of the various refrigeration system components. The most significant improvement was the increase in compressor efficiency, from an EER of about 4 to about 5.5. Other system improvements included more efficient fan motors, more effective heat transfer by the evaporator and the condenser, and less defrost energy. In the early 1980s, both the Whirlpool Corporation and White Consolidate Industries introduced electronic defrost controls. Heretofore, an electric timer initiated the defrost cycle, typically every t A elve hours, whether the evaporator needed it or not. With the electronic control the defrost inteiwal is more a function of frost accumulation than of time, and thus referred to as a variable defrost control or as adaptive defrost. It saves energy by being activated only when needed. 

Fig. 1. Components of a refrigeration system A, condenser outlet B, evaporator inlet C, evaporator outlet D, compressor discharge.

Main Components The main components of steam-jet refrigeration systems are ... 

Jotile-Thomson Valves The principal function of a J-T valve is to obtain isenthalpic coohng of the gas flowing through the valve. These valves generally are needle-type valves modified for cryogenic operation. They are an important component in most refrigeration systems, particularly in the last stage of the liquefac tion process. Joule-Thomson valves also offer an attractive alternative to turboexpanders for small-scale gas-recovery applications. 

Surfaces will absorb radiant heat and this factor is expressed also as the ratio to the absorptivity of a perfectly black body. Within the range of temperatures in refrigeration systems, i.e. - 70°C to + 50°C (203-323 K), the effect of radiation is small compared with the conductive and convective heat transfer, and the overall heat transfer factors in use include the radiation component. Within this temperature range, the emissivity and absorptivity factors are about equal. 

A refrigeration system can be built with only the four essential components ... 

More complex refrigeration systems may have components for specihc... 

Fault tree analysis is based on a graphical, logical description of the failure mechanisms of a system. Before construction of a fault tree can begin, a specific definition of the top event is required for example the release of propylene from a refrigeration system. A detailed understanding of the operation of the system, its component parts, and the role of operators and possible human errors is required. Refer to Guidelines for Hazard Evaluation (CCPS, 1992) and Guidelines for Chemical Process Quantitative Risk Assessment (CCPS, 2000). 

As it turned out, CFCs were ideal for the purpose. The members of this chemical family are nonflammable, noncorrosive, nontoxic, odorless, and very stable. Within a short period, they became widely popular for a variety of industrial applications. In addition to their applications in refrigeration systems, they became popular as aerosol propellants, cleansing agents for electrical and electronic components, and foaming agents in the manufacture... 

Finally, the receiver will accumulate any noncondensable (or hard-to-condense) components that have accidentally entered the system. Air left in the vessels on start-up is one such example. Traces of methane and ethane in a propane refrigerant system is another. These light vapors may be vented from the top of the receiver during normal operations. 

Flow Sheet and Mass Balances. Figure 2 represents a flow sheet of the 15,000-gallon-per-day pilot plant. The four major components are the freezer, the wash-separation column, the ice melter, and the vapor-handling device. The other essential components are the deaerator, which removes air from the saline water before it enters into the evacuated freezer the auxiliary refrigeration system, which removes heat leakage into the system and thermal inefficiencies of the process an ice scraper, pumps, controls, and instruments. 

All system components related to the refrigerant such as thermostatic expansion... 

The top portion of this figure shows the main components of a refrigeration system. The bottom portion describes the refrigeration cycle, which consists of two isothermal and two isen-tropic processes. 

Vendor shall supply a completely piped and wired skid mounted packaged refrigeration system, which shall include but not be limited to the following all components, piping, valves, instruments, alarms, shutdowns, control, control panels, special tools and equipment necessary to operate the unit at its rated capac ity. ... 

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