Evaporator, refrigeration

For chilling and crystallizing with an evaporating refrigerant, a 27-in shell with seven 6-in pipes is available (Heniy Vogt Machine... 

In most process systems, the evaporation of the refrigerant is carried out in shell and tube heat exchange equipment, and allowance must he made for a reasonable temperature approach between the process fluid and the evaporating refrigerant. The process fluid always leaves the evaporator at a higher temperature (by 3°-15°F) than the refrigerant. 

Evaporator, refrigerant side 23.8 psig (38.5 psia). This corresponds to a boiling or evaporating refrigerant temperature of the required 10°F. See Reference 1 or other ammonia tables. 

The next step is to decide a suitable evaporating temperature. This will be set by the required load condition and the appropriate temperature differential (AT) across the evaporator. In the context of evaporator selection, the AT used is the difference between the evaporating refrigerant and the temperature of the fluid entering the cooler, not the log mean temperature difference (see [1-5]). 

Figure 6.3 shows the comparison between the cooling powers supplied by a 3He evaporation refrigerator and a DR. The cooling power produced by the evaporation of 3He from the concentrated to the diluted phase is ... 

The primary medicinal use of alcohol is external, us an antiseptic, preservative, mild countcrirritunt. or solvent. Rubbing alcohol is u.scd us an astringent, rubefacient, and a mild local anesthetic. The anesthetic effect is due to the evaporative refrigerant action of alcohol when applied to the skin. Ethanol has even been injetied near nerves and ganglia to alleviate pain, it has a low narcotic potency and has been used inlcmally in diluted form as a mild. sedative, a weak va.sodilator, and a carminative. 

The evaporation temperature of the refrigerant must further compensate for the temperature difference through the ice layer to the evaporating refrigerant. 

FROSTING TYPE EVAPORATOR - Refrigerating system which maintains the evaporator at frosting temperatures during all phases of cycle. 

STATE - Refers to the form of a fluid, either liquid, gas or solid. Liquids used in environmental systems are water, thermal fluids such as ethylene glycol solutions, and refrigerants in the liquid state. Gases are steam, evaporated refrigerants and the air-water vapor mixture found in the atmosphere. Some substances, including commonly used refrigerants, may exist in any of three states. A simple example is water, which may be solid (ice), liquid (water), or gas (steam or water vapor). 

The temperature difference AT between the cold surface and the evaporating refrigerant. For an efficient vapor trap it is necessary to have a combination of a large cross-sectional area for the vapor flow (low AP), an efficient deicing system (low AT,, and an efficient refrigerating system (low ATj f,). 

AEjefr temperature difference between the cold surface and the evaporating refrigerant, K p void fraction in the dried layer... 

The name "brine" refers to a liquid used in a refrigeration system, which is usually an aqueous solution of calcium chloride or sodium chloride, that is externally cooled by an evaporating refrigerant (Figure 1.31). The addition of salt lowers the freezing point of the solution. The lowest temperature which can be reached by a solution of sodium chloride is about -21 °C (-7°F). That for calcium chloride is -52°C (-52°F). 

Refrigerant accumulator Throttle valve Evaporator Refrigerant fluid... 

TRO = Evaporator refrigerant side outlet temperature UA = A number proportional to the evaporator heat-transfer coefficient... 

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