Refrigerant heated evaporators

The released ammonia forms a pool of refrigerated liquid which evaporates by heat transfer from the soil. A constant mass value was assumed for the evaporation rate and a heavier-than-air gas dispersion model was used. 

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. 

In mechanical refrigeration, a multicomponent refrigerant consisting of nitrogen, methane, ethane, and propane is used through a cascade cycle. When these liquids evaporate, the heat required is obtained from... 

The desirable energy output of the refrigeration cycle is the heat added to the evaporator (or heat removed from the inner space or the low-temperature reservoir of the refrigerator). The energy input to the cycle is the compressor work required. The energy produced is the turbine work. The net work (fTnet) required to operate the cycle is (lVi2 + Thus, the coefficient of performance (COP) of the cycle is... 

EVAPORATOR - The heat exchanger in which the medium being cooled, usually air or water, gives up heat to the refrigerant through the exchanger transfer surface. The liquid refrigerant boils into a gas in the process of the heat absorption. 

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

The working fluid (refrigerant) at low pressure is vaporized in the evaporator by heat drawn from the exhaust humid air. At the same time, condensation of moisture occurs as the exhaust air temperature goes below dew point temperature. Thus, the process air is dehumidified. The working fluid then goes to... 

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