Refrigeration systems refrigerant receiver

Looking at Fig. 22.1, the need for the refrigerant receiver is not immediately obvious. It does not appear to serve any process function. Many refrigerant systems are constructed without this vessel. However, it does have several important uses. For one thing, it provides a quiet zone for entrained lubricating and seal oils to settle out. 

In Fig. 31.1, there are two levels that must be controlled the evaporator level and the refrigerant receiver level. It is impossible to control both levels with two level-control valves. One level must be held with a level-control valve. The other level must be held by adjusting the system liquid refrigerant inventory. It is usually better to add makeup refrigerant to keep a decent liquid level in the receiver and control the flow of refrigerant into the evaporator. However, reversing this control scheme by adjusting inventory control in the evaporator is also possible. 

The price for an increase in heat-transfer characteristics is a more complex system with more anxihary eqnipmeut low-pressure receivers, refrigerant pumps, valves, and controls. Liquid refrigerant is predominantly pumped by mechanical pumps, however, sometimes gas at condensing pressure is used for pumping, in the variety of concepts. 

Direct-expansions are more appropriate for smaller systems which should be compact, and where there are just one or few evaporators. Overfeed (recirculation) systems should be considered for aU applications where first cost for additional equipment (surge drums, low-pressure receivers, refrigerant pumps, and accessories) is lower than the savings for the evaporator surface. 

The situation changes when the system pressure becomes high enough for refrigerant to condense in the condenser and reject the resulting latent heat to the environment. Further addition of heat to the adsorbate desorbs more refrigerant which condenses in the condenser and trickles down into the receiver. The system pressure stays approximately constant as desorption and condensation proceed. 

Receiver system refrigerant volume for shut-down refrigerant storage... 

Example 6.8 The evaporator and condenser of a system hold a total of 115 kg of R.717. Determine the receiver size and dimensions, pressure relief specification, and the total refrigerant charge for the plant. 

The refrigerant charge of such a system is critical, since it must not exceed the working capacity of the evaporator. It is not possible to have a receiver in circuit and this control cannot feed more than one evaporator, since it cannot detect the needs of either. 

Other gases, mainly ambient air, may enter a refrigeration system as a result of incomplete evacuation before charging, opening of parts for maintenance or repair, or inward leaks on circuits operating below atmospheric pressure. These gases will be circulated with the refrigerant vapour until they are all in the condenser and receiver. They cannot move further around the circuit because of the liquid seal at the outlet to the expansion valve. 

Many systems are shut down for periods of the year, either for process closure or if not required in winter. The advice of the supplier should be sought as to the correct procedure. In the case of refrigerant circuits, it is advisable to pump down into the receiver or condenser to minimize leakage losses. Water towers should be drained in winter in this climate, if not in use, and the tank heater disconnected. 

Receiver coil, superconducting, 23 860-861 Receivers, in refrigeration systems,... 

Modern pipeline milking systems convey the milk into a refrigerated tank equipped with mechanical agitation to cool it rapidly and maintain it at < 5°C. Milk is normally held on the farm for 24-72 hr and is then transported to the processing plant. Upon arrival at the processing plant, milk is examined for temperature, flavor, and acidity. It is then sampled and tested for fat, total solids, and antibiotics content. If acceptable, the milk is received and stored in refrigerated tanks until it is processed further. 

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. 

Heat Loads in Cryogenic Systems. In any cryogenic system, the heat load transferred to the cold surface determines the refrigeration capacity required to maintain the low temperature. Analysis has shown that the thermal loads received by a surface at cryogenic temperatures are due to ... 

In Chapter 13, six main ways of inhibiting the Maillard reaction in foods received attention refrigeration, the use of sulfur dioxide, lowering of pH, adjusting aw, and removing one or other of the reactants. Four of these are clearly not appropriate for in vivo systems, which normally cannot be refrigerated, have their pH or aw adjusted, or be exposed to sulfur dioxide. The reactants (and intermediate products derived from them) therefore become the main targets. 

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