Pipelines and accessories
From a thermodynamic point of view, only a necessary substance refrigerant in the system, everything else is undesirable. Of other substances that can find their reflection in the system only in the lubricant, and that is only because the compressor does not require its proper operation. Thus, the air, water and dirt do not want, and all possible steps should be taken to ensure that they are missing. Their total elimination may be impossible, but assistance in choosing the right materials and workmanship and charging, can minimize its presence.
The pipes must be made from a material that will not be attacked by the refrigerant (for example, copper is acceptable fluorinated hydrocarbons, but not with ammonia) and, in addition, that the necessary structural properties, it should be clean and hydrated prior to use. The same is true for all fittings, valves and other components used.
The pipeline should be large enough to permit the flow of refrigerant without undue pressure and, most importantly, it should allow lubrication system to be transported to the place where he is wanted, that is, to the crankcase.
Inevitably, some-fired with a high-pressure refrigerant in the compressor, the condenser. When refrigerant is a liquid, it is good miscible with mineral oil, if it fluorinated hydrocarbons, and both are easily carried along. When the refrigerant is in vapor state, however, mixing occurs. If used mineral oil turns into the fog and pipes must be of a size to give REFRIGERANT gas speed is high enough to pass lubrication.
Hence, it is clear that the problem may occur in conditions of partial load when the system not to escalate the design volumes of gas. Mineral oil is usually accumulate on the walls of pipes and drains into the lower points of the system. For this reason, proper oil return into the crankcase, can be helped keel tube. Oil separator between the compressor and condenser is also useful, especially in air-conditioning, where large load fluctuations occur. Lubricants which are not mineral oil have their own characteristics. Oil pressure switch failure is essential. This is interlocked with the compressor engine, starter, so that if the pressure falls below the minimum value, the compressor is stopped and the damage from lack of lubrication prevented.
The water in the system may cause problems in a number of ways to minimize this dryer is inserted in the pipeline. This should not be regarded as a valid substitute for proper dehydration in the Assembly and setting to work, but should be considered in addition to her. The filters must be installed before expansion valve and any solenoid valve that may accompany it.
Sight glasses are important. They should be placed in the liquid line between the condenser or liquid receiver and the expansion valve. Their aim is to ensure that you have enough charge in the system and monitor the status of fluid inlet of the expansion valve. Sensors are also important, although they are not always installed on some high-packaged plant. They provide the proper control of stored on the launch of the plant and their assistance during commissioning of the plant and problem determination.
Gauge glasses are needed, although they may not always be present. Their goal is to establish the levels of fluid in capacitors and receivers, and this is especially important for the filling system.
If the condensing pressure is less than the ambient air pressure, air and possibly other not condensible gases will take place in a capacitor and automatic cleaning system becomes necessary. (Note that some slight leakage of the refrigerant into the atmosphere will always occur when the automatic cleaning works.) Non-condensible gases collected in the condenser and their presence raises the total pressure (according to Dalton's law), reduction of cooling capacities and increase of capacity necessary for compression. Oxygen in gases can cause mineral oil oxidation in the presence of high temperature and do not condensible gases can form a film on the heat transfer surfaces inside the condenser. Webb et al. (1980) showed as little interest condensible gases cause a large reduction in the film heat transfer coefficient shell and tube condensers...