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Absorption refrigeration system refrigers - Vapor absorption cycle in recreational vehicle

Technical information Industrial Absorption Refrigeration Systems

Absorption Refrigerating Systems

Absorption refrigeration cycles of use of heat source for the creation and maintenance of refrigerating effect in small fridge-freezer units and. large water coolers. Absorption cycle is used in chilled water applications where water is pumped over through the cooler barrel surrender to heat the refrigerant in the dying system. It is used also in small refrigerators and freezers used in recreational vehicles. Absorption refrigeration cycle is similar to the vapor-compression cycle in that both use volatile refrigerant, which in turn evaporated under low pressure in the evaporator and condenses in the conditions of high pressure in the condenser. Both cycles also use the temperatures of ambient air condenses die high pressure, high temperature steam in the condenser. The main difference between these cycles die method used for the circulation of the refrigerant through the system while maintaining the required pressure differential between evaporation and condensation processes.

A simple scheme of the absorption cycle is depicted.

The system consists of four main components: the evaporator and absorber, located on-chip low-pressure side of the system and generator, condenser, located on the high-pressure side of the system. In addition to these components, two fluids are also used in the system, refrigerant, and absorbent. RSS cycle for refrigerant from the condenser to the evaporator absorber, a generator and back of the capacitor. Absorbent passes from the shock-absorber of generator and back to the absorber.

The absorption cycle refrigerant is water or ammonia. Refrigerant evaporates in the evaporator, absorbing heat from the water flowing through the cooler barrel. Water returning from the air handling units (52F, 11C) is pumped through a tube sheet barrel. The refrigerant is fed through the nozzle, spray the surface of the pipes. The refrigerant flows in thin film, evaporates from the surface of the tube, absorbing latent heat. Process of the water leaving the evaporator (42F 5.6C) and is pumped to the heat exchange coils in the building.

Not compress refrigerant vapor raise the saturation pressure and temperature, vapour is absorbed by the liquid chemical solution, located in die absorber section of the unit. This solution is called die absorbent its defining characteristic is that it has a chemical affinity (attraction) for refrigerant vapor. Solution pump sprays absorbent/refrigerant through the absorber, to increase the quantity of absorbent impact of refrigerant vapors, increase of efficiency of process of absorption. As a refrigerant pair absorbed absorbent, the partial pressure of the refrigerant is reduced, lowering the pressure in the absorber section of the vessel. Ibis action establishes the driving force that keeps die refrigerant moving from high pressure in the evaporator section absorber section.

In addition to reducing the steam pressure in the absorber, the acquisition process also releases latent heat absorbed by the refrigerant in the evaporator. As a refrigerant changes state in liquid during the absorption process, he exchanges its latent heat with the decision of the absorber. This heat must be removed in order to maintain the pressure difference between the evaporator and the absorber and, consequently, to die a process of decomposition. Latent heat, gave refrigerant is transmitted to die ambient dirough capacitor or cooling tower. In large chillers, water (85F, 30C) return from a cooling tower is pumped through the outlet of the heat tube sheets located in the absorber. As an absorbent/refrigerant solution is sprayed on the pump solution flows over the heat removal from the surface of the tube, he transfers the heat to the water tower. This heated water is pumped from the tube, absorber die tubes in the condenser, absorb more heat. After leaving the condenser hot water is pumped to a cooling tower, where it transfers heat to the environment.

As the mass fraction of the refrigerant in the absorbent increases the ability of a decision to continue to absorb pair refrigerant is reduced. If the refrigerant is not extracted from the solution, the cooling process stops. Absorbent is called a weak solution when it becomes so diluted refrigerant that it can no longer effectively absorb pair. The generator is used to separate the refrigerant from the weak absorbent solution. The source of thermal energy supplied generator

to provide the energy needed to drive the refrigerant from the solution. In a direct-fired units, the heat source can be from fossil fuel burners or electrical energy. In the indirect-fire units, the source of heat can come from the steam, hot liquids or clean the hot exhaust gases from the turbine generators and motors. When the exhaust gases are used as die source of energy generator is called a generator of heat. Refrigerant evaporates from a weak solution and a condenser. This process increases the mass fraction of absorbent solution and the solution's ability to absorb the refrigerant vapor in the absorber. Absorbent returning to the absorber is called a strong solution, as the refrigerant was borrowed from the mixture. Strong solution is sprayed over the heating pipes and mixed with a weak solution in the absorber. To improve die efficiency of the cycle, a heat exchanger is installed for the transmission of energy between the warm weak solution is pumped to the generator and high temperature, strong solution to the return of die generator absorber. Because this heat exchange process increases the temperature of the weak solution of going to the generator, less energy must be input into the generator. At the same time, the temperature of a strong solution of returning to the absorber is reduced, reducing the amount of cooling by means of heat transfer tubes, located in die of shock absorber.

The refrigerant vapor generator driven off by lifting the condenser section, where they change phase, abandoning the latent heat to the surface of the tubes through which the tower fed water. The heated water (105F, 40.6C) is sent to the tower, where transfers the energy to the surrounding through mass and energy transfers, before returning to the absorber section. To simplify the design and installation of the machine, die condenser section of the pipe is typically supplied in series with the heat exchange tube section of the shock absorber. Consequently, the water inlet to the condenser for a couple of degrees warmer than the cold of the water leaving the tower. Since the generator heats the refrigerant vapors much higher temperatures than in the absorber, water tower still has a sufficient potential for vapor condensation of the refrigerant in the condenser. High pressure liquid refrigerant from the condenser passes to the evaporator expansion device or limiter to reduce the pressure in the evaporator. Refrigerant absorbs heat from the water flowing through the tube sheet and the cycle continues.

Control the low side (evaporator) temperature and pressure is controlled by changing the concentration of absorbent solution. Thus, the size of the shock absorber unit varied by adjusting the amount of heat entering the generator. But the energy transferred by the generator increased, the quantity of available refrigerant grows with increase in concentration of a strong solution. The increase in these variables makes a corresponding increase in the amount of refrigerant absorption and therefore, refrigeration effect.p..

 
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