Vapour Absorption Refrigerator

We manufacture Vapor Absorption Refrigerator with advanced working and easy operational features. These are self contained Refrigerators working on absorption technology. In the absence of a compressor or pump, the circulation takes place by density difference. The Vapor Absorption Refrigerator absorbs the vapor emitted in the industries and laboratories, and prevents the heating of the place.

Attributes

• Consumes less electricity
• Does effective cooling
• Long service life
• Low maintenance

How It Operates?

• The system is pre-charged with three fluids namely water, ammonia and hydrogen. Hydrogen is used as an â��inert gasâ�� and does not undergo any phase change and heat transfer processes. Its purpose is to keep the pressure of the system constant
• It uses an electrically operated generator, where, the ammonia vapors dissolved in water are separated and pure ammonia vapors enter the condenser
• In the condenser, the high pressure vapors reject its latent heat to the surroundings and get liquefied
• The liquid ammonia expands through expansion device where its pressure and temperature is reduced and cold low pressure vapor enters the evaporator where it absorbs heat from the space to be cooled and then vaporized ammonia absorbs in water
• This strong solution then enters the generator and the cycle repeats

List of Experiments

• To study construction and working of a vapour absorption refrigerator
• To evaluate performance of the refrigerator by calculating the C.O.P of the system

Principle of Operation
Electrolux principle works on 3-fluid system. There is solution circulation pump. Total pressure is the same throughout the system. The third fluid remains mainly in the evaporator thus reducing partial pressure of refrigerant to enable it to evaporate at low pressure and hence low temperature.
The schematic diagram of the Electrolux refrigerator working on NH₃-H₂O system with H₂ as the third fluid is shown in figure. Liquid NH₃ evaporates in the evaporator in the pressure of H₂. Hydrogen is chosen as it is non â��corrosive and insoluble in water.
A thermosyphon bubble pump is used to lift the weak aqua from the generator to the separator. The discharge tube from the evaporator the generator is extended down below the liquid level in the generator. The bubbles rise and carry slugs of weak NH₃-H₂O solution into the separator.
Two U-bends are provided as vapour- locks to prevent H₂ from getting into the high side or solution circuit. Partial pressure of H2 provides the pressure difference of NH₃ between the condenser and evaporator. Accordingly, we have:

• In condenser pure NH₃ vapour pressure = Total pressure
• In evaporator NH₃ vapour pressure = Total pressure - partial pressure H₂

For example, Consider the condenser temperature at 50 C and evaporator temperature as -15 C
The corresponding vapour pressures of NH₃ are :

• Condenser, Pk = 20.33bar
• Evaporator outlet Po2 = 2.6bar

The approximate pressures in various parts of the system, then will be as given in the table.

It has been assumed that vapours leaving generator top are in equilibrium with entering rich solution at 40 C, at which temperature saturation pressure of NH₃ is 15.45bar. It has also been assumed that the temperature at evaporator inlet is -25 C at which temperature saturation pressure of NH₃ is 1.516 bar.

Technical Specifications