VAPOUR ABSORPTION REFRIGERATION SYSTEMS Submitted to : Mr. Sumit Sharma Presented By : Akshay Mistri, Rahul Kumar Tarun Sharma, Zubin Rizwan Section : 6MAE3Y

CONTENTS Introduction Introduction Simple Vapour Absorption System Simple Vapour Absorption System Practical Vapour Absorption System Practical Vapour Absorption System C.O.P of Ideal Vapour Absorption System C.O.P of Ideal Vapour Absorption System Properties of Ideal Refrigerant and Absorbent Properties of Ideal Refrigerant and Absorbent Properties of Ideal Refrigerant-Absorbent combination Properties of Ideal Refrigerant-Absorbent combination Advantages of Absorption system over Compression system Advantages of Absorption system over Compression system Domestic Electrolux Refrigerator Domestic Electrolux Refrigerator Principle & Working of Domestic Electrolux refrigerator Principle & Working of Domestic Electrolux refrigerator Advantages & Disadvantages of Domestic Electrolux Refrigerator Advantages & Disadvantages of Domestic Electrolux Refrigerator References References

INTRODUCTION It is a heat operated system. It is a heat operated system. It is quite similar to Vapour Compression systems. Condensation and evaporation takes place at two different pressure levels to achieve refrigeration. It is quite similar to Vapour Compression systems. Condensation and evaporation takes place at two different pressure levels to achieve refrigeration. The main motive is to raise the temperature of the refrigerant from evaporator pressure to condenser pressure. The main motive is to raise the temperature of the refrigerant from evaporator pressure to condenser pressure. Here refrigerant is dissolved in inert liquid in absorber and pumped to condenser. Here refrigerant is dissolved in inert liquid in absorber and pumped to condenser. After raising pressure of refrigerant it is separated from solution by heating. After raising pressure of refrigerant it is separated from solution by heating. After condensation in condenser, refrigerant is throttled by expansion valve and then it evaporates in evaporator providing the refrigeration effect. After condensation in condenser, refrigerant is throttled by expansion valve and then it evaporates in evaporator providing the refrigeration effect.

SIMPLE VAPOUR ABSORPTION SYSTEM Ammonia vapour from evaporator is absorbed by water in absorber. Condensation heat released is absorbed by cooling water. Ammonia vapour from evaporator is absorbed by water in absorber. Condensation heat released is absorbed by cooling water. After being pumped to generator, heat is supplied which gives ammonia vapour. Weak sol. sent back to absorber. After being pumped to generator, heat is supplied which gives ammonia vapour. Weak sol. sent back to absorber. High pressure vapour is condensed to high pressure liquid ammonia in condenser. High pressure vapour is condensed to high pressure liquid ammonia in condenser. Liquid ammonia is throttled by expansion valve, and then it evaporates absorbing heat from evaporator. Liquid ammonia is throttled by expansion valve, and then it evaporates absorbing heat from evaporator. Simple Vapour Absorption System

PRACTICAL VAPOUR ABSORPTION SYSTEM Practical Vapour Absorption System

COEFFICIENT OF PERFORMANCE OF IDEAL ABSORPTION SYSTEM

C.O.P OF IDEAL ABSORPTION SYSTEM (CONTINUED) Various energy transfers in VARS

C.O.P OF IDEAL ABSORPTION SYSTEM (CONTINUED)

PROPERTIES OF IDEAL REFRIGERANT & ABSORBENT Properties of ideal refrigerant : It should boil b/w 2˚-10 ˚C and condense at 40 ˚C or above. (pressure around atmospheric) It should boil b/w 2˚-10 ˚C and condense at 40 ˚C or above. (pressure around atmospheric) Large latent heat of vaporization. Large latent heat of vaporization. High critical temperature. High critical temperature. Low specific heat. Low specific heat. Stability in complete cycle. Stability in complete cycle. Properties of ideal absorbent : Greater affinity for refrigerant. Heat released during absorption of refrigerant should be minimum. High boiling point. Low specific heat. Chemical stability.

PROPERTIES OF IDEAL REFRIGERANT- ABSORBENT COMBINATION Refrigerant should have high affinity for absorber at low temperatures & less affinity at high temperatures. Refrigerant should have high affinity for absorber at low temperatures & less affinity at high temperatures. Mixture should have low specific heat and viscosity. Mixture should have low specific heat and viscosity. It should be non-corrosive. It should be non-corrosive. Large difference in normal boiling points of refrigerant and absorbent. Large difference in normal boiling points of refrigerant and absorbent. Commonly used combinations in air- conditioning applications : Ammonia-water Lithium-bromide water

ADVANTAGES OF ABSORPTION SYSTEM OVER COMPRESSION SYSTEM No moving part except pump-motor, which is comparatively smaller than compressor system. No moving part except pump-motor, which is comparatively smaller than compressor system. Quiet in operation, low maintenance cost. Quiet in operation, low maintenance cost. Can work only with thermal energy as an input. Can work only with thermal energy as an input. Can be built for huge working capacities. (even for above 1000 TR) Can be built for huge working capacities. (even for above 1000 TR) Can be operated at designed C.O.P’s or even at part loads by varying generator temperature. Can be operated at designed C.O.P’s or even at part loads by varying generator temperature. Space and Auto. control requirements favour absorption system. Space and Auto. control requirements favour absorption system.

DOMESTIC ELECTROLUX REFRIGERATOR Developed from an invention by “Carl Munters” & “Baltzer Von Platen”. Developed from an invention by “Carl Munters” & “Baltzer Von Platen”. Also known as “Three-fluid absorption system” and “Munter’s Platen System”. Also known as “Three-fluid absorption system” and “Munter’s Platen System”. Three fluids used are ammonia, hydrogen and water. Three fluids used are ammonia, hydrogen and water. Domestic Electrolux Refrigerator

PRINCIPLE & WORKING OF ELECTROLUX REFRIGERATOR Working cycle of Electrolux Refrigerator

POINTS WORTH NOTING (FOR ELECTROLUX REF.) Complete cycle is carried out entirely by flow of gravity of refrigerant. Complete cycle is carried out entirely by flow of gravity of refrigerant. With this type of machine, efficiency is not important since the energy input is very small. With this type of machine, efficiency is not important since the energy input is very small. Due to low C.O.P, it cannot be used for industrial purposes. Due to low C.O.P, it cannot be used for industrial purposes. ROLE OF HYDROGEN Helps in maintaining uniform total pressure throughout the system. Helps in maintaining uniform total pressure throughout the system. Permits the refrigerant to evaporate at low temperature in evaporator, corresponding to its partial pressure. Permits the refrigerant to evaporate at low temperature in evaporator, corresponding to its partial pressure.

ADVANTAGES (ELECTROLUX REF.) No pump/compressor required. No pump/compressor required. No mechanical troubles, low maintenance. No mechanical troubles, low maintenance. No lubrication required, no wear-tear. No lubrication required, no wear-tear. Completely leak proof. Completely leak proof. Noiseless. Noiseless. Easy control, only by heat input. Easy control, only by heat input. More complicated in construction and working. Low C.O.P. If spoiled once, cannot be repaired and has to be replaced fully. DISADVANTAGES (ELECTROLUX REF.)

REFERENCES Er. R.K. Rajput.Vapour Absorption Refrigeration Systems. Feb 03, 2014, “A textbook of Refrigeration & Air-conditioning-2013”. Er. R.K. Rajput.Vapour Absorption Refrigeration Systems. Feb 03, 2014, “A textbook of Refrigeration & Air-conditioning-2013”. Prof. M. Ramgopal. Various energy transfers in VARS (image). Feb 02, 2014, from Prof. M. Ramgopal. Various energy transfers in VARS (image). Feb 02, 2014, from Prof. R. C. Arora. Domestic Electrolux Refrigerator (image). Feb 02, 2014, from contents/IIT%20Kharagpur/Ref%20and%20Air%20Cond/pdf Prof. R. C. Arora. Domestic Electrolux Refrigerator (image). Feb 02, 2014, from contents/IIT%20Kharagpur/Ref%20and%20Air%20Cond/pdf contents/IIT%20Kharagpur/Ref%20and%20Air%20Cond/pdf contents/IIT%20Kharagpur/Ref%20and%20Air%20Cond/pdf