This document summarizes a low-grade thermally driven adsorption refrigeration system. The system uses an adsorbent like silica gel and a refrigerant like water. It works similar to vapor absorption refrigeration using a thermal compressor instead of a mechanical one. The adsorbent adsorbs the refrigerant vapor at low temperature and pressure, then desorbs it at high temperature, allowing it to be condensed and evaporated to produce cooling. Key advantages are its ability to use low-grade heat, operate without ozone-depleting refrigerants, and have few moving parts. Disadvantages include lower efficiency and larger size compared to conventional vapor compression systems.

1. Piyush Patil

2. Low grade thermally Driven System.
Helps to reduce CO2 emission from combustion.
Zero Ozone Depletion Potential refrigerant.
Contains Thermal Compressor which operates on
heat.
Same as Vapour absorption refrigeration system.

3. Thermally driven Compressor.
Evaporator.
Condenser
An Expansion valve
Adsorbent(or Sorbent)[Ex. Activated Carbon, Silica –
Gel etc.]
Refrigerant[Water, Ammonia, Methonol]

4. Adsorption refers to binding of molecules to the
surface of material without chemical change.
Adhesion of atoms, ions, or Molecules from gas, liquid,
or dissolved solid to the surface.
Adsorption capacity is enhanced when surface area is
more and when sorbent material is activated.
Refrigerant is based on ability of adsorber material to
adsorb large amount of refrigerant vapour at low
temperature and pressure. and desorbs refrigerant at
high pressure and temperature.

6. These container is initially at low temperature and pressure. In
which refrigerant concentration is high in adsorbed
refrigerant(silica-gel etc). And another container contain
Refrigerant(water etc)
Fig (b): Adsorbent refrigerant is heated which leads to
refrigerant in gaseous form and it is driven out from the
adsorbent and pressure of the system is increases. this process
called as desorption.
Desorbed refrigerant is cooled and condensed in evaporator-
condenser. And heat is rejected as shown in fig(b)
Fig(c):- When generator reached at the desirable refrigerant
combination as shown in fig(c). It is then cooled to the initial
pressure and temperature. and adsorb refrigerant back. this
Process is called as adsorption Process

7. The lower pressure causes the liquid refrigerant to
evaporater.In evaporator-condenser.
This Evaporation at lower pressure produce refrigeration
effect.

8. Physical Adsorption :
Ex:- Activated carbon and Silica gel
Chemical Adsorption :
Caused due to the reaction between sorbet and surface
molecule of sorbent.
Only one layer of adsorbate react with the surface molecule of
chemical adsorbent .
Phenomenon is salt swelling which is critical for heat and mass
transfer performance
Ex: metal Chloride and ammonia.

9. Noise free operation
Ability to work in mobile condition
Wide range of adsorbent.
Capability of handling variable temperature heat source.
Very few moving part
No dangerous chemicals.
Zero ozone depletion potential refrigerant.
Less maintenance.

10. COP is less
layer thickness of the adsorber bed is limited
The size of the system is large .
Not economical Yet.

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