Refrigeration Systems

1. Vapor Absorption
Refrigeration Systems
Based On Ammonia-Water Pair

2. • Vapour absorption refrigeration system based on ammonia-
water is one of the oldest refrigeration systems.
• Ammonia is used as a refrigerant and water is used as an
absorbent.
• Lithium bromide systems operate under very low pressures,
the ammonia-water system is operated at pressures much
higher than atmospheric .
• Ammonia is both toxic and flammable. Hence, these systems
need safety precautions.

3. Vapor Absorption
Refrigeration Systems
Based On Ammonia-Water Pair

4. For Ammonia-Water
pair
Circulation ratio
- Is the ratio of the
mass of the weak
solution to the
refrigerant mass
flowrate.
λ=mws/m

5. Condenser
m1= m2= m
Qc=m(h1-h2)
Expansion Valve
m2=m3=m
h2=h3
Evaporator
m3=m4=m
QE=m(h4-h3)

6. Absorber
m + mss = mws
QA=mh4+λh10-(1+λ)mh5
Pump
m5=m6=mws
Wp=mws(h6-h5)
Wp=λm(h6-h5)
Heat Exchanger
m6=m7=mws
m8=m9=mss

7. Generator
m7=m8+m1
QG=mh1+λmh8-(1+λ)mh7
Expansion Valve
m9=m10=mws
h9=h10
COP=QE/(QG+Wp)

8. Comparison Between Compression and Absorption
Refrigeration Systems