Refrigeration Systems Based On Ammonia-Water Pair
Vapor AbsorptionRefrigeration Systems Based On Ammonia-Water Pair
• 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.
Vapor AbsorptionRefrigeration Systems Based On Ammonia-Water Pair
For Ammonia-Water pair
Circulation ratio- Is the ratio of the mass of the weak solution to the refrigerant mass flowrate.
=mλ ws/m
Condenserm1= m2= m
Q c=m(h1-h2)
Expansion Valvem2=m3=m
h2=h3
Evaporatorm3=m4=m
QE=m(h4-h3)
Absorberm + mss = mws
QA=mh4+λh10-(1+λ)mh5
Pumpm5=m6=mws
Wp=mws(h6-h5)
Wp=λm(h6-h5)
Heat Exchangerm6=m7=mws
m8=m9=mss
Generatorm7=m8+m1
QG=mh1+λmh8-(1+λ)mh7
Expansion Valvem9=m10=mws
h9=h10
COP=QE/(QG+Wp)
Comparison Between Compression and Absorption Refrigeration Systems