6) Foundations required and noise : The compressor of the vapor compression system is operated at very high speeds and it makes lots of vibrations and noise. It also requires very strong foundation so that it can remain intact under vibrations and high pressures of the refrigerant. In the absorption refrigeration system there are no major moving parts hence they don’t vibrate, don’t make noise and also don’t require heavy foundations. The absorption refrigeration systems operate silently.
7) Maintenance : Compressor is the crucial part of the vapor compression cycle, and it has number of moving parts. It is very important to do the thorough lubrication of the compressor and also keep checking it regularly for any defects. The compressor also requires changing of the piston, piston rings, cylinder liner etc. from time-to-time. Thus the vapor compression system requires lots of maintenance. Failure of compressor can be very expensive at times as the suction and the discharge valve of the compressor are very expensive. Even the motor of the compressor is very heavy and expensive. The compressor also requires cooling, for which special pump is required to pump the water from the cooling tower to the compressor. Since there are number of moving parts of the compressor that move at very fast speed some or the other failure occurs regularly. In the absorption refrigeration system the only moving part is the small pump that fails rarely. Thus the maintenance required by the vapor compression system is much more than that required by the vapor absorption system.
8) Capacity control of the system : In the vapor compression cycle the capacity control of the system is done from the compressor and in most of the cases stepwise capacity control is obtained. In case of the absorption refrigeration system it is possible to obtain stepless capacity control and zero capacity when there is no load on the system. Though these days compressors with stepless capacity control are available, but they will consume lots of power even if there is zero load on the refrigeration system. In absorption system, when there is zero load the power consumption is almost zero.
9) Type of refrigerant used and its cost : In ammonia-water absorption refrigeration system, ammonia is used as the refrigerant, which is easily and cheaply available. In lithium bromide system, water is used as the refrigerant, which is also available cheaply and easily. In case of the vapor compression refrigeration system halocarbons are used as the refrigerants, which are very expensive.
10) Leakage of the refrigerant : In the absorption refrigeration system there are no (or very few) leakages of the refrigerant and the refrigerant itself is very cheap. Thus there are almost zero refrigerant recharging costs. In case of the vapor compression systems there are lots of leakages of the refrigerant thus regular recharge of the refrigerant is required which is very expensive.
11) Greenhouse effect : Most of the halocarbon refrigerants used in the compression refrigeration system produces greenhouse effect. As per the Montreal Protocol, their use has to stop completely by the year 2020. In the absorption refrigeration system no refrigerant produces the greenhouse effect, so their use won’t be stopped in future.