Construction And Working Of Steam Jet Refrigeration System

If water is sprayed into a chamber where a low pressure is
maintained, a part of the water will evaporate. The enthalpy
of evaporation will cool the remaining water to
its saturation temperature at the pressure in the
chamber. Obviously lower temperature will require lower
pressure. Water freezes at 0 deg.C hence temperature lower
than 4 C cannot be obtained with water. In this
system, high velocity steam is used to entrain the
evaporating water vapour. High-pressure motive steam
passes through either convergent or convergent
divergent nozzle where it acquires either
sonic or supersonic velocity and low pressure of

order of 0.009 kPa corresponding to an evaporator
temperature of 4 deg C. The high momentum of
motive steam entrains or carries along with it the water
vapour evaporating from the flash chamber. Because of
its high velocity it moves the vapours against the pressure
gradient up to the condenser where the pressure is
5.6-7.4 kPa corresponding to condenser temperature
of 35-45 deg.The motive vapour and the evaporated vapour
both are condensed and recycled. This system is known as
steam jet refrigeration system. Figure shows a schematic of
the system. It can be seen that this system requires a
good vacuum to be maintained. Sometimes, booster ejector
is used for this purpose. This system is driven by low-
grade energy that is

process steam in chemical plants or a boiler. 

Steam Jet Refrigeration System
Fig. Steam Jet Refrigeration

In 1838, the Frenchman Pelletan was granted a patent for the
compression of steam by  means of a jet of motive steam.
Around 1900, the Englishman Charles Parsons studied
the possibility of reduction of pressure by an
entrainment effect from a steam jet. However, the credit
for constructing the steam jet refrigeration system goes to
the French engineer, Maurice Leblanc who developed the
system in 1907-08. In this system, ejectors were used to
produce  a high velocity steam jet (≈ 1200 m/s). Based
on Leblanc’s design the first commercial  system was
made by Westinghouse in 1909 in Paris. Even though the
efficiency of the steam

jet refrigeration system was low, it was still attractive as
water is harmless and the system can run using exhaust
steam from a steam engine. From 1910 onwards, stem jet
refrigeration systems were used mainly in breweries,
chemical factories, warships etc. In 1926, the
French engineer Follain improved the machine by
introducing multiple stages of vaporization
and condensation of the suction steam. Between
1928-1930, there was much interest in this type of
systems in USA. In USA they were mainly used for air
conditioning of factories, cinema theatres, ships and
even railway wagons. Several companies such as Westinghouse,
Ingersoll Rand and Carrier started commercial production
of these systems from 1930. However, gradually these
systems were replaced by more efficient vapour absorption
systems using LiBr-water. Still, some east European
countries such as Czechoslovakia and Russia manufactured
these systems as late as 1960s. The ejector principle can
also be used to provide refrigeration using fluids other
than water, i.e., refrigerants such as CFC-11, CFC-21,CFC-22,
CFC-113, CFC-114 etc. The credit for first developing these
closed vapour jet refrigeration systems goes to the
Russian engineer, I.S. Badylkes around 1955.
Using refrigerants other than water, it is possible to
achieve temperatures as low as –100C with a single stage
of compression.

The advantages cited for this type of systems are
simplicity and robustness, while difficult design and
economics are its chief disadvantages.