Steam Jet Refrigeration System
Steam Jet Refrigeration.ppt (Size: 393.5 KB / Downloads: 176)
If the pressure is reduced, water boils at low temperatures
Water boils at 6⁰C, when the pressure on the surface is 5 cm of Hg
The high vacuum can be maintained by throttling the steam through jets or nozzles
Key design parameters
The compression ratio of the injector,P2/P1 , is defined as ratio of the injectors's outlet pressure to the inlet pressure of the suction fluid .
The entrainment ratio of the injector(Ws/Wi) is defined as the amount of motive fluid (in kg/hr) required to entrain and compress a given amount (in kg/hr) of suction fluid.
A flash chamber contains 100 kg of water.
Reduce Pressure by throttling steam through nozzles
If 1 kg of water is removed by boiling,
Approximately 2385 kJ of heat will be removed from the water, (heat of evaporation of water)
Thus by continuing this process, the remaining water can be made to freeze.
Water is the refrigerant used in the steam jet refrigeration system.
High pressure steam from the boiler is expanded in the nozzle
Water vapor from the flash chamber is entrained with the high velocity steam jet
It is then compressed in the thermo compressor.
The kinetic energy of the mixture is converted into static pressure
Exhaust is discharged to the condenser.
The condensate is usually returned to the boiler.
1% evaporation of water in the flash chamber is sufficient to decrease the temperature of chilled water to 6⁰C
Chilled water in the flash chamber is circulated by a pump
a) It is flexible in operation; cooling capacity can be easily and quickly changed.
b) It has no moving parts as such it is vibration free.
c) It can be installed out of doors.
d) The weight of the system per ton of refrigerating capacity is less.
e) The system is very reliable and maintenance cost is less.
a) The use of direct evaporation to chilled water is usually limited as Tremendous volume of vapour is to be handled.
b) About twice as much heat mustbe removed in the condenser of steam jet per Ton of refrigeration compared with the vapour compression system.