Working Principal of Steam jet refrigeration system
Department of Mechanical Engineering
National Institute of Technology, Patna
Patna-800005, Bihar (India)
This is to certify that seminar report entitled Working principle of Steam jet refrigeration system has been prepared by me under the supervision of Dr. Amarnath Sinha Professor of Mechanical Engg. Department N.I.T, Patna has not been submitted by me elsewhere for award of any degree
Student of second semester
M.Tech (Mechanical Engg.)
Steam jet ejector
Advantage and Disadvantage
Recent Development in Steam jet refrigeration system
In steam jet refrigeration systems, water can be used as the refrigerant. Like air, it is perfectly safe. These systems were applied successfully to refrigeration in the early years of this century. At low temperatures the saturation pressures are low (0.008129 bar at 4°C) and the specific volumes are high (157.3 m3/kg at 4°C). The temperatures that can be attained using water as a refrigerant are not low enough for most refrigeration applications but are in the range which may satisfy air conditioning, cooling, or chilling requirements. Also, these systems are used in some chemical industries for several processes, e.g. the removal of paraffin wax from lubricating oils. Note that steam jet refrigeration systems are not used when temperatures below 5°C are required. The main advantages of this system are the utilization of mostly low-grade energy and relatively small amounts of shaft work. here water is used as the refrigerant and the cooling effect is produced in the steam jet refrigeration continuous cycle by vaporization of a part of the water in the evaporator at a low absolute pressure level. The steam jet refrigeration system (also known as ejector system refrigeration system) is one of the oldest methods of producing refrigeration effect. The basic components of this system are an evaporator, a compressor device, a condenser and a refrigerant control device. This system employs a steam injector or booster (instead of mechanical compressor) to compress the refrigerant to the required condenser pressure level. In this system, water is used as the refrigerant. Since the freezing point of water is 0°C, therefore, it cannot be used for applications below 0°C. The steam jet refrigeration system is widely used in food processing plants for pre-cooling of vegetables and concentrating fruit juices, gas plants, paper mills, breweries etc.
Principle of steam jet refrigeration system: -
The boiling point of a liquid changes with change in external pressure. In normal conditions, pressure exerted on the surface of a liquid is the atmospheric pressure. If this atmospheric pressure is reduced on the surface of a liquid, by some means, then the liquid will start boiling at lower temperature, because of reduced pressure. This basic principal of boiling of liquid at lower temperature by reducing the pressure on its surface is used in steam jet refrigeration system. The boiling point of pure water at standard atmospheric pressure of 760 mm of Hg is 1 00°C. It may be noted that water boils at 12′C if the pressure on the surface of water is kept at 0.014 bar and at 7′C if the pressure on the surface of water is 0.01 bar. The reduced pressure on the surface of water is maintained by throttling the steam through the jets or nozzles.
WORKI NG OF STEAM JET REFRIGERATION SYSTEM...
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