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THERMO-ELECTRIC & VORTEX TUBE REFRIGERATION CLASS NOTES

THERMO-ELECTRIC & VORTEX TUBE REFRIGERATION CLASS NOTES Thermo-electric refrigeration uses semi-conductors. A semiconductor is a combination of two materials having high electrical conductivity and low thermal conductivity. The property defining the quality of thermo-couple is  ‘Figure of Merit’. Figure of Merit = Z= α2σ/k Where α is the Seebeck coefficient of the two materials of the semiconductor σ…

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CRYOGENICS-LIQUEFACTION CLASS NOTES FOR ENGINEERING

 CRYOGENICS-LIQUEFACTION CLASS NOTES FOR ENGINEERING    Cryogenics  involves the study of temperatures below -1500C. It is of interest to know how to produce such temperatures. These temperatures are produced by liquefaction of gases. In addition , it is of interest is know which materials are suitable at these temperatures. There are many areas of interest…

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 VAPOR ABSORPTION REFRIGERATION CLASS NOTES

. VAPOR ABSORPTION REFRIGERATION CLASS NOTES   As cooling requirements increase, volume of refrigerant increase. It increases the size of the compressor and the power requirements. Volume reduction decreases Power requirements. Here comes the role of absorption. Water has extremely high affinity for ammonia and Lithium Bromide has high affinity for water. Water in the absorber…

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QUESTION ANSWERS-EXPANSION VALVES & CONTROLS

QUESTION ANSWERS- EXPANSION VALVES & CONTROLS  Question answers make the concept absolutely clear. The basic principles become easily applied to practical applications.  List the various types of expansion devices with their practical applications. Various types of expansion devices are 1.Capillary Tube This tube is very small diameter ( fraction of a mm) tube with no…

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OZONE DEPLETION AND GLOBAL WARMING CLASS NOTES

 OZONE DEPLETION AND GLOBAL WARMING CLASS NOTES Ozone depletion is decrease of ozone layer. This depletion of ozone will allow harmful ultra-violet radiations reach earth. Global warming is Increase in the average temperature of earth and sea. It is due to absorption of infra red radiations by green house gases. Both are harmful to all…

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REFRIGERATOR /HEAT ENGINE/ HEAT PUMP CLASS NOTES

REFRIGERATOR/HEAT ENGINE/  HEAT PUMP CLASS NOTES Heat engine converts heat into mechanical motion/electricity. Refrigerator produces cooling effect. Heat pump produces heating effect.   Q. COMPARE HEAT ENGINE, REFRIGERATOR AND A HEAT PUMP WHEN WORKING ON CARNOT CYCLE OR REVERSE CARNOT CYCLE Heat Engine ηheat engine = (TH—TL)/TL COP refrigerator  = TL/(TH–TL) COP heat pump =Th/(TH–TL) In…

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ON AND OFF CONTROLS REFRIGERATION CLASS NOTES

ON AND OFF CONTROLS- REFRIGERATION CLASS NOTES On and off controls makes the operation automatic.  These save electricity. They also act as safety for the machine.     There are number of automatic off and on controls for the motor compressor of a refrigeration system. These are pressure, voltage and temperature controls. (i)                 Suction Pressure…

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REFRIGERANT FLOW CONTROLS

REFRIGERANT FLOW CONTROLS Flow controls are fitted between the condenser and the evaporator. These produce the required pressure drop. These also control the rate of flow of refrigerant as per cooling required. There are five types of refrigerant flow controls. These are used in different applications. FIVE TYPES (i)  Capillary Tube (ii)  Automatic Expansion Valve…

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SPECIFIC REFRIGERANTS CLASS NOTES FOR MECHANICAL ENGINEERING

  SPECIFIC REFRIGERANTS CLASS NOTES  FOR MECHANICAL ENGINEERING Different refrigerants have different properties. Different applications require different refrigerants. Their selection is a compromise of properties for an application. Ammonia suits best for large scale cooling requirements. There is a prohibition on the manufacture and use of R-11 and R-12. These have high Ozone depletion & Global…

GAS REFRIGERATION CLASS NOTES FOR MECHANICAL ENGINEERING

GAS REFRIGERATION CLASS NOTES FOR MECHANICAL ENGINEERING Air refrigeration cools all types of air-crafts in the world. air is the refrigerant. It is safe and cheap. Its COP is < 1. It gives the cooling as sensible effect. Cooling effect is quiet less.  Plant size increases. The main function of a refrigeration cycle is absorb…