Rac Lab Manual

April 2, 2018 | Author: Aftab Alam | Category: Air Conditioning, Refrigeration, Gas Compressor, Evaporation, Vapor


Comments



Description

RAC LAB MANUALDEPARTMENT OF MECHANICAL ENGINEERING, GECC GOVERNMENT ENGINEERING COLLEGE, CHAIBASA (Run/Managed By Techno India Group) DEPARTMENT OF MECHANICAL ENGINEERING REFRIGERATION AND AIR CONDITIONING LAB (ME 1610-P) RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING, GECC INSTRUCTION MANUAL VAPOUR COMPRESSION CYCLE SYSTEM TEST RIG 2|Page RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING, GECC EXPERIMENT NO-1 Aim:- To study Vapour Compression refrigeration cycle, determine of coefficient of performance of cycle. TECHNICAL DETAIL: 1. COMPRESSOR: - HERMETICALLY SEALED COMPRESSOR 1/3 TR TO WORK ON 220V AC50HZ OPERATE ON REFRIGERANT R-134 A WITH STANDARD ELECTRICAL ACCESSORIES. 2. CONDENSER: - FINS AND TUBE TYPE NATURAL AIR-COOLED CONDENSER. 4.. CAPILLARY EXPANSION VALVE 4. EVAPORATOR : AIR COOLED BASED EVAPORATOR. CONTROLS AND STANDARD ACCESSORIES 1. ENERGY METER FOR COMPRESSOR . 2. FILTER DRIER. 3. PRESSURE GAUGES SUCTION AND DISCHARGE IMPORTED ESPECIALLY FOR R 134 A REFRIGERANT. 4. DIGITAL TEMPERATURE INDICATOR AT VARIOUS POINTS IN 0C WITH PT. 100 PROBES. 5. SWITCHES FOR OTHER PARTS. 6. GAS CHARGING VALVE. THEORY: VAPOUR COMPRESSION REFRIGERATION CYCLE A VAPOUR COMPRESSION REFRIGERATION SYSTEM IS AN IMPROVED TYPE OF AIR REFRIGERATION SYSTEM IN WHICH A SUITABLE WORKING SUBSTANCE, TERMED AS REFRIGERANT IS USED. IT CONDENSES AND EVAPORATES AT TEMPERATURES AND PRESSURES CLOSE TO THE ATMOSPHERIC CONDITIONS. THE REFRIGERANT USED DOES NOT LEAVE THE SYSTEM BUT IS CIRCULATED THROUGHOUT THE SYSTEM ALTERNATELY CONDENSING AND EVAPORATING. THE VAPOUR COMPRESSION REFRIGERATION SYSTEM IS NOW DAYS USED FOR ALL-PURPOSE REFRIGERATION. IT IS USED FOR 3|Page VIZ. USING OPERATIONAL AMBIENT CONDITIONS. THROTTLING DEVICE 4|Page . KIND OF APPLICATION VIZ AIR-CONDITIONING. THE SUPER-HEATED VAPOUR PRESSURE IS INCREASED TO A LEVEL BY THE COMPRESSOR TO REACH A SATURATION PRESSURE SO THAT HEAT ADDED TO VAPOUR IS DISSIPATED/ REJECTED INTO THE ATMOSPHERE. THE COMPONENTS USED ARE: 1. RECIPROCATING DEVICE 3. THE OPERATION DESIGN PARAMETERS. CONDENSER 4. A REFRIGERANT HAVING SPECIAL PROPERTIES OF VAPORIZING AT TEMPERATURES LOWER THAN THE AMBIENT AND CONDENSING BACK TO THE LIQUID FORM. TYPE OF REFRIGERANT USED. THE VAPOUR COMPRESSION REFRIGERATION CYCLE IS BASED ON A CIRCULATING FLUID MEDIA. WHEN THE REFRIGERANT EVAPORATES OR BOILS AT TEMPERATURES LOWER THAN AMBIENT. THE SYSTEM EQUIPMENTS/ COMPONENTS PROPOSED TO BE USED IN THE SYSTEM.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. IT EXTRACTS OR REMOVES HEAT FROM THE LOAD AND LOWER THE TEMPERATURE CONSEQUENTLY PROVIDING COOLING. WITH COOLING MEDIAS THE LIQUID FROM AND RECYCLED AGAIN TO FORM THE REFRIGERATION CYCLE. THUS. EVAPORATOR 2. AT SLIGHTLY HIGHER THAN AMBIENT CONDITIONS BY CONTROLLING THE SATURATION TEMPERATURE AND PRESSURE. REFRIGERATION. GECC ALL INDUSTRIAL PURPOSE FR0OM A SMALL DOMESTIC REFRIGERATOR TO A BIG AIR CONDITIONING PLANT. DEHUMIDIFICATIONETC. THE VAPOUR COMPRESSION REFRIGERATION CYCLE IS BASED ON THE FOLLOWING FACTOR:  REFRIGERANT FLOW RATE. RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. GECC THE WORKING OF VAPOUR COMPRESSION REFRIGERATION CYCLE AND FUNCTION OF EACH ABOVE COMPONENT IS GIVEN BELOW. THE “TEMPERATURE-PRESSURE RELATION CHART” TABLE CAN DETERMINE THE PRESSURE AND TEMPERATURE IN THE EVAPORATOR. OR SHELL AND TUBE COOLERS (FLOODED OR DIRECT EXPANSION TYPE). TO ENABLE THE SUPER HEATED REFRIGERANT TO CONDENSE AT NORMAL AMBIENT CONDITION. ON ABSORBING THE HEAT TO BE EXTRACTED FROM MEDIA TO BE COOLED. THE REFRIGERANT GAINS LATENT HEAT TO VAPORIZES AT SATURATION TEMPERATURE/ PRESSURE AND FURTHER ABSORBS SENSIBLE HEAT FROM MEDIA TO BE COOLED AND GETS FULLY VAPORIZED AND SUPER HEATED. DIFFERENT TYPES OF COMPRESSORS ARE RECIPROCATING. DURING THIS PROCESS HEAT IS ADDED TO THE REFRIGERANT AND KNOWN AS HEAT OF COMPRESSION RATION TO RAISE THE PRESSURE OF REFRIGERANT TO SUCH A LEVEL THAT THE SATURATION TEMPERATURE OF THE DISCHARGE REFRIGERANT IS HIGHER THAN THE TEMPERATURE OF THE AVAILABLE COOLING MEDIUM. PRESSURE. 5|Page . (A)EVAPORATOR: THE LIQUID REFRIGERANT FROM THE CONDENSER AT HIGH PRESSURE IS FED THROUGH A THROTTLING DEVICE TO AN EVAPORATOR AT A LOW PRESSURE. THESE ARE DIFFERENT TYPE OF EVAPORATORS USED FOR DIFFERENT APPLICATION AND ARE ACCORDINGLY DESIGNED. (B) COMPRESSOR THE COMPRESSOR IS KNOWN AS THE HEART OF THE REFRIGERATION SYSTEM. WITHOUT ANY CHANGE OF GASEOUS STATE AND THE SAME IS DISCHARGE INTO CONDENSER. SUPERHEATED VAPOUR FROM THE EVAPORATOR IS CONVEYED THROUGH SUCTION LINE AND COMPRESSED BY THE COMPRESSOR TO A HIGH PRESSURE. RACEWAY TYPE OF BAUD LET COOLERS. THE LIQUID REFRIGERANT BOILS ACTIVELY IN THE EVAPORATOR AND CHANGES STATE. ROTARY AND CENTRIFUGAL AND ARE USED FOR DIFFERENT APPLICATIONS. THESE ARE IN THE FORM OF COOLING COILS (FINNED OR PRIME SURFACE TYPE) MADE OUT OF COPPER OR STEEL. FOR ICE ACCUMULATION OR ICE BANKS ETC. THE LOW TEMPERATURE. IT PUMPS THE REFRIGERANT VAPOUR IN REFRIGERATION CYCLE AS THE HEART PUMPS BLOOD IN THE BODY. THE LIQUID LINE SHOULD BE PROPERLY SIZED TO HAVE MINIMUM PRESSURE DROP. (D) THROTTLING DEVICE THE HIGH-PRESSURE LIQUID FROM THE CONDENSER IS FED TO EVAPORATOR THROUGH DEVICE. THIS SUPER HEATED REFRIGERANT VAPOUR ENTERS THE CONDENSER TO DISSIPATE ITS HEAT IN THREE STAGES. AIR-COOLED CONDENSERS ARE PRIME SURFACE TYPE. IN EVAPORATIVE COOLED CONDENSER. FIRST ON ENTRY THE REFRIGERANT LOSES ITS SUPER HEAT. THESE ARE WATER-COOLED. GECC (C) CONDENSER THE HEAT ADDED IN THE EVAPORATOR AND COMPRESSOR TO THE REFRIGERANT IS REJECTED IN CONDENSER AT HIGH TEMPERATURE/ HIGH PRESSURE. WHICH SHOULD BE DESIGNED TO PASS MAXIMUM POSSIBLE LIQUID REFRIGERANT TO OBTAIN A GOOD REFRIGERATION EFFECT. BOTH AIR AND WATER ARE USED. 6|Page . SHELL AND COIL. FINNED TYPE OR PLATE TYPE. AIR COOLED OR EVAPORATIVE COOLED CONDENSERS. IN THE WATER-COOLED CONDENSER THERE ARE SEVERAL TYPES VIZ. FURTHER AND THE REFRIGERANT LEAVES THE CONDENSER AS A SUB COOLED LIQUID. SHELL AND TUBE. THIS LIQUID LOSES ITS SENSIBLE HEAT. IT ALSO REDUCES THE PRESSURE FROM THE DISCHARGE PRESSURE TO THE EVAPORATOR PRESSURE WITHOUT ANY CHANGE OF STATE OF THE PRESSURE REFRIGERANT. THE THROTTLING DEVICE IS A PRESSURE-REDUCING DEVICE AND A REGULATOR FOR CONTROLLING THE REFRIGERANT FLOW. TUBE IN TUBE ETC. THE SUB-COOLED LIQUID FROM CONDENSER IS COLLECTED IN A RECEIVER (WHEREVER PROVIDED) AND IS THEN FED THROUGH THE THROTTLING DEVICE BY LIQUID LINE TO THE EVAPORATOR. THE HEAT TRANSFER FROM REFRIGERANT TO COOLING MEDIUM (AIR OF WATER) TAKES PLACE IN THE CONDENSER. THERE ARE SEVERAL METHODS OF DISSIPATING THE REJECTED HEAT INTO THE ATMOSPHERE BY CONDENSER.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. IT THEN LOSES ITS LATENT HEAT AT WHICH THE REFRIGERANT IS LIQUEFIED AT SATURATION TEMPERATURE PRESSURE. TYPE OF REFRIGERANT. THE OPERATING PARAMETERS (SUCH AS SUCTION AND DISCHARGE PRESSURES).RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. SUMMARY THE WORKING PRESSURES. IN FIG. COMMONLY KNOWN AS THE HIGH SIDE AND THE LOW SIDE. THE REFRIGERANT FLOW RATE. CAPABLE OF COMPENSATING ANY VARIATIONS/ FLUCTUATIONS IN LOAD BY ALLOWING ONLY LIQUID REFRIGERANT TO FLOW TO THE EVAPORATOR. 7|Page . TEMPERATURES AND STATES OF THE REFRIGERANT IN DIFFERENT PARTS OF THE REFRIGERATION CYCLE ARE SHOWN. THE “HIGH SIDE” IS REFERRED TO HIGH PRESSURE PREVAILING FROM COMPRESSOR ONWARD RIGHT UP TO THE INLET OF THE THROTTLING DEVICE AND FROM THE THROTTLING DEVICE UP TO THE SUCTION OF THE COMPRESSOR IS CALLED THE “LOW SIDE”. BASED ON THE SYSTEM DESIGN. 10 REFRIGERATION TONS. THE CAPILLARY IS A COPPER TUBE HAVING A SMALL DIAORIFICE AND IS SELECTED. GECC THE TYPES OF THROTTLING DEVICES ARE:  CAPILLARY TUBES THE MOST COMMONLY USED THROTTLING DEVICE IS THE CAPILLARY TUBE FOR APPLICATION UPTO APPROX. THERE ARE MAINLY TWO PRESSURES OPERATING IN THE REFRIGERATION CYCLE. T6 = Temperature Sensor : Inside the Chamber. T5 = Temperature Sensor : Fixed after Capillary tube (Evaporator IN) 6. T4 = Temperature Sensor : Fixed after Condenser 5. T1 = Temperature Sensor : Fixed at Compressor Discharge Line 2.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. 3 T3 = Temperature Sensor : Fixed before Condenser 4. GECC Temperature sensor details :1. 8|Page . T2 = Temperature Sensor : Fixed at Compressor Suction Line. by the refrigeration when passing through the evaporator of the system. GECC Theory :The coefficient of performance of refrigeration plant is given by the ratio of heat absorbed. Wh Where m = mass of water kept in cooling chamber Cp = specific heat of water = 4.18 Kj / kg K ΔT = temperature of cooling water (Initial – Final) Kwh = VxIx0. to the working input to the compressor to compress the refrigeration.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. Co – efficient of Performance = Heat removed by refrigeration / Power input Cop Plant = m Cp ΔT / K.9/1000 x 3600 KJ/sec. 9|Page . COP = Heat removed by refrigerant / Power input = m x CpΔT / K.CpΔT / KwH Where (mr). mass flow rate of the refrigerant = Q x 1208 Kg / sec Cp = Specific heat of refrigerant (Liquid) = 1. GECC Co – efficient of refrigeration cycle is given by the ratio of net refrigeration effect to the power required to run the compressor. COP (cycle) Net refrigerant effect in unit time / Power input in unit time = mr . to the work input. = mass flow rate of the refrigerant Kg / sec. Wh Where. m = mass of water kept in cooling chamber Cp = specific heat of water = 4.26 Kj / kg K ΔT = Temperature different (T1 – T5) The co – efficient of performance of a refrigeration system is given by the ratio of heat absorb.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. Liquid density at 25 °C (77 °F) : 1208 kg/m3 Flow rate Q : _______ LPH = _______/3600 x 1000 m3/sec. 10 | P a g e .18 Kj / Kg K ΔT = temperature of cooling water Kwh = power consumed by the compressor in unit time. RAC LAB MANUAL INSTRUCTION MANUAL REFRIGARATION TEST RIG 11 | P a g e DEPARTMENT OF MECHANICAL ENGINEERING. GECC . 100 PROBES. SWITCHES FOR OTHER PARTS.FINS AND TUBE TYPE AIR-COOLED CONDENSER.. CAPILLARY EXPANSION VALVE 5. PRESSURE GAUGES SUCTION AND DISCHARGE IMPORTED ESPECIALLY FOR R 134 A REFRIGERANT. 4.To study refrigeration cycle. FILTER DRIER. CONTROLS AND STANDARD ACCESSORIES 1. determine of coefficient of performance of cycle & determine of tonnage capacity of refrigeration unit. FAN MOTOR: . 3. HP LP CUT OUT 5. 3. EVAPORATOR : WATER BASED EVAPORATOR. COMPRESSOR: . 6.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. 7. 4. ENERGY METER FOR COMPRESSOR . 2.CONDENSER FAN MOTOR WITH FAN. 2. GAS CHARGING VALVE. DIGITAL TEMPERATURE INDICATOR AT VARIOUS POINTS IN 0C WITH PT. TECHNICAL DETAIL: 1.HERMETICALLY SEALED COMPRESSOR 1/3 TR TO WORK ON 220V AC50HZ OPERATE ON REFRIGERANT R-134 A WITH STANDARD ELECTRICAL ACCESSORIES. GECC EXPERIMENT NO-2 Aim:. 12 | P a g e . CONDENSER: . THUS. TYPE OF REFRIGERANT USED. VIZ. THE VAPOUR COMPRESSION REFRIGERATION SYSTEM IS NOW DAYS USED FOR ALL-PURPOSE REFRIGERATION. IT EXTRACTS OR REMOVES HEAT FROM THE LOAD AND LOWER THE TEMPERATURE CONSEQUENTLY PROVIDING COOLING. THE VAPOUR COMPRESSION REFRIGERATION CYCLE IS BASED ON THE FOLLOWING FACTOR:  REFRIGERANT FLOW RATE. THE REFRIGERANT USED DOES NOT LEAVE THE SYSTEM BUT IS CIRCULATED THROUGHOUT THE SYSTEM ALTERNATELY CONDENSING AND EVAPORATING. THE SYSTEM EQUIPMENTS/ COMPONENTS PROPOSED TO BE USED IN THE SYSTEM. GECC THEORY: VAPOUR COMPRESSION REFRIGERATION CYCLE A VAPOUR COMPRESSION REFRIGERATION SYSTEM IS AN IMPROVED TYPE OF AIR REFRIGERATION SYSTEM IN WHICH A SUITABLE WORKING SUBSTANCE. AT SLIGHTLY HIGHER THAN AMBIENT CONDITIONS BY CONTROLLING THE SATURATION TEMPERATURE AND PRESSURE. WITH 13 | P a g e . THE SUPER-HEATED VAPOUR PRESSURE IS INCREASED TO A LEVEL BY THE COMPRESSOR TO REACH A SATURATION PRESSURE SO THAT HEAT ADDED TO VAPOUR IS DISSIPATED/ REJECTED INTO THE ATMOSPHERE. A REFRIGERANT HAVING SPECIAL PROPERTIES OF VAPORIZING AT TEMPERATURES LOWER THAN THE AMBIENT AND CONDENSING BACK TO THE LIQUID FORM. TERMED AS REFRIGERANT IS USED. KIND OF APPLICATION VIZ AIR-CONDITIONING. THE OPERATION DESIGN PARAMETERS. THE VAPOUR COMPRESSION REFRIGERATION CYCLE IS BASED ON A CIRCULATING FLUID MEDIA. IT IS USED FOR ALL INDUSTRIAL PURPOSE FR0OM A SMALL DOMESTIC REFRIGERATOR TO A BIG AIR CONDITIONING PLANT. DEHUMIDIFICATIONETC. USING OPERATIONAL AMBIENT CONDITIONS. WHEN THE REFRIGERANT EVAPORATES OR BOILS AT TEMPERATURES LOWER THAN AMBIENT. IT CONDENSES AND EVAPORATES AT TEMPERATURES AND PRESSURES CLOSE TO THE ATMOSPHERIC CONDITIONS.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. REFRIGERATION. THE “TEMPERATURE-PRESSURE RELATION CHART” TABLE CAN DETERMINE THE PRESSURE AND TEMPERATURE IN THE EVAPORATOR. THE REFRIGERANT GAINS LATENT HEAT TO VAPORIZES AT SATURATION TEMPERATURE/ PRESSURE AND FURTHER ABSORBS SENSIBLE HEAT FROM MEDIA TO BE COOLED AND GETS FULLY VAPORIZED AND SUPER HEATED. THESE ARE IN THE FORM OF COOLING COILS (FINNED OR PRIME SURFACE TYPE) MADE OUT OF COPPER OR STEEL. FOR ICE ACCUMULATION OR ICE BANKS ETC. 14 | P a g e . RACEWAY TYPE OF BAUD LET COOLERS. GECC COOLING MEDIAS THE LIQUID FROM AND RECYCLED AGAIN TO FORM THE REFRIGERATION CYCLE. EVAPORATOR 2.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. THROTTLING DEVICE THE WORKING OF VAPOUR COMPRESSION REFRIGERATION CYCLE AND FUNCTION OF EACH ABOVE COMPONENT IS GIVEN BELOW. RECIPROCATING DEVICE 3. THE COMPONENTS USED ARE: 1. (A)EVAPORATOR: THE LIQUID REFRIGERANT FROM THE CONDENSER AT HIGH PRESSURE IS FED THROUGH A THROTTLING DEVICE TO AN EVAPORATOR AT A LOW PRESSURE. ON ABSORBING THE HEAT TO BE EXTRACTED FROM MEDIA TO BE COOLED. OR SHELL AND TUBE COOLERS (FLOODED OR DIRECT EXPANSION TYPE). THESE ARE DIFFERENT TYPE OF EVAPORATORS USED FOR DIFFERENT APPLICATION AND ARE ACCORDINGLY DESIGNED. CONDENSER 4. THE LIQUID REFRIGERANT BOILS ACTIVELY IN THE EVAPORATOR AND CHANGES STATE. FURTHER AND THE REFRIGERANT LEAVES THE CONDENSER AS A SUB COOLED LIQUID. TO ENABLE THE SUPER HEATED REFRIGERANT TO CONDENSE AT NORMAL AMBIENT CONDITION. DURING THIS PROCESS HEAT IS ADDED TO THE REFRIGERANT AND KNOWN AS HEAT OF COMPRESSION RATION TO RAISE THE PRESSURE OF REFRIGERANT TO SUCH A LEVEL THAT THE SATURATION TEMPERATURE OF THE DISCHARGE REFRIGERANT IS HIGHER THAN THE TEMPERATURE OF THE AVAILABLE COOLING MEDIUM. THE LOW TEMPERATURE. DIFFERENT TYPES OF COMPRESSORS ARE RECIPROCATING. SUPERHEATED VAPOUR FROM THE EVAPORATOR IS CONVEYED THROUGH SUCTION LINE AND COMPRESSED BY THE COMPRESSOR TO A HIGH PRESSURE. IT PUMPS THE REFRIGERANT VAPOUR IN REFRIGERATION CYCLE AS THE HEART PUMPS BLOOD IN THE BODY. PRESSURE. THE HEAT TRANSFER FROM REFRIGERANT TO COOLING MEDIUM (AIR OF WATER) TAKES PLACE IN THE CONDENSER. ROTARY AND CENTRIFUGAL AND ARE USED FOR DIFFERENT APPLICATIONS. (C) CONDENSER THE HEAT ADDED IN THE EVAPORATOR AND COMPRESSOR TO THE REFRIGERANT IS REJECTED IN CONDENSER AT HIGH TEMPERATURE/ HIGH PRESSURE. THIS LIQUID LOSES ITS SENSIBLE HEAT. 15 | P a g e . WITHOUT ANY CHANGE OF GASEOUS STATE AND THE SAME IS DISCHARGE INTO CONDENSER. FIRST ON ENTRY THE REFRIGERANT LOSES ITS SUPER HEAT. GECC (B) COMPRESSOR THE COMPRESSOR IS KNOWN AS THE HEART OF THE REFRIGERATION SYSTEM. THIS SUPER HEATED REFRIGERANT VAPOUR ENTERS THE CONDENSER TO DISSIPATE ITS HEAT IN THREE STAGES. THE SUB-COOLED LIQUID FROM CONDENSER IS COLLECTED IN A RECEIVER (WHEREVER PROVIDED) AND IS THEN FED THROUGH THE THROTTLING DEVICE BY LIQUID LINE TO THE EVAPORATOR.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. IT THEN LOSES ITS LATENT HEAT AT WHICH THE REFRIGERANT IS LIQUEFIED AT SATURATION TEMPERATURE PRESSURE. GECC THERE ARE SEVERAL METHODS OF DISSIPATING THE REJECTED HEAT INTO THE ATMOSPHERE BY CONDENSER. THESE ARE WATER-COOLED. (D) THROTTLING DEVICE THE HIGH-PRESSURE LIQUID FROM THE CONDENSER IS FED TO EVAPORATOR THROUGH DEVICE. IN EVAPORATIVE COOLED CONDENSER. AIR COOLED OR EVAPORATIVE COOLED CONDENSERS. BOTH AIR AND WATER ARE USED. THE LIQUID LINE SHOULD BE PROPERLY SIZED TO HAVE MINIMUM PRESSURE DROP. WHICH SHOULD BE DESIGNED TO PASS MAXIMUM POSSIBLE LIQUID REFRIGERANT TO OBTAIN A GOOD REFRIGERATION EFFECT. TUBE IN TUBE ETC.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. THE REFRIGERANT FLOW RATE. IT ALSO REDUCES THE PRESSURE FROM THE DISCHARGE PRESSURE TO THE EVAPORATOR PRESSURE WITHOUT ANY CHANGE OF STATE OF THE PRESSURE REFRIGERANT. FINNED TYPE OR PLATE TYPE. AIR-COOLED CONDENSERS ARE PRIME SURFACE TYPE. 10 REFRIGERATION TONS. THE OPERATING PARAMETERS (SUCH AS SUCTION AND DISCHARGE PRESSURES). TYPE OF REFRIGERANT. THE CAPILLARY IS A COPPER TUBE HAVING A SMALL DIAORIFICE AND IS SELECTED. SHELL AND COIL. SHELL AND TUBE. IN THE WATER-COOLED CONDENSER THERE ARE SEVERAL TYPES VIZ. CAPABLE OF COMPENSATING ANY VARIATIONS/ FLUCTUATIONS IN LOAD BY ALLOWING ONLY LIQUID REFRIGERANT TO FLOW TO THE EVAPORATOR. 16 | P a g e . THE THROTTLING DEVICE IS A PRESSURE-REDUCING DEVICE AND A REGULATOR FOR CONTROLLING THE REFRIGERANT FLOW. THE TYPES OF THROTTLING DEVICES ARE:  CAPILLARY TUBES THE MOST COMMONLY USED THROTTLING DEVICE IS THE CAPILLARY TUBE FOR APPLICATION UPTO APPROX. BASED ON THE SYSTEM DESIGN. COMMONLY KNOWN AS THE HIGH SIDE AND THE LOW SIDE. 17 | P a g e . THERE ARE MAINLY TWO PRESSURES OPERATING IN THE REFRIGERATION CYCLE.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. TEMPERATURES AND STATES OF THE REFRIGERANT IN DIFFERENT PARTS OF THE REFRIGERATION CYCLE ARE SHOWN. THE “HIGH SIDE” IS REFERRED TO HIGH PRESSURE PREVAILING FROM COMPRESSOR ONWARD RIGHT UP TO THE INLET OF THE THROTTLING DEVICE AND FROM THE THROTTLING DEVICE UP TO THE SUCTION OF THE COMPRESSOR IS CALLED THE “LOW SIDE”. GECC SUMMARY THE WORKING PRESSURES. IN FIG. RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. GECC Temperature sensor details :1. T2 = Temperature Sensor : Fixed at Compressor Suction Line. T0 = Thermometer : Inside Chamber (Glass Thermometer Type) 2. T4 = Temperature Sensor : Fixed after Condenser 6. T3 = Temperature Sensor : Fixed before Condenser 5. T5 = Temperature Sensor : Fixed after Capillary tube (Evaporator IN) 7. T1 = Temperature Sensor : Fixed at Compressor Discharge Line 3. T6 = Temperature Sensor : Fixed at Evaporator OUT 18 | P a g e . 4. Wh Where m = mass of water kept in cooling chamber Cp = specific heat of water = 4. 19 | P a g e . to the working input to the compressor to compress the refrigeration. Co – efficient of Performance = Heat removed by refrigeration / Power input Cop Plant = m Cp ΔT / K. by the refrigeration when passing through the evaporator of the system.9/1000 x 3600 KJ/sec. GECC Theory :The coefficient of performance of refrigeration plant is given by the ratio of heat absorbed.18 Kj / kg K ΔT = temperature of cooling water (Initial – Final) Kwh = VxIx0.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. Liquid density at 25 °C (77 °F) : 1208 kg/m3 Flow rate Q : _______ LPH = _______/3600 x 1000 m3/sec. GECC Co – efficient of refrigeration cycle is given by the ratio of net refrigeration effect to the power required to run the compressor. = mass flow rate of the refrigerant Kg / sec.26 Kj / kg K ΔT = Temperature different (T1 – T5) The co – efficient of performance of a refrigeration system is given by the ratio of heat absorb. mass flow rate of the refrigerant = Q x 1208 Kg / sec Cp = Specific heat of refrigerant (Liquid) = 1. Wh Where. COP = Heat removed by refrigerant / Power input = m x CpΔT / K.CpΔT / KwH Where (mr).RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING.18 Kj / Kg K ΔT = temperature of cooling water Kwh = power consumed by the compressor in unit time. m = mass of water kept in cooling chamber Cp = specific heat of water = 4. to the work input. COP (cycle) Net refrigerant effect in unit time / Power input in unit time = mr . 20 | P a g e . Measure initial temperature of water. T2. Note down the energy meter reading. 2. 3.e making of 1 ton of ice at 0°C in 24 hours. 6. This capacity of machine is given by standard commercial ton of refrigeration.e. T4 . T6 also note down the suction and discharge pressure by the respective gauges. T5. Note down the power consumed by compressor till the Chamber Temperature at 4°C. GECC Tonnage capacity : The capacity of a refrigeration machine is the refrigeration effect in a given time from a body. 1TR=1TON*LATENT HEAT*24 HOURS =1000kg X 335kj/KG X 24 x 60 x 60 sec = 3. 21 | P a g e . This is called as refrigeration effect i. After starting the compressor note down the temperature T1 at the interval of every 15 minutes and note it down as T1c. Fill the chamber a measured quantity of water by Measuring Jar. T3. 4.5 kj /s Tonnage capacity of the machine = Net refrigeration effect of machine / 3. T1.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. Switch on the compressor and let it run for considerable time. At 4°C of Measuring Bottle note down all the temperature i.5 Procedure : 1.5 = m x CpΔT / 3. 5. 18 ΔT = T1i – T1c 22 | P a g e Temperatur e of chilling water initial final ΔT T0 T1 T2 T3 T4 T5 T6 . Energy Meter Reading Initial Final (a) (b) Mass of water C = (a-b) Calculation : 1- COP (plant) = m x CpΔT / KWH Where m = Mass of water kept in cane (kg) Cp = Specific heat of water = 4.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. GECC Observation Table Sr. No. RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. GECC INSTRUCTION MANUAL DETERMINE OF EFFICIENCY OF REFRIGERATION TESTING MACHINE 23 | P a g e . Capillary tube.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. determine of coefficient of performance of cycle & determine of tonnage capacity of refrigeration unit. GECC EXPERIMENT NO-3 Aim:. Apparatus used :Refrigeration test Rig consist of (Compressor (rotary). to refrigeration system hermetically sealed compressor is fitted on stand with the help of flexible foundation bolts to minimize vibrations. voltmeter. Air cooler condenser. controlling devices and measuring instruments those are fitted on a stand and a control panel. and Chamber Description of the Test Rig :The experimental refrigeration cycle test rig consist of a compressor unit. cooling chamber. 24 | P a g e . evaporator. current meter. Electric power input to the compressor is given through thermostatic switch. vacuum gauge. Thermocouple pressure gauge.To study refrigeration cycle. condenser. Evaporator coil. The apparatus is fabricated in such a way. to the working input to the compressor to compress the refrigeration.I x 3600 KJ KWH = reading of energy meter. T3 = Temperature Sensor : Fixed before Condenser 5.I x KJ = V. 25 | P a g e . T4 = Temperature Sensor : Fixed after Capillary tube (Evaporator IN) 6. T5 = Temperature Sensor : Fixed at Evaporator OUT 7. Wh Where m = mass of water kept in cooling chamber Cp = specific heat of water = 4. T0 = Temperature Sensor : Inside Chamber 2. 4.18 Kj / kg K ΔT = temperature of cooling water Kwh = 1000 x V. T6 = Temperature Sensor :Fixed at Compressor Discharge Line Theory :The coefficient of performance of refrigeration plant is given by the ratio of heat absorbed.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. GECC Temperature sensor details :1. T2 = Temperature Sensor : Fixed at Compressor Suction Line. T1 = Temperature Sensor : Fixed after Condenser 3.I x 60 x 60 KJ = V. Co – efficient of Performance = Heat removed by refrigeration / Power input Cop Plant = m Cp ΔT / K. by the refrigeration when passing through the evaporator of the system. Cp = Specific heat of refrigerant (Liquid) = 1. COP (cycle) Net refrigerant effect in unit time / Power input in unit time = Q. to the work input.CpΔT / KwH Where (Q). The co – efficient of performance of a refrigeration system is given by the ratio of heat absorb.51 Kj / kg K ΔT = Temperature different (T7 – T5) KWH = Kilowatt hours energy meter reading. GECC Co – efficient of refrigeration cycle is given by the ratio of net refrigeration effect to the power required to run the compressor.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING.18 Kj / Kg K ΔT = temperature of cooling water Kwh = power consumed by the compressor in unit time. COP = Heat removed by refrigerant / Power input = m x CpΔT / K. 26 | P a g e . = mass flow rate of the refrigerant m3 / sec. Wh Where. m = mass of water kept in cooling chamber Cp = specific heat of water = 4. T7 also note down the suction and discharge pressure by the respective gauges. Fill a measured quantity of water in ice cane (100 gm) and put it into cooling chamber.e. Note down the energy meter reading. 6. Note down the power consumed by compressor till ice forms i. At 0°C of ice cane note down all the temperature i. 27 | P a g e .e melting of 1 ton of ice at 0°C in 24 hours. This capacity of machine is given by standard commercial ton of refrigeration. T6.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING.e temperature T1 should reach 0°C. 4. This is called as refrigeration effect i. TR = 336 x 1000 / 24 x 60 x 60 = 3. 2. GECC Tonnage capacity : The capacity of a refrigeration machine is the refrigeration effect in a given time from a body.88 = m x CpΔT / 3. T3. After starting the compressor note down the temperature T1 at the interval of every 15 minutes and note it down as T1c.88 Kj / sec. T5 . 5. Note down the flow rate of refrigerant by rotometer. Tonnage capacity of the machine = Net refrigeration effect of machine / 3. Measure initial temperature of water before putting into cooling chamber. T4. 3. T2. Switch on the compressor and let it run for considerable time.88 Procedure : 1. Tonnage capacity of cycle = Net refrigerating effect produced by refrigerant / 14000 Kj /h = m x CpΔT / 14000 tones Where. Tonnage capacity of the plant = Net refrigerant effect of plant / 14000 KJ / hour = m x CpΔT / 14000 Where. m = mass of water kept in cooling chamber Cp = specific heat of water = 4. Tc = final temperature of water. m 28 | P a g e = mass flow rate of refrigerant Cp = Specific heat of refrigerant ΔT = Temperature of refrigerant at discharge and suction = T7.18 Kj / Kg K ΔT = Ti = initial temp .RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. GECC Hence Refrigeration effect TR = 336 x 1000 / 24 x 14000 KJ / hour Where latent heat of fusion of ice = 336 KJ / kg.Tc = final temperature water (Ti – Tc) T1 = initial temperature of water. T5 . No.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. 29 | P a g e T1 T2 T3 T4 T5 T6 T7 . Energy meter reading Initial Final (a) (b) Mass of water Temperature of chilling water initial final ΔT C= (a-b) Calculation : 1- COP (plant) = m x CpΔT / KWH Where m = Mass of water kept in cane (kg) Cp = Specific heat of water = 4. GECC Observation Table Sr.18 ΔT = T1i – T1c KWH = Total energy meter reading (Final value – initial value of energy meter. RAC LAB MANUAL INSTRUCTION MANUAL AIR CONDITIONER TEST RIG 30 | P a g e DEPARTMENT OF MECHANICAL ENGINEERING. GECC . because complete unit including compressor. condenser. humidity etc. 2. Theory: Air conditioning equipment is used to maintain controlled atmospheric conditions as per required. Control panel assembly – it includes the switched those required to control the entire AC system as per the requirement. are kept in a common enclosure. a fan and a motor and suitable bracket for it. Air conditioning systems are classified in two groups. 31 | P a g e . evaporator. This AC is mounted with the room which is required for controlled atmosphere. fan motor etc. Central Unit A packed unit is self-contained unit.R. Motor with blower & fan assembly includes. expansion device. The controlled atmospheric conditions may be required for human comfort or manufacturing processes of engineering goods.75 T.Compressor. a double ended shaft motor. System assembly includes compressor. IC temperature. Packed Units 2. and filter. Capillary Tube. 1. 4.RAC LAB MANUAL DEPARTMENT OF MECHANICAL ENGINEERING. Cabinet and air distributing assembly – it includes a cabinet as enclosure for whole system. 3.To Determine COP and Tonnage capacity of a Air Conditioning system. Capacity of packed or window AC is 0. evaporator. Apparatus: . A window AC mainly consists of following sub-assemblies: 1. Evaporator. an air distributing system. GECC EXPERIMENT NO-4 Aim: . Condenser. Energy Meter. condenser. T7 – T6 T7 = Surrounding temperature T6 = Air duct temperature Mass of circulated air can be calculated by m = Va / Vsa 3|Page . Window type air conditioner The performance of an air-conditioning system is expressed in terms of co-efficient of performance.75 T sealed compressor unit. a finned condenser (heating coil) and evaporator (cooling coil).e. to determine the performance and to study its working principle. a pressure gauge to measure pressure of discharge side compound vacuum gauge to measure suction side pressure. And COP is the ratio of net refrigerating effect and power supplied to do the work i. The desired temperature find out by changing position of selector switch with it. = Specific heat of air = Difference in temperatures. The AC test Rig consist a 0. COP = Rn / W Where Rn = heat removed by system = m. Cp T Where m Cp T = mass of air supplied / minute. Control panel consist of 1 p hase energy meter to measure power consumed by compressor.The AC Test Rig is designed and fabricated. The velocity of the air passing through the coil is measured by using Digital Anemometer. a digital temperature indicator to measure temperature at various places. a motor to run fan and another blower and fitted on a Frame stand. T3 = Temperature Sensor : Fixed after Condenser 4. Procedure: Switch on the power supply to system i. which is sucked by blower cools. W = Power input time and measured by energy meter reading. Now compressed refrigerant passing through the condenser and after condensing. T6 = Temperature Sensor : Fixed at Evaporator Air Duct. After few minute the air at the outlet of air duct will become cool at that time. start the compressor simultaneously start fan blower motor also. It goes to evaporator. T1 = Temperature Sensor : Fixed at Compressor Discharge Line 2. T4 = Temperature Sensor : Fixed at Compressor Suction Line 5. T2 = Temperature Sensor : Fixed before Condenser 3. Temperature sensor details: 1.Where Va = Quantity of air supplied m3 / min. Vsa = Area of duct x velocity of the air. where due to cooling effect air. T5 = Temperature Sensor : Fixed at after Capillary.e. 4|Page . 6. Observation Table: SL NO. OF REVOLUTION POWER CONSUMED Precautions: 1. The control valve of pressure and compound gauge should open partly. 3. Run the system for quite some time before taking readings. Insure considerable cooled air output from air duct. The system should not switch OFF immediately after once switched ON. T7 T6 PRESSURE VACUUM W= TOTAL NO. 2. 6. Do not twist any pipe line and handle all switches valves very carefully only as and when required. 4. Note down number of revolutions of energy meter carefully with the help of stop watch. 5. 5|Page . when it is required to measure pressure otherwise valves must be closed. Btu/lboF) to = outlet temperature (oC. Btu/lb) hi = inlet enthalpy (kJ/kg.sensible heat and latent heat (kW.hi) (2) where cp = specific heat air (kJ/kgoC. HEATING COILS Sensible heating : Air flows over a heating coil • Surface temperature ts higher than tdb of air The Sensible Heat Ratio .express the ratio between the sensible heat load and the total heat load and can be expressed as: SHR = qs / qt (1) where SHR = sensible heat ratio (ratio of sensible heat load to total heat load) qs = sensible heat (kW.SHR .ti) / (ho . Heating can be achieved by passing the air over heating coil like electric resistance heating coils or steam coils. Btu/lb) 6|Page . oF) ti = inlet temperature (oC.HEAT FACTOR : SENSIBLE HEAT PROCESS – HEATING OR COOLING Heating or cooling of air without addition or subtraction of moisture is termed as SENSIBLE HEATING OR COOLING . Btu/hr) (1) can be modified to: SHR = cp (to . Btu/hr) qt = total heat . Sensible cooling can be achieved by passing the air over cooling coli like evaporating coil of the refrigerant cycle or secondary brine coil. oF) ho = outlet enthalpy (kJ/kg. 7|Page .
Copyright © 2024 DOKUMEN.SITE Inc.