Refrigeration Manual - HVACRinfo
Refrigeration ManualPart 4 - System Design
This is the fourth of a series of publications comprising the Emerson Climate Technologies,Inc. Refrigeration Manual. Although each separate part covers a specific area of refrigeration theory and practice, each successive publication presumes a basic understanding ofthe material presented in the previous sections.Part 1Part 2Part 3Part 4Fundamentals of RefrigerationRefrigeration System ComponentsThe Refrigeration LoadSystem DesignThe application and design recommendations are intended only as a general guide. Theexact requirements of a given installation can only be determined after the specific designcriteria and desired operating conditions are known. 1969 Emerson Climate Technologies, Inc.All rights reserved.
Part 4SYSTEM DESIGN Section 17. BASIC APPLICATIONRECOMMENDATIONSSection 19. LOW TEMPERATURE SYSTEMSSingle Stage Low Temperature Systems. 19-1Two Stage Low Temperature Systems. 19-2Volumetric Efficiency. 19-2Two Stage Compression andCompressor Efficiency. 19-2Compressor Overheating at ExcessiveCompression Ratios. 19-5Basic Two Stage System. 19-6Two Stage System Components. 19-6Piping on Two Stage Systems. 19-9Cascade Refrigeration Systems. 19-13Fundamental Design Principles. 17-1Compressor Selection. 17-1System Balance. 17-1Refrigerant. 17-2Compressor Cooling. 17-2Compressor Lubrication. 17-3Oil Pressure Safety Control. 17-3Oil Separators. 17 4Suction Line Accumulators. 17-4Pumpdown System Control. 17-5Crankcase Heaters. 17-5Crankcase Pressure Regulating Valves. 17-6Low Ambient Head Pressure Control. 17-6Liquid Line Filter-Drier. 17 6Sight Glass and Moisture Indicator. 17-7Liquid Line Solenoid Valve. 17-7Heat Exchanger. 17-7Thermostatic Expansion Valves. 17-7Evaporators. 17-8Suction Line Filters. 17-9High and Low Pressure Controls. 17-9Interconnected Systems. 17-10Electrical Group Fusing. 17-10Section 20. TRANSPORT REFRIGERATIONCompressor Cooling. 20-1Compressor Speed. 20-1Compressor Operating Position. 20-2Compressor Drive. 20-2Refrigerant Charge. 20-2Refrigerant Migration. 20-2Oil Charge. 20-3Oil Pressure Safety Control. 20-3Oil Separators. 20-3Crankcase Pressure Regulating Valve. 20-3Condenser. 20-4Receiver. 20-4Purging Air in a System. 20-4Liquid Line Filter-Drier. 20-4Heat Exchanger. 20-5Liquid Line Solenoid Valve. 20-5Suction Line Accumulator. 20-5Crankcase Heaters. 20-5Pumpdown Cycle. 20-5Forced Air Evaporator Coils. 20-5Thermostatic Expansion Valves. 20-6Defrost Systems. 20-6Thermostat. 20-7High-Low Pressure Control. 20-7Eutectic Plate Applications. 20-7Refrigerant Piping. 20-10Vibration. 20-10Electrical Precautions. 20-10Installation. 20-11Field Troubleshooting on Transport Units. 20-12Section 18. REFRIGERATION PIPINGBasic Principles of RefrigerationPiping Design. 18-1Copper Tubing for Refrigerant Piping. 18-2Fittings for Copper Tubing. 18-2Equivalent Length of Pipe. 18-2Pressure Drop Tables. 18-5Sizing Hot Gas Discharge Lines. 18-5Sizing Liquid Lines. 18-14Sizing Suction Lines. 18-15Double Risers. 18-21Suction Piping for Multiplex Systems. 18-22Piping Design for Horizontal andVertical Lines. 18-23Suction Line Piping Design at theEvaporator. 18-24Receiver Location. 18-25Vibration and Noise. 18-25Recommended Line Sizing Tables. 18-261 1969 Emerson Climate Technologies, Inc.All rights reserved.
Section 21. CAPACITY CONTROLInternal Capacity Control Valves.21-1External Capacity Control Valves.21-1Hot Gas Bypass.21-1Bypass into Evaporator Inlet.21-3Bypass into Suction Line.21-3Solenoid Valves for Positive Shut-offand Pumpdown Cycle.21-5Desuperheating Expansion Valve.21-5Typical Multiple-EvaporatorControl System.21-5Power Consumption withHot Gas Bypass.21-6Section 22. LIQUID REFRIGERANT CONTROLIN REFRIGERATION AND AIR CONDITIONINGSYSTEMSRefrigerant-Oil Relationship.22-1Refrigerant Migration.22-1 1969 Emerson Climate Technologies, Inc.All rights reserved.Liquid Refrigerant Flooding.22-2Liquid Refrigerant Slugging.22-2Tripping of Oil Pressure Safety Control.22-2Recommended Corrective Action.22-2Section 23. ELECTRICAL CONTROL CIRCUITSTypical Lockout Control Circuit.23-1Control Circuit for CompressorProtection Against LiquidRefrigerant Flooding.23-3Control Circuits to Prevent Short Cycling.22-3Control Circuits for Compressors withCapacity Control Valves.23- 5
INDEX OF TABLESTable 20AVentilation Air Requirements for Machine Rooms CFM/1000 BTU/HR at10 F. Air Temperature Rise. 17-3Table 21Recommended Minimum Low Pressure Control Setting. 17-9Table 22Dimensions and Properties of Copper Tube. 18-3Table 23Weight of Refrigerant in Copper Lines. 18-4Table 24Equivalent Length in Feet of Straight Pipe For Valves and Fittings. 18-5Table 25Pressure Drop Equivalent for 2 F. Change in Saturation Temperature atVarious Evaporating Temperatures. 18-15Table 26Maximum Recommended Spacing Between Pipe Supports for Copper Tubing. 18-26Table 27Recommended Liquid Line Sizes. 18-27Table 28Recommended Discharge Lines Sizes. 18-28Table 29Recommended Suction Line Sizes, R-12, 40 F. 18-29Table 30Recommended Suction Line Sizes, R-12, 25 F. 18-30Table 31Recommended Suction Line Sizes, R-12, 15 F. 18-31Table 32Recommended Suction Line Sizes, R-12, –20 F. 18-31Table 33Recommended Suction Line Sizes, R-12, –40 F. 18-32Table 34Recommended Suction Line Sizes, R-22, 40 F. 18-32Table 35Recommended Suction Line Sizes, R-22, 25 F. 18-33Table 36Recommended Suction Line Sizes, R-22, 15 F. 18-34Table 37Recommended Suction Line Sizes, R-22, –20 F. 18-35Table 38Recommended Suction Line Sizes, R-502, 25 F. 18-35Table 39Recommended Suction Line Sizes, R-502, 15 F. 18-36Table 40Recommended Suction Line Sizes, R-502, –20 F. 18-37Table 41Recommended Suction Line Sizes, R-502, –40 F. 18-38Table 42Efficiency Comparison of Single Stage vs. Two Stage Compression TypicalAir Cooled Application with Refrigerant R-502. 19-6Table 43Recommended Discharge Line Sizes for Two Stage Compressors. 19-10Table 44Recommended Liquid Line Sizes for Two Stage Compressors. 19-10Table 45Recommended Suction Line Sizes for Two Stage Compressors, –60 F. 19-11Table 46Recommended Suction Line Sizes for Two Stage Compressors, –60 F. 19-11Table 47Recommended Suction Line Sizes for Two Stage Compressors, –80 F. 19-12Table 48Recommended Suction Line Sizes for Two Stage Compressors, –80 F. 19-12 1969 Emerson Climate Technologies, Inc.All rights reserved.
Section 17BASIC APPLICATION RECOMMENDATIONSFUNDAMENTAL DESIGN PRINCIPLESOperation at evaporating temperatures above the approved operating range may overload the compressormotor. Operation at evaporating temperatures below theapproved operating range is normally not a problem ifthe compressor motor can be adequately cooled, anddischarge temperatures can be kept within allowable limits. Evaporating temperatures below -40 F. are normallybeyond the practical lower limit of single stage operationbecause of compressor inefficiencies and excessivedischarge gas temperatures. Because of problems ofmotor cooling or overloading, some motor-compressorsmay have approval for operation at limited condensingor evaporating temperatures within a given range, andif so, these limitations will be shown by limited performance curves on the specification sheet.There are certain fundamental refrigeration designprinciples which are vital to the proper functioning ofany system.1. The system must be clean, dry, and free from allcontaminants.2. The compressor must be operated within safetemperature, pressure, and electrical limits.3. The system must be designed and operated so thatproper lubrication is maintained in the compressorat all times.4. The system must be designed and operated so thatexcessive liquid refrigerant does not enter the compressor. Refrigeration compressors are designedto pump refrigerant vapor, and will tolerate only alimited quantity of liquid refrigerant.A given compressor may be approved in two differentoperating ranges with different refrigerants, for example,high temperature R-12 and low temperature R-502. Sincethe power requirements for a given displacement withboth R-22 and R-502 are somewhat similar, in somecases a compressor may be approved in the sameoperating range for either of these refrigerants.5. Proper refrigerant feed to the evaporator must bemaintained, and excessive pressure drop in therefrigerant piping must be avoided.Two stage compressors may be approved for evaporating temperatures as low as -80 F., but individualcompressor specifications should be consulted for theapproved operating range.If these give steps are accomplished, then operation ofthe system is reasonably certain to be trouble free. Ifany one is neglected, then eventual operating problemsare almost certain to occur. These basic fundamentalsare closely inter-related, and must always be kept inmind with regard to the application of any component,or whenever any change in system operation is contemplated.Operation at temperatures below -80 F. is normallybeyond the practical efficiency range of Copeland brand two stage compressors, and for lower evaporatingtemperatures, cascade systems should be employed.COMP
Inc. Refrigeration Manual. Although each separate part covers a specific area of refrigera-tion theory and practice, each successive publication presumes a basic understanding of the material presented in the previous sections. Part 1 Fundamentals of Refrigeration Part 2 Refrigeration System Components Part 3 The Refrigeration Load Part 4 .
Category A: Refrigeration Fundamentals Task 1. Refrigeration principles Analyze system conditions, using a Pressure/Temperature (P/T) chart Identify refrigeration system components Explain the operation of a "simple" refrigeration system Calibrate a Thermometer Read temperatures in a refrigeration system Define refrigeration cycle terminology
Refrigeration Basics. 7 What is Refrigeration? In vapor-compression refrigeration, a refrigerant is used to move . Commonly used in low and multi-temperature refrigeration systems Can be designed with or without recirculation pumps Ammonia refrigerant. 19 B A C F H IGH P RESSURE V APOR H IGH P RESSURE L IQUID M ED P
– Chiller specifications Refrigeration Cycles Refrigeration process Change thermodynamic state of refrigerant with energy & work transfer 1 ton of refrigeration (TR) 12,000 Btu/hr (3.516 kW) Refrigeration Cycle – Vapor compression Mechanical refrigeration using compressors,
Refrigeration system controls Refrigeration system controls Refrigeration system controllers vary enormously in function and complexity. The simplest control is a thermostat which simply controls the temperature of the cooled space. More complex refrigeration systems, such as those with multiple compressors, ideally require more sophisticated .
tion theory and practice, each successive publication presumes a basic understanding of the material presented in the previous sections. Part 1 Fundamentals of Refrigeration Part 2 Refrigeration System Components Part 3 The Refrigeration Load Part 4 System Design The application and design recommendations are intended only as a general guide. The
Jan 28, 2013 · · Flush the refrigeration system with “dry” nitrogen (-75 F dewpoint) as follows: 1. Connect nitrogen source to both process lines of the refrigeration system to purge the system before brazing system connections. 2. Purge the refrigeration system with dry nitrogen for at least 10-m
2.2.3 Carnot Refrigeration Cycle 2.2.4 Temperature Limitations 2.2.5 Difference between Refrigeration and Heat Pump Cycles 2.3 Vapour Absorption System . The low pressure and temperature vapour refrigerant from evaporator is drawn into the compressor through the inlet or suction valve A, where it is compressed to a .
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