Chapter 14A: VC AND AC REFRIGERATION CYCLES AND SYSTEMS

Slides:



Advertisements
Similar presentations
Basic Refrigeration, Its Components, and Its Cycle
Advertisements

Chapter 11 Refrigeration Cycles Study Guide in PowerPoint to accompany Thermodynamics: An Engineering Approach, 5th edition by Yunus A. Çengel.
Refrigeration Cycles د/ محمود عبدالوهاب.
Refrigeration Cycles CHAPTER 11: PTT 201/4 THERMODYNAMICS
Refrigeration Cycles Chapter 11.
Refrigeration and Cryogenics Maciej Chorowski Faculty of Mechanical and Power Engineering.
Vapor and Combined Power Cycles
Chapter 1 VAPOR AND COMBINED POWER CYCLES
Department of Mechanical Engineering ME 322 – Mechanical Engineering Thermodynamics Lecture 29 The Vapor Compression Refrigeration (VCR) Cycle.
Power Generation Cycles Vapor Power Generation The Rankine Cycle
Advanced Thermodynamics Note 8 Refrigeration and Liquefaction
Objective Learn about Cooling and Cooling systems Define heat pump Learn about energy storage systems.
Pacific School Of Engineering. Guided By:- Asst.Prof.Vatsal patel Submitted by:-  Kotadiya Reshma :  Ladva Piyush : 
Refrigeration Cycles Chapter 11: ERT 206/4 THERMODYNAMICS
Chapter10 Refrigeration Cycle 10-1 Vapor-Compression Cycle The Reversed Carnot Cycle T s THTH TLTL Coefficient of Performance.
Lesson 8 SECOND LAW OF THERMODYNAMICS
Chapter 15 Refrigeration Refrigeration systems: To cool a refrigerated space or to maintain the temperature of a space below that of the surroundings.
Refrigeration Basics 101.
Vapour Compression Refrigeration Systems
Heat Diagram of H2O.
Refrigeration Cycles (YAC: 7-13 trough 7-16)
Chapter 10 Vapor and Combined Power Cycles Study Guide in PowerPoint to accompany Thermodynamics: An Engineering Approach, 7th edition by Yunus.
Chapter 11 Refrigeration Cycles Study Guide in PowerPoint to accompany Thermodynamics: An Engineering Approach, 8th edition by Yunus A. Çengel.
Vapor compression cycle performance. 1- Effect of evaporation pressure “ or temperature” for the following figs: R-22, 4.5% clearance, 50 L/s displacement.
Objectives Cooling Cycles –Examples Cooling system components Refrigerants.
Refrigeration and Cryogenics Maciej Chorowski Faculty of Mechanical and Power Engineering.
Objectives Empathize with refrigerant Describe refrigeration cycles Analyze cycles on T-s diagrams Compare real cycles to ideal cycles Basis for discussion.
HW2 AHU problems: Book: 8.5, 8.25, 8.27, 8.28, 8.22 Cooling Cycles Problems: - Book: 3.1 (page 69), - Book: 3.5 ((page 70), - Out of book: Same like 3.5.
Chapter 9. Refrigeration and Liquefaction (냉동과 액화)
Vapour Compression Cycle You will Learn: 1 Vapour Compression Cycle Actual Vapour Compression Cycle Components in a Vapour Compression Plant Multistage.
VAPOUR ABSORPTION REFRIGERATION SYSTEM
Prepared by:- B.S.Bhandari Faculty HNBGU.  Refrigeration is a science of producing and maintaining temperature below that of the surrounding temperature.
Chapter 12B: PROPERTY TABLES, REFRIGERATION CYCLES AND HX 1) Boiling of pure substances: water and steam tables 2) Refrigerant tables 3) Binary mixtures.
HCB 3- Chap 17A: Compressors and Exp Devices 1 Chapter 17A: COMPRESSORS AND EXPANSION DEVICES Agami Reddy (July 2016) Compressor types Reciprocating compressors:
Chapter 11 Refrigeration Cycles Study Guide in PowerPoint to accompany Thermodynamics: An Engineering Approach, 7th edition by Yunus A. Çengel.
SNS COLLEGE OF ENGINEERING Coimbatore-107 Subject: Thermal Engineering
Vapor ,Gas and Combined Power Cycles
Refrigeration & air conditioning
Refrigeration and Heat Pump Systems
Chapter 11 REFRIGERATION CYCLES
SNS COLLEGE OF ENGINEERING Coimbatore-107 Subject: Thermal Engineering
SNS COLLEGE OF ENGINEERING Coimbatore-107 Subject: Thermal Engineering
Thermodynamics Processes.
HVAC EQUIPMENT: COOLING SOURCES (see Chapter 16)
prepared by Laxmi institute tech. Mechanical eng. Department.
Lecture Objectives: Continue with Sorption Cooling
Power and Refrigeration Systems
Mohamed Iqbal Pallipurath
SNS COLLEGE OF ENGINEERING Coimbatore-107 Subject: Thermal Engineering
Chapter 11 Refrigeration Cycles Study Guide in PowerPoint to accompany Thermodynamics: An Engineering Approach, 5th edition by Yunus A. Çengel.
Chapter 5 The First Law of Thermodynamics for Opened Systems
ICE 101 REFRIGERATION BASICS
Chapter 7 Entropy: A Measure of Disorder
9 CHAPTER Vapor and Combined Power Cycles.
Chapter 17A: COMPRESSORS AND EXPANSION DEVICES
Objectives Cooling Cycles Cooling system components Refrigerants
Lecture Objectives: Learn more about cooling cycles.
Working with Phases and Properties of Substances
Scotsman Refrigeration 101
Lecture Objectives: Analyze cooling cycles.
Mass and Energy Analysis of Control Volumes (Open Systems)
Objectives Cooling Systems
Chapter 11 Refrigeration Cycles Study Guide in PowerPoint to accompany Thermodynamics: An Engineering Approach, 5th edition by Yunus A. Çengel.
Refrigeration and Air Conditioning
Refrigeration and Air Conditioning
Chapter Three: Part One
Objectives Solve one more example related to the psychometrics in AHU and building systems Learn about the psychometrics related to the cooling towers.
Chapter Three: Part One
10 CHAPTER Refrigeration Cycles.
Chapter 17A: COMPRESSORS AND EXPANSION DEVICES
Presentation transcript:

Chapter 14A: VC AND AC REFRIGERATION CYCLES AND SYSTEMS Agami Reddy (July 2016) Standard vapor compression (VC) refrigeration cycle Use of refrigerant property tables and p-h diagrams Analysis of different processes Actual VC refrigeration cycle Chiller systems and effect of HX Chiller maps and manufacturer tables Absorption systems description Components Types of systems Thermodynamic analysis HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Introduction Basic types of refrigeration systems: - vapor compression refrigeration and heat pumps - gas refrigeration - absorption - adsorption - thermoelectric Applications: - building air conditioning - automotive - industrial - food processing, food distribution….. HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Recall: Carnot Refrigeration Cycle Here work is put in (in the form of electricity) so as to achieve heat extraction or cooling HCB 3- Chap 14A: Refrigeration Cycles and Systems

Practical Modifications to Carnot Cycle Figure 14.2 Schematic diagram of the standard VC refrigeration cycle arrangement of mechanical components, plot on T-s coordinates showing wet compression, plot on p-h coordinates showing wet compression. HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Quantities of Interest Table 14.1 HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Expander Turbine Throttling process of Rankine cycle produces no useful work If throttling is replaced by energy recovery, external work input requirement is less and COP will increase HCB 3- Chap 14A: Refrigeration Cycles and Systems

Modified VC Cycle: Subcooling Practical advantages: -Ensures that compressor is dry (but may result in greater power reqd.) -Results in smoother flow of refrigerant at expansion valve (bubbles are reduced Figure 14.3 Modified VC cycle with a heat exchanger meant to superheat vapor leaving the compressor and subcool condenser liquid (a) System diagram, (b) P-h diagram HCB 3- Chap 14A: Refrigeration Cycles and Systems

Isentropic efficiency of compressor Second difference: Isentropic efficiency of compressor Figure 14.4 p-h diagram showing the various state points for the three cycles: the standard VC cycle (1-2-3-4), the modified VC cycle (1’-2’-3’-4’), and the effect of isentropic compression (1’-2”-3’-4’) HCB 3- Chap 14A: Refrigeration Cycles and Systems

Third difference between actual refrigeration cycle and standard VC cycle: Depends on specific system piping and layout Fig. 14.5 Pressure losses due to friction Compressor discharge valves, Compressor suction valves Discharge lines, Liquid lines, Suction Lines Condenser, Evaporator HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Modified VC cycle 2 2’ 2” HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Effect of Change in Evaporator Temperature Fig. 14.13 As the evaporator temperature increases with fixed condenser temp. : Compression work 1-2 is markedly less than that of 1a-2a, So refrigerant flow rate will increase Cooling effect is reduced a little due to the shape of the saturation dome (from 4-1 to 4a-1a), However, the effect of the increased refrigerant flow rate is to increase the cooling capacity. HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Effect of Change in Condenser Temperature Fig. 14.14 As the condensing temperature increases: - Refrigerant flow decreases because the compressor has to pump the refrigerant through a higher pressure ratio. Cooling effect also reduces (from 4-1 to 4a-1) Cooling capacity decreases Even with reduced refrigerant flow rate, the power input increases due to the higher pressure ratio. COP decreases as the pressure ratio decreases. HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Chiller Systems Actual heat exchangers need a certain temperature difference in order for them to operate. Refrigerant temperature in the condenser > Tsink (=Tl) while the boiling refrigerant temperature in the evaporator < Tsource (=Th). The wider refrigerant temperature levels will reduce the cycle COP Fig. 14.8 Schematic diagram showing essential components of basic liquid chiller and relation to vapor compression cycle. HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Figure 14.9 The standard VC refrigeration cycle drawn on a p-h diagram along with the sink and source temperatures HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Figure 14.11 Vapor compression cycle equipment with typical R-22 operating temperatures and pressures. A direct expansion (DX) evaporator is used. The state points are based on a compressor efficiency of 85 percent and an evaporator outlet superheat of 9° F (5° C). HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Larger chillers have orifice plates or guide vane refrigerant control and flooded type of condensers and evaporators and water loops Figure 14.10 Sketch of a water cooled refrigeration system with flooded evaporator and condenser showing the two coolant water loops (14.24) (14.25) HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Example 14.4 HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Chiller Performance Maps Figure 14.12 Example of “performance map” for reciprocating chiller; based on R-22, 10 F subcooling, 20o F superheat, and 1725 r/min compressor speed. For an evaporating temperature of 45 oF (7.2 oC) and a condensing temperature of 118 oF (47.8 oC): Power= 13.5 kW and Capacity = 160,000 Btu/hr (46.9 kW) So COP = about 3.5 or 1.0 kW/ton (typical value for a small unit). HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Caution: In many cases, the data is not experimental data but generated by a regression model fit to experimental data HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Example 14.11: Regression Model to Table 14.5 Data HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Absorption Cooling Invented by Ferdinand Carre who took out a U.S. patent in 1860 Used for refrigeration by the South during the Civil War Aqua-Ammonia systems used extensively for early refrigeration systems Lithium-Bromide/Water systems were predominantly used for large chillers during 40’s and 50’s in the U.S. Absorption still accounts for 75% of tonnage in Japanese Industrial / Commercial Applications Renewed interest as a result of increase in combined heat and power systems HCB 3- Chap 14A: Refrigeration Cycles and Systems

Main Types of Absorption Systems Aqua-ammonia ( ammonia is the refrigerant) - caustic, toxic - explosive with Cu and its alloys - needs rectification 2) Lithium Bromide/Water (water is the refrigerant) - water freezes at 32o F (limits cooling to 3-4o C) - must operate below atmospheric atmosphere - LiBr is a solid at room temperature and pressure HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Components HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Example 14.3 :Lithium bromide cooling cycle   Condensing temperature 104°F Evaporator temperature 50°F. Heat is added to the generator at 212°F and removed from the absorber at 86°F . Pump flow rate is 4800 lbm/h, Determine: COP and the heat rates at generator, absorber, condenser, and evaporator? Assume: State points 4 & 5 are saturated HCB 3- Chap 14A: Refrigeration Cycles and Systems

Specific volume, ft3/lbm Internal energy, Btu/lbm Saturated Steam Tables Pressure, psia Saturation temp.,  °F Specific volume, ft3/lbm Internal energy,  Btu/lbm Enthalpy,  Btu/lbm Sat. liquid Sat. vapor Evap. p Tsat vf vg uf ufg ug hf hfg hg 0.08866 32.018 0.016022 3302 0.00 1021.2 0.01 1075.4 0.09992 35 0.016021 2948 2.99 1019.2 1022.2 3.00 1073.7 1076.7 0.12166 40 0.016020 2445 8.02 1015.8 1023.9 1070.9 1078.9 0.14748 45 2037 13.04 1012.5 1025.5 1068.1 1081.1 0.17803 50 0.016024 1704.2 18.06 1009.1 1027.2 1065.2 1083.3 0.2563 60 0.016035 1206.9 28.08 1002.4 1030.4 1059.6 1087.7 0.3632 70 0.016051 867.7 38.09 995.6 1033.7 1054.0 1092.0 0.5073 80 0.016073 632.8 48.08 988.9 1037.0 48.09 1048.3 1096.4 0.6988 90 0.016099 467.7 58.07 982.2 1040.2 1042.7 1100.7 0.9503 100 0.016130 350.0 68.04 975.4 1043.5 68.05 1105.0 1 101.70 0.016136 333.6 69.74 974.3 1044.0 1036.0 1105.8 2 126.04 0.016230 173.75 94.02 957.8 1051.8 1022.1 1116.1 HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Superheated Steam Pressure Temperature v u h s psia °F ft3/lbm Btu/lbm Btu/lbm·°R 1.0 (101.70°F) Sat. 333.6 1044.0 1105.8 1.9779 200 392.5 1077.5 1150.1 2.0508 240 416.4 1091.2 1168.3 2.0775 280 440.3 1105.0 1186.5 2.1028 320 464.2 1118.9 1204.8 2.1269 360 488.1 1132.9 1223.2 2.1500 400 511.9 1147.0 1241.8 2.1720 440 535.8 1161.2 1260.4 2.1932 500 571.5 1182.8 1288.5 2.2235 600 631.1 1219.3 1336.1 2.2706 700 690.7 1256.7 1384.5 2.3142 800 750.3 1294.9 1433.7 2.3550 1000 869.5 1373.9 1534.8 2.4294 1200 988.6 1456.7 1639.6 2.4967 1400 1107.7 1543.1 1748.1 2.5584 HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems

HCB 3- Chap 14A: Refrigeration Cycles and Systems Outcomes Understanding the practical limitations of the Carnot Refrigeration Cycle Knowledge of the Carnot cycle modifications considered in standard VC refrigeration cycles Knowledge of the important quantities of interest while analyzing standard VC cycles and be able to solve problems Knowledge of how actual VC cycles differ from standard VC cycles Be able to analyze practical VC cycles Knowledge of how changes in evaporator and condenser refrigerant temperatures affect practical VC cycle performance Understanding actual chiller systems and how they differ from practical VC cycles Knowledge of chiller performance maps and performance tables Understanding of the operation and various components of an absorption chiller Be able to solve simple problems involving absorption cycles HCB 3- Chap 14A: Refrigeration Cycles and Systems