ABSTRACT
This project illustrates the use of an exergetic approach to analyze the performance of a vapor compression refrigeration system using a refrigerant solution of a nanoparticle (TiO2), mineral oil, and R410a (base refrigerant). Exergy investigation is a thermodynamics strategy which allows for the assessment and improvement of a refrigeration system in terms of efficiency and performance with basis placed on the 2nd law of thermodynamics. The primary objectives of this project are to explore means by which the adverse effects of hydrocarbon refrigerants (R410a) on the environment can be drastically reduced, to assess the thermal conductivity of the nano-R410a in the VCR system and to examine the exergy losses for each component. The scope of this project will be to assess, via several experimentations, every one of the parts in a VCR system which includes the evaporator, compressor, condenser and throttling valve, to check the temperature and pressure, to analyze the gathered results with a goal to assess the measure of exergy losses for each refrigerator part and evaluating the second law efficiency through valid calculation.
TABLE OF CONTENTS DECLARATION ........................................................................................................................ i CERTIFICATION ................................................................................................................... ii DEDICATION ......................................................................................................................... iii ACKNOWLEDGEMENT ....................................................................................................... iv ABSTRACT ............................................................................................................................... v TABLE OF CONTENTS ......................................................................................................... vi LIST OF FIGURES .................................................................................................................. ix LIST OF TABLES ..................................................................................................................... x LIST OF SYMBOLS ................................................................................................................ xi CHAPTER ONE ........................................................................................................................ 1 1 INTRODUCTION ............................................................................................................. 1 1.1 BACKGROUND STUDY ........................................................................................... 1 1.1.1 Refrigeration ............................................................................................................. 2 1.1.2 Domestic Refrigeration ............................................................................................. 3 1.1.3 Environmental Impacts ............................................................................................. 3 1.1.4 Nanoparticles ............................................................................................................ 4 1.1.5 Nano-Fluids .............................................................................................................. 5 1.1.6 Nano-Refrigerants..................................................................................................... 6 1.2 EXERGY ANALYSIS ................................................................................................. 7 1.3 PROBLEM STATEMENT ......................................................................................... 7 1.4 AIM ............................................................................................................................... 8 1.5 OBJECTIVES .............................................................................................................. 8 1.6 SCOPE OF STUDY..................................................................................................... 8 1.7 LIMITATIONS ........................................................................................................... 8 1.8 JUSTIFICATION OF STUDY................................................................................... 9 CHAPTER TWO ..................................................................................................................... 10 2 LITERATURE REVIEW ............................................................................................... 10 2.1 INTRODUCTION ..................................................................................................... 10 2.2 REFRIGERATION SYSTEM ................................................................................. 11
vii 2.2.1 Vapor Compression Refrigeration System (VCRS) ............................................... 11 2.2.2 Vapor Cycle Description ........................................................................................ 14 2.3 BASE REFRIGERANT- R410a ............................................................................... 16 2.4 THE CONCEPT OF EXERGY ANALYSIS .......................................................... 16 2.5 REVIEW OF SOME PREVIOUS STUDIES ON THE APPLICATION OF NANOFLUIDS IN VAPOUR COMPRESSION REFRIGERATION SYSTEMS ..................................................................................................................................... 18 2.6 REVIEW OF PAST STUDIES USING THE EXERGETIC APPROACH TO ANALYSE THEPERFORMANCE OF VAPOUR COMPRESSION REFRIGERATION SYSTEMS ............................................................................... 28 CHAPTER THREE ................................................................................................................. 36 3 MATERIALS AND METHODOLOGY ....................................................................... 36 3.1 DESCRIPTION OF EXPERIMENTAL SETUP. .................................................. 36 3.2 INSTRUMENTATION ............................................................................................. 41 3.3 EXPERIMENTAL PROCEDURE .......................................................................... 41 3.3.1 Cleansing and Charging of the Setup ..................................................................... 42 3.3.2 Baseline Testing of the Vapor Compression Refrigeration System with Pure Refrigerant (R410A) Alone .................................................................................... 42 3.3.3 Synthesis of Nano-fluids......................................................................................... 42 3.3.4 Nano-Refrigerant Concentration ............................................................................ 45 3.3.5 Exergy Destruction in the VCR System Components ............................................ 46 3.3.6 Total Exergy Supplied ............................................................................................ 50 3.3.7 Exergetic Efficiency(ex) ........................................................................................ 50 3.3.8 Exergy Destruction Ratio (EDR) ............................................................................ 50 CHAPTER FOUR ................................................................................................................... 51 4 RESULTS AND DISCUSSIONS .................................................................................... 51 4.1 INTRODUCTION ..................................................................................................... 51 4.2 EXPERIMENTAL RESULT DATA ....................................................................... 51 4.3 RESULTS ANALYSES ............................................................................................ 55 4.3.1 Effect of Evaporating Temperature on Coefficient of Performance ...................... 55
viii 4.3.2 Effect of Evaporating Temperature on Individual Exergy Losses in the Pure VCR System. ................................................................................................................... 56 4.3.3 Effect of Evaporating Temperature on Individual Exergy Losses in the TiO2-R410a VCR System ................................................................................................ 56 4.3.4 Effect of Evaporating Temperature on Total Exergy Losses in the VCR System . 57 4.3.5 Effect of Evaporating Temperature on Exergetic Efficiency ................................. 58 4.3.6 Variation of Cooling Capacity, Power Consumption and Heating Capacity. ........ 59 4.3.7 Variation of Irreversibility in the Individual Components of the System with TiO2 Lubricant Concentration. ........................................................................................ 60 4.3.5 Variation of Irreversibility with Evaporator Temperature...................................... 62 4.3.6 Effect of Evaporating Temperature on Exergy Destruction Ratio (EDR) .............. 62 CHAPTER 5 ............................................................................................................................. 64 CONCLUSION AND RECOMMENDATION ..................................................................... 64 5.1 CONCLUSION .......................................................................................................... 64 5.2 RECOMMENDATION ............................................................................................ 65 REFERENCES ........................................................................................................................ 66
ix LIST OF FIGURES Figure 1.1: Length scale of nanofluids. .................................................................................... 5 Figure 2.1: Diagrammatic Representation of a Typical Vapor Compression Refrigeration System using a Liquid-Vapor Heat Exchanger. ................................................................... 15 Figure 2.2: Pressure-Enthalpy Diagram of a Vapor Compression Refrigeration System. ................................................................................................................................................... 15 Figure 2.3: Comparison of Coefficient of Performance (COP) for the three cases. .......... 21 Figure 2.4: The COP comparison of the systems working with different refrigerants and nano-refrigerants ..................................................................................................................... 22 Figure 2.5: Picture showing a uniform distribution of TiO2 nanoparticles in minera1 oi1700 h after preparation (a) 0.01% volume fractions of TiO2 nanoparticles in minera1 oi1 (b) Raw minera1 oi1. ......................................................................................................... 23 Figure 3.1: Analog pressure gauges employed during the experiment. ............................. 37 Figure 3.2: Schematic diagram of the table top refrigerator. ............................................. 38 Figure 3.3: Pressure-Enthalpy Chart Showing the Ideal Refrigeration Cycle .................. 39 Figure 3.4: Mineral Oil before adding the nanoparticles .................................................... 44 Figure 3.5:Solution of nanoparticle (TiO2) mixed in the mineral oil .................................. 44 Figure 3.6: Ultrasonication Process of Al2O3 and TiO2 ....................................................... 45 Figure 3.7: P-H Diagram of a Vapor Compression Refrigeration System......................... 47 Figure 4.1: Effect of evaporating temperature on the coefficient of performance (COP) of the system ................................................................................................................................. 55 Figure 4.2: Effect of evaporating temperature on individual exergy losses. ...................... 56 Figure 4.3: Effect of evaporating temperature on individual exergy losses ....................... 57 Figure 4.4: Variation of the effect of evaporating temperature on the total exergy losses in the VCR system ................................................................................................................... 58 Figure 4.5: Effect of evaporating temperature on the exergetic efficiency of the VCR system ........................................................................................................................................ 59 Figure 4.6: Variation of cooling capacity, power consumption and heating capacity with power ........................................................................................................................................ 60 Figure 4.7: Irreversibility in the system’s individual components with TiO2 lubricant Nano concentration. ................................................................................................................ 61 Figure 4.8: Variation of total irreversibility with evaporating temperature. .................... 62 Figure 4.9: Effect of evaporating temperature on EDR ...................................................... 63
x LIST OF TABLES Table 1: Refrigeration System Specifications ....................................................................... 37 Table 2: Thermo-physical Properties of Base Refrigerant .................................................. 40 Table 3: General Properties of Titanium Oxide ................................................................... 40 Table 4: Measuring Instruments and Their Capacity ......................................................... 41 Table 5: Experimental Result Data 1 for Pure R410a ......................................................... 51 Table 6: Experimental Result Data 2 for Pure R410a ......................................................... 51 Table 7: Experimental Result Data 3 for Pure R410a ......................................................... 52 Table 8: Experimental Results Data 1 for TiO2-R410a ....................................................... 53 Table 9: Experimental Results Data 2 for TiO2-R410a ....................................................... 54 Table 10: Experimental Results Data 3 for TiO2-R410a ..................................................... 54
