Reversible R744 (CO2) heat pumps applied in public trains ... - NTNU

TABLE OF CONTENTS
ABSTRACT............................................................................................................................... 1
TABLE OF CONTENTS............................................................................................................ i
TABLE OF FIGURES ..............................................................................................................iii
LIST OF TABLES .................................................................................................................... vi
ABBREVATIONS...................................................................................................................vii
PREFACE .................................................................................................................................. 1
A INTRODUCTION.............................................................................................................. 2
A.1 Background ................................................................................................................ 2
A.1.1 Global Warming Potential (GWP) ........................................................................... 3
A.1.2 Green house gas........................................................................................................ 3
A.1.3 EU directive restrictions of use of GWP gasses in air condition systems for
vehicles............................................................................................................................... 3
A.2 Carbon dioxide as a refrigerant .................................................................................. 4
A.2.1 CO2 Properties.......................................................................................................... 4
A.2.2 CO2 systems are small and compact......................................................................... 5
A.2.3 Typical design and components of a CO2 system .................................................... 5
A.2.4 Gas cooler pressure .................................................................................................. 6
A.2.5 Two stage compression ............................................................................................ 7
A.2.6 Life Cycle Climate Performance (LCCP) ................................................................ 9
A.2.7 GREEN-MAC-LCCP©.......................................................................................... 11
A.3 Alternative refrigerants ............................................................................................ 12
A.4 Reversible R744 heat pumps in the Norwegian public train sector ......................... 13
A.4.1 Mobile MACs in transport sector other than road transport .................................. 14
B SYSTEM .......................................................................................................................... 17
B.1.1 System specifications ............................................................................................. 17
B.1.2 Fresh air flow.......................................................................................................... 17
B.1.3 Temperatures .......................................................................................................... 17
B.1.4 Maximum and minimum exterior temperatures ..................................................... 18
B.1.5 Air ducts ................................................................................................................. 18
B.1.6 System safety.......................................................................................................... 18
B.2 System layout ........................................................................................................... 19
B.2.1 Solution I ................................................................................................................ 21
B.2.2 Solution II............................................................................................................... 24
B.2.3 Solution III.............................................................................................................. 26
B.3 Discussion of system layout..................................................................................... 28
C COMPUTER SIMULATION .......................................................................................... 29
C.1 Cooling mode ........................................................................................................... 29
C.1.1 System description.................................................................................................. 29
C.1.2 Simulation using Excel and RnLib......................................................................... 30
C.2 Simulation using HXsim and ProII .......................................................................... 32
C.2.1 Deciding heat exchanger layout in HXsim............................................................. 33
C.2.2 ProII model cooling mode ...................................................................................... 34
C.2.3 Presentation and discussion of HXsim/ProII results cooling model ...................... 36
C.3 Heating mode ........................................................................................................... 39
C.3.1 Simulation using Excel and RnLib......................................................................... 39
C.3.2 New system circuit ................................................................................................. 40
C.3.3 Simulation using HXsim and ProII ........................................................................ 41
C.3.4 Presentation and discussion of HXsim/ProII results heating model....................... 42
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