The Oak Ridge Heat Pump Models: I. A Steady-State Computer Design Model of Air-to-Air Heat ...

204 Pages·1999·10.84 MB·English

Printed in the United States of America. Available from
National Technical Information Service
U.S. Department of Commerce
5285 Port Royal Road, Springfield, Virginia 22161
NTIS price codes-Printed Copy: ,410 Microfiche ,401
This report was prepared as an account of work sponsored by an agency of the
UnitedStatesGovernment. NeithertheUnitedStatesGovernment noranyagency
thereof, nor any of their employees, makes any warranty, express or implied, or
assumes any legal liability or responsibility for the accuracy, completeness, or
usefulness of any information, apparatus, product, or process disclosed, or
represents that its usewould not infringe privately owned rights. Reference herein
to any specific commercial product, process, or service by trade name, trademark,
manufacturer, or otherwise, does not necessarily constitute or imply its
endorsement, recommendation, or favoring by the United StatesGovernment or
any agency thereof. The views and opinions of authors expressed herein do not
necessarily state or reflect those of the United StatesGovernment or any agency
thereof.
ORNL/CON-80/Rl
Contract No. W-7405-eng-26
Energy Division
The Oak Ridge Heat Pump Models: I. A Steady-State Computer
'/ Design Model for Air-to-Air Heat Pumps
i
S. K. Fischer
C. K. Rice
: DEPARTMENT OF ENERGY
Division of Building Equipment
, Date Published: Auqust 1983
OAK RIDGE NATIONAL LABORATORY
Oak Ridge, Tennessee 37830
operated by
UNION CARBIDE CORPORATION
for the
DEPARTMENT OF ENERGY
. -
TABLE OF CONTENTS
r
Page
LIST OF FIGURES ................................................ vii
LIST OF TABLES ................................................. ix
ABSTRACT ....................................................... 1
1. INTRODUCTION AND BACKGROUND. .............................. 3
2. UTILIZATION ............................................... 7
*I
3. CALCULATIONAL PROCEDUREA ND ORGANIZATION .................. 9
3.1 Modeling Procedure for the Vapor Compression Cycle ...
3.2 Organization of the Computer Program ................. 1:
3.3 Input and Output Description ......................... 16
4. COMPRESSORM ODELS .........................................
4.1 Introduction .........................................
4.2 General Calculational Scheme .........................
4.3 Map-Based Compressor Model ...........................
4.4 Loss and Efficiency-Based Compressor Model ...........
5. FLOW CONTROL DEVICES ...................................... 37
5.1 Introduction ......................................... 37
5.2 Capillary Tube Model .................................
5.3 Thermostatic Expansion Valve Model ................... z;
5.4 Short Tube Orifice Model ............................. 44
6. CONDENSERA ND EVAPORATORM ODELS ........................... 47
6.1 Introduction ......................................... 47
6.2 Single-Phase Heat Transfer Coefficients in Heat
Exchanger Tubes ...................................... 50
6.3 Two-Phase Heat Transfer Coefficients in Heat Exchanger
Tubes ................................................ 51
6.4 Air-Side Heat Transfer Coefficients .................. 55
6.5 Heat Exchanger Performance ...........................
6.6 Fan Motor and Compressor Shell Heat Losses ........... 2:
7. AIR-SIDE PRESSURE DROPS AND FAN POWERS .................... 65
8. PRESSURE AND ENTHALPY CHANGES IN REFRIGERANT LINES ........
iii
Page
.
9. MODEL VALIDATION .......................................... 73 .
9.1 Introduction ........................................ 73
9.2 Compressor Modeling ................................. 73
9.3 Heat Exchanger Calibration .......................... 74 .
9.4 Heat Pump Validation at 5.4"C (41.7OF) Ambient
9.5 Heat Pump Validation at 10.6"C (51.0°F) Ambient'::::: ::
9.6 Cooling Mode Results ................................ 81
10. RECOMMENDATIONS . . . . . . . . . . . . . ..*.......................... 83
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
APPENDIX A. DEFINITIONS OF INPUT DATA . . . . . . . . . . . . . . . . . . . . . . . . 89
APPENDIX B. SAMPLE INPUT AND OUTPUT DATA . . . . . . . . . . . . . . . . . . . . . 95
APPENDIX C. DEFINITIONS OF CONSTANTS ASSIGNED IN BLOCK DATA
SUBROUTINE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
APPENDIX D. DEFINITIONS OF VARIABLES IN COMMONB LOCKS . . . . . . . . 105
APPENDIX E. CROSS-REFERENCE OF COMMONB LOCKS . . . . . . . . . . . . . . . . . 131
APPENDIX F. SUBROUTINE DESCRIPTIONS AND CROSS-REFERENCE OF
SUBROUTINE CALLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
APPENDIX G. ALGEBRAIC NOTATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
APPENDIX H. DERIVATION OF DEHUMIDIFICATION SOLUTION . . . . . . . . . . 147
H.l Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
H.2 Heat Transfer Equations - Air to Wall . . . . . . . . . . . . . . . 147
H.3 Heat Transfer Equations - Air to Mean Surface
Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
H.4 Heat Transfer Equations - Mean Surface to Refrigerant
Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
H.5 Derivation of Coil Characteristic and Total Heat Flow
Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
H.6 Derivation of the Solution for the Exit Effective
Surface Temperature, Tf, ,(x0) . . . . . . . . . . . . . . . . . . . . . . 153
H.7 Derivation of the Soluti6n for the Exit Air Dry Bulb
Temperature T (x ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
References for App%aixOH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
APPENDIX I. DESCRIPTION OF THE DEHUMIDIFICATION ALGORITHM . . . . 163
References for Appendix I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
APPENDIX J. RATIOS OF GEOMETRIC PARAMETERS USED IN HEAT
EXCHANGERC ALCULATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
iv
Page
.
APPENDIX K. AVAILABILITY AND DISTRIBUTION OF THE HEAT PUMP
MODEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
.
APPENDIX L. LISTING OF COMPUTERM ODEL ........................ 185
APPENDIX M. SAMPLE INPUT DATA ................................ 185
APPENDIX N. LISTING OF THE MAP FITTING PROGRAM . . . . . . . . . . . . . . . 185
APPENDIX 0. SAMPLE COMPRESSORM AP DATA . . . . . . . . . . . . . . . . . . . . . . . 185
APPENDIX P. LISTING OF THE INTERACTIVE SUBROUTINES . . . . . . . . . . . 185
APPENDIX Q. LISTING OF THE INTERACTIVE PREPROCESSOR. . . . . . . . . . 185
.
.
V
.
LIST OF FIGURES
Page
c
Fig. 3.1 Pressure vs. Enthalpy Diagram for the Heat
Pump Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Fig. 3.2 Block Diagram of Iterative Loops in the Main
Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Fig. 4.1 Computational Sequence in the Compressor Models 21
Fig. 4.2 Components of Compressor Energy Balance . . . . . . . . 27
Fig. 4.3 Iteration on Internal Energy Balance for the
Loss and Efficiency-Based Compressor Model . . . . . 31
Fig. 6.1 General Structure of the Condenser Model . . . . . . . 48
Fig. 6.2 General Structure of the Evaporator Model . . . . . . 49
Fig. 6.3 Computational Sequence in the Condenser Model . . 57
Fig. 6.4 Computational Sequence in the Evaporator
Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Fig. I.1 Block Diagram of the Dehumidification Algorithm 164
Fig. J-1 Sample Tube-and-Fin Heat Exchanger . . . . . . . . . . . . . 172
vii
.
*
.
.
.