Experimental Investigation of Void Fraction During Horizontal Flow in Larger Diameter Refrigeration Applications M. J. Wilson, T. A. Newell, and J. C. Chato ACRC TR-I40 For additional information: Air Conditioning and Refrigeration Center University of Illinois Mechanical & Industrial Engineering Dept. 1206 West Green Street 1206 West Green Street Urbana, IL 61801 (217) 333-3115 July 1998 Prepared as part of ACRC Project 74 Experimental Investigation of Void Fraction During Refrigerant Condensation and Evaporation T. A. Newell and J. C. Chato, Principal Investigators
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Experimental Investigation of Void Fraction During Horizontal Flow in Larger Diameter
Refrigeration Applications
M. J. Wilson, T. A. Newell, and J. C. Chato
ACRC TR-I40
For additional information:
Air Conditioning and Refrigeration Center University of Illinois Mechanical & Industrial Engineering Dept. 1206 West Green Street 1206 West Green Street Urbana, IL 61801
(217) 333-3115
July 1998
Prepared as part of ACRC Project 74 Experimental Investigation of Void Fraction
During Refrigerant Condensation and Evaporation T. A. Newell and J. C. Chato, Principal Investigators
The Air Conditioning and Refrigeration Center was founded in 1988 with a grant from the estate of Richard W. Kritzer, thefounder of Peerless of America Inc. A State of Illinois Technology Challenge Grant helped build the laboratory facilities. The ACRC receives continuing support from the Richard W. Kritzer Endowment and the National Science Foundation. The following organizations have also become sponsors of the Center.
Amana Refrigeration, Inc. Brazeway, Inc. Carrier Corporation Caterpillar, Inc. Copeland Corporation Dayton Thermal Products Delphi Harrison Thermal Systems Eaton Corporation Ford Motor Company Frigidaire Company General Electric Company Hill PHOENIX Hydro Aluminum Adrian, Inc. Indiana Tube Corporation Lennox International, Inc. Modine Manufacturing Co. Peerless of America, Inc. The Trane Company Whirlpool Corporation York International, Inc.
For additional information:
Air Conditioning & Refrigeration Center Mechanical & Industrial Engineering Dept. University of Illinois 1206 West Green Street Urbana IL 61801
2173333115
Abstract
EXPERIMENTAL INVESTIGATION OF VOID FRACTION DURING HORIZONTAL FLOW IN LARGER DIAMETER REFRIGERATION APPLICATIONS
Michael Jay Wilson Department of Mechanical and Industrial Engineering
University oflllinois at Urbana-Champaign, 1998 Ty Newell and John C. Chato, Advisors
Void fractions were measured for R134a and R410A for a smooth tube with inside
diameter of 6.12 mm (0.241"), an axially grooved tube of base diameter 8.89 mm
(0.350"), and a 18° helically grooved of base diameter 8.93 mm (0.352"). The experiment
covered mass fluxes from 75 kg/m2s to 700 kg/m2s (55 - 515 klbnJ'ft2-hr) and average test
section qualities from 5% to 99% with an inlet temperature of 5°C (41°F). Several
existing models are examined for accuracy and a simple adjusted model is presented to
accurately predict the data and data presented in a companion study by Yashar[1998].
The experimental apparatus and methodology are also discussed.
iii
Table of Contents
Page
List of Tables ............................................................................................................ viii
List of Figures ........................................................................................................... ix
Nomenclature ........................................................................................................... xx
Chapter
I Introduction ............................................................................................................ 1
2 Literature Review ................................................................................................... 2
2.3 Hughmark flow parameter K as a function of Z .................................................. 11
3.1 Dimensions of grooved tubes............................................................................. 15
4.1 Void fraction uncertainty for given quality range and tube .................................. 28
A.1 Raw data for 6.12 mm inner diameter smooth tube ............................................ 88
B.1 Raw data for 8.89 mm base diameter axially grooved tube ............................... 103
C.1 Raw data for 8.93 mm base diameter helically grooved tube ............................ 119
viii
List of Figures
Figure Page
3.1 Schematic of refrigerant loop ............................................................................. 20
3.2 Chiller system .................................................................................................... 20
3.3 Micro-fm tubes dimensions and features for 8.93 mm inner diameter micro-finned test section ............................................................................................... 21
3.4 Test section dimensions and features ................................................................... 22
3.5 Void fraction tap where OD is the outside diameter of the test section the tap will fit on to .................................................................................................. 22
3.6 Pressure tap where OD is the outside diameter of the test section the tap will fit on to ........................................................................................................ 23
3.7 Thermocouple placement in thick walled tubes .................................................... 23
3.8 Thermocouple placement in thin walled tubes ...................................................... 24
4.1 Example error analysis plot for the helically grooved tube ................................... 29
5.1 Void fraction vs. average quality 6.12 mm inner diameter smooth tube ................ 35
5.2 Void fraction vs. average quality using R134a in 6.12 mm inner diameter smooth tube. Mass flux (G) given in kglm2s ...................................................... 35
5.3 Void fraction vs. average quality using R410A in 6.12 mm inner diameter smooth tube. Mass flux (G) given in kglm2s ....................................................... 36
5.4 Void fraction vs. average quality using R134a in a 6.12 mm inner diameter smooth tube. Test section heat flux (Q) given in W/m2 ....................................... 36
5.5 Void fraction vs. average quality using R410A in a 6.12 mm inner diameter smooth tube. Test section heat flux (Q) given in W/m2 ...................................... 37
5.6 Void fraction vs. average quality for a 4.26mm and 6.12mm inner diameter smooth tube using R134a and R410A ................................................................ 37
5.7 Void fraction vs. Homogenous correlation for 6.12mm inner diameter smooth tube using R134a and R410A Mass flux (G) is in kglm2s ....................... 38
ix
5.8 Void fraction vs. Rigot correlation for 6.12mm inner diameter smooth tube using Rl34a and R41OA. Mass flux (G) is in kglm2s .......................................... 38
5.9 Void fraction vs. Zivi correlation for 6.12mm inner diameter smooth tube using Rl34a and R41OA. Mass flux (G) is in kglm2s .......................................... 39
5.10 Void fraction vs. Ahrens-Thorn correlation for 6.12mm inner diameter smooth tube using R134a and R410A. Mass flux (G) is in kglm2 •••••••••••••••••••••• 39
5.11 Void fraction vs. Smith correlation for 6. 12mm inner diameter smooth tube using Rl34a and R41OA. Mass flux (G) is in kglm2s ........................................ 40
5.12 Void fraction vs. Wallis correlation for 6.12mm inner diameter smooth tube using R134a and R41OA. Mass flux (G) is in kglm2s ........................................ 40
5.13 Void fraction vs. Baroczy correlation for 6. 12mm inner diameter smooth tube using R134a and R41OA. Mass flux (G) is in kglm2s ................................. 41
5.14 Void fraction vs. Tandon correlation for 6.12mm inner diameter smooth tube using R134a and R41OA. Mass flux (G) is in kglm2s ................................. 41
5.15 Void fraction vs. Premoli correlation for 6.12mm inner diameter smooth tube using R134a and R410A. Mass flux (G) is in kglm2s ................................. 42
5.16 Void fraction vs. Hughmark correlation for 6.12mm inner diameter smooth tube using R134a and R41OA. Mass flux (G) is in kglm2s ................................. 42
5.17 Void fraction vs. Graham's condenser correlation for 6.12mm inner diameter smooth tube using R134a and R41OA. Mass flux (G) is in kglm2s ....................................................................................................... 43
6.1 Void fraction vs. average quality for a 8.89 mm base diameter axially grooved tube ...................................................................................................... 48
6.2 Void fraction vs. average quality using R134a in a 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s ........................................... 48
6.3 Void fraction vs. average quality using R410A in a 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s ........................................... 49
6.4 Void fraction vs. average quality using R134a in a 8.89 mm base diameter axially grooved tube. Test section heat flux (Q) given in W/m ............................ 49
x
6.5 Void fraction vs. average quality using R410A in a 8.89 mm base diameter axially grooved tube. Test section heat flux (Q) given in W/m2 ........................... 50
6.6 Void fraction vs. average quality for 8.89 mm and 7.25 mm base diameter axially grooved tube using R134a and R410A ..................................................... 50
6.7 Void fraction vs. average quality for 6.12 mm inner diameter smooth tube and 8.89 mm base diameter grooved tube using R134a and R41OA ..................... 51
6.8 Void fraction vs. Smith correlation for 8.93 mm base diameter axially grooved tube using R134a and R41OA. Mass Flux (G) in kglm2s ........................ 51
6.9 Void fraction vs. Wallis correlation for 8.93 mm base diameter axially grooved tube using R134a and R41OA. Mass Flux (G) in kglm2s ........................ 52
6.10 Void fraction vs. Tandon correlation for 8.93 mm base diameter axially tube using R134a and R41OA. Mass Flux (G) in kglm2s ........................ 52
6.11 Void fraction vs. Premoli correlation for 8.93 mm base diameter axially tube using R134a and R41OA. Mass Flux (G) in kglm2s ........................ 53
6.12 Void fraction vs. Smith correlation for 7.25 mm and 8.93 mm base diameter axially grooved tube using R134a and R41OA ..................................... 53
6.13 Void fraction vs. Wallis correlation for 7.25 mm and 8.93 mm base diameter axially grooved tube using R134a and R41OA ..................................... 54
6.14 Void fraction vs. Tandon correlation for 7.25 mm and 8.93 mm base diameter axially grooved tube using R134a and R41OA ..................................... 54
6.15 Void fraction vs. Premoli correlation for 7.25 mm and 8.93 mm base diameter axially grooved tube using R134a and R41OA ..................................... 55
7.1 Void fraction vs. average qUality for a 8.93 mm base diameter 18° helically grooved tube ...................................................................................................... 60
7.2 Void fraction vs. average quality using R134a in a 8.93 mm base diameter 18° helically grooved tube. Mass Flux (G) given in kglm2s .................................. 60
7.3 Void fraction vs. average quality using R410A in a 8.93 mm base diameter 18° helically grooved tube. Mass flux (G) given in kglm2s .................................. 61
xi
7.4 Void fraction vs. average quality using R134a in a 8.93 mm base diameter 18° helically grooved tube. Test section heat flux (Q) given in W/m2 .................. 61
7.5 Void fraction vs. average quality using R410A in a 8.93 mm base diameter 18° helically grooved tube. Test section heat flux (Q) given in W/m2 ................... 62
7.6 Void fraction vs. average quality for 8.93 mm base diameter 18° helically grooved tube using R134a and R41OA ................................................................ 62
7.7 Void fraction vs. average quality for 8.93 mm base diameter helically grooved tube and 6.12 mm inner diameter smooth tube ....................................... 63
7.8 Void fraction vs. average quality for 8.93 mm base diameter helically grooved tube and 8.89 mm base diameter axially grooved tube ......................................... 63
7.9 Void fraction vs. Smith correlation for 8.93 mm base diameter 18° helically grooved tube using R134a and R41OA. Mass flux (G) in kglm2s ....................... 64
7.10 Void fraction vs. Wallis correlation for 8.93 mm base diameter 18° helically grooved tube using R134a and R41OA. Mass flux (G) in kglm2s ..................... 64
7.11 Void fraction vs. Tandon correlation for 8.93 mm base diameter 18° helically grooved tube using R134a and R41OA. Mass flux (G) in kglm2s ...................... 65
7.12 Void fraction vs. Premoli correlation for 8.93 mm base diameter 18° helically grooved tube using R134a and R41OA. Mass flux (G) in kglm2s ...................... 65
7.13 Void fraction vs. Smith correlation for 7.26 mm and 8.93 mm base diameter helically grooved tube using R134a and R41OA. ................................................ 66
7.14 Void fraction vs. Wallis correlation for 7.26 mm and 8.93 mm base diameter 'helically grooved tube using R134a and R41OA ................................................. 66
7.15 Void fraction vs. Tandon correlation for 7.26 mm and 8.93 mm base diameter helically grooved tube using R134a and R410A .................................. 67
7.16 Void fraction vs. Premoli correlation for 7.26 mm and 8.93 mm base diameter helically grooved tube using R134a and R410A .................................. 67
8.1 Void fraction vs. average quality for Graham's R134a condenser data ................. 76
8.2 Void fraction vs. average quality for Graham's R410A condenser data ................ 76
8.3 Taitel-Dukler Map for 4.26 mm inner diameter smooth tube ................................ 77
xii
8.4 Taitel-Dukler Map for 6.12 mm inner diameter smooth tube ................................ 77
8.5 Taitel-Dukler Map for 7.25 mm base diameter axially grooved tube .................... 78
8.6 Taitel-Dukler Map for 8.89 mm base diameter axially grooved tube .................... 78
8.7 Taitel-Dukler Map for 7.25 mm base diameter helically grooved tube .................. 79
8.8 Taitel-Dukler Map for 8.93 mm base diameter helically grooved tube .................. 79
8.9 Taitel-Dukler Map for Graham's data .................................................................. 80
8.10 Void fraction vs. adjusted Premoli correlation for smooth tubes ........................ 80
8.11 Void fraction vs. adjusted Premoli correlation for axially grooved tubes ............ 81
8.12 Void fraction vs. adjusted Premoli correlation for helically grooved tube ........... 81
8.13 Void fraction vs. FtlG for smooth tube data ...................................................... 82
8.14 Void fraction vs. Ft*D/G213 for axially grooved tube .......................................... 82
8.15 Void fraction vs. FtlG213 for helically grooved tube ............................................ 83
A.l Void fraction vs. average quality with a heat flux of 0 W 1m2 using R134a in a 6.12 mm inner diameter smooth tube. Mass flux (G) given in kglm2s .......... 90
A.2 Void fraction vs. average quality with a heat flux of 3 W 1m2 using R134a in a 6.12 mm inner diameter smooth tube. Mass flux (G) given in kglm2s .......... 90
A.3 Void fraction vs. average quality with a heat flux of 10 W/m2 using R134a in a 6.12 mm inner diameter smooth tube. Mass flux (G) given in kglm2s .......... 91
AA Void fraction vs. average qUality with a heat flux of 0 W 1m2 using R410A in a 6.12 mm inner diameter smooth tube. Mass flux (G) given in kglm2s .......... 91
A.5 Void fraction vs. average quality with a heat flux of 3 W 1m2 using R410A in a 6.12 mm inner diameter smooth tube. Mass flux (G) given in kglm2s .......... 92
A.6 Void Fraction vs. average qUality with a heat flux of 10 W/m2 using R410A in a 6.12 mm inner diameter smooth tube. Mass flux (G) given in kglm2s .......... 92
A.7 Void fraction vs. average quality with a mass flux of75 kglm2s using R134a in a 6.12 mm inner diameter tube. Heat flux (Q) in W/m2 .................................. 93
xiii
A.8 Void fraction vs. average quality with a mass flux of 200 kglm2s using R134a in a 6.12 mm inner diameter tube. Heat flux (Q) in W/m2 ....................... 93
A.9 Void Fraction vs. average quality with a mass flux of 500 kglm2s using R134a in a 6.12 mm inner diameter tube. Heat flux (Q) in W/m2 ••••••••••••••••••••••• 94
A.I0 Void fraction vs. average quality with a mass flux of75 kglm2s using R410A in a 6.12 mm inner diameter tube. Heat flux (Q) in W/m2 .................... 94
A.ll Void fraction vs. average quality with a mass flux of 200 kglm2s using R410A in a 6.12 mm inner diameter tube. Heat flux (Q) in W/m2 .................... 95
A.12 Void fraction vs. average quality with a mass flux of 500 kglm2s using R410A in a 6.12 mm inner diameter tube. Heat flux (Q) in W/m2 .................... 95
A.13 Void Fraction vs. homogenous correlation showing diameter effects for 4.26 mm and 6.12 mm inner diameter smooth tube ........................................... 96
A.14 Void Fraction vs. Rigot correlation showing diameter effects for 4.26 mm and 6.12 mm inner diameter smooth tube ......................................................... 96
A.15 Void Fraction vs. Zivi correlation showing diameter effects for 4.26 mm and 6.12 mm inner diameter smooth tube ......................................................... 97
A.16 Void Fraction vs. Ahrens-Thorn correlation showing diameter effects for 4.26 mm and 6.12 mm inner diameter smooth tube ........................................... 97
A.17 Void Fraction vs. Smith correlation showing diameter effects for 4.26 mm and 6.12 mm inner diameter smooth tube ......................................................... 98
A.18 Void Fraction vs. Wallis correlation showing diameter effects for 4.26 mm and 6.12 mm inner diameter smooth tube ......................................................... 98
A.19 Void Fraction vs. Baroczy correlation showing diameter effects for 4.26 mm and 6.12 mm inner diameter smooth tube ........................................... 99
A.20 Void Fraction vs. Tandon correlation showing diameter effects for 4.26 mm and 6.12 mm inner diameter smooth tube ........................................... 99
A.21 Void Fraction vs. Premoli correlation showing diameter effects for 4.26 mm and 6.12 mm inner diameter smooth tube ......................................... 100
A.22 Void Fraction vs. Hughmark correlation showing diameter effects for 4.26 mm and 6.12 mm inner diameter smooth tube ......................................... 100
xiv
A.23 Void Fraction vs. Graham's condenser correlation showing diameter effects for 4.26 mm and 6.12 mm inner diameter smooth tube ........................ 101
B.1 Void fraction vs. average quality with a heat flux of 0 W/m2 using R134a in a 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s ................................................................................................ 105
B.2 Void fraction vs. average quality with a heat flux of 3 W/m2 using R134a in a 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s ................................................................................................ 105
B.3 Void fraction vs. average quality with a heat flux of 10 W/m2 using R134a in 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s ................................................................................................ 106
B.4 Void fraction vs. average quality with a heat flux of 0 W/m2 using R410A in a 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s ................................................................................................ 106
B.5 Void fraction vs. average quality with a heat flux of 3 W/m2 using R410A in a 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s ................................................................................................ 107
B.6 Void fraction vs. average qUality with a heat flux of 10 W/m2 using R410A in a 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s ................................................................................................ 107
B.7 Void fraction vs. average quality with a mass flux of75 kglm2s using R134a in a 8.89 mm base diameter axially grooved tube. Heat flux (Q) in W/m2 ........................................................................................................... 108
B.8 Void fraction vs. average quality with a mass flux of 200 kglm2s using R134a a 8.89 mm base diameter axially grooved tube. Heat flux (Q) in W/m2 ........................................................................................................... 108
B.9 Void fraction vs. average quality with a mass flux of 500 kglm2s using Rl34a in a 8.89 mm base diameter axially grooved tube. Heat flux (Q) in W/m2 ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 109
B.1O Void fraction vs. average qUality with a mass flux of75 kglm2s using R410A in a 8.89 mm base diameter axially grooved tube. Heat flux (Q) in W/m2 ......................................................................................................... 109
xv
B.11 Void fraction vs. average quality with a mass flux of 200 kglm2s using R410A in a 8.89 mm base diameter axially grooved tube. Heat flux (Q) in W/m2 ......................................................................................................... 110
B.12 Void fraction vs. average quality with a mass flux of 500 kglm2s using R410A in a 8.89 mm base diameter axially grooved tube. Heat flux (Q) in W 1m2 ......................................................................................................... 110
B.13 Void fraction vs. homogenous correlation for 8.89 mm base diameter axially grooved tube using R134a and R41OA. Mass flux (G) in kglm2s ......... 111
B.14 Void fraction vs. homogenous correlation for 7.25 mm and 8.89 mm base diameter axially grooved tubes using R 134a and R410A ................................ 111
B.15 Void fraction vs. Rigot correlation for 8.89 mm base diameter axially grooved tube using R134a and R41OA. Mass flux (G) in kglm2s ................... 112
B.16 Void fraction vs. Rigot correlation for 7.25 mm and 8.89 mm base diameter axially grooved tubes using R134a and R410A ................................ 112
B.17 Void fraction vs. Zivi correlation for 8.89 mm base diameter axially grooved tube using R134a and R41OA. Mass flux (G) in kglm2s ................... 113
B.18 Void fraction vs. Zivi correlation for 7.25 mm and 8.89 mm base diameter axially grooved tubes using R134a and R41OA ............................................... 113
B.19 Void fraction vs. Ahrens-Thorn correlation for 8.89 mm base diameter axially grooved tube using R134a and R41OA. Mass flux (G) in kglm2s ......... 114
B.20 Void fraction vs. Ahrens-Thorn correlation for 7.25 mm and 8.89 mm base diameter axially grooved tubes using R134a and R41OA ......................... 114
B.21 Void fraction vs. Baroczy correlation for 8.89 mm base diameter axially grooved tube using R134a and R41OA. Mass flux (G) in kglm2s ................... 115
B.22 Void fraction vs. Baroczy correlation for 7.25 mm and 8.89 mm base diameter axially grooved tubes using R134a and R410A ................................ 115
B.23 Void fraction vs. Hughmark correlation for 8.89 mm base diameter axially grooved tube using R134a and R41OA. Mass flux (G) in kglm2s .................... 116
B.24 Void fraction vs. Hughmark correlation for 7.25 mm and 8.89 mm base diameter axially grooved tubes using R134a and R410A ................................ 116
xvi
B.25 Void fraction vs. Graham's condenser correlation for 8.89 mm base diameter axially grooved tube using R134a and R41OA. Mass flux (G) in kglm2s ........................................................................................................ 117
B.26 Void fraction vs. Premoli correlation for 7.25 mm and 8.89 mm base diameter axially grooved tubes using R134a and R410A ................................ 117
C.1 Void fraction vs. average quality with a heat flux of 0 W 1m 2 using R 134a in a 8.93 mm base diameter axially grooved tube. Mass flux (G) given in kglm 2S ••• •••••••••••• ••••• ••••••• ••••••••••••••••••••••••• •••••••••••• •••••• •••••••••••••••••••••• •••• 121
C.2 Void fraction vs. average quality with a heat flux of 3 W/m2 using R134a in a 8.93 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s .......................................................................................................... 121
C.3 Void fraction vs. average quality with a heat flux of 10 W/m2 using R134a in 8.93 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s .......................................................................................................... 122
CA Void fraction vs. average quality with a heat flux of 0 W/m2 using R410A in a 8.93 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s .......................................................................................................... 122
C.5 Void fraction vs. average quality with a heat flux of 3 W/m2 using R410A in a 8.93 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s .......................................................................................................... 123
C.6 Void fraction vs. average qUality with a heat flux of 10 W/m2 using R410A in a 8.93 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s .......................................................................................................... 123
C.7 Void fraction vs. average quality with a mass flux of75 kglm2s using R134a in a 8.93 mm base diameter axially grooved tube. Heat flux (Q) in W/m2 ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 124
C.8 Void fraction vs. average quality with a mass flux of 200 kglm2s using R134a a 8.93 mm base diameter axially grooved tube. Heat flux (Q) in W/m2 ........................................................................................................... 124
C.9 Void fraction vs. average quality with a mass flux of 500 kglm2s using RI34a in a 8.93 mm base diameter axially grooved tube. Heat flux (Q) in W/m2 ........................................................................................................... 125
xvii
C.1O Void fraction vs. average qUality with a mass flux of75 kglm2s using R4l0A in a 8.93 mm base diameter axially grooved tube. Heat flux (Q) in W/m2 ......................................................................................................... 125
C.ll Void fraction vs. average quality with a mass flux of 200 kglm2s using R4l0A in a 8.93 mm base diameter axially grooved tube. Heat flux (Q) in W/m2 ......................................................................................................... 126
C.12 Void fraction vs. average quality with a mass flux of 500 kglm2s using R4l0A in a 8.93 mm base diameter axially grooved tube. Heat flux (Q) in W/m2 ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 126
C.13 Void fraction vs. homogenous correlation for 8.93 mm base diameter helically grooved tube using R134a and R41OA. Mass Flux (G) given in kglm2s ........................................................................................................ 127
C.14 Void fraction vs. homogenous correlation for 7.25 mm and 8.93 mm base diameter helically grooved tubes .................................................................... 127
C.15 Void fraction vs. Rigot correlation for 8.93 mm base diameter helically grooved tube using R134a and R41OA. Mass Flux (G) given in kglm2s .......... 128
C.16 Void fraction vs. Rigot correlation for 7.25 mm and 8.93 mm base diameter helically grooved tubes............ ...... ....... ........ ....... ..... .............. ...... .................. 128
C.17 Void fraction vs. Zivi correlation for 8.93 mm base diameter helically grooved tube using R134a and R41OA. Mass Flux (G) given in kglm2s ......... 129
C.18 Void fraction vs. Zivi correlation for 7.25 mm and 8.93 mm base diameter helically grooved tubes ................................................................................... 129
C.19, Void fraction vs. Ahrens-Thorn correlation for 8.93 mm base diameter helically grooved tube using R134a and R41OA. Mass Flux (G) given in kglm2s ........................................................................................................ 130
C.20 Void fraction vs. Ahrens-Thorn correlation for 7.25 mm and 8.93 mm base diameter helically grooved tubes .................................................................... 130
C.2l Void fraction vs. Baroczy correlation for 8.93 mm base diameter helically grooved tube using R134a and R41OA. Mass Flux (G) given in kglm2s ......... 131
C.22 Void fraction vs. Baroczy correlation for 7.25 mm and 8.93 mm base diameter helically grooved tubes. ............ ..... ...... ................ ....... ..................... 131
xviii
C.23 Void fraction vs. Hughmark correlation for 8.93 mm base diameter helically grooved tube using R134a and R41OA. Mass Flux (G) given in kglm2s ......... 132
C.24 Void fraction vs. Hughmark correlation for 7.25 mm and 8.93 mm base diameter helically grooved tubes .................................................................... 132
C.25 Void fraction vs. Graham's condenser correlation for 8.93 mm base diameter helically grooved tube using R134a and R41OA. Mass Flux (G) given in kglm2s ........................................................................................................... 133
C.26 Void fraction vs. Graham's condenser correlation for 7.25 mm and 8.93 mm base diameter helically grooved tubes ............................................................. 133
D.1 Void fraction vs. FtlG for smooth tube showing refrigerant effects ................... 135
D.2 Void fraction vs. FtlG for smooth tube showing diameter effects ...................... 135
D.3 Void fraction vs. Ft*D/G213 for axially grooved tube showing refrigerant effects .............................................................................................................. 136
D.4 Void fraction vs. Ft*D/G213 for axially grooved tube showing diameter effects ............................................................................................................. 136
D.5 Void Fraction vs. FtlG213 for helically grooved tubes showing refrigerant effects.................... ............................... ........................................................... 137
D.6 Void Fraction vs. FtlG213 for helically grooved tubes showing diameter effects... .......................................................................... ... .............................. 137
xix
Nomenclature
Di Inner Diameter
(for grooved tubes Di = base diameter)
FI Premoli correlation variable 1 Equation 2.19
F2 Premoli correlation variable 2 Equation 2.20
Fr Froude number ( J 1 Gx Equation 2.26
= gcDj ~Pg
Ft Froude rate Equation 2.31
Fro Taitel-Dukler Froude number
F(XtJ Tandon's Lockhart-Martinelli function Equation 2.18
G Mass Flux
gc Gravity
K Smith's entrainment ratio Equation 2.9
~ Hugbmark correction factor Table 3.3
m Mass
m? Specific mass reading in Chapter 4
P Pressure
P.!.l Property Index 1 Equation 2.6
P.I.2 Property Index 2 Equation 2.7
Rea Hugbmark's Reynolds number Equation 2.25
R~ Liquid Reynolds number =GDj Equation 2.17
ilL
S Slip ratio Equation 2.2
T Temperature
v Specific volume
'Its Test section volume
G 2D. W~ Liquid Weber number 1 Equation 2.22 =
crPlgc
x Quality
xx
Xs Static quality Equation 4.9
Xtt Lockhart-Martinelli parameter Equation 2.11
y Premoli's volumetric quality ratio Equation 2.21
YL Hugbmark liquid volume fraction Equation 2.27
Z Hugbmark flow parameter Equation 2.24
a Void Fraction
J3 Volumetric quality = 1
l+e~xx:: ) Equation 2.23
Am Change in mass Equation 4.1
'Y Thorn's slip factor Equation 2.8
J.L Viscosity
J.LI Viscosity of saturated liquid
J.Lg Viscosity of saturated vapor (gas)
P Density
PI Density of saturated liquid
pg Density of saturated vapor (gas)
(j Surface tension
xxi
Chapter 1
Introduction
Since the second world war, two-phase flow has been studied by several
researchers. This research has found void fraction to be an integral to part to models of
pressure-drop, heat transfer, and overall system simulation. Most void fraction
correlations were built upon air-water or steam-water data in smooth tubes. Little is
known about how well these correlations work for refrigerants or in micro-finned tubes.
This study will discuss refrigerant void fraction in smooth and micro-finned tubes.
This paper was created to present and correlate experimental void fraction data.
Chapter 2 first presents background information on void fraction. Several existing models
are discussed. Chapter 3 discloses the experimental setup and the measuring techniques
used. In Chapter 4 the experimental methodology is discussed. Void fraction data for
smooth, axially grooved, and helically grooved tubes is presented in Chapters 5,6 and 7,
respectively. These chapters also discuss the accuracy of the correlations discussed in
Chapter 2. Chapter 8 concludes all of the work and suggests a void fraction model which
correlates the data.
1
Chapter 2
Literature Review
Over the last half-century many researchers have studied void fraction and derived
models to predict void fraction. The study of void fraction is important for many
applications such as pressure drop correlations, heat transfer predictions, and overall
system simulation. Many of these models were reviewed by Rice [1987] who separated
the models into four categories: homogenous, slip-ratio, Lockhart-Martinelli, and mass
flux dependent. The purpose of this literature review is to explain the history, intended
use, and accuracy of each model.
2.1- Homogenous
The homogenous relation considers the liquid and gaseous phases to be traveling
as a homogenous mixture. The relation can be derived by simplification of fundamental
thermodynamic property relations and relates the void fraction to average quality by
1 (2.1)
2.2- Slip Ratio
Five correlations are of the form
1 (2.2)
2
where S is the slip ratio. In a physical sense the slip ratio is the ratio of vapor velocity to
liquid velocity. The homogenous correlation is a special case where the slip ratio is unity.
2.2.1- Rigot Correlation
Rigot [1973] correlation is one of the simplest correlations in which he suggests a
constant slip ratio of
S=2 (2.3)
2.2.2- Zivi Correlation
Zivi [1964] derived a model based on the assumption that in a steady state
thermodynamic process the rate of entropy production is minimized. Zivi assumed that
the flow was steady and annular, wall friction was negligible, and he did not account for
liquid entrainment. Using these assumptions, Zivi derived the slip ratio S to be
(2.4)
and thus void fraction can be calculated by
1 a-------- 2 (2.5)
l+C:x )(~:)'
Using the data from Martinelli and Nelson [1948], Larson [1957], and Maurer
[1960] to evaluate his model, Zivi concluded that his model provided the lower bound
while the homogenous model provided the upper bound. Zivi also noted that these two
3
models approach each other as pressure is increased. Zivi proposed that liquid entrainment
was needed to interpolate between the two models. He suggested that further
experiments and theoretical modeling be done to explore liquid entrainment.
2.2.3- Smith Correlation
Smith [1969] derived a model based on equal velocity heads. Smith's assumptions
were that the flow is annular with a liquid phase and a homogenous mixture phase, the
homogenous and liquid phase have the same velocity heads (pN12=Pm Vm2), the
homogenous mixture behaves as a single fluid with variable density, and that thermal
equilibrium exists.
Smith then established the variable K defined as the mass ratio of water flowing in
a homogenous mixture to the total mass of water flowing. This ratio simply describes the
amount of water entrained in the homogenous mixture. From these assumptions the slip
ratio was found to be
1 _1 +K(l-X) 2
~ x
S = K + (1- K) ...;..P-=-l --::-----:--
l+Ke~x) (2.9)
Smith found that an entrainment ratio of 40% (K=.4) correlated the data quite well. He
compared his correlation to steam-water and air-water data and found his correlation to be
accurate within 10%.
4
2.2.4- Ahrens-Thorn
Before discussing the Ahrens-Thorn correlation it is useful to define property
index 1 (P.I1) and property index 2 (P.I.2). The property indexes were given in Rice's
[1987] analysis and are used in other correlations.
(2.6)
III Pg III ( JO.2 (JO.2
P.L2 = Ilg e ~ = Ilg
e P.LI (2.7)
Ahrens [1983] suggested the steam/water data presented by Thorn [1964]
generalized by P.I.2 to be a suitable void fraction model. Thorn proposed a void fraction
model of the form
yex a=--.!----
l+xe(y-l)
in which the slip factor y is a constant at any given pressure. Ahrens redefmed the
independent variable as P.L2 instead of pressure. Rice presents the Ahrens-Thorn
Figure 5.4 Void fraction vs. average quality in test section using R134a in a 6.12 mm inner diameter smooth tube. Test section heat flux (Q) given in W/m2•
--.----------,---------------.---------------~---------------T-------------I I I I I I I I I • I I , I I I
I I I I
, " , " , " , " I I I I
................................ r ................. "''' ................................................................................................ -,- ................................ .. I I I I I • I I
I I I I
:: ~~------~ , , , ,
20 40 60
Average Quality
o x
Q=O
Q=3
• Q=lO
80 100
Figure 5.5 Void fraction vs. average quality using R410A in a 6.12 mm inner diameter smooth tube. Test section heat flux (Q) given in W/m2•
d o .... ... ~ "0 .... o >
1
0.8
0.6
0.4
0.2
o
, , , : M: 0·: , , "- ' , O : 0 ~'D .: : I I • •
-~--PC-D---- --- ----1--- --- --- -- --- -1- ------------ --1--- --- ---- -- --I • I I
O I I • •
• I I I I I I I I I I I
I I I I -B--- .. -_ .. _ ....... !- -- .......... - ..... -- ..... -~ .. - ......... -_ ...... -_ ...... ~-- --- --- ................ ~- ....................... .. I • , I
I I I I , , , , , ,
, , o D=4.26mm Rl34a -------------~---------------T---------------, , , , , , , , o D=4.26mm R410A
-------~----II---~- ... -------,------~-!-II------!---------~---------~-------I • I 0 I I • I I • I I I I I
• I I I , I
: • I , I I I I
............................................ : ......................................... -~ ....................... -;_ ..................... ~- ...................... ~ ................... .. • I I I , I
I I f I I I
I I I I I I
0.65 0.7 0.75 0.8
Ahrens-Thorn
.
0.85 0.9 0.95 I
Figure 5.10 Void fraction vs. Ahrens-Thorn correlation for 6.12mm inner diameter smooth tube using RI34a and R41OA. Mass flux (G) is in kglrn2s.
I I I , I 0.7 .............. --: ............. -_ ... : ........ _ .... -: .. _ .......... --: ................. -:- .... ... • G=75R41OA , I , I I
I I t I I , • G=200R41OA 0.65 • G=500R41OA
O. 6 ~..L...L..J.-L...J.-1--L...JL.......L....L.-L....L.-L...L...L..J.-L....L.....L-'-'--L...JL.......L....L.-L....L.-L...J.-L...L...L....L...JL.......L...~J-.J
0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1
Premoli Correlation
Figure 5.15 Void fraction vs. Premoli correlation for 6. 12mm inner diameter smooth tube using R134a and R410A Mass flux (G) is in kglm2s.
1
0.9
0.8
0.7
0.6
0.5
• • • ••••••••••••• ~r ••••••••••••
,
, ---_ ....... _--- ..... --. , , , , , , , .
--------------.---------------~
0.6 0.7 0.8
Hughmark Correlation
0 G=75 R134a 0 G=200R134a <> G=500R134a
• G=75R41OA
• G=200R410A
• G=500R410A
0.9 1
Figure 5.16 Void fraction vs. Hugbmark correlation for 6. 12mm inner diameter smooth tube using R134a and R410A Mass flux (G) is in kglm2s.
42
1
0.9
s:: 0.8 0 .,:1
~ ~ 0.7 ~ .... 0 >
0.6
0.5
0.4
0.4
? 0 • , t I • Q I -----------i ------------i-------------t -----~ ----:t:lI-. -0-0 • f ----------: : • : I
0.5 ........................ ~ .. a ................... ! ........................... ~- ........................ "':- ................... .. I I I I I I • I
I , I I
I I • I I • , I
0.4
0.4 0.5 0.6 0.7 0.8 0.9 1
Wallis Correlation
Figure 6.13 Void fraction vs. Wallis correlation for 7.25 mm and 8.93 mm base diameter axially grooved tube using R134a and R410A
O 6 r------------.-~---------------~---------------!---------------!---------------. : : : ; I I • I
I I • I
I I • I I I • I I • • I I • I I I , • ,
0.4 -_ ........................ -t ............................... -r ............................ -~ ................................. ~- ........................... --I I I I I I • I
Figure 7.2 Void fraction vs. average qUality using R134a in a 8.93 mm base diameter 18° helically grooved tube. Mass Flux (G) given in kglm2s.
60
= o .... .... ~ tt '0 .... ~
1
0.8
0.6
0.4
0.2
! ! ! ~x U'
: I 0; : i 4'x 8'f i i --- --- --- --- ---k----- -0- -- --- -:-- --- --- --- --- --;- --- --------- ---;- ----- ------ ---
'.0: : : : X: : : : ~: : : :
I I I I r-" -- ........ -- .. -_ .. ~- .. -_ .. -_ .. --- -_ .. -~ ........ -_ .. -.... -_ .. -- ~ _ .......... -_ ... -- .... - .. ; .... -_ .. -_ .. -_ .. ---I I I I I I I I
Figure 7.4 Void fraction vs. average quality using R134a in a 8.93 mm base diameter 18° helically grooved tube. Test section heat flux (Q) given in W/m2•
Figure 7.5 Void fraction vs. average quality using R410A in a 8.93 mm base diameter 18° helically grooved tube. Test section heat flux (Q) given in W/m2•
I I I I I I I I I I .. -- .... -.. 1--~---- .. : ..... -- ...... ~ .... ---- .. -f .. --- .... -- .. f-- .... -.. ---r-- .... -----r- .... -.... -• I I , I I I
0.65 0.7 0.75 0.8 0.85
Wallis Correlation
0.9 0.95 1
Figure 7.10 Void fraction vs. Wallis correlation for 8.93 mm base diameter 18° helically grooved tube using R134a and R41OA. Mass flux (G) in kglm2s.
If the mass flux was non-dimensionalized by Gref = 300 kglm2s the new fit is
* 2( Ft J ( Ft J a = -0.0062 In G£ + 0.0935 * In G£ + 0.6726 /G ref /Gref
(8.5)
This fit is accurate to within 10% with an average deviation of 2.15%.
8.2.2.2- Axially Grooved Tubes
The micro-finned tubes experimental void fraction appeared to show mass flux
dependence, but not as strong as that seen by Graham[I998] for condenser operation in
the wavy-stratified range. In order to account for this dependence the Froude rate must
be adjusted accordingly to have a small dependence on mass flux.
When trying to correlate the axially grooved tube data against FtlG three curves
appeared for the three different mass fluxes used. Recalling Figure 6.3 and 6.4 the axial • tubes showed void fraction to vary with Ihass flux. The data is re-correlated with FtlG213
as the governing parameter to leave some mass flux dependence in the correlating
parameter. This collapses the data nicely, but a diameter dependence appears. This
diameter dependence is also shown in Figure 6.6. Rearranging the correlating parameter
the new parameter is Ft*D/G2I3• A plot of void fraction versus this new parameter is in
Figure 8.14 and the corresponding curve fit is
73
(8.6)
Non-dimensionalizing with respect to Gref and adding a reference diameter Dref = 8.00 mm,
the new correlation is
ex = -o.0105*ln2
D Ft*-
D ref 2
(G:Y
D Ft*--
+0.1200* In Dre~ +.6473
(G:Y (8.7)
It is found that this correlation is accurate within 10% with an average deviation of 2%.
Plots in Appendix D show that the data is well scattered with respect to refrigerant,
diameter, and mass flux.
8.2.2.3- Helically Grooved Tubes
The helically grooved tube when plotted against FtlG showed three lines with
respect to each mass flux used in the experiment. When reducing the strength of the
den~minator the void faction is found to correlate well with respect to FtlG2I3. A plot of
void fraction versus FtlG2/3 appears in Figure 8.15 and the corresponding curve fit is
(8.8)
If the reference mass flux is used the correlation becomes
74
ex = -0.0035 * In 2 Ft Ft
-( -G-J%-:-3 + 0.0883 * In -( -G-J%-:-3 +.6808
G ref Gref
(8.9)
This correlation correctly predicts the data to within 14.6% with an average deviation of
2%. If the most outlying data point is removed the correlation is accurate to within 8%.
8.3- Conclusions
Many observations were made during this study of void fraction in evaporation. In
smooth tubes it was found that void fraction was not dependent on mass flux. In axially
grooved tubes void fraction is dependent on both mass flux, and diameter. In helically
grooved tubes void fraction is dependent on mass flux, but not diameter. The correlations
described above can be used to determine the void fraction to within 10%.
Figure 8.15 Void fraction vs. FtlG2/3 for helically grooved tube.
83
.
10
Bibliography
Ahrens, F.W. 1983. "Heat pump modeling, simulation, and design." Heat Pump Fundamentals. Proceedings of the NATO Advanced Study Institute on Heat
Pump Fundamentals, Espinho, Spain, 1980. I. Berghmans, ed. The Hague, Netherlands: Martinus Nijhoff Publishers.
Bankoff, S. G. 1960. "A variable density single-fluid model for two-phase flow with particular reference to steam-water flow." Transactions ASME, Journal of Heat Transfer, Vol. 82, pp. 265-272.
Baroczy, C. I. 1965. "Correlation of liquid fraction in two-phase flow with application to liquid metals." Chemical Engineering Progress Symposium Series, Vol. 61, No. 57, pp. 179-191.
Christoffersen B.C. 1993. "Heat transfer and flow characteristics ofR-22, R-321R-125, and R-134a in smooth and micro-finned tubes." M.S. Thesis, University of illinois.
De Guzman N.M. 1997. "Evaporative heat transfer characteristics in a vertical channel with obstructions." M.S. Thesis, University of TIlinois.
Dobson, M.K. 1994. "Heat transfer and flow regimes during condensation in a horizontal tube." Ph.D. Dissertation, University of TIlinois.
Domanski, P., and D. Didion. 1983. Computer Modeling of the Vapor Compression Cycle with Constant Flow Area Expansion Device. NBS Building Science Series 155.
Graham, D.M. 1998. "Experimental investigation of void fraction during refrigerant condensation." M.S. Thesis, University of TIlinois.
Hughrnark, G. A. 1962. "Holdup in gas-liquid flow." Chemical Engineering Progress, Vol. 58, No.4, pp. 62-65.
Hurlburt, E. T. and T.A. Newell. 1997. "Prediction of the circumferential film thickness distribution in horizontal annular gas-liquid flow." Submitted to Int. I. Multiphase Flow.
Larson, H. C. 1957. "Void fractions of two-phase steam watetmixtures." M.S. Thesis, University of Minnesota.
Levy, S. 1960. "Steam slip- theoretical prediction from momentum model." Transactions ASME, Journal of Heat Transfer, Series C, Vol. 82, pp. 113-124.
84
Lockhart, R. W. and R. C. Martinelli. 1949. "Proposed correlation of data for isothermal two-phase, two-component flow in pipes." Chemical Engineering Progress, Vol. 45, No.1, pp. 39-48.
Maurer, G. 1960. "A method for predicting steady-state boiling vapor fractions in reactor coolant channels." Bettis Technical Review, W APD-BT-19.
Martinelli, R. C., and D. B. Nelson 1948. "Prediction of pressure drop during forcedcirculation boiling of water." Transactions ASME, Vol. 70, pp. 695-702.
NIST 1993. "NIST Thermodynamic properties of refrigerants and refrigerant mixtures", version 4.01. Computer software. National Institute of Standards and Technology.
Panek J.S. 1992. "Evaporation heat transfer and pressure drop in ozone-safe refrigerants and refrigerant oil mixtures." M.S. Thesis, University of Illinois.
Ponchner, M. 1995. "Condensation of HFC-134a in an 18_ helix angle micro-finned tube." M.S. Thesis, University oflllinois.
Premoli, A., D. Francesco, and A. Prina. 1971. "A dimensional correlation for evaluating two-phase mixture density." La Termotecnica, Vol. 25, No.1, pp. 17-26.
Rice, C.K. 1987. "The effect of void fraction correlation and heat flux assumption on refrigerant charge inventory predictions." ASHRAE Transactions, Vol. 93, Part 1, pp.341-367.
Smith, S. L. 1969. "Void fractions in two-phase flow: a correlation based upon an equal velocity head model." Proc. Instn. Mech Engrs., London, Vol. 184, Pt. 1, No. 36, pp. 647-664.
Tandon, T. N., H. K. Varma, and C. P. Gupta. 1985. "A void fraction model for annular two-phase flow." International Journal of Heat and Mass Transfer, Vol. 28, No.1, pp. 191-198.
Thorn, J. R. S. 1964. "Prediction of pressure drop during forced circulation boiling of water." International Journal of Heat and Mass Transfer, Vol. 7, pp. 709-724.
Wallis, G. B. 1969. One-Dimensional Two-Phase Flow. New York: McGraw-Hill, pp. 51-54.
Wattlet, J.P. 1994. "Heat transfer flow regimes of refrigerants in a horizontal-tube evaporator." Ph.D. Dissertation, University of lllinois.
Yashar D.A 1998. "Experimental investigation of void fraction during horizontal flow in smaller diameter refrigerant applications." M.S. Thesis, University of lllinois.
85
Zivi, S. M. 1964. "Estimation of steady-state steam void-fraction by means of the principle of minimum entropy production." Transactions ASME, Journal of Heat Transfer, Series C, Vol. 86, May, pp. 247-252.
86
Appendix A
Smooth Tubes
This appendix presents raw data taken for the 6.12 mm smooth tube. The 4.26
mm smooth tube data appears in Yashar. Data will be presented first in tabular format,
and second in graphical forms.
87
Table A.l Raw data for 6.12 mm inner diameter smooth tube.
-- ......... 0. ............ : ... _-_ .......... - .. ----- ... !.. ... _ .. _- -- ....... - -- --: ........ _ .. ----- .. --- --: ..... - .. - ...... -_ ........ --I I • I I I I • I I • I I I • I I • • I
: : : : : : : :
-------------- .. 1 .. --------------~--------- .. -----T------- --------! .... --- ...... -------I : I : · . . · . . : : : · . . I : I I
: I : I ~- ............................ ,. .............................. -:- ............................ -, ............................... -:- ............................. -
Figure A.l Void fraction vs. average quality with a heat flux of 0 W/m2 using R134a in a 6.12 mm inner diameter smooth tube. Mass flux (G) given in kglm2s.
s .... ... ~
d;: "t:I .... o >
1
0.8
0.6
0.4
0.2
o o
. . • 0:
I x: , I I I t O. I I I .. -...... -~-- f ...... -...... --------f------------- .. 1---------------1-- .... ----_ ...... _-I I I I I I I • I I I I
• I I I · .. · .. · .. --- .. -.. -------~------- .. -------~---------------~-------- -------T-------------
• • • I
-------------~---------------T---------------r---------------~-------------I I I I I I I I
Figure A.2 Void fraction vs. average quality with a heat flux of 3 W/m2 using R134a in a 6.12 mm inner diameter smooth tube. Mass flux (G) given in kglm2s.
90
1
0.8
0.6
0.4
0.2
o
! ! ! ! • X I • 0: I
: • X : : 0: I :
I I I I
t--- ..................... ¥ ........................... -:- ............................. ~- ............................... ~ .......................... --o 0 o 0 o 0 o
o o
o 0 0 I I I I
~-------------~---------------~---------------~---------------~---------------I I I I I I , • I I , ,
I I I I I I I I I I • I I I I • o 0 0
---------------~---------------f---------------f---------------~----------------I I , I I I • ,
: : : ,...---0 ___ ...
o G=75 o 0 0
---------------:---------------~---------------r------- x
• G=2oo 1-
G=5oo 0 0 0 o 0 0
o 0 0 o 0 0
o 0 0
o 0 0
i i i I
o 20 40 60 80 100
Average Quality
Figure A.3 Void fraction vs. average quality with a heat flux of 10 W/m2 using R134a in a 6.12 rom inner diameter smooth tube. Mass flux (G) given in kglm2s.
o 0 0 o 0 0 ---- .. --- .. -.. -.... -~----- .. -.. -------~---------------!-------0 0
o 0 o 0 o 0 o 0 o 0
i i i
o 20 40 60 Average Quality
o x •
I
80
G=75 G=2oo -
G=5oo
100
Figure A.4 Void fraction vs. average quality with a heat flux of 0 W/m2 using R410A in a 6.12 rom inner diameter smooth tube. Mass flux (G) given in kglm2s.
91
1
0.8
0.6
0.4
0.2
! , , , , ! ! , ,
,
~'U
• , I I : ~ 0: : : ~~-------------~---------------~--------------~------- --------,----------------
x
• o. . I I , , , ,
, , o 0 0
---------------~---------------~---------------~------- --------:---------------I I I I I I I I I t I I I I I I o 0
o 0 , , o ,
---------------~---------------!---------------~---------------~---------------I I I I I I I I : : ~--~o------~ , , , , , , , , ,
Figure A.5 Void fraction vs. average quality with a heat flux of 3 W/m2 using R410A in a 6.12 mm inner diameter smooth tube. Mass flux (G) given in kglm2s.
c: o .:;1
~ ~ "0 .~
.0 >
1
0.8
0.6
0.4
0.2
! ! ! !.' I I I I
• 0 o 0 . o· x: 0
I ~: : I -_ ..................................... ~ ................................... -:- .................................... -:- .................................... -:- ............................... --
x: : : : I • I I . : : : : I • • I I I I I
• • I I , I I I
r--------------~---------------~---------------!- ... -- ......................... -.. ~- ...... -.. -.. -- ...... --• I I • • I • I • • I I I I I I O. 0 o. 0 o. 0 o. •
• I I I : : : .------------.1 · . , o 0 0 o 0 0 · , . o 0 0 r-- .. -...... -.. -........ -~ ..... -........ -- ... -- .... -.. ~ .. -... -...... -- ....... -..... ~ .. -... -- .... --o 0
• 0 · . o 0 o 0 · .
o 20 40 60 Average Quality
a x
•
80
G=75 G=200 G=500
100
Figure A.6 Void Fraction vs. average quality with a heat flux of 10 W/m2 using R410A in a 6.12 mm inner diameter smooth tube. Mass flux (G) given in kglm2s.
92
§ .'= ~ tt '0 ..... o >
1
0.8
0.6
0.4
0.2
! ! , ! .: x: · 0 e: I I I I I ,
_ .......... Goo ........ x ~ ............................... :. ............................ -:- ............................. -: ............................ -I I I I , , , o 0 0 o 0 , o 0 0 o 0 0 o , , o 0 0 I • I • I • t I
r--------------~---------------~ .. --------------!---------------!------ ...... ------• I I I , • I • , I I I
• I I I • , I I o 0 0 o 0 0 o 0 0 -_ ......................... -~ .............................. -~ ............................. -~ ................................ -:- ........................... --I I I I I I I • I , I • : : : .--_001...-__ -.
Figure A.7 Void fraction vs. average quality with a mass flux of 75 kglm2s using RI34a in a 6.12 mm inner diameter tube. Heat flux (Q) in W/m2•
§ ..... -~ tt :s o >
1 ! o
! , ! , cpx • • I ox: , • I I I
0.8 r-- ............................................................. :. ............................. -:- ............................... : .................................. -X I I I I
o : : o 0
o 0 o 0 o 0 o 0 0
0.6 I I • I
r--------------~--- ... ------ ... -... --~- ...... ----- ............ -... -~ ... ----- ... --------:---------------· . . . • • I I I I I I I • I I I • I I
• • I I • I I I I • • I
0.4 I I I I ---...... --......... ---... -~ ...... -.. -... ---.. -----:- ............. ---...... -....... -:- ........... ---... ---... ---:- ... -......... --................. -I I I I
, " -- .. -_ ... -_ ......... -_ .. ~- .. --- -_ .. ----_ .... ~ ... _-_ .. -_ ....... -_ .. -- ~ -_ .. -_ .. -_ .. -_ ........ ;_ ......... -_ ........ ----I I I I I I I I
I t I •
I I I I I I I I I I I •
I I I I , • I I
f--- .......................... ~ ................................ -~ ............................. -:- ............................. -:- ........................... -I I I I
Figure B.l Void fraction vs. average quality with a heat flux of 0 W/m2 using R134a in a 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s.
Figure B.2 Void fraction vs. average quality with a heat flux of 3 W/m2 using R134a in a 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s.
105
c:: o ...... ~ ~ "0 .-o >
1 ! ! ! ! u ,
0 , , ,
0 , , , ,
0 0 , , , I I I •
0.8 <> I I I I
i.....-_ .................... '0 .. ~ ............................ _~ ............................ _~ ............................ _;_ .......................... _ I I I I
I I I I
I I I I I I I I
I I , I
I I I I
" , I I I I
0.6 1-- .......................... ~ ............................... ~ .............................. ~ .............................. ~ .......................... -I I I I • I I I
Figure B.3 Void fraction vs. average qUality with a heat flux of 10 W/m2 using R134a in 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s.
Figure BA Void fraction vs. average quality with a heat flux of 0 W/m2 using R410A in a 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s.
106
1 ~~~~~~~~~~~~~~~~~~~~~~ l l l lx l!) · . · . · . • , • I
0.6 I I • I -- .. -.. -- .. -.. ---- .. ~ .. ------------- .. ~-- ...... -.. --------! .. ------ -----_ .. _;---------------• I I • • , I • • , I I I I • I · .. · .. , " .. .
Figure B.5 Void fraction vs. average quality with a heat flux of 3 W/m2 using R410A in a 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s.
1
0.8
0.6
0.4
0.2
o
! ! ! ! x , · , , , · · · : a · · , , ex · · : · · , ,
, I • I -_ ........................... ~ ...... 0 ............... ..... -:- ................................ -:- .............................. -: ............................. -• • • I
X : : : : e : : · , · . I • I I
I I I I
~- .. -.. ------ .. -.. ~ .. --- .... -- .. ---- .... ~- .. ------------ .. ~------- --------;---------------I I I I , I • I
Figure B.6 Void fraction vs. average quality with a heat flux of 10 W/m2 using R410A in a 8.89 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s.
Figure B.7 Void fraction vs. average quality with a mass flux of 75 kglm2s using R134a in a 8.89 mm base diameter axially grooved tube. Heat flux (Q) in W/m2_
c: o .= ~ ~ -0 .... ·0 >
1
0.8
0.6
0.4
0.2
e: , 0>< , I I I I
................................ ~ .............................. ........ !,. .................................... :.. ................................... -:- ........................... .. • • I I
Figure B.8 Void fraction vs. average quality with a mass flux of 200 kglm2s using R134a a 8.89 mm base diameter axially grooved tube. Heat flux (Q) in W/m2•
Figure B.9 Void fraction vs. average quality with a mass flux of 500 kglm2s using R134a in a 8.89 mm base diameter axially grooved tube. Heat flux (Q) in W/m2•
Figure B.1O Void fraction vs. average quality with a mass flux of75 kglm2s using R410A in a 8.89 mm base diameter axially grooved tube. Heat flux (Q) in W/m2•
109
1
0.8
0.6
0.4
0.2
o
• • I I
: . : : : ............................ ~ ............ &- .... ....... :., ............................... :- ............................... : ............................. -I I I I . : : : :
o 0 0
o 0 0 o 0 0 _x 0 0
-----~~-----,------ .. --------~ .. --------------~------ .. -.. ------1-------------I I I I
• I I I I I • I , I I I
, I I I I • I I I • I I
If' I o 0 0
I I • I ............................... po .......................... ........ ,.. ............................................................... -.- ............................ ...
o 0 0
o 0 0
o 0 0
-------------,------------ .. _ .. ,---------------.-------o 0 0 o 0 0 o 0 0
o 0 0 o o o o
20 40 60
Average Quality
o x
•
o
80
Q=O
Q=3
Q=lO
100
Figure B.ll Void fraction vs. average quality with a mass flux of 200 kglm2s using R410A in a 8.89 mm base diameter axially grooved tube. Heat flux (Q) in W/m2•
1
0.8
0.6
0.4
0.2
o
! ! ! ! 0 0 0 0
0 0 0 0
0 0 0
C!I' 0
0 : 0 0 , I • I
~- ............................. ~ ............................. -:- ............................ ""!- ............................... ~ ............................... -• I • I I t I I
I I I I
ttl' ~ ~ : ~ • • I I I I I I -------- .. ------~---------------~--- .. -----------~------- --------:---------------I I I I , , I f
f , I •
• I I • I , , ,
I , • •
I I I I o 0 0
~------.------~---------------!---------------:.--.-----------~---------------I • I • I • • I
: : : ~ __ o ______ ~
o 0 0 o 0 0 o 0 0
---------------!---------------~---------------~------- --o 0 0 o 0 0 o 0 0
o 0 0 o 0 o 0 o 0
i i i
o 20 40 60
Average Quality
o x
• 80
Q=O Q=3
Q=1O
100
Figure B.12 Void fraction vs. average quality with a mass flux of 500 kglm2s using R410A in a 8.89 mm base diameter axially grooved tube. Heat flux (Q) in W/m2•
... ----~---------~---------.---------~---------!---.----~~iE1------~-------I I I I • I I I I I I • I , • , • I • I I
I I I , I I I
...................... ~ .......................... ' ..................... ~ ....................... :.. ........... -..... : ......... Q .. :- ................... :- ............. .. I I I I • I I • , • •• I I I
: : : .: : : :
0.65 0.7 0.75 0.8 0.85 0.9 0.95
Homogenous Correlation
1
Figure B.13 Void fraction vs. homogenous correlation for 8.89 mm base diameter axially grooved tube using R134a and R41OA. Mass flux (G) in kglm2s.
1
0.9 o D=7.25 mm Rl34a
o D=7.25 mm R410A
c:: 0.8 0 .,:j
~ tt 0.7 "0 .... 0 '>
D=8.89 mm Rl34a
• D=8.89 mm R410A ~ 0 0
: : : : rP im -----------:-------------;----------- . -------0-,.-'---r1'-- :-----------: : : .: I I I I I • I I I I I I
•
0.6 ----------~----------- I ------- ... --rj-------------~------------~----------I I I I
I •• I I : ' .~ 0: ........ I ................ _:_ .... _~ ...... :_ ................... _:_ ............ ..
: 0 :-.: : I I I •
I I I I • I I
.... -----~---------~---------f -.------ .. ~ .. ---E3-!---------~---------~-------I I I • I I I
~ 0.75 • I I • I • I • I • I , I •
O 7 ----- ---~ -------- .. : ~- .. -_ .. ~--- ---- .... FJ---- ----~----- .. -_ .. -~- .. -.... ----~- --- -...... . """ I I I I I I I I I I I I I I I I I I
0.65
O. 6 1oLL-J....J....L...l......L-.J.....L...L....L....J....J.....L....L-J....J....L...l......L....L...L...L....L....J....J.....L.-L-~"'_'_ .............. ...L...L....L....J....J.....L....I
0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 I
Rigot Correlation
Figure B.15 Void fraction vs. Rigot correlation for 8.89 mm base diameter axially grooved tube using R134a and R410A. Mass flux (G) in kglm2s.
I I I I I ........ --- ..... :0- ........ ----:- ............. --- I ............................................. " ........................ I ................... _ .
o D=7.25mm R134a --E3---~----------' ---------~--- o D=7.25mm R410A
e D=8.89mm R134a
· . . • • I · . . · . I I · .
0.4 0.5 0.6 0.7 0.8 0.9
Zivi Correlation
1
Figure B.l8 Void fraction vs. Zivi correlation for 7.25 mm and 8.89 mm base diameter axially grooved tubes using R134a and R41OA.
Figure B.25 Void fraction vs. Graham's condenser correlation for 8.89 mm base diameter axially grooved tube using R134a and R41OA. Mass flux (G) in kglm2s.
Figure C.I Void fraction vs. average quality with a heat flux of 0 W/m2 using R134a in a 8.93 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s.
Figure C.2 Void fraction vs. average quality with a heat flux of 3 W/m2 using Rl34a in a 8.93 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s.
------ .. -.. -.. ----~---------------~----- .. ------- .. -~---------------:------_ ........ _ .. --I • I I . . , , • , , I
I I I I , , , roo ........................... ~ ............................. -~ .............................. -:- .............................. -:- ........................... -
Figure C.3 Void fraction vs. average quality with a heat flux of 10 W/m2 using Rl34a in 8.93 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s.
Figure C.4 Void fraction vs. average quality with a heat flux of 0 W/m2 using R410A in a 8.93 mm base diameter axially grooved tube. Mass flux (G) given in kglm2s.
Figure C.S Void fraction vs. average quality with a heat flux of 3 W/m2 using R410A in a 8.93 mm base diameter axially grooved tube. Mass flux (G) given in kg/m2s.
Figure C.6 Void fraction vs. average quality with a heat flux of 10 W/m2 using R410A in a 8.93 mm base diameter axially grooved tube. Mass flux (G) given in kg/m2s.
123
1
0.8
0.6
0.4
0.2
o o
: ! • x· : . . : 0: : :
.................................... ~- .................................... :.. ........................................... : .......................................... -:- ................................... .. • I I I I I I I I , I I , I I I
a : · · . · . -------------,---------------~---------------~---------------~-------------• I I I I I I ,
• I I I , , • I
I I f I I • I I I • I I
I I I I I I I I I I I ,
...................................... r .................................... -r ....................................... -,- ......................................... -,- ................................ ...
Figure C.7 Void fraction vs. average quality with a mass flux of 75 kglm2s using RI34a in a 8.93 mm base diameter axially grooved tube. Heat flux (Q) in W/m2•
Figure C.8 Void fraction vs. average quality with a mass flux of 200 kglm2s using RI34a a 8.93 nun base diameter axially grooved tube. Heat flux (Q) in W/m2•
124
1 ! ! ! ! , , , , , , , , · · · , · · . · · · . · 0.8 I , I I
~ ............... ~ .................. ~ ................................... ...... -:-- ........................................ -:- .......................................... -: ....................................... -• I I I
o • I • I
0.6 -- ...... -... ---- ......... --1----- ...... -...... -...... --1------ ..................... -... t---- ......... -- ... --- ...... f-- .................. --- ...... --I I • I I , • I , I I I I • I I I I , •
Figure C.9 Void fraction vs. average quality with a mass flux of 500 kglm2s using R134a in a 8.93 mm base diameter axially grooved tube. Heat flux (Q) in W/m2•
1
0.8
§ .... -~ d::
0.6
'0 .... . ~ 0.4
0.2
! · · · ! ,
, . ! · e:
· x: : I
X'
• .• ' I I ~ ......................................... ~ ........................................ ~ ...................................... -!.. .......... ............................. -! ..................................... --
Figure C.1O Void fraction vs. average quality with a mass flux of75 kglm2s using R410A in a 8.93 mm base diameter axially grooved tube. Heat flux (Q) in W/m2•
Figure C.ll Void fraction vs. average quality with a mass flux of 200 kg/m2s using R410A in a 8.93 mm base diameter axially grooved tube. Heat flux (Q) in W/m2•
1
0.8
0.6
0.4
0.2
o
! ! ! ! It. I · . · . .
I I I I · . : (j<: : :
~- ............................. ~ ............................. -;- ............................... -: .................................. -:"' ............................. -I I • , cS· . . . . , I I I .. . .. . .. . · . I I , I
I I I I ------- .. -- .. --- .. ~-- .. - .... --- .. --- .. -~--- .... - .. --------~ .. - .. ---- ...... _----!"' .......... _- .......... --I I I I · .. · .. · .. · .. · .. · .. · .. , , I I 1---- - ..... - -- - -_ ......... :- ........ - ............... - ............... i ......... - - ......... -- .............. : ...... _ .............. -- ................. :- ............ - - ................ -I I , ,
Figure C.12 Void fraction vs. average quality with a mass flux of 500 kg/m2s using R410A in a 8.93 mm base diameter axially grooved tube. Heat flux (Q) in W/m2•
126
1
0.95 0 R134aG=75
0.9 0 R134aG=200 <> R134aG=500
---;- -------- -;-- -------. --- ------;- --fB--I , I I
I I I I I I I I
s:: 0.85 0 .,:::
~ ~ 0.8 '0 .... 0 > 0.75
• R41OAG=75
• R41OAG=200
•
I I I I ---:----- ----: --- ------ :-- ----t"! ------: ! : 0 -. 0 --; --------+ ---------j- ---.. i\ -------___ . ___ . ___ . _.0;1: : <? :
I I I I I I I .............. : .................. : .................. : .................. : .................. ! .... ii" .... ~ : -8- .......... ; ............ .. I I I I I I I
I I • I I I I
0.7 I I I I I I I -- .. -_ .. --~ -_ .. --- ---: -- -_ .. -_ .. -~ ........ -_ .. --~ -_ .. -.. -- -:* ...... -t:t;- .. -_ .. -- .... -;- -- .. -- .... I I I '. I , I : : : .: : : :
0.65
0.6
0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1
Homogenous Correlation
Figure C.13 Void fraction vs. homogenous correlation for 8.93 mm base diameter helically grooved tube using R134a and R41OA. Mass Flux (G) given in kglm2s.
------ -----;- --- ---------: -- ----------: ------- -0 -tt-·--- [JI- -if----------l ~ ~ • ~ I I I •
I I I I
0.6 -_ .. -_ .. --- .... ~ ............... _--- .. :- ............ -......... d- -- .... -.. -- ........ : .... -- ................ : ........ -- ........ .. I I I I I I I I I •
I I , I •
I I I I I I I I I I .
0.5
0.4
0.4 0.5 0.6 0.7 0.8 0.9 1
Homogenous Correlation
Figure C.14 Void fraction vs. homogenous correlation for 7.25 mm and 8.93 mm base diameter helically grooved tubes.
Figure C.19 Void fraction vs. Ahrens-Thorn correlation for 8.93 mm base diameter helically grooved tube using Rl34a and R41OA. Mass Flux (G) given in kglm2s.
Figure C.21 Void fraction vs. Baroczy correlation for 8.93 mm base diameter helically grooved tube using R134a and R41OA. Mass Flux (G) given in kglm2s.
i i o.~ i -------------: ---------------: -----<i -.,:: -.- --. ---------------: -------------
I • '!:1' I I : : . : . ..0 -- --- --- --- ---~ -- --~- -.-- --- -: ----- -- --- ---. .
:IJI •
0.6 0.7 0.8
o o <>
•
R134aG=75
R134aG=200
R134aG=500
R41OAG=75
• R410A G=200
• R41OAG=500
0.9
Hugbmark Correlation
1
Figure C.23 Void fraction vs. Hughmark correlation for 8.93 mm base diameter helically grooved tube using R134a and R410A. Mass Flux (G) given in kglm2s.
1
0.9
I:: 0
0.8 ..... ..... ~ ~ "0 .....
. ~ 0.7 0 D=7.25mm R134a 0 D=7.25mm R410A
0.6 • D=8.93mm R134a
• D=8.93mm R410A
0.5 0.6 0.7 0.8 0.9 1 Hugbmark Correlation
Figure C.24 Void fraction vs. Hughmark correlation for 7.25 mm and 8.93 mm base diameter helically grooved tubes.
Figure C.25 Void fraction vs. Graham's condenser correlation for 8.93 mm base diameter helically grooved tube using R134a and R41OA. Mass Flux (G) given in kglm2s.