Greek Letters ?ri = the number fraction of particles in cell i U N ~ , I J O= ~ mixture variances at t = NT and t = 0, respecti1Y IC, = variance reduction ratio
Chen, S.J., Fan, L. T., Watson, C. A,, J. food Sci., 36,688 (1971). Chen, S.J., Fan, L. T.. Watson, C. A,, A G M J . , le(5).984 (1972). Iirotie. Y., Yarnaguchi, K.,Kagaku Kogaku, 33, 286 (1969). Lacey, P. M. C., Trans. lnst. Chem. Eng., 21,53(1943). Lacey, P. M. C.. J. Appl. Chem., 4, 257 (1954). Pattison, D. A., Chem. €ng., 11, 94 (1969). Parzen, E., "Stochastic Processes", HoMenDay, Inc., San Francisco, Calif.,
1962.
L i t e r a t u r e Cited
Received for review October 29,1974 Accepted M a y 19,1975
Armeniades, C. D., Johnson, W. C., Raphael, T., mixing device, U.S. Patent
3,286,992(1965).
Evaporation Heat Transfer Coefficients for Thin Sea Water Films on Horizontal Tubes Leroy S. Fletcher,"
Valentlnas Sernas, and Walter H. Parken
Mechanical, Industrial and Aerospace EngineeringDepartment, Rutgers University, New Brunswick, New Jersey 08903
Evaporation heat transfer coefficients are presented for thin sea water films flowing over the outside of horizontal copper-nickel desalination tubes. Tests were conducted using both 1.O- and 2.0-in. diameter electrically heated smooth tubes, as well as a 2.0-in. diameter electrically heated knurled tube. Heat transfer data were obtained for saturation temperatures ranging from 120 to 26OoF, with feedwater flow rates up to I 105 Ib,/hr-ft of tube length and heat fluxes up to 20,000 Btu/hr ft2. Some boiling of the film was observed. The experimental heat transfer coefficients for the evaporation process are presented, discussed, and compared with previously reported data.
Introduction The horizontal tube multiple effect (HTME) desalination system concept incorporates a series of horizontal tube bundles with brine evaporating from a thin film on the outside of the tubes and steam condensing on the inside of the tubes. The brine film on the outside of each horizontal tube is formed by dripping or spraying the brine over the tube bundle. The latent heat for evaporating the brine film is provided by condensing steam on the inside of the tubes. Cannizzaro et al. (1972) reported limited heat transfer data for a single instrumented tube within a HTME pilot plant tube bundle. The sea water film flowing around the instrumented 2.0-in. diameter smooth tube could not be observed, and no provisions were made to measure the sea water flow rates over the tube. Average flow rates for the complete bundle were reported as the flow rates for the instrumented tube. The primary conclusion of the investigation was that the controlling factor in the overall heat transfer coefficient for the tube was the heat transfer coefficient for the sea water evaporation side of the tube. Although their efforts produced some data for tubes within tube bundles, the nature of their experimental facility did not permit investigation of the various factors influencing the evaporation heat transfer coefficient. In the present investigation, a well controlled systematic study was undertaken to evaluate the influence of the various factors on the evaporation coefficient of a single tube with a sea water film, without the interference of adjacent tubes within a bundle. The factors investigated in this Address correspondence t o this author a t the Department of Mechanical Engineering, University of Virginia, Charlottesville, Va. 22901.
study included the sea water flow rate, the heat flux, the tube diameter, the tube surface enhancement, and the saturation temperature. An experimental investigation of the evaporation occurring in thin distilled water films flowing ovel smooth horizontal tubes reported by Fletcher and Sernas (1972) and Fletcher et al. (1974) formed the initial portion of this study. The evaporation of sea water films flowing over horizontal tubes was studied for both smooth and knurled tubes by Parken et al. (1973), and the results are presented in this paper. Experimental Investigation The experimental facility used in this investigation has been described previously by Fletcher and Sernas (1972) and Fletcher et al. (1974). The single tube thin film evaporation test facility consisted basically of the evaporation tube with the surrounding chamber, a recirculating feedwater system, and associated control systems. The feedwater distribution on the evaporation tube is shown schematically in Figure 1. Three evaporation tubes were assembled and instrumented for testing, and their characteristics are noted in Table I and Figure 2. The newly manufactured smooth tube surface was polished with a medium coarse steel wool (no. 2 grade). The construction of the smooth tubes was reported by Fletcher et al. (1974). A schematic of the construction and instrumentation of the 2.0-in. diameter knurled tube is shown in Figure 3. The sea water for these evaporation tests was obtained near Long Branch, N.J., one to two days before each set of evaporation tests was started. Samples of this sea water were tested and found to be standard (i.e., 3.45% dissolved solids by weight) as defined by the Office of Saline Water Ind.
Eng. Chem., Process Des. Dev., Vol. 14,No. 4, 1975
411
Steam to
Condenser 11 grooves per i n c h
Figure 2. Details of knurled tube (cf. Table I).
Falling f l l m
-T
(-
Horizontal
P4
Heated Tube
ii Chamber Wall
u Silver Soldered t o Surface
power Leads
I S AWG Dlam Nichrome V
Healer Wire
Figure 3. Schematic of the electricallyheated knurled evaporation
I-
I
tube. Return to Pump
Figure 1. Schematic of the feedwater distribution in the evaporation chamber.
Table I. Evaporation Tube Characteristics
Tube no.
Tube material
1" 2*
90/10 Cu-Ni 90/10 Cu-Ni 90/10 Cu-Ni
Tube diam- Wall Surface e t e r , thickin. ness, in. finish, pin. 1.0 2.0 2.0
0.041 0.032 0.058
30 i 5
25
i
5
Knurledd Sample tube courtesy of Oak Ridge National Laboratory. b Sample tube courtesy of Dr. P. T. Gilbert, Yorkshire Imperial Metals Limited, England. Sample tube courtesy of OSW Wrightsville Beach Test Facility. d See Figure 2 for dimensions of knurled tube. 3'
Specifications for Sea Water (1972). Saturation temperatures were found in the Saline Water Conversion Engineering Data Book (1971). The pH of the sea water was also tested and found to range from 7.6 to 8.2 a t 77OF. After treatment with sulfuric acid, the pH of the sea water was 6.3-6.5. For start-up of the single tube thin film test facility, the feedwater pump was turned on and the sea water was heated a t atmospheric pressure with electrical preheaters to just below the desired saturation temperature. The pH of the sea water was checked, and sulfuric acid was added as required. A pressure corresponding to the desired saturation temperature was imposed upon the system, and the sea water was then heated to this boiling point. The boiling point of the sea water was determined by use of several thermocouples placed in three strategic locations: the sea water inlet to the evaporation chamber, the sea water distribution tray, and the sea water outlet from the 412
Ind. Eng. Chem., Process Des. Dev., Vol. 14, No. 4, 1975
evaporation chamber. The sea water inlet was under slight pressure and was therefore superheated, with respect to the evaporation chamber pressure, by approximately 2 to 3OF. The distribution tray thermocouples were located on the level surface of the sea water in the distribution tray. Since any superheat occurring there would flash, these thermocouples measured the saturation temperature of the sea water. The thermocouple located in the sea water outlet of the evaporation chamber also measured the saturation temperature of the sea water. During the heating of the sea water, electric power was applied to the evaporation tube, and the sea water was allowed to evaporate at the preselected saturation temperature and heat flux for 1-2 hr before data were taken. Temperatures were monitored to ensure that a steady state existed. For each test, saturation temperature was maintained constant while the heat flux and flow rate were varied. At the highest heat fluxes, less than 2% of the feedwater evaporated as it flowed over the tube; therefore the salinity of the sea water in the bottom of the evaporation chamber did not change significantly. When the saturation temperatures measured in the distribution tray and evaporation chamber outlet were equal, these measured saturation temperatures were found to agree within f0.2OF of standard sea water saturation temperatures. Results a n d Discussion The evaporation coefficients were calculated from the electrical power to the evaporation tube and appropriate temperatures as follows
The heat flux per unit area was based on the heated portion of the evaporation tube, and the wall superheat (temperature above saturation point) was determined from the average tube wall temperature and the feedwater saturation temperature.
Table 11. Averaged Experimental Evaporation Data 1.O-in. 90/10 Copper-Nickel Smooth Evaporation Tube
r,
Tsat 7
Q I A,
AT,,
lbdhr-ft
O F
Btu/hr ft2
O F
328
120
328
150
328
180
328
212
328
240
328
260
452
120
452
150
4 52
180
4 52
212
4 52
240
452
260
64 0
120
64 0
150
64 0
180
640
212
640
240
640
260
20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930 20,020 14,900 10,930
20.4 15.2 12.2 17.7 13.8 10.4 11.4 9 .o 8 .O 11.8 10.2 8.1 8.9 7.7 6.9 6.2 5.9 5.6 18.5 13.3 10.8 16.4 12.6 7.9 13.O 10.2 7.9 11.3 9.8 7.6 9.6 7.8 6.7 8.1 6.1 6.5 16.1 11.5 10.0 13.7 11.0 8.8 11.5 93 7.6 10.0 8.6 6.4 9.6 7.9 6.5 8.9 6.7 5.5
he, Btu/hr ft2 "F 981 980 896 1127 1073 1041 1756 1655 1366 1700 1460 1350 2240 1927 1580 3260 2520 1960 1082 1120 1012 1219 1175 1383 1540 1461 1383 1770 1525 1438 2065 1888 1618 2470 2430 1685 1243 1296 1093 1460 1352 1230 1740 1590 1427 2002 1725 1695 2071 1864 1657 2250 2210 1990
During the evaporation tests, individual evaporation tube wall temperatures were observed to fluctuate as much as f1.0"F on the 2.0-in. tubes and f0.5"F on the 1.0-in. tube. Thermocouple data, however, were time-averaged over a 10-sec period with a Hewlett-Packard digital voltmeter and recorded by means of a Kaye thermocouple recorder. The resulting temperature data were found to be relatively consistent.
Table 111. Averaged Experimental Evaporation Data 2.0-in. 90/10 Copper-Nickel Smooth Evaporation Tube
r,
Tsat,
lb/hr ft
OF
657
120
657
150
657
180
657
212
657
240
657
260
904
120
904
150
904
180
904
212
904
240
904
260
Q/A, Btu/hr ft2
AT,,
"F
he, Btu/hr ft2 "F
16,600 11,180 7,450 16,600 11,180 7,450 16,600 11,180 7,4 50 16,600 11,180 7,450 16,600 11,180 7,450 16,600 11,180 7,450 16,600 11,180 7,450 16,600 11,180 7,450 16,600 11,180 7,450 16,600 11,180 7,450 16,600 11,180 7,450 16,600 11,180 7,450
10.9 7.4 6.1 9.3 6.9 5.6 7.6 5.3 4.5 8.1 7 .O 5.5 8.4 6.2 4.6 6.7 5.5 4 .O 9.1 6.6 5.1 8.8 6.2 5.2 6.6 6.2 4.1 7.7 6.2 4.5 8 .O 5.9 4.3 6.5 5.5 4 .O
1523 1510 1221 1785 1620 1330 2184 2109 1657 2049 1597 1355 1976 1803 1620 2478 2032 1863 1824 1694 1461 1886 1803 1433 2515 2149 1817 2171 1803 1656 2075 1894 1733 2554 2032 1863
Temperatures obtained along the evaporation tube indicated that the axial temperature variation averaged approximately 1.0"F. Circumferential temperatures indicated a variation of up to a maximum of 5.0°F, depending upon the tube diameter and saturation conditions. For the 2.0-in. diameter knurled tube a t a heat flux of 17,100 B t u h r ft2, a feedwater flow rate of 884 lb,/hr ft, and a saturation temperature of 120°F) the wall superheat was 8.0°F on the top of the tube, 9.9OF on the sides of the tube, and 10.2OF on the bottom of the tube. At the same conditions and a saturation temperature of 240°F, the wall superheat was 5.4OF on the top of the tube, 6.1°F on the sides of the tube, and 6.6OF on the bottom of the tube. The average tube wall temperatures reported in this investigation were the average of the temperatures measured on the sides of the evaporation tubes. Although these average temperature values were slightly higher than the average of all of the axial and circumferential temperatures measured on the evaporation tube, these side temperature values were more representative and repeatable. The maximum deviation of an individual side wall temperature from the average was 1.l"F. Experimental Results. The evaporation heat transfer coefficients based on the averaged wall temperature data are listed in Tables 11-IV, and shown as a function of the saturation temperature in Figures 4-6. The data for the Ind. Eng. Chem., Process Des. Dev., Vol. 14. No. 4, 1975
413
Table IV. Averaged Experimental Evaporation Data
I" Smooth Tube
2.0-in. %/lo Copper-Nickel Knurled Evaporation Tube ~
r, IbJhr
560
ft
Q / A7
ATw,
O F
Btu/hr ft2
O F
he, Btu/hr ft2 O F
17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680 17,100 11,540 7,680
12.4 8.9 6.6 10.6 7.9 5.4 10.0 7.4 5.0 10.1 6.9 5.1 9.2 6.6 4.9 7.8 6.3 4.9 10.0 7.3 5.4 9.3 6.5 4.9 9 .o 6 .O 4.6 8.5 6.2 4.4 9.3 5.9 4.7 8.1 6.2 4.6 9.2 6.7 4.9 8.2 5.9 4.5 7.8 5.7 4.5 7.7 5.6 3.9 7.9 5.I 4.1 7.8 5.3 4.1
1379 1297 1163 1613 1461 1422 1710 1560 1535 1693 1673 1505 1859 1749 1476 2192 1832 1567 1710 1581 1422 1839 1775 1567 1900 1923 1669 2012 1861 1669 2012 1956 1745 2111 1861 1669 1859 1722 1567 2085 1956 1706 2192 2025 1706 2221 2061 1968 2165 2025 1872 2192 2177 1872
120 150
560
180
560
212
560
240
560
260
884
120
884
150
884
180
884
212
884
240
1105 1105 1105 1105
260 120 150 180 212
1105
240
1105
260
1.0-in. smooth tube indicate an1 increasing evaporation coefficient with increasing saturation temperature. The data for the 2.0-in. smooth tube indicate a slight increase in evaporation coefficient at the lower saturation temperatures and a relatively constant value of evaporation coefficient a t the higher saturation temperatures. Note that this trend is exhibited at all feedwater flow rate conditions. The 414
Lbm/hrft
Seo Waler
~~
Ts*t >
560
884
~~~~
Ind. Eng. Chem., Process Des. Dev., Vol. 14, No. 4, 1975
Hnal Flur Btu/hr aq f t A 20,020
Lbm/hrfl
0 14.900
Lbm/hr t l
t
TSEI
I
*F
Figure 4. Variation of evaporation coefficient with saturation temperature for a 1.0-in. diameter smooth 90/10 copper-nickel tube with a sea water film.
30001 2000
e
'
A
r
0
'904 L b m / h r f I
2" Smooth Tube
Heal Flua
Blu / hr rq f l
Sea Water
0
7.450 11,180 A 16,600
a Y
r
c
3000 2000
F1
~ 6 5 7L b m / h r tt
looo~
100
140
180 Tsa1
220 8
260
300
*F
Figure 5. Variation of evaporation coefficient with saturation temperature for a 2.0-in. diameter smooth W/10 copper-nickel tube with a sea water film.
data for the 2.0-in. knurled tube are shown in Figure 6 and exhibit the same trend as the 2.0-in. smooth evaporation tube, though they are lower in magnitude. The sea water evaporation data obtained during this investigation have been compared with previously reported studies in order to determine some of the characteristics of evaporation from thin sea water films on horizontal tubes. Of particular interest is the comparison between the heat transfer characteristics of distilled water and sea water films. In order to demonstrate the difference between smooth tube heat transfer characteristics and knurled tube charac-
[
'Ooo
b r
LU
= 1105 Lbm/hr f t
1000
o t :N
3000[
-
- -
,..
r
Flux
3000
I
1000-
5
:8 8 4
Lbrn/hrft
2" Knurled Tube S e a Water
'hrrqft
01
.
0 7.680 0 11,540 A 17.100
0'
J
5
2000
Lbm/hr f l
1000
0
IS W A , BN/hr tI2
20
25.03
Figure 7. Comparison between the sea water and distilled water test results for feedwater flow rates of 884 < I' < 988 lb,/hr ft.
I
IO0
140
I80
220
260
300
TI01 , * F
Figure 6. Variation of evaporation coefficient with saturation temperature for a 2.0-in. diameter knurled 90/10 copper-nickel tube with a sea water film. C o p p r 122 Tuba ,/ I
teristics, and the differences between distilled and sea water heat transfer characteristics, a comparison of evaporation coefficients for 2.0-in. diameter desalination tubes was made at similar mass flow rate conditions. The variation of evaporation coefficient with heat flux for a saturation temperature of 200'F is shown in Figure 7 for feedwater flow rates of 884 to 988 lb,/hr ft. The distilled water heat transfer coefficients for a smooth tube are the lowest; the use of a knurled tube with a sea water film provides higher heat transfer coefficients; and a smooth tube with a sea water film provides the highest heat transfer coefficients. The fact that the highest heat transfer coefficients were exhibited by a smooth tube with a sea water film has been reported previously by Cox et al. (1969) and Cannizzaro et al. (1972). A convective heat transfer coefficient should not be a direct function of heat flux. The increase in heat transfer coefficient with heat flux evident in Figure 7 suggests that boiling is influencing the heat transfer coefficient. The experimental evaporation coefficients obtained for distilled water and sea water films are compared with evaporation data reported by Cannizzaro et al. (1972) in Figure 8. Feedwater flow rates ranged from 750 to 988 lb,/hr f t for the data shown. The comparison is made for 2.0-in. diameter smooth tubes with similar feedwater mass flow rate test conditions. The sea water and distilled water evaporation data obtained in this investigation are for a single tube at an average of all heat flux test conditions. The remaining data shown in Figure 8, however, are for an evaporation tube located in the center of a tube bundle with a sea water film. The experimental data of this investigation compare favorably with the reported data at the lower saturation temperatures; however, as the saturation temperature increases, the experimental data appear to diverge. It may be noted that the evaporation coefficients for a 2.0-in. smooth tube with a sea water film are 20 to 50% higher at saturation temperatures of 120 and 260°F, respectively, than for a 2.0-in. smooth tube with a distilled water film. Overall Heat Transfer Coefficients. The overall heat transfer coefficient serves as a measure of the thermal effi-
LL
2000 -
P n r r n t Data
9040 Copp.r-Mckrl T u k
Sea
S r a Watrr
Watar
N
.
t
'
/
r
\ I
'
h
0
0
L
m e .'
v
o
90/10 C o w - N i c k d T u k
1000
-
Distilled Water Fletcher, et
al (1974)
F IO0
140
Io
220
260
300
Tsat I 'F
Figure 8. Comparison of the experimental test results averaged over all heat fluxes with reported data of Cannizzaro et al. (1972). All data for 2.0-in. diameter smooth tubes for feedwater flow rates of 750 < r < 988 lb,/hr ft.
ciency or effectiveness of a tube and may be calculated from the resistances due to evaporation and condensation, since the resistances due to wall conduction and surface scaling were negligible in this study. The experimental data obtained in this investigation for evaporation from sea water films on horizontal tubes and for condensation within these tubes were combined to produce the overall heat transfer coefficients shown in Figure 9 for comparison with data reported by Cox et al. (1969) and Cannizzaro et al. (1972). As in the case of the evaporation coefficient comparison (Figure 8), the data of this investigation are slightly lower than the reported data. This effect is to be expected due to the difference in test conditions and the fact that the steam shear effects and interactions between tubes within a tube bundle can have a pronounced effect on the heat transfer characteristics, as noted by Dukler (1960). Observations of the Boiling Process. The design of the single tube thin film evaporation test facility permitted Ind. Eng. Chem., Process Des. Dev., Vol. 14, No. 4, 1975
415
P N
7-
I5O0
t
01. (lase)
Cox, et
,
Cannlrraro , et
01.
(1972)
Smooth COpW-Nckel Tuber __/---
I
500 Copper-Nlckel Tubes
r z 900
-
Lbm/hr f t
I1,500Btu/hr sq f t 1802" Diameter 220 Tuber 260 Q/A
0 Kx)
140
xx)
Tat, OF
Figure 9. Comparison o f the overall heat transfer coefficients for data obtained in this investigation w i t h reported data o f Cox et al. (1969) and Cannizzaro et al. (1972).
observation of the falling fiim through any of the four test chamber windows. Still pictures were taken of the falling film with flash illumination to show the nature of the falling film and the bubbles. High-speed movies were also obtained during a series of evaporation tests to show the growth rate of the bubbles. I t was observed that the newly manufactured tube possessed many active nucleating sites. With time, the tube aged and became less active, and the surface appeared much smoother than it was in its original manufactured state. The data presented in this paper were obtained after approximately 10 hr of tube aging. After this aging period, only a few cavities remained active on the instrumented length of heated tube at the lowest values of heat flux reported. The heat flux a t incipient boiling was not recorded. At low saturation temperatures, nucleation frequency was low, and bubbles grew explosively to a large diameter. At higher saturation temperatures, the bubble diameters were smaller, and the nucleation frequency was higher. This trend is in keeping with the pool boiling observations of Ivey (1967) and Lorenz et al. (1972), who noted that the bubble frequency and diameter are inversely related. All of the evaporation heat transfer coefficient curves (Figures 4-6) appear to increase with increasing saturation temperatures. This trend is probably due to the change of thermal properties in the convective heat transfer coefficient, rather than the increase in boiling.
Conclusions An experimental investigation of evaporation from thin sea water films surrounding horizontal tubes has been conducted. The evaporation heat transfer data were obtained for saturation temperatures ranging from 120 to 260OF. Evaporation data for sea water were obtained for both 1.0and 2.0-in. diameter smooth tubes and a 2.0-in. diameter
416
knurled tube a t heat fluxes up to 20,000 Btu/hr ft2 with feedwater flow rates of up to 1105 lb,hr-ft of tube length. The sea water evaporation data obtained in this investigation are slightly lower than reported sea water data for tubes located in tube bundles. Comparison between the sea water and distilled water evaporation data indicate that the evaporation heat transfer coefficients for sea water films were as much as 50% higher than those for distilled water films. Evaporation heat transfer coefficients for the 1.0-in. diameter smooth tube with a sea water film were higher than those for the 2.0-in. diameter smooth tube with a sea water film. The evaporation heat transfer coefficients for the 2.0-in. diameter knurled tube with a sea water film were lower than those for the 2.0-in. diameter smooth tube. This investigation provides heat transfer data for evaporation from thin sea water films on horizontal tubes. These data contribute to a better understanding of some of the factors influencing vapor generation from individual tubes within horizontal tube bundle desalination systems. Comparison of the present data with HTME heat transfer data may permit determination of the effects of steam shear, neighboring tubes, and other tube bundle characteristics on the overall heat transfer coefficient.
Ind. Eng. Chem.. Process Des. Dev., Vol. 14, No. 4, 1975
Acknowledgment The authors wish to acknowledge the laboratory assistance of Terry Clark. Nomenclature he = evaporation heat transfer coefficient, B t u h r ft2 O F Q/A = heat flux density, B t u k r ft2 Tw = wall temperature, O F TSat= saturation temperature, O F ATw = wall subcooling (T,,, - Tw),O F U = overall heat transfer coefficient, B t u k r ft2 O F J? = mass rate of flow per unit length of tube, lb,/hr ft Literature Cited Cannizzaro. C. J., Karpf, J. Z. Kosowski, N., Pascale, A. S., 4th HTME Progress Report, Universal Desalting Corporation, July 1972. Cox, R. B. Matta, G. A,, Pascale, A. S., Stromberg, K. G., OSW R & D Report 492, U.S. Department of the Interior, Oct 1969. Dukler. A. E., Cbern. Eng. Progr. Symp. Ser., 56, 1 (1960). Fletcher, L. S., Sernas, V., Engineering Report RU-TR 139-MAE-H, Rutgers University, June 1972. Fletcher, L. S., Sernas, V., Galowin, L. S..Ind. Eng. Chem., Process Des. D e w . , 13, 265-269 (1974). Ivey, H. J., Int. J. Heat Mass Transfer, 10, 1023-1040 (1967). Lorenz. J. J., Mikic, B. B., Rohsenow, W. M.. EPL Engineering Report DSR 73413-79, Massachusetts Institute of Technology, Dec 1972. Office of Saline Water, Specifications for Batches of Sea Water Used in Heat Transfer Tests, Revised Specifications, May 1972. Parken, W. H., Fletcher, L. S., Sernas. V., Engineering Report RU-TR 141MIAE-H. Rutgers University, June 1973. Saline Water Conversion Engineering Data Book, 2nd ed, U.S. Government Printing Office, Washington, D.C., Nov 1971.
Receiued for Reuiew October 21,1974 Accepted April 7,1975 T h e authors gratefully acknowledge the financial support o f the U n i t e d States Department o f Interior, Office of Saline Water, Contract 14-30-2907, and the facilities o f the Rutgers University Mechanical, Industrial, and Aerospace Engineering Department.
