A - JACKET. SOy LENGTH
OF 3"
F
PIPE.
- NONCONDENSABLE MANOMETER O U T L E T
0 25" COUPLING.
G A ~OUTLET. 0 . 5 .
'
CLOSE NIPPLE.
(INCLINED
CDUPLINC.
POSITIONS) - -
FIGURE1. EXPERIMENTAL CONDENSER
Heat Transfer Coefficients
WITHOUT CALMINGSECTIONS. inclination The effecton of the caaacitv angle of oftube the experimental condenser codd best be determined by changing the angle of inclination while keeping all other factors constant. To attain the necessary flexibility, a 6foot section of 1-inch (1.25 inches i. d.) steam hose was clamped to each end of the copper condenser tube. The other ends of the steam hoses led to water inlet and outlet pipes. I n order to approach the c o n d i t i o n s which would have existed had calming sections been used, the hoses were supported by a series of ropes and pulleys in such D. F. JURGENSEN, JR.,' AND G. H. MONTILLON a manner as to give a s smooth a curve and one of as long a radius as University of Minnesota, Minneapolis, Minn. possible. The ends of the co per a tube were stream-lined inside short distance to minimize entrance effects. WITHCALMING SECTIONB.During these tests'a 46-inch length of Bakelite tubing of the HE experimental condenser used (Figure 1) same internal diameter as the copper tube replaced the steam consisted of two concentric pipes: the inhose at each end of the condenser. The copper tube was cut ner, a 1-inch copper tube of standard iron back at each end far enough t o remove all traces of the inpipe size (1.062 inch i. d., 1.315 inch 0 . d.), and the outer, a ternal stream lining previously mentioned. The Bakelite tubing was held in place against the ends of the copper tube by standard 3-inch wrought iron pipe. Cooling water flowed short sections of steam hose clamoed in such a way as to act as through the inner tube and steam through the annular space. a coupling. The length of the condenser was 60 inches between tube sheets. A steam boiler was provided to furnish 100 per cent dry steam Steam was introduced into the condenser through a coupwith no superheat to the condenser. The boiler was kept about half full of water. Steam from the supply mains was introling near the left end. Condensate was removed through a duced under water through a perforated 1.25-inch pi e, and steam coupling a t the right end and through a small outlet drilled for the condenser was withdrawn through a 2-incl dry pipe in through the adjacent stuffing box. These two condensate the vapor space. The steam outlet from the boiler was connected outlets were necessary to provide complete drainage a t all to the steam inlet of the condenser with a 1-inch flexible copper hose. angles of inclination. They were brought together immediately below the condenser into a steam trap, from which a piece of rubber hose led to a covered condensate receiver mounted on a scale. Experimental work on a 45' inclined test Noncondensable gases were swept out of the condenser by evaporator recently completed at the Uniexcess steam through a coupling 5 inches from the right-hand versity of Minnesota ( l a ) indicated the need end, Six couplings were provided for thermocouple wire outlets and three for manometer leads. Radiation lpsses were for a study of the effect of the angle of tube minimized by proper lagging. The condenser was clamped inclination on condensing steam film heat into a bearing a t a point near the steam inlet and was thus sustransfer coefficients. A n experimental pended in a suitable stand. It could be readily set at any single tube condenser has been built for desired angle from the horizontal (0' inclined) to the vertical, that purpose. The results obtained show inclusive. Cooling water was taken from the city mains. A pressure that the angle of inclination is of major equalizer was placed in the supply line to minimize momenimportance in determining the capacity of tary fluctuations in the supply pressure. the apparatus. Indeed, under one set of Two methods were used to introduce and remove cooling conditions the rate of heat transfer may be water from the condenser. With each method both possible increased by as much as 50 per cent merely directions of water flow (parallel and countercurrent to the direction of steam flow) were tested. These two methods by changing from the vertical to the horiwere characterized as follows: zontal position.
on Inclined
Tubes
8r
T
1
Present addresa, U. S. Gypaum Company, Chicago, I11
1466
DECEMBER, 1933
INDUSTRIAL AND ENGINEERING CHEMISTRY
Temperature Measuring Equipment All temperatures were measured by the use of copper-constantan thermocouples. The couples were made from 24-gage wire according to the method recommended by the U. S. Bureau of Standards ( I A ) , and their recommended potentiometer circuit using reversing switches was used for the determination of thermocouple elect.romotive forces. The calibration curve was obtained by checking the thermocouples against thermometers which had been calibrated by the U. S. Bureau of Standards, against the transition point of sodium sulfate, and against the boiling point of water. Cooling water temperatures were determined by thermocouples placed a t the end of the calming sections (steam hose or Bakelite tubing, properly lagged) away from the condenser. Mixing boxes were provided to obtain the true average water temperature. They were similar to those used by Montillon, Rohrbach, and Badger (16). The temperahre of the steam was determined with a shielded couple in the steam jacket, and couples in the steam inlet line and noncondensable gases outlet. The temperature of the condensate leaving the condenser mas determined by means of two double couples in the steam trap. The accurate determination of pipe surface temperatures is important since the possibilities of errors are great. Recently Colburn and Hougen ( 3 ) and Hebbard and Badger ( 6 ) have suggested solutions of the problem. The method suggested by Colburn and Hougen was ado ted for this research. The length of condenser tube between tge tube sheets was divided into four equal sections, and one quadruplet couple was placed at the center of each of these sections. They were designated PC1, PC2, PC3, and PC4, in order. PC1 was the couple in the end section away from the steam inlet. The thermocouple wire outlets were similar to those used by Montillon, Rohrbach, and Badger (Is), except that the flanges were replaced by female two-third unions equipped with special brass plugs.
Method of Operation T o put the equipment in operation, i t was necessary only to establish the desired water rate and to adjust the steam feed to the boiler as required. d period of from 15 to 30 minutes after the desired conditions had been obtained wa,s generally sufficient for the equipment to reach equilibrium. All tests were on a 30-minute basis, timed by a stop watch. The con-
Z
u
30d
1467
I
,
'
'
2
I
11 3
7000
600
1
I
4
'
l
l
5
1
6000
L L
G
8 2
-J W
B
WATER
FIGURE 2.
RATE
-
LBS. PER 30 I..!?
