Nukiyama

INFRARED TECHNOLOGY AND RAMAN SPECTROSCOPY - INFRARED TECHNOLOGY] (Vol 14) Nukiyama-Tanasawa equations... 

If point F in Fig. 2 is reached without physical burn-out occurring, then, as shown by Nukiyama, a further increase in heat flux will raise the surface temperature in the direction of E until physical burn-out does occur. If, however, the heat flux at point F is decreased, the surface temperature does not revert to the value at C, but moves along the curve towards D. On reaching D, it was observed by Nukiyama that the surface temperature undergoes another jump discontinuity along the dotted line DG, and stabilizes at G in the nucleate-boiling region. Both the transition lines CF and DG can be passed only in the direction shown by the arrows in Fig. 2. 

Nukiyama was unable to establish a condition on the line CD, and in his original experimental curves he shows this line dotted. However, Farber and Scorah (F2) have reported that with special surface treatment and very careful experimentation, quasistable conditions can be set up on a curve such as CD in pool boiling. Their procedure was to first reach point D by way of ACFD and then to very carefully increase the heat flux. However, any disturbance or sudden change of heat flux when in the region CD caused the system to revert to the stable regions GC or DF. 

N3. Nukiyama, S., Experiments on the determination of the maximum and minimum values of the heat transferred between a metal surface and boiling water, J. Soc. Mech. Engrs. (Japan) 37, 367 (1934) [English transl. by Brickley, S. G., AERE-Transl. 854 (I960)]. 

In boiling liquids on a submerged surface it is found that the heat transfer coefficient depends very much on the temperature difference between the hot surface and the boiling liquid. The general relation between the temperature difference and heat transfer coefficient was first presented by Nukiyama(77) who boiled water on an electrically heated wire. The results obtained have been confirmed and extended by others, and Figure 9.52 shows the data of Farber and Scorah<78). The relationship here is complex and is best considered in stages. 

Nukiyama, S., 1934, Maximum and Minimum Values of Heat Transmitted from Metal to Boiling Water under Atmospheric Pressure, J. Soc. Mech. Eng. Jpn. 37 361. (1)... 

Nuclides, reaction with monomers, 14 248 NuDat database, 21 314 Nukiyama-Tanasawa function, 23 185 Null-background techniques, in infrared spectroscopy, 23 139-140 Number-average molecular weight, 20 101 of polymers, 11 195, 196 Number density, of droplets, 23 187 Number of gas-phase transfer units (Nq), packed column absorbers, 1 51 Number of overall gas-phase transfer units (Nog), packed column absorbers, 1 52 Number of transfer units (Nt, NTU), 10 761... 

Nukiyama, and Tanasawa1791 proposed a relatively simple function for adequate description of some actual droplet size distributions ... 

Most of the investigators have assumed the effective drop size of the spray to be the Sauter (surface-mean) diameter and have used the empirical equation of Nukiyama and Tanasawa [Trans. Soc. Mech. Eng., Japan, 5, 63 (1939)] to estimate the Sauter diameter ... 

Because of such factors as wave formation, jet turbulence, and secondary breakup, the drops formed are not of uniform size. Various ways of describing the distribution, including the methods of Rosin and Rammler (R9) and of Nukiyama and Tanasawa (N3), are discussed by Mugele and Evans (M7). A completely theoretical prediction of the drop-size distribution resulting from the complex phenomena discussed has not yet been obtained. However, for simple jets issuing in still air, the following approximate relation has been suggested (P3) ... 

The Leidenfrost phenomenon was first discussed in 1756 (LI). This phenomenon is the occurrence of a repulsion between a liquid and a very hot solid. For example, a drop of water on a hot plate will dance around noisily for some time before evaporating. On a moderately warm plate the phenomenon does not appear, and evaporation is very rapid. Nukiyama s test shed some light on this mystery. 

In 1926 Mosciki and Broder (M10) made some studies of electrically heated, vertical wires submerged in cold water and in heated water. They showed that subcooled boiling results in greater heat fluxes than can be obtained with the liquid at its boiling point. These tests anticipated in part the tests made soon after by Nukiyama. 

In 1934 Nukiyama (N2) carried out a simple experiment which resulted in a great advance in the science of boiling. He submerged a thin platinum wire in water at 212° F. and heated the wire electrically to produce boiling. He discovered that the rate of heat transfer from the wire to the water increased steadily as the wire temperature was increased until the wire temperature reached about 300° F. At this temperature an unexpected thing happened the wire temperature jumped suddenly to about 1800° F. A further increase in the wire temperature resulted in a smooth increase in the heat transfer rate. 

The sudden temperature jump for the platinum wire was puzzling, and so Nukiyama tried wires of nickel and alloys having melting points lower than platinum has. When these wires experienced the temperature jump they melted. This was the phenomenon now known as bumovt. 

Nukiyama next investigated the in-between region of 300° to 1800° F. He used platinum, allowed the jump to occur, and then lowered the metal temperature gradually. It was possible to cool the wire to about 570° F. A smooth decrease in the heat flux occurred as the temperature was decreased. At 570° F. another temperature jump occurred, to less than 300° F. 

Nukiyama s boiling curve is shown in Fig. 1. He concluded that at least two types of boiling occur for water, one was below 300° F. and one above 570° F. He postulated that a third type might exist, represented by the dotted line on the figure. It was obvious that if this third type.existed it would have a.peculiar characteristic any increase in the... 

Subsequent evidence proved that Nukiyama was right. At least three types of boiling exist. In Fig. 3, which shows some recent data (W3) for methanol boiling on a horizontal copper tube, the portion of the curve... 

Fig. 1. The first boiling curve. Nukiyama s results for water boiling on a platinum wire are shown (N2).

B) have found excellent correlation between the measured sizes of drops atomized by high-velocity gas streams with the equations developed by Nukiyama and Tanasawa (6L), so long as conditions are held within certain limits. The behavior of sprays of 7i-heptane, benzene, toluene, and other fuels has been studied by Garner and Henny (SB) by use of a small air-blast atomizer under reduced pressures. A marked increase in the Sauter mean diameter was obtained for benzene and toluene as compared with n-heptane, which parallels their poor performance in gas turbines. Duffie and Marshall (2B) give a theoretical analysis of the breakup characteristics of a viscous-jet atomizer and show high-speed photographs of the process. 

Three widely used distribution equations, discussed by Bevans (JL), include the Rosin-Rammler (7L) and Nukiyama-Tanasawa (6L) equations as well as the log-probability equation. A fourth relationship, the upper-limit equation of Mugele and Evans (5L), is also discussed. Hawthorne and Stange also discuss the Rosin-Rammler relationship (4L, 8L). An excellent analysis of distributions is given by Dubrow (SL), who has studied atomized magnesium powders. 

In contrast to the large variety of averages and measures of dispersion prevalent in the literature, the number of basic distributions which have proved useful is relatively small. In droplet statistics, the best known distributions include the normal, log-normal, Rosin-Rammler, and Nukiyama-Tanasawa distributions. The normal distribution often gives a satisfactory representation where the droplets are produced by condensation, precipitation, or by chemical processes. The log-normal and Nukiyama-Tanasawa distributions often yield adequate descriptions of the drop-size distributions of sprays produced by atomization of liquids in air. The Rosin-Rammler distribution has been successfully applied to size distribution resulting from grinding, and may sometimes be fitted to data that are too skewed to be fitted with a log-normal distribution. 

Table II shows the mathematical forms of the normal, log-normal, Rosin-Rammler, and Nukiyama-Tanasawa distributions for an arbitrary ptb-weighted size distribution. As in Table I, the formulas yield the surface increment in the size interval, t to t + dt, for p = 2 number or volume increments are obtained by setting p equal to 0 or 3, respectively. In these expressions 6 and n are constants, and a denotes an appropriate shape factor.

AP is the pressure drop, cm of water pt and pg are the density of the scrubbing liquid and gas respectively, g/cm3 Ug is the velocity of the gas at the throat inlet, cm/s Q,IQg is the volumetric ratio of liquid to gas at the throat inlet, dimensionless lt is the length of the throat, cm Cm is the drag coefficient, dimensionless, for the mean liquid diameter, evaluated at the throat inlet and di is the Sauter mean diameter, cm, for the atomized liquid. The atomized-liquid mean diameter must be evaluated by the Nukiyama and Tanasawa [Trans. Soc. Mech Eng. (Japan), 4, 5, 6 (1937-1940)] equation ... 

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