In order to know the effects of wall temperature and thermal conductivities of packings on heat transfer mechanisms in packed beds, effective thermal conductivities k and overall heat transfer coefficients h_o were observed in packed beds of several kinds of solid, usinga calorized steel tube whose inner diameter was 52.9mm.
Packings
iron sphere llmm, insulating fire-brick granule 10mm,
cemenent clinker 6mm, 3.5mm; glass sphere 6mm
Range of experiments
wall temperature t_w=100-500°C
modified Reynolds number D_pG/μ=40-500
According to the experimetal result, the effective thermal conductivities in packed beds were found to depend upon both the mean temperature of bed and the thermal conduities of packings, as shown in Fig. 7, and the experimental data could be predicted fairly well from the author's theoretical equations [Eqs. (1) and (2)].
Overall heat transfer coefficient seemed not to be influenced so much by the wall temperature as shown in Fig.9.
Then, simplifying themechanisms of latcrial heat transfer in packed bed, approcximate equations [Eqs. (16) and (17)] were obtained, by means of which to discuss the relations among the effective thermal conductivity, film heat transfer coefficient and overall heat transfer coefficient. The adequacy of the above equations were proved by comparing (A) the values of film heat. transfer coefficient, calculated from the data on overall heat transfer by means of Eqs. (16) and (17), with (B) the data on film heat transfer coefficient ever repord a shown in Fig.10
Equation (19) for film heat transfer coefficient coincided fairly well with the data presented for packed beds of solid spheres.

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In order to eliminate the end effect of the ordinary rotational viscometer, we designed a new viscometer which was constructed of a conical vessel with a concentrically situated inner cone as shown in Fig.1. The outer cone was rotated by a motor. By comparing the experimental data on the operation of this viscometer with the theoretically calculated values, we obtained a good stable agreement between the two. By means of this viscometer, we were able to measure more accrately even low viscosity as well as high viscosity than by any other rotational viscometer.
The experimental apparatus is shown in Fig.2. A general equation for the torque of the rotational viscometer (with outer cylinder rotated) may be expressed with the aid of Eqs.(3), (4)and (5)as in Eq.(21). From this, a theoretical equation for the cone type rotational viscometer may be derived using Fig.6, which will be expressed as shown in Eq. (28),
By introducing the constants of this apParatus, (t₁, t₀, H, r₀) and (h, M, N) into Eq. (28), we obtained the coeffcient of viscosity η of the sample liquid. Eq. (31) shows the relation between the moment M and the angle of deflection θ of torsion wire.
The experimental data are shown in Figs.7, 8 and 9. In Figs.7 and 8, we find the sample liquids having the quality of the Newtonian liquid, and the data represented by linear lines through the origin. As seen from these results, the end effect was completely eliminated from this apparatus, and the experimental data obtained with it were well ordered and had good reproductivity. Fig. 10 shows the relation between torque M and the dipped height of the inner cone into liquid, it having been proved that M is proportional to h³ and that there is a good agreement between Eq. (33) and the experimental results.
The comparison of the experimental data on this cone type rotational viscometer and those of the other viscometers is shown in Fig.12. For water, the difference between the two was about 50%. It may be considered somewhat greater than ususal, but such is common with ordinary viscometers. The data on other oils and resin varnishes obtained with this viscometer were approximately equal to those obtained with other viscometers, measurements being always stable and having good reproductivity.

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Specific surface of finished product and its size-distribution may be independently controlled by closed-circuit grinding. However, there has hardly been established any standard for the techniques: how to design, select and operate a mill and classifier, how to determine the capacity of powder transportation equipments, etc.
Based on the Rosin-Rammler exponcntial law, the authors drew up the"Charts"(Figs.2 and 3), by which one can easily obtain the values of several variables such as fineness of mill discharge, amount of product and recycle from the classifier in correlation to the circulating load, cut-off size of a classifier and constants of size-distribution.
The authors pursued, on the basis of these charts, general, chaages of size-distributioa of the product, and of the specific surface of various powders in accordance with the increment of the circulating load, and found that when Cl=1.5 or 3, there existed finest value, hence may be optimum, of the composite feed to a mill, which value was dependent upon the required property of the finished product.
By comparing the specifice surface of the product obtained by closed-circuit grinding with that obtained by open-circuit grinding, the authors found that the theoretical increase of the capacity of grinding mill was somewhat greater than the practical one, provided the constant of Rittinger's law remained, unchanged regardless of the speed-up of powder movement through the mill.

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Various references have hitherto been made on screw characteristics of an extruder for molding Newtonian viscous materials. Recently the Bingham plastic matcrial was made an object of an advanced research. In some cases the extruding process was investigated in these references as an isothermal one, while in others, as an adiabaticone. In practising extrusion of molten plastics, however, it was assumed that an ideal temperature distribution was obtained along the screw axis mostly by heating the location, paying due regards to the properties of the material to be molded.
In this research of ours was attempted “a graphical representation of screw characteristics of an extruder for molding pseudoplastic materials” based on the data on flow characteristics of the materials, dimensions of the screw and temperature distribution thereof.
Analysis was made on the assumption that the materials did not slip on the surface of the screw and barrel, but flowed in accordance with the Rabinowitsch rheological equation (Eq. 1). With the aid of the following non-dimensional terms,
(6)
a non-dimensional diagram (Fig.3) was drawn up. For any cross section of screw channel, the values of S, h, m and η were found to remain constant. Hence, the values of σ and w were calculated for constant Q_m=60_ρQ and V (or N) and the values of z obtained by consulting Fig.3. In the like manner, the value of ξ in that section of screw channel was obtained. Thus, for any constant N, each ξ-distribution curve along the screw channel would be drawn in reference to respective Q_M as shown in Figs.8-12.
It may be assumed that the pressure rise begins at that section of screw channel that fills first of all with the perfectly molten materials. We call the distance from this section to the screw front along the middle of screw channel “Melt Length”. The area enclogd by the ξ-distribution curve and the “Melt Length” gives the pressure rise P for N and Q_M. Plotting the points (P, Q_M) for constant N, the screw characteris tics were represented in lines as shown in Fig.13. Fig.8-12 are made for polyethylene whose flow charxteristics are shown in Fig.5, and for an experimental extruder of compression type as shown in Fig.1. Temperature distribution is assumed as shown in Figs.8-12.
For polyethylene the melting point is 110-115°C, and assuming that the distance from the section in which the temperature is 130°C, as judged from the motion of the materials and from the existence of the short transient region in a state bitween pellet and fluid, to the screw front to be the “Melt Length, ” we obtained the screw characteristics (dotted lines in Fig.13) which lie in the neighbourhood of experimental data. Furthermore, by amending the “Melt Length” by the experimental data (Fig.6), we obtained the amended screw characteristics (chain lines in Fig.13) which show good approximation to the experimental data.
Change of screw characteristics, by the way, due to a slight difference in the “MeltLength” is small. Consequently this graphical representation of screw characteristics may be available for design of a screw extruder and selection of operating conditions thereof when molding pseudoplastic materials like polyethylene which flow according to the Rabinowitsch rheological equation and do not slip on the surface of the screw and barrel.

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