An approximate method is presented for estimating the effects of heat evolution which is accompanied with chemical reaction on heat transfer in packed beds.
It is assumed that the radial temperature profile at any axial position of the catalyst bed is geometrically similar to that in a model reactor, although the temperature level itself may be different from one another.
In order to evaluate the effect of reaction heat on heat transfer coefficients, the reaction coefficient for heat transfer, Ø, is defined by Eq.(28) for model reactor type 1. The value of Ø for real reactors may be derived from the value of the model reactor and found to be approximately the same.
As a result, it may be concluded that chemical reaction increases the overall heat transfer coefficients in packed beds. This is mainly due to the change of radial temperature profile which originated in the heat of reaction.

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In our previous papers, equations for the liquid-side and the gas-side mass transfer coefficients in towers packed with Raschig rings and Berl saddles had been obtained. In this paper, experiments with ceramic spheres were made in order to clarify the influence of the shape of packings.
By measuring the wetted surface area (a^w) in towers packed with 1/2″-, 1″-spheres, the relation was expressed by Eq.(2).
The liquid-side and the gas-side capacity coefficients (k_La, k_Ga) in towers packed with 1/2″-, 1″-, 4/3″-spheres, respectively, were measured by means of the absorption of pure carbon dioxide and/or ammonia by water, and their correlated equations with liquid and gas flow rates were obtained as shown in Table 2 and Table 3.
Assuming that the effective surface area (a) is equal to the wetted surface area (a_w) as described in the authors' previous reports, k_L and k_G were obtained by dividing k_La and k_Ga by aw respectively.

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The effect of various factors on the size of bubbles from single submerged orifices ranging from 4 to 16mm in diameter was investigated. The twelve kinds of liquid listed in Table 1 were employed for the experiment.
The results are represented by using mean geometric diameter (d) and standard deviation (s), because the bubbles formed are almost in cornformity to the logarithmic probability distribution.
In the experiment in which gas chamber volume (V_e) is kept to a small value, (d) increases at N_w<16, and decreases at N_w>16, , with increasing gas flow rate.
The dependence of bubble size on Ve shows three distinct regions:
(1) N_e<1, : d is independent of V_e
(2) 1<N_e<9, : d corresponds to V_e
(3) 9<N_e: d is independent of V_e
The reason is that the inner pressure of bubbles varies with the diameter of the bubble attached to the orifice.

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In the Piazza centrifugal gas absorber or centrifugal gas-liquid contactor which has been developed by us, mass transfer may be carried out in both liquid flow patterns of spray and wetted wall.
In this report, pure CO₂ gas absorption by a rotating wetted wall whose water travelling length is short is considered theoretically and experimentally.
Theoretically, the surface velocity of a rotating aqueous wetted wall is defined by Eq.(23). And if the surface velocity and the average velocity of liquid is found, the Murphree absorption efficiency is calculated from Eq.(33).
Experiment of absorption is proceeded in pure CO₂ gas and water at 20°C, CO₂ gas is sent countercurrently contacting with a rotating wetted wall flow of water.
It is shown that experimental results correspond with the results of theoretical calculations which are based on a wellknown unsteady diffusional equation.
It is concluded that in such type of contactor the amount of mass transfer in the flow at the wetted wall is comparatively smaller than in the flow of spray.

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Observations had been made on the flow of air and water on sieve trays without downcomers.
When air and water reached a certain flow rate, disconnected pressure drops were observed in the trays, which made the liquid suddenly become unstable.
It leads to the conclusion that there are practical limits to this type of tray. Such limit can be expressed as a function of the slot velocity of liquid and vapor.
This paper made it possible for us not only to design a column having this type of tray but enabled us to determine the column capacity.

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In a preceding paper, the graphical solution of heat and material balance equations for the stirred tank flow reactor has been presented for simple reactions. This method is also useful for fractional-order reactions, reversible reactions, simultaneous reactions and consecutive reactions.
The behavior of the stirred tank reactors in series may be estimated by repeated applications of this method. Assuming that a tubular reactor is approximately equivalent to n-stage tank reactor sequence, the temperature and concentration profiles in a tubular reactor may be calculated by the graphical method for the stirred tank reactors in series. Parametric sensitivity of tubular reactors is easily estimated by the same method. These methods are also applicable to the reactor system with the heat exchanger.

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