The progress of the two-phase flow reseach has been divided into four stages. These period are 1948-1959, 1960-1970, 1971-1979, and 1980-1990. In this 9th Report, the development of researches on the flow instabilities in boiling channels in the latter half of the second period (1965-1970) has been described. The progress of experimental researches, which were conducted in universities in USA and Japan, on density wave oscillation, pressure drop oscillation, system-induced oscillation, thermal oscillation, flow distribution in parallel channels, and flow excursion, has been described with the historical aspect.
In order to remove polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in exhaust from refuse incineration plants, the treatment of the gases by using a fabric filter with activated carbon injection is available as one of the applicable methods. This method using a fabric filter with activated carbon enabled efficient removal of PCDDs/PCDFs in operating plant. In particular, the concentration of PCDDs/PCDFs was successfully reduced to 0.1ng/Nm3-TEQ.
The new law regulation for dioxins has been published in Dec. 1997, and it gives a special attention to municipal solid waste incinerators. In order to observe the strict regulation for dioxins, the greater part of existing municipal solid waste incinerators must be carried out some reduction of dioxins. This paper presents the removal systems for dioxins using Activated Coke (AC). These systems are effective for reduction of dioxins at existing municipal solid waste incinerators.
For the reduction of PCDDs/DFs emission, catalytic decomposition method is one of the useful high technological waste gas treatment system. In this paper, on the flue gas of MSW incineration plant, study as to decomposition of PCDDs/PCDFs by catalyst is described.
A direct mixing type axial flow cyclone heat exchanger between gas and high temperature particles is proposed which serves as particle separator as well and its heat transfer performance was examined both experimentally and numerically. In this heat exchanger, the particles, after being mixed directly with gas, transfer their heat to the gas in the form of quasi-counter-flow and are effectively re-separated by centrifugal force due to swirling motion of the gas. The following results were obtained from the experiments by using the mock-up apparatus: high heat transfer performance was achieved by mounting a particle diffuser just below the particles' feeding nozzle in order to promote the dispersion of particles in the vessel. Furthermore, by investigating the effect of the location of particles' feeding nozzle on the heat transfer performance, the case when the nozzle was flush with the gas inlet was concluded to be most suitable.
The purpose of this report is to predict the shape of the droplet on a solid surface through numerical analysis. The shape of the droplet is determined by the equilibrium of the forces of gravity and surface tension. The two-dimensional cylindrical droplet is analyzed numerically by SOLA (solution algorithm)-VOF (volume of fluid) method using the contact angle as the initial condition. The curvature of the droplet surface was calculated from the position of marker particles put on the droplet surface, subsequently, the droplet shape is obtained with high accuracy. The droplet shape on a solid surface predicted by this method is in good agreement with the photograph of the droplet as well as the contact angle. As the inclination angle of solid surface gets larger, both the front side angle and the back side angle of the droplet gradually changed, until finally, the droplet slipped along the slope. The droplet shape could be satisfactorily simulated by use of the SOLA-VOF method.
In order to simplify condensation heat transfer calculations for feed water heaters, one dimensional (1D) analyses were compared with three dimensional (3D) analyses. The results showed that average condensation heat transfer coefficients by I D analyses with 1/2 rows of heat transfer tubes agreed with those by 3D analyses within 7%. Using the 1D analysis model, effects of the pitch of heat transfer tubes were evaluated. The results showed that the pitch did not affect much on heat transfer rates and that the size of heat transfer tube bundle could be decreased by a small pitch.
A film flowing on a wall exhibits as many distinct wave features. The produced interfacial waves show fascinating non-linear phenomena, including solitary waves and complex disordered patterns. Abundant measurements have been made of these phenomena using electrical resistance or electrical-capacity methods, optical methods, and laser beam methods. In this paper, a new way of measurement of the interfacial waves is presented using laser focus displacement meters which allow accurate measurements of film thickness in real time with a sensitivity of 2 microns and 1 kilohertz. With this method, detailed information on the waves was obtained on a film flowing down a vertical wall in an entry region. The measured average film thickness and wave velocity agreed with that calculated using Nusselt's law, indicating the flow to be laminar in the entry region even at a high flow rate. Research on multifluid with progress and improvement in microscopic measuring is expected to be conducted increasingly in the future.