Shigeru Hinata

Novel method to evaluate the net wear volume of bag-filter by fly ash

In order to study the wear of bag-filter by ash dust, sintered magnetite (Fe(3)O(4)) compact was used for counter material for sliding wear test. The precise amount of magnetite particles embedded into bag-filter was determined by a vibration sample magnetometer (VSM) measurement. It is found that net amount of wear of the bag-filter could be precisely determined by the magnetic measurement. It is also found that the net amount of sliding wear of the bag-filter increases with increasing the wear distance, sliding speed and applied load. To discuss the validity of proposed method, shot peening test with deoxidized iron particles was also carried out for bag-filter sample. The data obtained by the shot peening test is consistent with that obtained by the sliding wear test. The proposed method is, thus, very useful to evaluate the net amount of wear of bag-filter by the fly ash.

Onset of Multilayer Convection in a Partially Heated Circular Cavity

In this article, the time-dependent double-diffusive natural convection is investigated inside a circular cavity containing stably stratified brine solution. The container is heated partially through its sidewalls by a constant heat flux rate. By using Galerkin finite element method, numerical solutions to the Navier-Stokes equations under the Boussinesq flow assumptions have been systematically organized and developed. The evolutions of the stream function, temperature and concentration fields are presented in each evaluated case. Steep and sharp concentration variation in the interfaces together with wavy distribution of temperature within the layers is observed. At first a length scale, which is the vertical displacement of a heated element of the fluid, in a stably stratified solution under Neumann boundary condition is defined. Then a special form of Rayleigh number based on the length scale is obtained and named as universal Rayleigh number. A categorization based on single, two and multilayer formation is established. Temperature distribution along the cavity in the different cases shows a correlation between heat transfer coefficient and the rate of formation and degradation of the layers.

Dry Sand Erosion Damage Characteristic of Fibers Induced by Solid Particle Impact

Bag filters made of fibrous components are widely used for cleaning exhaust gas. Filter damage caused by dust collection results from the erosion of the filter during particle collision. We developed an experimental and evaluation method to investigate the erosion characteristics of fibers. Using the suggested kinetic energy of impact, we evaluated the erosion wear characteristics of fibers under different experimental conditions. The results demonstrated that fiber erosion wear depended on the kinetic energy of impact. The level of erosion wear changes based on the material characteristics (brittle or ductile) and on the impact angle of solid particles. In addition, erosion characteristics are greatly influenced by strength and elongation properties of materials.

Numerical Simulation Analysis of Stirling Engines. Effects on Mesh Number of Regenerator Matrix.

The regenerator is the component having the most significant effect on Stirling engine performance. This paper is concerned with analyzing the effects of varying design parameters on the regenerator, especially the mesh numbers of the matrix, by numerical cycle simulation. The numerical cycle simulation is based on the nodal analysis. This approach proceeds by subdividing the working space of the engine into a number of one-dimensional control volumes. Differential equations of the continuity and energy of the working gas, as well as energy of the regenerator matrix, are developed. In particular, the regenerator space is subdivided into the order of 100 control volumes in order to accurately estimate the quantity of enthalpy carried by the working gas flow in the regenerator. The experimental results are also discussed to confirm its validity. It is shown that this method is applicable to optimization of the design parameters on the regenerator.

Void fraction and temperature Measurements for Pool Boiling around a Horizontal Cylindrical Surface.

An experimental study of void fraction and temperature profiles in nucleate pool boiling of Freon-11 around a horizontal cylindrical copper surface is reported. The results obtained from the amplitude probability distributions of temperature fluctuations show that temperatures within the thermal sublayer region fluctuate widely, and beyond this region the distribution curve changes from Gaussian to the chi-squared type distribution function. It is found that the bubble boundary layer near the heated wall has an effect on the thickness of the superheat layer.