Yoshitaka Inui

Numerical analysis of the effect of local diameter reduction on the critical temperature of thermoacoustic oscillations in a looped tube

The installation of a phase adjuster (PA) has been proposed to improve the cooling effect of loop-tube-type thermoacoustic cooling systems. Installing a PA in a circular tube is equivalent to reducing the tube diameter locally. In this paper, we report our numerical investigation of the effects of the configuration parameters of a PA, i.e., diameter reduction and installation position, on the critical temperature of thermoacoustic gas oscillations by utilizing the transfer matrix method. The PA was modeled considering reflections due to the impedance mismatch at the boundaries between different diameters. The calculation results indicate that the critical temperature significantly decreases when a certain level of diameter reduction at appropriate positions is set, and these results correspond to empirical configurations that were experimentally chosen and verified in past studies.

Effect of the relative installation position of two enlarged prime movers on the onset temperature in loop-tube-type multistage thermoacoustic system

Reducing the driving temperature of a thermoacoustic system to effectively utilize the unused low-temperature heat source is important for improving the performance of the system. The driving temperature of the thermoacoustic system was reduced by installing multiple stages of prime movers in series, a heat-to-sound transducer, and a prime mover with an increased cross-sectional area. In this study, the oscillation temperature was investigated both experimentally and by stability analysis in order to verify whether the system is operable, and to determine its operating temperature, when changing the installation position of the two-stage prime mover with increased cross-sectional area.

Fabrication and characteristics of p-type Cu2O thin films by ultrasonic spray-assisted mist CVD method

P-type cuprous oxide (Cu2O) thin films were fabricated by an ultrasonic spray-assisted mist chemical vapor deposition (mist CVD) method. Copper(II) acetylacetonate was used as a precursor and deionized water was used as a solvent. Cu2O was grown at a temperature of 350 ?C and the films were gradually changed from Cu2O to CuO by increasing the growth temperature. The Cu2O film grown at 350 ?C showed p-type conductivity with a carrier concentration of 3.3 ? 1015 cm?3 and a Hall mobility of 0.2 cm2?V?1?s?1.

Influence of degradation in units of PV modules on electric power output of PV system

ABSTRACTThe time variations and daily integrated amounts of electric power output of a photovoltaic (PV) system for domestic use were calculated for various degradation cases and diurnal insolation...

One factor of resonant wavelength shift from onewavelength to two-wavelength resonance in loop-tube-type thermoacoustic cooling system

Results of this study show that the resonant wavelength of the sound generated in a loop-tube-type thermoacoustic cooling system shifts from one-wavelength to two-wavelength resonance during system operation. The effect of the viscous boundary layer upon the resonant wavelength shift is discussed. The viscous boundary layer thickness is always less than the stack channel radius because the loop tube increases the resonance frequency and shifts the resonant wavelength from one-wavelength to two-wavelength resonance, which reduces the influence of viscosity and allows the loop tube to maintain the thermoacoustic self-sustained sound.