Thermoacoustic energy converting element part and thermoacoustic energy converter

A thermoacoustic energy converter configured to amplify acoustic wave energy in a fluid using heat of a wall in contact with the fluid, the thermoacoustic energy converter comprising:

• a thermoacoustic energy converting element part;
• a guide tube forming a travelling route of acoustic waves travelling in the fluid and configured to guide the acoustic waves to through holes in the thermoacoustic energy converting element part so as the acoustic waves travel along an extending direction of the through holes;
• and
• a pair of heat exchanging units provided on both ends of the thermoacoustic energy converting element part and configured to generate temperature gradient along the extending direction between both ends of the thermoacoustic energy converting element part, wherein
• the guide tube includes an output end which is configured to output acoustic waves having sound pressure energy amplified by using the temperature gradient and to be coupled to a converter configured to convert resulting amplified sound pressure energy of output acoustic waves into other form of energy,
• the thermoacoustic energy converting element part includes a wall extendingly surrounding each of a plurality of the through holes and configured to exchange heat with the fluid, the plurality of through holes penetrating the thermoacoustic energy converting element part to extend in a direction and serving as travelling routes of acoustic waves,
• the through holes include a through hole that has a hydraulic diameter of 0.4 mm or smaller,
• an open area ratio of the plurality of the through holes in the thermoacoustic energy converting element part is 60% or higher,
• wherein the thermoacoustic energy converting element part satisfies all of the following conditions:
• a thermal conductivity of the thermoacoustic energy converting element part in fluid atmosphere is 0.4 W/m/K or lower,
• a heat capacity of the thermoacoustic energy converting element part at 400° C. in the fluid atmosphere is higher than 0.5 J/cc/K and equal to or lower than 3 J/cc/K;
• and
• a thermal expansion along an extending direction of the plurality of through holes in the thermoacoustic energy converting element part under temperature from 20 to 800° C. is 6 ppm/K or lower, and
• wherein the thermoacoustic energy converting element part is made of a material containing 80% or higher by mass of a component selected from cordierite, mullite, aluminum titanate, alumina, zirconia, silicon nitride, and silicon carbide.

A thermoacoustic energy converter configured to generate temperature gradient on a wall in contact with a fluid by using acoustic wave energy in the fluid, the thermoacoustic energy converter comprising:

• a thermoacoustic energy converting element part;
• a guide tube forming a travelling route of acoustic waves travelling in the fluid and configured to guide the acoustic waves to through holes in the thermoacoustic energy converting element part so as the acoustic waves travel along an extending direction of the through holes;
• and
• a heat exchanging unit provided on a first end of the thermoacoustic energy converting element part and kept at a constant temperature;
• and
• a heat output unit provided on a second end of the thermoacoustic energy converting element part and configured to provide a temperature different from the temperature of the heat exchanging unit by using a temperature gradient generated in the thermoacoustic energy converting element part between the heat exchanging unit and the heat output unit by travelling of the acoustic waves, wherein
• the thermoacoustic energy converting element part includes a wall extendingly surrounding each of a plurality of the through holes and configured to exchange heat with the fluid, the plurality of the through holes penetrating the thermoacoustic energy converting element part to extend in a direction and forming travelling routes of acoustic waves,
• the through holes include a through hole that has a hydraulic diameter of 0.4 mm or smaller,
• an open area ratio of the plurality of the through holes in the thermoacoustic energy converting element part is 60% or higher,
• wherein the thermoacoustic energy converting element part satisfies all of the following conditions:
• a thermal conductivity of the thermoacoustic energy converting element part in fluid atmosphere is 0.4 W/m/K or lower,
• a heat capacity of the thermoacoustic energy converting element part at 400° C. in the fluid atmosphere is higher than 0.5 J/cc/K and equal to or lower than 3 J/cc/K;
• and
• a thermal expansion along an extending direction of the plurality of through holes in the thermoacoustic energy converting element part under temperature from 20 to 800° C. is 6 ppm/K or lower, and
• wherein the thermoacoustic energy converting element part is made of a material containing 80% or higher by mass of a component selected from cordierite, mullite, aluminum titanate, alumina, zirconia, silicon nitride, and silicon carbide.