Abstract: A GaAs-based compound semiconductor crystal includes a straight body portion having a cylindrical shape, wherein the straight body portion has a diameter of more than or equal to 110 mm and has a length of more than or equal to 100 mm and less than or equal to 400 mm, and the straight body portion has a first end surface and a second end surface having a higher specific resistance than a specific resistance of the first end surface, and a ratio R20/R10 of a specific resistance R20 at the second end surface side to a specific resistance R10 at the first end surface side is more than or equal to 1 and less than or equal to 2.

Abstract: A GaAs-based compound semiconductor crystal includes a straight body portion having a cylindrical shape, wherein the straight body portion has a diameter of more than or equal to 110 mm and has a length of more than or equal to 100 mm and less than or equal to 400 mm, and the straight body portion has a first end surface and a second end surface having a higher specific resistance than a specific resistance of the first end surface, and a ratio R20/R10 of a specific resistance R20 at the second end surface side to a specific resistance R10 at the first end surface side is more than or equal to 1 and less than or equal to 2.

Abstract: The countercurrent direct-heating-type heat exchanger that is able to suppress drift in the case when a fluid to be heated is supplied. The heat exchanger is equipped with a feed pipe, a feed nozzle, ring-like straightening plates and umbrella-type dispersing plates of the above fluid to be heated, characterized in that the above feed nozzle has the shape of a pipe having a circular cross section and the dimension satisfying the following formula (1) and formula (2): Ln/Dn?1??Formula (1) wherein, Ln indicates the length of the feed nozzle; and Dn indicates the inside diameter of the feed nozzle; and 1.5?Sp/Sn?2.0??Formula (2) wherein, Sp indicates the inner cross-sectional area of the feed pipe; and Sn indicates the inner cross-sectional area of the feed nozzle.

Abstract: The countercurrent direct-heating-type heat exchanger that is able to suppress drift in the case when a fluid to be heated is supplied, to prevent local abrasion of the members and also to carry out efficient heat exchange. The countercurrent direct-heating-type heat exchanger equipped with a feed pipe, a feed nozzle, ring-like straightening plates and umbrella-type dispersing plates of the above fluid to be heated, characterized in that the above feed nozzle has the shape of a pipe having a circular cross section and the dimension satisfying the following formula (1) and formula (2): Ln/Dn?1 ??Formula (1) (wherein, Ln indicates the length of the feed nozzle; and Dn indicates the inside diameter of the feed nozzle) 1.5?Sp/Sn?2.0 ??Formula (2) (wherein, Sp indicates the inner cross-sectional area of the feed pipe; and Sn indicates the inner cross-sectional area of the feed nozzle).