Author: Oscar A. BuchmannPublisher:
ISBN:
Category :
Languages : en
Pages : 766
Book Description
A design concept and internal design details were developed for an annular core configuration heat exchanger for hydrogen-air service with maximum air inlet temperatures of 3000 degrees R and maximum metal temperatures of 2600 degrees R. The heat exchanger was subdivided into three metal temperature zones. Tube wall thickness of less than 0.010-in. and structurally minimum gauges in other areas were specificed objectives and were used in core construction. For the high temperature section of the heat exchanger, TD Nickel was selected. Satisfactory coating systems for the extreme temperature environment were found unaviable; the maximum permissible service temperature for the brazed bare TD Nickel tubing (0.009-in. wall) was 2410 degrees R.A series of sub-elements and an 1120 tube heat exchanger were satisfactorily fabricated of TD Nickel. The latter was thermally cycled with flowing air. The lack of high temperature ductility of this material is a limitation for applications encountering high thermal strains. For the intermediate temperature section of the heat exchanger, L605 alloy was selected. Those areas less than 0.015-in. thick were coated on both sides with Misco MDCIA. Sub-elements and a 3000-tube exchanger were fabricated with flowing air under conditions of thermal cycling. For the low temperature section of the heat exchanger, uncoated Hastelloy X tubing with 0.003-in.-thick walls was used. Susceptibility of the Hastelloy X to erode when brazed with Nicrobraz 30 or other available alloys with melting points above 2000F was noted. A 444-tube heat exchanger module was fabricated and evaluated. (Author).
