Behavior of thermal insulations for hot gas ducts of high temperature gas cooled reactors

Four types of insulations have been tested mainly in a high pressure wind tunnel at a pressure up to 40 bars and a temperature up to 4000C. Both air and helium have been used as coolant. The test body was mounted horizontally. The cooling system welded to the outside of the pressure tube was subdivided into four sectors over the circumference. Thus, it was possible to study the influence of free convection at different operating conditions. Some tests in stagnant gas have been carried out in vertical position of the test tube. In this case electrical heating has been applied. The highest temperature achieved was 7600C at nearly 40 bars. Radial and axial temperature distributions, thermal fluxes, and effective thermal conductivities have been measured