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International Heat Transfer Conference 13

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

INTELLIGENT THERMAL INSULATION LAYERS WITH A SHAPE MEMORY SCREEN

Hirofumi Tanigawa
Kyushu Institute of Technology, Japan

Takashi Masuoka
The University of Kitakyushu, and Department of Mechanical Engineering, Kyushu University, Kyushu, Japan

DOI: 10.1615/IHTC13.p22.270
12 pages

Abstract

A new method is proposed in this study to improve the insulation performance of thermal insulating material. The present study proposes a thermal screen consisting of a shape memory alloy to form a new thermal insulation structure “Intelligent Thermal Insulation Layer” as a way of controlling convection, which automatically adapt the insulation performance for the change in an environmental temperature, where the “Shape Memory Screen” (Tanigawa et al., 2001, 2002) changes the effective permeability, i.e. flow resistance, according to the temperature variation in the environment. A numerical analysis is made to examine how the shape memory screen affects internal convection and temperature fields, and how it affects the insulation performance both for horizontal and vertical insulation layers. The following findings have been derived:
(1) A shape memory screen set up in thermal insulation layers brings the temporally variable partition, where the flow resistance to high-temperature convective currents is caused, and therefore the convective enthalpy transport is suppressed and the associated heat transfer rate is decreased.
(2) The compulsory deviation of the flow patterns from those of the preferred wave length occurs due to the flow resistance owing to the variable partition of the shape memory screen, which results in the decreased heat transfer rate compared with the case of the static partition.
(3) The degree of the decrease of the heat transfer rate depends not only on the non-dimensional blockage temperature θB, i.e. the non-dimensional deformation temperature of the shape memory screen, but also on the screen position H.
Then it is shown that the intelligent heat-transfer control becomes possible by utilizing the shape memory screen which can automatically select the suitable and effective thermal insulation performance according to the temperature level of the environment.

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Measurement of fluid temperature with an arrangement of three thermocouples