Transient experimental technique for the determination of the thermal diffusivity of fibrous insulation

Journal Article · Mon Feb 01 00:00:00 EST 1988 · Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States)

DOI:https://doi.org/10.1115/1.3250467· OSTI ID:6099660

Rooke, S P; Taylor, R E ^[1]

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1. Purdue Univ., West Lafayette, IN (United States)

The current investigation is an attempt to develop a transient technique that will circumvent these long experiment times. The present technique is fundamentally different from the hot-wire and hot-strip techniques, currently the only practical (but limited) transient techniques available for determining the thermal conductivity of insulators. In 1983, a step heat technique involving planar geometry was presented (Bittle, 1983; Bittle and Taylor, 1984; Bittle and Taylor, 1985) that allowed for the measurement of large-grained and nonfibrous insulators up to 400-500C. The technique is an extension of the flash technique in that it allows for larger sample sizes and longer heating times. It was found that the step heat technique is inappropriate for fibrous insulators because of boundary condition violations. At the front face of the sample, the assumption of constant heat flux into the surface of a semi-infinite medium being heated with irradiation is invalid for radiant fluxes and time durations typical in measuring poorly conducting materials. In addition, at the rear of the sample where the temperature rise is monitored, the assumption of no heat loss is violated; this is especially true for insulators at elevated temperatures. While the apparatus for the present technique and the step heat technique are similar, the present technique involves the substitution of measured values for mathematical approximations and thus is marked departure from previous practices.

• OSTI ID: 6099660
• Journal Information: Journal of Heat Transfer (Transactions of the ASME (American Society of Mechanical Engineers), Series C); (United States), Vol. 110:1; ISSN 0022-1481
• Country of Publication: United States
• Language: English

Related Subjects

47 OTHER INSTRUMENTATION
36 MATERIALS SCIENCE
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
THERMAL DIFFUSIVITY
MEASURING METHODS
THERMAL INSULATION
THERMAL CONDUCTIVITY
DATA
FURNACES
INFORMATION
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
440800* - Miscellaneous Instrumentation- (1990-)
360606 - Other Materials- Physical Properties- (1992-)
320107 - Energy Conservation
Consumption
& Utilization- Building Systems- (1987-)