Comparison of Models for Heat Transfer in High-Density Fibrous Insulation

Area of Science:

• Materials Science
• Thermal Engineering
• Heat Transfer

Background:

• Accurate calculation of effective thermal conductivity is crucial for fibrous insulation performance.
• Coupled radiation and conduction heat transfer significantly influence insulation properties.
• Standard Reference Material 1450c provides a benchmark for evaluating thermal models.

Purpose of the Study:

• To evaluate and compare various models for calculating the effective thermal conductivity of fibrous insulation.
• To assess the impact of coupled radiation and conduction heat transfer on model accuracy.
• To validate model predictions using certified values of Standard Reference Material 1450c.

Main Methods:

• Fiber diameter distribution was measured using X-ray computed tomography.
• Radiative heat transfer was evaluated using diffusion, Schuster-Schwarzschild, and Milne-Eddington approximations.
• Conduction was modeled using kinetic theory for gas and a semi-empirical model for fibers.
• Radiative properties were assessed using large specular reflecting and Mie theory approaches.

Main Results:

• Model predictions were compared against certified values for Standard Reference Material 1450c.
• The study analyzed the coupled effects of radiation and conduction heat transfer.
• The accuracy of different radiative and conductive heat transfer models was assessed.

Conclusions:

• The study provides a comparative evaluation of thermal conductivity models for fibrous insulation.
• Accurate characterization of fiber diameter distribution is essential for model inputs.
• The findings contribute to the development of more reliable insulation performance prediction methods.