In the fields of high-end building energy conservation and industrial high-temperature and low-temperature insulation, aerogel is considered a representative high-performance insulation material. Thermal conductivity is the core indicator for evaluating the thermal insulation performance of aerogel and a key technical characteristic that distinguishes it from traditional insulation materials. This article will systematically analyze the thermal conductivity performance of aerogel from the perspectives of material structure, heat transfer mechanism, and application performance.

I. What is Thermal Conductivity and Its Importance

Thermal conductivity is usually expressed as λ (W/(m·K)) and is used to measure a material's ability to conduct heat.

The lower the value, the stronger the material's ability to block heat transfer, and the better its insulation performance.

In the selection of insulation materials, thermal conductivity directly determines:

The required insulation layer thickness

The overall energy efficiency of the system

The operational stability of equipment or building

Aerogel stands out among many insulation materials precisely because of its extremely low thermal conductivity.

II. Overview of Aerogel Material Properties

Aerogels are porous solid materials made from inorganic or organic sols through gelation and special drying processes. Their internal structure has the following typical characteristics:

Nanoscale pore size

Extremely high porosity

Extremely low solid framework ratio

Low material density

Structurally, aerogels belong to nanoporous thermal insulation materials, which is the fundamental reason for their extremely low thermal conductivity.

III. Structural Basis for the Low Thermal Conductivity of Aerogels

1. Inhibition of Gas Thermal Conductivity by the Nanoporous Structure

The pore size inside aerogels is typically in the nanoscale range. When the pore size is smaller than the mean free path of gas molecules:

The frequency of gas molecule collisions with the pore walls increases.

The heat transfer between gas molecules is significantly restricted.

This phenomenon is called the Knudsen effect, a key mechanism behind the extremely low thermal conductivity of aerogels.

2. The solid framework's heat conduction path is severely weakened.

The solid framework of aerogels exhibits an extremely fine and poorly continuous network structure:

There are few solid heat transfer channels.

Heat is difficult to form continuous conduction paths.

This effectively reduces the proportion of solid heat conduction in the overall heat transfer.

IV. Analysis of the Main Components of Aerogel Thermal Conductivity

The overall thermal conductivity of aerogels is generally composed of the following three parts:

1. Solid thermal conductivity: from the framework structure

2. Gas thermal conductivity: from the gas in the pores

3. Radiative heat transfer: from the thermal radiation effect

Through structural design, aerogels have achieved effective control over these three aspects:

Minimally small solid component → Low solid thermal conductivity

Nanopores inhibit gas heat transfer → Low gas thermal conductivity

Porous structure scatters radiative energy → Limits radiative heat transfer

V. Main Factors Affecting the Thermal Conductivity of Aerogels

1. Density and Porosity

Within a reasonable range:

Higher porosity

Lower solid content

Typically lower thermal conductivity

However, excessively low density may affect the structural stability of the material; therefore, a balance needs to be struck between performance and strength.

2. Operating Temperature Range

As temperature increases:

The proportion of heat radiation transfer increases.

The thermal conductivity may show a certain upward trend.

Therefore, in high-temperature or low-temperature applications, it is necessary to select the appropriate type of aerogel product based on the operating conditions.

3. Moisture Content

If aerogel is exposed to moisture:

The air in the pores is replaced by water.

The thermal conductivity will increase significantly.

Therefore, in practical applications, aerogel products are usually used in conjunction with protective layers or composite structures.

VI. Performance Advantages of Aerogel Thermal Conductivity in Practical Applications

1. Ultra-thin Insulation Advantage

With the same insulation effect, the required thickness of aerogel is significantly less than that of traditional insulation materials, making it suitable for engineering scenarios with limited space.

2. Stable Thermal Insulation Performance Over a Wide Temperature Range

Aerogel exhibits relatively stable thermal conductivity under high-temperature, low-temperature, and large temperature fluctuation conditions, making it widely applicable.

3. Applications in Industrial and Building Sectors

In industrial pipeline and equipment insulation systems, as well as building energy-saving systems, the high thermal conductivity of aerogels helps to:

Reduce system energy consumption

Reduce heat loss

Improve overall operating efficiency

Overall, the extremely low thermal conductivity of aerogels stems from their unique nanoporous structure and their comprehensive ability to suppress various heat transfer mechanisms. By limiting gas heat conduction, weakening solid heat transfer, and reducing radiative heat transfer, aerogels exhibit significant advantages in thermal insulation performance, becoming an important component of high-performance insulation material systems.