Research on the Influence of Enclosure Materials of Prefabricated Substations on Heat Dissipation Performance_Zhejiang Zhilu Transmission and Distribution Equipment Co., Ltd

16-06 2025

Zhejiang Zhilu Transmission and Distribution Equipment Co., Ltd

Research on the Influence of Enclosure Materials of Prefabricated Substations on Heat Dissipation Performance

Abstract

This research focuses on the impact of different enclosure materials of prefabricated substations on their heat dissipation performance. As prefabricated substations house high - voltage switchgear, transformers, and low - voltage distribution equipment, efficient heat dissipation is crucial to ensure stable operation and extend the lifespan of internal components. By analyzing the thermal conductivity, specific heat capacity, and radiation characteristics of common enclosure materials, this study aims to provide a theoretical basis for optimizing material selection to enhance heat dissipation in prefabricated substations.

1. Introduction

Prefabricated substations play a vital role in modern power distribution systems due to their compact structure and quick installation. However, during operation, internal electrical components, especially transformers, generate a large amount of heat. If heat cannot be dissipated effectively, it may lead to overheating, component failure, and reduced system reliability. The enclosure material of prefabricated substations not only provides mechanical protection but also significantly affects heat transfer processes, including conduction, convection, and radiation.

2. Heat Transfer Mechanisms in Prefabricated Substations

2.1 Conduction

Heat conduction occurs within the enclosure material itself and between the internal components and the enclosure. The rate of heat conduction is determined by Fourier's law:

Q = - k A \frac{d T}{d x}

, where

Q

is the heat transfer rate,

k

is the thermal conductivity of the material,

A

is the cross - sectional area, and

\frac{d T}{d x}

is the temperature gradient. Materials with lower thermal conductivity act as better insulators, impeding heat transfer from the inside to the outside of the substation.

2.2 Convection

Convection involves the transfer of heat through the movement of fluids (usually air) near the enclosure surface. Natural convection occurs due to density differences caused by temperature variations, while forced convection can be enhanced by fans. The heat transfer coefficient

h

in the convection equation

Q = h A Δ T

is influenced by the surface roughness and geometry of the enclosure, which are related to the material's properties and manufacturing process.

2.3 Radiation

Thermal radiation is the transfer of heat in the form of electromagnetic waves. The amount of radiation emitted by the enclosure surface is described by the Stefan - Boltzmann law:

Q = ε σ A T^{4}

, where

ε

is the emissivity of the surface,

σ

is the Stefan - Boltzmann constant,

A

is the surface area, and

T

is the absolute temperature. Materials with different surface finishes and chemical compositions have different emissivity values, affecting their radiation heat transfer capabilities.

3. Common Enclosure Materials and Their Heat Dissipation Characteristics

3.1 Steel

Thermal Conductivity: Steel has a relatively high thermal conductivity (about 50 - 60 W/(m·K)), which means it can conduct heat quickly. While this may seem beneficial for heat transfer, it can also lead to uneven temperature distribution on the enclosure surface if not properly insulated.
Surface Treatment: Painted or galvanized steel surfaces can change the emissivity. For example, a matte black paint can increase the emissivity to around 0.9, enhancing radiation heat transfer. However, steel enclosures are prone to corrosion, and corrosion products can further affect heat transfer.

3.2 Aluminum

Thermal Conductivity: Aluminum has a higher thermal conductivity than steel (approximately 205 W/(m·K)), making it an excellent conductor of heat. It can quickly transfer heat from internal components to the outer surface, facilitating convection and radiation.
Lightweight and Corrosion Resistance: Its lightweight nature reduces the overall weight of the substation, and good corrosion resistance ensures long - term stable heat dissipation performance. However, the surface emissivity of pure aluminum is relatively low (about 0.05 - 0.1), and anodizing or coating is often required to increase emissivity for better radiation heat transfer.

3.3 Glass - Reinforced Plastic (GRP)

Thermal Conductivity: GRP has a much lower thermal conductivity (around 0.2 - 0.4 W/(m·K)) compared to metals, acting as an effective thermal insulator. This can prevent excessive heat loss in cold environments but may also impede heat dissipation from internal components in normal operation.
Surface Properties: GRP enclosures can be molded into complex shapes, and their surface can be designed to optimize convection. Additionally, additives can be used to adjust the emissivity, improving radiation heat transfer.

3.4 Stainless Steel

Thermal Conductivity: Stainless steel has a lower thermal conductivity than carbon steel (about 15 - 20 W/(m·K)). Its corrosion - resistant properties make it suitable for harsh environments. However, the lower conductivity may require additional heat dissipation measures, such as increasing the surface area or using forced convection.
Surface Finish: A brushed or polished surface finish affects emissivity. A rough surface can increase emissivity, promoting radiation heat transfer, while a smooth surface may reduce it.

4. Experimental Analysis

4.1 Experimental Setup

A series of test models of prefabricated substations with enclosures made of different materials (steel, aluminum, GRP, and stainless steel) were constructed. Identical electrical heating elements were installed inside to simulate the heat generation of internal components. Temperature sensors were placed at various positions inside and outside the enclosures to monitor temperature changes over time.

4.2 Results and Discussion

Temperature Distribution: The aluminum enclosure showed the lowest internal temperature rise due to its high thermal conductivity, effectively transferring heat to the surface. In contrast, the GRP enclosure had the highest internal temperature rise, as its low thermal conductivity restricted heat transfer.
Heat Transfer Efficiency: By calculating the overall heat transfer coefficient of each enclosure, it was found that the aluminum enclosure had the highest heat transfer efficiency, followed by steel, stainless steel, and GRP. The difference in heat transfer efficiency was mainly attributed to the combined effects of thermal conductivity, surface emissivity, and convective heat transfer characteristics.

5. Optimization Strategies for Heat Dissipation

5.1 Material Selection

For areas with high heat generation and good ventilation conditions, aluminum or steel with appropriate surface treatment (e.g., high - emissivity coating) is recommended to enhance heat dissipation.
In environments where corrosion resistance and insulation are more critical, such as coastal areas or regions with high humidity, stainless steel or GRP with optimized heat dissipation designs (e.g., adding heat dissipation fins) can be used.

5.2 Structural Design

Incorporating heat dissipation fins on the enclosure surface can increase the surface area for convection and radiation, regardless of the material used.
Designing ventilation holes or installing fans to enhance forced convection can significantly improve heat dissipation performance, especially for materials with lower thermal conductivity like GRP.

6. Conclusion

The enclosure material of prefabricated substations has a significant impact on heat dissipation performance through its effects on conduction, convection, and radiation. Aluminum generally provides the best heat dissipation capabilities due to its high thermal conductivity, while materials like GRP require additional design measures to overcome their insulating properties. By carefully considering material properties and implementing appropriate optimization strategies, the heat dissipation performance of prefabricated substations can be effectively improved, ensuring the safe and reliable operation of power distribution systems. Future research could focus on developing new composite materials with both excellent heat dissipation and mechanical properties for prefabricated substation enclosures.

Tags: Photovoltaic Stainless steel casing