Tunneling is an activity that requires careful planning and execution, as it involves working in extreme conditions underground. One of the most important aspects to consider is the ventilation system, which aims to guarantee air quality and the safety of users.
Tunnel fans are the equipment responsible for supplying and extracting air in underground works, both during the construction and operation phases. These fans must meet the most rigorous design, manufacturing, and testing standards to ensure their reliability and resistance to emergencies, such as fires or explosions.
In this article, we are going to explain the main types of tunnel fans, their characteristics, and advantages, as well as the criteria that must be considered to select the most suitable one for each project. In addition, we will talk about SODECA, a leading company in the manufacture of tunnel fans, which has extensive experience and a specialist department in this field. SODECA offers a range of tunnel fans of high quality, efficiency, and safety, adapted to the needs and specifications of each work. SODECA has participated in numerous tunnel ventilation projects around the world, providing its experience and innovative technology.
Types of tunnel fans
Tunnel fans can be classified according to their function, location, and configuration. Below, we describe each of these criteria and the most common examples of fans that fit them.
According to its function
Tunnel fans can have distinct functions, depending on the stage of the work and the ventilation needs. Some of these functions are:
- Primary ventilation: It is responsible for introducing fresh air from the outside to the inside of the tunnel, using fans located in the portals or at the mouths of the ventilation shafts. This ventilation is necessary both in the construction and operation phases, to maintain adequate environmental conditions for workers and users.
- Secondary ventilation: It is responsible for distributing fresh air throughout the tunnel, using fans located inside it or in the transverse galleries. This ventilation is especially important in the construction phase, to eliminate dust, smoke and gases generated by machines and explosions.
- Emergency ventilation: It is responsible for extracting contaminated or stale air in the event of a fire, an explosion, or a gas leak in the tunnel, using fans located in the portals or at the mouths of the ventilation shafts. This ventilation is essential for the safety of workers and users, as it controls smoke and facilitates evacuation and rescue.
Depending on location
Tunnel fans can be in various locations, depending on the length, geometry, and topography of the tunnel. Some of these locations are:
- In the portals: These are the fans that are located at the ends of the tunnel, where it connects with the outside. These fans can have a primary or emergency ventilation function, depending on the direction of air flow. For example, in a bidirectional tunnel, fans on one portal can introduce fresh air, while those on the other portal can extract stale air.
- In the ventilation shafts: These are the fans that are located at the mouths of the vertical shafts that connect the tunnel with the outside. These fans can have a primary or emergency ventilation function, depending on the direction of air flow. For example, in a long tunnel or with a steep slope, shaft fans can introduce fresh air, while portal fans can extract stale air.
- Inside the tunnel: These are the fans that are located along the tunnel, in the space between the roof and the lining. These fans have a secondary ventilation function, distributing fresh air throughout the tunnel. For example, in a tunnel with multiple sections or branches, interior fans can create differential pressure zones to direct airflow.
Depending on configuration
Tunnel fans can have different configurations, depending on the shape, size and number of the blades or propellers that make them up. Some of these configurations are:
- Axial: These are fans that have the blades arranged in a cylinder shape, so that the air flows in the same direction as the axis of the fan. These fans usually have a large diameter and a high number of blades, which allows them to generate high flow and low pressure. They are best suited for primary and emergency ventilation as they can move large volumes of air at low speeds.
- Centrifugal: These are fans that have the blades arranged in the shape of a disc, so that the air flows in a direction perpendicular to the axis of the fan. These fans typically have a small diameter and a reduced number of blades, allowing them to generate low flow and high pressure. They are best suited for secondary ventilation, as they can overcome pressure losses and tunnel resistances.
- Mixed: These are fans that combine the characteristics of axial and centrifugal fans, so that the air flows in a direction intermediate between the axis and the plane of the fan. These fans usually have a medium diameter and a moderate number of blades, which allows them to generate an intermediate flow rate and pressure. They are the most versatile for tunnel ventilation since they can be adapted to different conditions and requirements.
Features and benefits of tunnel fans
Tunnel fans are equipment that have a series of characteristics and advantages that make them ideal for application in underground works. Some of these features and advantages are:
- Toughness: Tunnel fans are designed and manufactured to withstand the extreme conditions that occur underground, such as humidity, temperature, corrosion, dust, noise, and vibrations. In addition, they are equipped with protection and security systems, such as grilles, dampers, sensors, alarms and remote-control devices, which guarantee their correct operation and easy maintenance.
- Efficiency: Tunnel fans are optimized to consume the least amount of energy possible, without compromising performance and capacity. To achieve this, light and resistant materials, high-efficiency electric motors, frequency converters, heat recovery systems and intelligent control systems are used, which allow the air flow and pressure to be adjusted according to the needs of each moment.
- Flexibility: Tunnel fans can adapt to the distinct phases and situations that occur in underground works, both in construction and operation. To do this, modular, portable, reversible, and redundant systems are used, which allow the location, orientation, direction, and number of fans to be changed according to the characteristics and requirements of each project.
Selection criteria for tunnel fans
Tunnel fans are equipment that must be selected according to a series of technical, economic, and environmental criteria, which ensure their suitability for the project and their long-term profitability. Some of these criteria are:
- Capacity and pressure: The fans must be capable of supplying the required air flow for each ventilation scenario, both under normal and emergency conditions, and of overcoming system pressure losses. The air flow is determined based on vehicle emissions, permissible pollutant concentrations and applicable regulations. The pressure is calculated based on the length of the tunnel, the cross section, the roughness, the curves, the mouths and the control and regulation elements.
- Efficiency and energy consumption: Fans must have high efficiency to minimize energy consumption and reduce associated CO2 emissions. Efficiency depends on fan design, operating point, and control system. It is recommended to use variable speed fans to adapt the air flow to real needs and optimize system performance.
- Noise and vibrations: The fans must generate the minimum noise and vibrations possible, both to avoid inconvenience to tunnel users and to comply with the established legal limits. The noise level depends on the type of fan, rotation speed, air flow and pressure. Acoustic insulation measures, such as silencers, baffles, or enclosures, can be used to reduce noise transmitted into the tunnel or outside.
- Safety and reliability: Fans must have an elevated level of safety and reliability, especially in the event of fire, where they must resist elevated temperatures and guarantee smoke control. Fans must comply with fire and occupational safety regulations, and be equipped with protection, monitoring, and maintenance systems. Fire resistance and performance tests must be carried out to verify the behavior of the fans under extreme conditions.
Summary
Tunnel fans are essential equipment to ensure air quality and safety in underground works. There are diverse types of tunnel fans, which can be classified according to their function, location, and configuration. Each type of fan has its characteristics and advantages, which make it suitable for each project. The selection criteria for tunnel fans must consider the dimensions, geometry, topography, environmental conditions, and safety requirements of the tunnel, as well as the efficiency, flexibility, and robustness of the equipment. Tunnel fans are an example of how engineering and technology can contribute to improving the development and sustainability of underground infrastructure.
SODECA is a leading company in the manufacture of tunnel fans, which has a specialist department in this field. SODECA offers a wide range of tunnel fans, adapted to the needs and specifications of each project. With more than 30 years of experience and constant innovation, SODECA has established itself as a benchmark in the tunnel ventilation sector, providing efficient, safe, and sustainable solutions. SODECA has factories located in different countries around the world that maintain the same quality standards with CE marking and have the experience of a team made up of specialized professionals, who not only offer ventilation equipment, but also solutions for specific projects. SODECA has participated in numerous tunnel ventilation projects around the world, providing its experience and innovative technology. Some examples of these projects are:
- Guadarrama Tunnel (Spain): SODECA supplied forty large diameter axial fans for primary and emergency ventilation of this high-speed railway tunnel, which has a length of 28.4 km and is the second longest in Spain.
- L?rdal Tunnel (Norway): SODECA supplied thirty-two reversible axial fans for primary and emergency ventilation of this road tunnel, which has a length of 24.5 km and is the longest in Europe and the second longest in the world.
- Gotthard Base Tunnel (Switzerland): SODECA supplied eighteen high-pressure centrifugal fans for the secondary ventilation of this railway tunnel, which has a length of 57 km and is the longest and deepest in the world.
