How Do Refrigerated Trailers Work?

Refrigerated trailers are essential for transporting temperature-sensitive goods, ensuring they remain fresh, safe, and high-quality throughout their journey. These trailers are specially designed to maintain a consistent internal temperature, no matter the conditions outside. They are vital for industries handling perishable goods, from frozen food and fresh produce to pharmaceuticals and bulk liquids.

Understanding how refrigerated trailers work can help businesses optimise their use, protect valuable goods, and ensure compliance with food safety standards. These trailers are equipped with advanced refrigeration systems and insulation to regulate cool air inside while preventing heat transfer from the environment. 

With features like temperature control and continuous cooling, they are a crucial part of supply chains requiring reliable cold storage during transport. Let’s explore the key components and how they work.

The Basics of Refrigerated Trailers – How Do They Work?

At their core, refrigerated trailers are insulated containers equipped with a refrigeration unit. This unit works to regulate the internal environment of the trailer, ensuring that the ambient temperature inside stays within the desired range, regardless of the outside air conditions. 

But how does this sophisticated system manage to keep cool air flowing while maintaining consistent cooling throughout the trailer?

Let’s break it down into key components and processes.

Key Refrigeration Components

1. Refrigeration Unit: The refrigeration unit is the heart of any refrigerated trailer. It includes a compressor, condenser, evaporator coil, and other essential parts that work together to remove heat from inside the trailer. These components ensure chilled air is consistently distributed, helping maintain adequate temperature controls for perishable goods.
2. Insulation: Insulation plays a vital role in maintaining the desired temperature. High-quality insulation prevents heat transfer from outside air into the trailer, reducing the workload on the refrigeration system and ensuring consistent temperature control.
3. Evaporator Coil: The evaporator coil is where the magic happens. Located inside the trailer, it cools the air by absorbing heat and humidity, which is then expelled outside. This process creates the cool air inside the trailer and keeps temperature-sensitive goods safe.
4. Power Supply: Refrigerated trailers can operate using an external power source or a diesel-powered reefer unit. Modern systems often feature cycles that reduce diesel consumption, making the operation more efficient and eco-friendly.

How the Cooling System Works

The cooling system in refrigerated trailers operates through a continuous cycle of heat removal and air circulation. Here’s a closer look at how it works:

1. Heat Removal: The refrigeration unit removes heat from the trailer’s interior by circulating a refrigerant through the evaporator coil. The refrigerant absorbs heat, turning it from a liquid to a gas. This gas is then compressed and cooled in the condenser, releasing the heat outside.
2. Cool Air Circulation: Fans distribute the chilled air evenly throughout the trailer, ensuring that all areas maintain the correct temperature. This circulation process prevents hotspots, which could compromise the quality of the goods being transported.
3. Temperature Control: Modern refrigerated trailers feature advanced temperature control systems, allowing operators to set and monitor multiple temperature zones. This is particularly useful for transporting mixed loads of frozen goods, fresh produce, and other temperature-sensitive items in the same journey.
4. Continuous Cooling: Continuous cooling ensures that the trailer maintains its set temperature even during loading and unloading, where outside air can briefly enter the trailer.

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Types of Refrigerated Trailers

Depending on the specific needs of the cargo, refrigerated trailers come in various configurations:

Freezer Trailers

Designed to maintain sub-zero temperatures, freezer trailers are ideal for frozen food and other goods that require colder air to stay preserved.

Chiller Trailers

These trailers are best suited for fresh produce and perishable goods that need to be kept at a cool, but not frozen, temperature.

Multi-Temperature Trailers

Some reefer trailers are equipped with multiple temperature zones, making them versatile for mixed loads of frozen, chilled, and ambient-temperature products.

Read More: A Guide To Refrigerated Trailer Weight & Capacity

The Role of Air Pressure and Heat Transfer

Maintaining consistent cooling isn’t just about lowering the temperature—it also involves managing air pressure and heat transfer. Properly sealed doors and high-quality insulation minimise the impact of outside air and keep cool air inside. 

Additionally, the placement of goods within the trailer can affect airflow and cooling efficiency. Overloading or blocking the airflow can create uneven temperatures, which is why correct loading practices are essential.

Why Temperature Control Matters

Temperature control is critical for businesses transporting temperature-sensitive goods. From maintaining food safety to preventing spoilage, keeping goods at the correct temperature ensures:

• Compliance with regulations: Food safety standards require that perishable goods are transported and stored at specific temperatures to prevent bacterial growth.
• Product quality: Consistent temperature control preserves the freshness and quality of goods, whether it’s chilled dairy products or frozen seafood.
• Reduced waste: Minimising temperature fluctuations reduces spoilage, saving costs and preventing product loss.

Innovations in Refrigerated Trailers

Modern refrigerated trailers are evolving to meet the demands of efficiency, sustainability, and precision. Features like cycles that reduce diesel consumption, smart monitoring systems, and advanced insulation materials are becoming standard. 

Some systems even integrate with GPS and telematics to provide real-time data on temperature and system performance, ensuring that temperature-sensitive goods are stored without compromise.

Maintaining Refrigerated Trailers

To ensure that a reefer trailer works efficiently, regular maintenance is essential. Key tasks include:

• Checking the refrigeration system for leaks or damage
• Cleaning the evaporator coil and fans to maintain airflow
• Inspecting door seals to prevent heat transfer
• Ensuring the power supply is reliable, whether it’s a diesel generator or an external power source

Routine inspections and servicing help prevent breakdowns and extend the lifespan of the refrigeration unit.

Choosing the Right Refrigerated Trailer

When selecting a refrigerated trailer, businesses should consider factors like the type of goods being transported, required temperature range, and journey length. Companies like North Star Hire in the UK offer a range of refrigerated and freezer trailers to meet diverse needs, ensuring that goods are transported safely and efficiently.

Looking for Refrigerated Trailer Hire Across The UK?

Refrigerated trailers are more than just a box on wheels—they are complex systems designed to preserve the quality of temperature-sensitive goods. By understanding how these trailers work, businesses can make informed decisions about their transport needs, ensuring fresh produce, frozen food, and other perishable goods reach their destination in top condition.

At North Star Hire we’re dedicated to delivering reliable, safe and hassle-free refrigeration. With years of experience in the cold storage and transport industry, we know what it takes to keep your goods at the ideal temperature.

Get a Quote Today!

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