What is a reefer?

What is a reefer?

In the trucking industry, “reefer” or “reefer trailer” are slang terms for a refrigerated container. These refrigerated trailers have insulated walls and self-powered refrigeration units.

Reefers are critical to cold chain efficiency, commonly used to transport food and other temperature-sensitive goods. Perishable goods may include products like fresh produce, dairy, and medicines. Non-perishable, but temperature-sensitive goods like paint, flowers, candles, hazardous materials and bulk liquids are also transported by reefers and refrigerated trucks.

Reefers are used in both full truckload (FTL) and less than truckload (LTL) shipping. Some trailers have multiple temperature zones, allowing different kinds of cargo to be transported within the same reefer.

Different types of reefer containers

There are several different types of reefer containers. Unlike dry vans, which can have walls, ceilings, and floors made of wood, reefers are usually made of metal or fiberglass to improve insulation.

• Closed reefers. These are the most conventional types of refrigerated containers. It’s a single unit with an all-electric cooling and heating system.

• Modified/controlled atmosphere (MA/CA) reefers. These reefer containers are insulated to regulate temperature control. They use an air exchange system to maintain a constant temperature setting.

• Automatic fresh air management (AFAM) reefers. These are the most advanced kinds of reefer trailers. They use a control system that automatically regulates the container’s air exchange to maintain a required temperature.

How reefer units work

Reefers are not intended to cool a product. Instead, they are designed to maintain a specific temperature for products. They do this by collecting and removing heat from the inside of the trailer.

Refrigerated trailers use three core components for their cooling system:

1. Compressor. A small diesel engine powers the compressor, which draws in gaseous refrigerant and compresses it. This compressed refrigerant liquefies into a high (hot) temperature gas and gets passed to the condenser.

2. Condenser. The condenser receives the gas from the compressor and begins a heat exchange process. Outside air flows through the condenser fan, causing heat to dissipate and the refrigerant to lose temperature. As the refrigerant cools, it condenses and turns from hot gas to regular temperature liquid.

3. Evaporator. The liquid refrigerant enters the evaporator through an expansion valve. This valve controls the flow of refrigerant, which in turn controls cooling. As the refrigerant passes through this valve, it becomes a cool liquid. Once in the evaporator, the liquid expands and turns into a warm gas again, absorbing the heat and air from inside the container. This gas gets sucked into the compressor, starting the cycle over again.

These components cause variations in air pressure to create airflow. Refrigeration works by pulling in outside and inside air to remove heat and redistribute colder air through the container. Because proper airflow throughout the reefer is key to maintaining a steady temperature, it is better to transport cargo loaded on pallets.

Household refrigeration, refrigerator cars on trains, and refrigerated shipping containers work similarly.

Refrigeration units run in two ways: cycles or continuous. Running the refrigeration unit in cycles reduces diesel consumption but creates more temperature variance. Frozen foods, which are less temperature-sensitive, can withstand variances. Continuous cooling is better for products and goods that can’t withstand temperature variances well.

4 key benefits of reefer trailers

1. Protecting perishable cargo

Reefer trailers are essential for preserving the quality of temperature-sensitive goods during transport. They maintain precise temperature control, preventing spoilage of items like fresh produce, dairy, meat, pharmaceuticals, flowers, and more. This ensures adherence to stringent food safety standards and guarantees cargo arrives in optimal condition.

2. Managing cargo for various temperatures

Reefer trailers offer adaptable temperature settings to accommodate diverse product needs:

• Frozen products: Maintaining sub-zero conditions for frozen goods like ice cream and seafood.

• Chilled goods: Providing a controlled cool environment for dairy, beverages, and fresh produce.

• Ambient cargo: Ensuring consistent, non-refrigerated temperatures when required.

3. Robust and reliable construction

Refrigerated trailers are engineered for durability, featuring key components such as reinforced structures and high-grade insulation to withstand demanding transport conditions. Some reefers also feature weather-resistant exteriors and heavy-duty components for transporting temperature-sensitive goods across far distances. This robust design minimizes maintenance and downtime, reducing cargo loss and maximizing operational efficiency.

4. Leveraging technology to improve reefer operations

Modern reefer trailers incorporate advanced technologies to improve performance and reduce costs, such as:

• Automated tire pressure monitoring systems for enhanced fuel efficiency and tire longevity.

• Fuel-efficient diesel engines powering refrigeration units, lowering operational expenses.

• Real-time trailer management systems help fleets remotely monitor reefer temperature, fuel, and system performance, streamlining issue resolution and minimizing cargo risk.

Improve efficiency and reduce operational costs with Samsara Smart Trailers

Innovative organizations today are now connecting their trailer fleet with the cloud, improving the efficiency, compliance, and safety of your reefer trailer operations. Trailer management solutions like Samsara Smart Trailers provide complete visibility within a single, consolidated platform across your entire trailer fleet.

• Increase operating efficiency: A powerful combination of wireless sensors and instant alerts provide visibility and control of your entire reefer trailer operation.

• Ensure product quality: Samsara's affordable reefer management solution monitors temperatures in-transit to prevent product spoilage and rejected deliveries.

• Simplify FSMA compliance: Automated, continuous temperature logging eliminates manual recordkeeping and makes it easy to provide temperature records on-demand

• Enhance operational efficiency: Transform your trailer operations by leveraging real-time visibility to streamline proactive maintenance, boost productivity, and improve driver safety.

DHL Group is one of the largest logistics companies worldwide, often transporting high-value and temperature-sensitive items for their customers. In the past, they manually tracked trailers to determine load status and location. If a shipment went missing, it could take up to two days to search the yard and locate the trailer, which was especially challenging with perishable goods. “Previously, trailer management was difficult—reporting was minimal and separate from our routing and ELD solutions,” said David Russeau, Systems Operations Manager.

With Samsara’s Smart Trailer solution, they have complete, real-time visibility into trailer location, cargo, and temperature. “Cargo Monitors allow us to report on which trailers have product and what the temperatures are, both in the yard and at delivery,” said Russeau. This visibility, along with real-time location tracking, enables DHL to eliminate manual yard hunts and quickly locate trailers and cargo. “Samsara consolidates this information into a single platform, allowing us to track our trailers’ location, status, and idle times,” said Russeau. As a result, their operators can more confidently monitor cargo location and integrity for their customers.

Watch Video

To learn more about how you transform your trailer operations, check out Samsara’s Smart Trailers solution and speak to our team today.