Refrigerated containers play a vital role in the transportation and storage of perishable goods. These containers, commonly known as reefers, are specially designed to maintain a controlled temperature and humidity level to prevent spoilage and preserve the quality of the goods. In this article, we will take a closer look at the technology behind cold storage and how refrigerated containers work.
Cold Storage: Ensuring Freshness and Safety
Cold storage is a critical component of the supply chain for various industries, including pharmaceuticals, food and beverages, and healthcare. The ability to keep products at specific temperature ranges ensures their freshness, extends their shelf life, and safeguards their quality and safety.
The Basics: Insulation and Refrigeration
To understand how refrigerated containers work, it is necessary to grasp the basic principles of insulation and refrigeration. These two elements work hand in hand to maintain the desired temperature inside the container.
The process starts with a well-insulated container made of materials with low thermal conductivity. The walls, roof, and floor of the container are constructed using materials such as polyurethane foam or polystyrene panels. These materials effectively minimize heat transfer between the inside and outside of the container.
Refrigeration units are the heart of these containers. These units use a compressor, condenser, expansion valve, and evaporator to remove heat from the container’s interior. They operate using either a mechanical vapor compression or absorption refrigeration system.
Mechanical Vapor Compression (MVC) System
The most commonly used refrigeration system in refrigerated containers is the mechanical vapor compression (MVC) system. It operates by compressing and expanding a refrigerant gas to absorb and release heat.
The process begins with the compressor compressing the refrigerant gas, increasing its pressure and temperature. The high-pressure gas then flows to the condenser, where it releases heat to the surrounding environment, causing the gas to condense into a high-pressure liquid.
The high-pressure liquid refrigerant then passes through an expansion valve, which reduces its pressure, causing it to evaporate and absorb heat from the container’s interior. This evaporation process cools down the container’s air and maintains the desired temperature.
The low-pressure gas is then drawn back into the compressor, and the cycle repeats, ensuring a continuous cooling process to maintain the desired temperature inside the container.
Absorption Refrigeration System
While less common, refrigerated containers may also utilize absorption refrigeration systems. These systems operate using a different principle compared to the MVC system.
In absorption refrigeration, a mixture of water and an absorbent, such as lithium bromide, is used instead of a refrigerant gas. The absorbent has a high affinity for water vapor, allowing it to remove heat from the container’s interior.
The process starts with a heat source, such as electric heating elements or natural gas burners, providing the required energy to drive the system. This heat source raises the temperature of the mixture, causing the water to evaporate.
The water vapor then passes through the condenser, where it is cooled, causing it to condense into a liquid. This liquid then flows back to the evaporator, where it absorbs heat from the container’s interior, evaporates, and completes the cycle.
Temperature and Humidity Control
Refrigerated containers offer precise control over both temperature and humidity levels. Temperature control is achieved by accurately monitoring the container’s internal temperature using sensors and adjusting the refrigeration system accordingly.
Humidity control is equally important, especially for products that require specific levels of moisture. To control humidity, refrigerated containers often incorporate a dehumidification system. This system removes excess moisture from the air, preventing condensation and maintaining the ideal conditions for the stored goods.
Advanced Features: Monitoring and Telematics
Modern refrigerated containers are equipped with advanced monitoring and telematics systems. These systems provide real-time information about the container’s temperature, humidity, and other essential parameters.
Temperature Mapping
Temperature mapping is a crucial process used to identify temperature variations inside the container. It involves placing temperature sensors throughout the container and recording data to ensure consistent temperature distribution.
By examining the temperature mapping data, potential issues such as hot spots or inadequate cold air circulation can be identified and rectified, ensuring uniform temperature distribution and minimizing the risk of spoilage.
Telematics and Remote Monitoring
Telematics systems in refrigerated containers enable remote monitoring and control. These systems use sensors, communication technology, and GPS to provide real-time data to the operators.
Operators can monitor temperature, humidity, and other essential parameters remotely, allowing them to make timely adjustments, receive alerts in case of deviations, and ensure the proper functioning of the refrigeration system.
Conclusion: Maintaining Freshness throughout the Journey
Refrigerated containers are an indispensable technology that enables the transportation and storage of perishable goods while maintaining their freshness and quality. Through the principles of insulation and refrigeration, these containers create a carefully controlled environment, ensuring the preservation of temperature-sensitive products.
With the advancements in monitoring and telematics systems, the transportation industry can now closely monitor the conditions inside the containers, respond to any deviations promptly, and guarantee the safe delivery of perishable goods. Refrigerated containers continue to play a crucial role in the supply chain, supporting industries worldwide and ensuring that fresh and safe products reach the consumers.