Heat is a form of energy, transferred by virtue of a difference in temperature. Heat exists everywhere, to a greater or lesser degree. As a form of energy, it can be created or destroyed. The work of heat transfer is traditionally driven by mechanical means, but can be also be driven by magnetism, electricity, laser or other means.
The process by which unwanted heat is removed from a selected object, substance, space or environment, and then transferred elsewhere, is known as refrigeration. The main goal of refrigeration systems is to remove heat, and maintain a constant, pre-determined temperature.
Heat Removal in Refrigerator Vehicles
One major misconception about home refrigerators and refrigerator vehicles is that they work by generating cold air, to keep their contents cool, but this is not actually the case. Coldness cannot be created from nothing. Refrigerators function as self-contained units that are sealed from outside heat, and use constant, cyclical processes, to keep the temperature inside, regulated.
In order to achieve a cold temperature, heat has to be absent. This is the basis of refrigeration mechanism in home refrigerators, freezers, air conditioning units and refrigeration vehicles. The most important step is to keep the heat out.
Three different apparatus work in unison, to keep cargo compartments refrigerated. They are the condenser, the compressor and the evaporator.
The condenser is a network of thin pipes, containing coolant fluid, designed to absorb heat in an efficient way. It is a heat exchanger that works by transferring the warmth from the condensed liquid gas, to the walls or fins of the tubing. The fins help by presenting more surface area, for cooling. Air is brought into the condenser through a fan.
It absorbs heat inside the system and it runs through the pipe system. As it circulates in the network of pipes, it absorbs the heat and becomes a gas. As the gas reaches the other end of the pipe network, it goes into the compressor.
The compressor is mounted to the fridge van’s engine, using a compressor mounting bracket. It is driven by a small engine, within the reefer unit. The compressor takes in gaseous refrigerant and compresses it. Refrigerant enters as a low pressure gas, and the compressor changes it to high pressure gas. When this gas reaches the other end of the pipe network, the compressor compresses it to an extremely high pressure.
The main component of the evaporator is the metering valve. The cool compressed liquid flows through the valve, which controls the amount of refrigerant that is discharged into the evaporator. The evaporator supplies gaseous refrigerant at low pressure. It then pushes air from the outside, into the high-pressure gas.
This process cools down the gas, and transforms it into liquid again. The fins help transfer heat from the flowing air over the refrigerant, and the air from inside the vehicle, is blown back over the evaporator. The heat is dispensed into the atmosphere and brings about a highly reduced temperature, inside the insulated area.
This constant process serves to effectively cool down the cargo compartment, and works in conjunction with temperature regulation mechanisms, to keep the area at the desired temperature.
Where Does The Heat Come From?
Refrigeration units fitted within new fridge or new freezer vans, do not make the cargo cold, rather they remove heat. The more heat is removed from an environment, the cooler it becomes. If a chilled or frozen produce is placed in a warm environment, it will absorb the heat, and start to warm up.
Heat can reach the inside of a new refrigerated vehicle from the following:
- Through leaks in the body of the vehicle
- Leaks in the insulation of the refrigerated vehicle
- Ambient air that gets in, each time the doors are opened
- Heat may still be produced by the load, even after it’s been cooled
Prevention of Heat Production in Refrigerated Vans
In order to prevent the dissemination of heat in the chiller van, two main processes are involved: insulation and installation of a refrigeration unit. The cargo compartment of the van is sealed or insulated, to prevent heat from entering, and a refrigeration system is used, to prevent the temperature from dropping, when the doors are opened.
The cargo compartment is sealed and insulated against heat, using a polymer foam, which allows temperatures to stay fairly stable, even before the use of a refrigeration system. The extremely high-density polymer foam contains billions of miniscule air bubbles, to stop heat from entering the vehicle.
As the van will be outside, and has a heat generating engine at the front, insulation is absolutely essential, for a successful vehicle, and the insulation used is often of a higher quality and thicker than that used in household fridges.
If the reefer system is not running, it will take a while before the temperature inside the cargo compartment drops, to a challenging level.
Installation of a refrigeration unit
In order to deliver used refrigerator vans that are capable of optimal, consistent cooling, for long periods, refrigeration systems are installed. At Glacier Vehicles, our refrigerated vehicles are built using state-of-the-art GAH refrigeration systems. They have the best solution, to meet every requirement you may have, while maintaining fuel efficiency.
During the installation of the refrigeration system, the vehicles can be set to the desired temperature and maintained at that temperature throughout the entire journey. Goods that need to be transported at deep freeze temperatures, can be set as low as -25 to -30C. New freezer vehicles can go as low -18C. Chiller vehicles can keep cargo sufficiently for long hours, maintaining a temperature slightly above 0 degrees.
At Glacier Vehicles, we have a wide range of petrol and diesel fridge and freezer vans. Based on your budget or other needs, we can provide you a new, or earlier model fridge vehicle, from top manufacturers such as Mercedes, Peugeot, Ford, Nissan, and so on.
We offer full fridge van conversion services that are tailored to meet your unique specifications, and storage requirements.