What Is a Radiator and Where Is It Used?
A radiator is a heat exchanger that transfers the heat carried by a hot fluid to the surroundings, most often to the air. This article explains in plain language how a radiator works, how water, air and oil radiators differ, and which industries use them.
What does a radiator do?
Every running machine turns some energy into heat. If that heat is not removed, parts, oils and seals are damaged. The radiator's job is to take heat from the hot fluid and release it safely to the environment.
A hot fluid (such as water, oil or compressed air) flows through the inside of the radiator. Air usually flows over the outside. Between the two sit a thin metal wall and the fins that spread the heat into the air.
How is heat transferred?
Two basic processes work together in a radiator.
- Conduction: Heat travels from the hot fluid through the metal wall to the outer surface. The thermal conductivity of the wall material matters here.
- Convection: The heat on the fin surface is picked up and carried away by the air passing over it. Air movement can be increased by a fan or by the vehicle's motion.
Despite the name "radiator", most of the heat leaves by these two routes rather than by radiation. That is why fin surface and airflow are the most decisive elements of the design.
Main types of radiators
- Water (engine cooling) radiators: They cool the engine coolant. They are common in cars, commercial vehicles and construction machinery.
- Air radiators: Units such as air conditioning radiators and intercoolers, which remove heat from air or work with air.
- Oil coolers (oil radiators): They keep the temperature of oils such as hydraulic oil, engine oil or transmission oil in balance. Because oil lines are under pressure, these radiators must withstand pressure.
For more detail on oil coolers, see the article what is oil cooling.
Radiator vs. heat exchanger
Heat exchanger is the general name for any device that transfers heat between two fluids. The radiator is its best-known type, and it most often uses air as the second fluid. Plate and shell-and-tube exchangers that work water-to-oil or water-to-water rely on the same principle, but the cooling fluid is water, not air.
An air-cooled radiator does not need a cooling water circuit, so it can work independently. That is why it is often preferred on mobile machines and at sites without water piping.
What determines efficiency?
- Surface area: The more fins and the larger the core, the more heat can be transferred to the air.
- Airflow: The more evenly the air from the fan or from vehicle speed passes through, the better the heat rejection.
- Internal flow structure: How the fluid is routed through the channels affects how heat reaches the wall.
- Cleanliness: Fins clogged with dust, oil or mud restrict airflow.
- Ambient temperature: The hotter the air, the less heat the same radiator can reject.
Where is it used?
Almost every machine that produces heat has a cooling need. Common areas include:
- Cars and commercial vehicles
- Construction machinery such as excavators and loaders, and forklifts
- Air compressors
- Hydraulic power units and hydraulic presses
- Construction equipment such as screed machines
For a broader look at which radiators are used where, the article where heat exchanger radiators are used is helpful.
When choosing the right radiator
Selection usually comes down to a few questions: What fluid is being cooled? What are the operating temperature and pressure? What are the ambient temperature and working environment (dust, oil, humidity)? How much space is there on the machine? For exact values, rely on the data from the machine and radiator manufacturer.
You can browse the Safkan product groups on the Products page. To identify the right model for your machine and get technical information, contact us.