A reliable comparison of radiator technical specifications requires knowing what to measure and under what conditions. Nominal values indicate a device's theoretical performance, but true comparability only arises when thermal capacity, material properties, and operating conditions are standardised to the same baseline. In the following sections, we will go through the factors that are crucial for a reliable comparison.
If you are looking for a practical starting point for your own assessment, Explore our cooling solutions and look at the demanding conditions they are designed for.
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The performance of a radiator is most influenced by thermal power (kW or MW per unit), material inlet and outlet temperatures, mass flow rate (t/h), and the parameters of the cooling medium. These four factors together form the framework within which the unit either meets or falls short of the process requirements.
Thermal power indicates how much energy a device can transfer away from a material per unit of time. This figure is the single most important value for comparison, but it loses its meaning without information about the material and the input temperature at which the power was measured.
The mass flow rate, or capacity in tonnes per hour, is another key parameter. However, a high nominal capacity does not automatically mean efficient cooling if the material's retention time in the equipment is too short. Retention time and mixing efficiency determine how effectively heat transfer is actually achieved.
The temperature, pressure, and flow rate of the cooling water or other cooling medium directly affect the thermal gradient, meaning the temperature difference between the material and the cooling medium. The greater the gradient, the more efficient the heat transfer. Therefore, cooling water parameters must always be stated in conjunction with specifications.
- Heat output (kW/MW per device)
- Inlet and outlet temperatures (°C)
- Mass flow rate (t/h)
- Coolant parameters (temperature, pressure, flow rate)
- Retention time and mixing efficiency
- Material particle size and specific heat capacity
How are heat capacity and the permeability of a material measured comparably?
Heat capacity and material permeability are only comparable when they have been measured or calculated with the same reference values: a standardised inlet temperature, the same material or its specific heat capacity, and identical cooling water parameters. Without these boundary conditions, comparing the figures is misleading.
Specific heat capacity (kJ/kg·K) indicates how much energy is required to raise the temperature of one kilogram by one degree. This value varies significantly between different materials: bottom ash, quicklime, and activated carbon all have different specific heat capacities, meaning the same device will cool them at different speeds and with different efficiencies.
The material's throughput, or its actual capacity under demanding conditions, also depends on how the device handles material flow. For instance, very hot and fine materials like fly ash tend to fluidise, which can disrupt flow and reduce actual throughput compared to the nominal value. Therefore, specifications should always state whether the capacity was measured under controlled laboratory conditions or in a real process environment.
In practical comparisons, it is advisable to request reference data from the supplier that uses similar materials and processing conditions to your own application. Theoretical computational performance and actual field performance can differ significantly, especially at extreme temperatures.
What is the difference between the specifications for dry coolers and water coolers?
Dry coolers and water chillers differ most in terms of specifications for cooling medium, achievable output temperature, and energy efficiency. Water chillers typically achieve lower output temperatures and higher thermal performance, whereas dry coolers are better suited for environments where water usage is restricted or not possible.
In water chillers, the temperature, pressure, and flow rate of the cooling water are key specification parameters. These values directly determine the achievable temperature gradient and, consequently, the actual cooling capacity of the unit. It is possible with water chillers to cool material to very low temperatures, for example, below 100 °C or even below 50 °C, depending on the process requirements.
In dry coolers, specifications highlight airflow, heat transfer surface area, and ambient temperature. As cooling capacity partly depends on the outside air temperature, dry cooler specifications should always be stated with a specific reference temperature for meaningful comparison. This is particularly important if the unit is to be installed in an environment where the temperature varies significantly with the seasons.
When comparing these two techniques, also pay attention to the maintenance cost specifications: in water coolers, the tightness and corrosion resistance of the water circuit are critical parameters, whereas in dry coolers, the durability of wear surfaces and filtration capacity become paramount.
When are nominal values not sufficient for a reliable comparison of coolers?
Nominal values are not sufficient for reliable comparison when the process conditions deviate significantly from standard conditions, the material is unusually abrasive or fine, or when the inlet temperature exceeds typical reference points. In these situations, nominal values provide too optimistic an impression of the actual performance.
At very high inlet temperatures, such as above 700-900 °C, material behaviour becomes unpredictable. Clogging and fluidisation are examples of phenomena that calculation models based on nominal values do not always take into account. If the equipment cannot manage these phenomena, the actual capacity and cooling performance can fall significantly below the nominal values.
The particle size distribution of the material is another factor that affects real-world performance but is often omitted from nominal value comparisons. Fine materials behave differently from coarser ones, and their fluid dynamics within the device can deviate significantly from what has been assumed in nominal value calculations.
Reliable comparison in these cases requires either actual field data from comparable reference objects or testing the device under process conditions that are as realistic as possible. Mere technical data sheets do not replace empirical knowledge of how the device performs under the specific conditions of your process.
Kopar has developed KRC Radiator specifically for extreme conditions where a comparison based on nominal values is no longer sufficient. KRC's patented design optimises mixing and residence time, maximising heat convection and conduction even when the material is extremely hot, abrasive or fine. Cooling capacity can be up to 1 MW per unit, and inlet temperatures can be as high as 900 °C.
If you want to assess how different cooling technologies are suitable for your process, Explore our cooling solutions or Contact our experts, These help you make a reliable comparison based on your own process conditions.
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