NAR Group provides the complete automotive cooling solutions for a variety of industries, including defence and more. Without fifty years of experience, we’ve become the premier manufacturer for cooling components. The manufacturing process begins with thermal design, a field in which we have extensive knowledge. Learn more about how we manage the thermal design below.

Importance of Thermal Design

Thermal Design is essential for ensuring the quality cooling solutions we produce will be as effective as possible. We simulate and tailor designs based upon their individual or group performance, carefully optimising designs and retesting for the best performance possible.

Thanks to thermal design, we can guarantee our cooling solutions are ready to perform at the maximum efficiency possible in the real world before the manufacturing process even begins. We can ensure every part of a cooling solution is as optimised in singularity as it is when working as a part of the system. This is vital for ensuring our designs are ready to be mass-produced. No one wants to receive a bulk order of a non-finalised product. In our opinion, trusting any cooling solution not carefully optimised and tested during thermal design should not be an option. For your cooling solutions to be as perfect as they need to be, trust NAR group and our thermal design process.

How does NAR Group Complete Thermal Design?

As aforementioned, our thermal design process involves an intense cycle of extensive testing and redesign/optimisation. This process is done on a per cooler basis, as well as on the overall cooling group. In order to provide the most accurate results possible, we use our own custom thermal sizing software. These allows us to comprehensively simulate heat transfer solution performance before said product has hit the manufacturing process. This software is built and based upon our own empirical (based upon actual observations, rather than theory) data. We convey this as Nusselt-Reynolds and Prandtl numbers.

This thermal design process can be applied for analysis for a wide range of applications, from vehicle cooling to electronic systems.

What are Nusselt-Reynolds and Prandtl Numbers?

Nusselt-Reynolds and Prandtl Numbers are used to describe the performance of a cooling solution. These numbers are the final sums of incredibly complex equations, used to quantify the complex science behind heat transfer. For the required understanding of our typical customer, we’ve simplified these definitions to the essential information required.

The Prandtl Number is a measurement of the ratio of diffusion (the net movement from an area of high concentration to low concentration)  of momentum to the diffusion of heat in a fluid. Most Prandtl numbers of fluids are high, but the lower they are the better heat is diffused.

The Nusselt-Reynolds number is a combination of two factors. The Nusselt number is essentially the overall measure of convective heat transfer. It is typically expressed as a function of the Reynolds and Prandtl numbers. The Reynolds number measures the correlation of frictional pressure drop and heat & mass transfer in convective flow.


We hope this article helps you understand the NAR Group thermal design process better. We are dedicated to employing our over fifty years of cooling system experience for your needs. Contact us today for your bespoke heat transfer and cooling solutions.