Applications for cooling solutions

Heat pipe system for UPS

A worldwide well known manufacturer of UPS systems, with its R & D department in France, wanted to equip the different models with the same cooling system. The technical team was already working on this project with a competitor of ours. This product line comprised 3 different power models: 300 – 400 – 500kVA. They ran into a technological limit on the 500kVA.

The thermal engineer knew Atherm from a previous professional experience and he introduced Atherm into a new loop.

From their specifications, we started modelling, calculating and simulating in order to reach the required thermal performances.

A close collaboration between both technical teams started with transparency and confidence. Together we modified the internal geometry of the cooler, the overall dimensions remaining unchanged.

Once the theoretical design beeing approved, Atherm received the prototype purchase order.

The second stage began with the realization of the first prototype and the corresponding test bench. Working closely together, we manufactured 18 prototypes before finding together the right answer to this very critical request.
The third stage was the qualification and industrialisation of this product and its manufacturing process.

Eventually large series over minimum 10 years with a new request from the customer: relocation near their mass production unit in India.

To meet this demand, we open a subsidiary in Bangalore India, belonging to Atherm France for 100%, with technological transfer.

Electronic rack made of sintered heat pipes linking 2 racks

For a military application, but this can be extended to any other kind of application using electronic racks, we imagine with our customer a cooled backplane for cards inside his electronic box. Sintered heat pipes link both parts of the backplane which become thus alternatively depending on its orientation “condenser” and “evaporator” blocks. Heat pipes transfer cards heat to the backplane which is cooled down by a cold plate located beneath the electronic box. 6 cards and the power supply dissipate altogether 290W.

In close collaboration with our customer, sharing documents, drawings, simulation…we achieve the required goal. To help them test in situ we also lent them a cold plate representing theirs which they didn’t have on that time.

This project being for a military application, components must be from French origin (Atherm manufactures grooved and sintered heat pipes in its French facility), besides quantities are limited but spread over years, meaning from Atherm sustainability and stability.

Insulated heat pipe system for an avionic or high power system

To cool down a component, for an avionic application our customer was looking for sintered heat pipes with electrical isolation: around 20W dissipation on a tiny space with difficult access.

We proposed a mechanical and thermal study, followed by the realization of parts as well as the dedicated thermal test bench to be designed and done in house.

First prototypes were delivered, tested, performed well. This solution is now qualified for series.

Air-air heat exchanger for cabinet

The original request came from a major actor in the railway sector. The aim was to cool down the internal ambient of the electric cabinet. Some applications allow forced convection with fans, other only use natural convection.

For this example, forced convection is required and the air-air heat exchanger is equipped with a ventilation duct to optimize the efficiency.

Starting with our long term railway partner’s specification, we quickly managed thermal calculation, taking into account the narrow space and difficult environment. Thanks to our friendly and transparent cooperation, a heat pipe heat exchanger was designed and prototypes manufactured in less than 6 weeks. More than 1000 parts have been delivered in these last 10 years.

This concept is now interesting suppliers of outdoor cabinets, especially for hot countries where dissipation by the cabinet itself is insufficient (internal and external ambient are quite the same within the day).

Insulated high power cold plate

Our historical railway customer developed traction with non-isolated components. As power to dissipate is important versus a small diameter in press pack assembly, we jointly dimensioned an isolated cold plate. This technology is being used for nearly 2 decades and after a period where isolated components were privileged, we see renewed interest for this technology with other components such as bus-bar.

Cold plate is much more efficient than heat pipe systems for the same volume. In this particular case, both sides of the plate are used allowing 4kW dissipation.

Improvement of existing heat sink

Thermal management is always easier when it is designed from the start of the project. It is rarely the case and we have to adapt our solution to thermal but also geometrical constraints. The challenge is to make the original design work without changing the environment.

To this respect, for a railway application, our customer came with a heat sink aimed at cooling components right in the middle of the sole. Most of the heat sink was thermally lost and components location should remain unchanged in this configuration.

We proposed to insert grooved heat pipes into the sole of the heat sink, making it efficient all over the surface. Embedded heat pipes spread the central hot spot all through the heat sink. Without changing anything in this wind speed application in terms of geometry and choice of components, heat pipes meet our customer’s expectation and thermal requirements at low cost.

This project started in 2008 and is still running with nearly 2000 parts sold. This solution being quite attractive, a similar project rises.

Loop heat pipe

 Atherm started working in 2009 as project leader with Thales as industrial partner, DGA (Army general direction) as final user on loop heat pipes. The target was for Atherm to become the French manufacturer and supplier of loop heat pipes to the French military branch.

Thanks to this RAPID project Atherm was able to invest in a sintering furnace with multiple purposes: sintering is used in loop heat pipes, sintered heat pipes and other kind of coolers we are working on.

At the end of this first project, we demonstrated our ability to manufacture small loop heat pipes powering up to 100W. We acquired technical skills in dimensioning the sintering granulometry, sintering, controlling fluid filling, dimensioning the loop heat pipe versus the application…