BUGATTI DEVELOPMENT – PERFECT TEMPERATURE CONTROL AT 400 KM / H
the atmosphere inside is pleasantly cool despite the cooking heat outside. no drafts can be felt at all – just the way things should be to create a feeling of comfort that is very noticeable even if it is completely invisible. as global technical coordinator of bugatti air conditioning systems – and holder of a doctorate in engineering – julia lemke designs new air conditioning systems to ensure that airflow and air conditioning work perfectly in the new chiron pur sport1, divo2 and all other chiron3 models. it is a task of great responsibility: two air conditioning condensers ensure the heat dissipation of the vehicle, a central air conditioner is responsible for control and a compressor drives the entire system. this system is made up of air conditioning lines with a considerable length of around 9.5 meters in total thanks to the concept of half-height engine.
Julia Lemke has worked in the automotive industry since 2013 and has worked at Bugatti for four years. It’s a brand whose fascination for Julia Lemke is not limited to performance, technology and craftsmanship, but also includes handling and usability – a unique combination of ultimate performance with design and convenience exclusive. “The Chiron, the Divo and even the extreme Chiron Pur Sport are easy and practical to drive every day – they are simple to use. Even inexperienced drivers can manage a Bugatti from the start, ”says Lemke.
As far as she is concerned, she has an absolute dream job. Julia Lemke grew up in southern Germany and became aware of her interest in technology early on during her school days. She helped her father and brother repair his bike and started tinkering with cars at an early age. His first car – an old VW Passat from 1985 – had neither power steering nor air conditioning. Despite her fascination with technology, Julia Lemke first obtained a degree in history – her second passion. She finished her studies with an archival qualification – but then went on to study energy and process engineering with a focus on thermodynamics in Brunswick.
“I realized that the current and future technical problems and their solutions are more fascinating than in the past. I was particularly interested in thermodynamics, ”explains Julia Lemke. After her studies, she conducted research at the Institute of Thermodynamics of the Technical University and wrote her doctoral thesis on “The energy evaluation of air conditioning systems in cars with secondary circuits”.
Everyone has their own feeling of temperature
One challenge when adjusting the air conditioning system is that each individual has their own individual temperature sensation. Europeans generally feel comfortable between 21 and 22 degrees, while most Americans prefer a few colder degrees. “For us, it is important to ensure that the selected temperature is quickly established. But there should be no drafts. The air conditioning system works best when the occupants do not notice it. We must make sure that it there are no drafts or noise – it’s only then that you feel comfortable, “she explains. The entire air conditioning system includes the cooling circuit of the indoor, air flow, electrical system, electronics and air conditioning unit as the system’s central control unit.
The demands are enormous: “Our vehicles drive very fast. For the air supply to work properly at maximum speed as well, we need to make sure that the ventilation and air conditioning are particularly well controlled, ”she says. To this end, the air conditioning system changes the air flow at high driving speeds. In conventional vehicles, air is forced inside at the lower end of the windshield, but in a Bugatti, this only happens up to around 250 km / h. From this moment there is a transition to negative pressure: a sophisticated control system with an additional air flap and an optimized fan ensures that the air continues to penetrate inside.
The hyper Bugatti sports car also has other unique features: because of the incredible speeds achieved, sometimes well above 400 km / h, the bodywork is designed to be particularly refined. This requires a flat windshield with an inclination of only 21.5 degrees. This increases the surface area of the glass to 1.31 square meters – a conventional compact car has a glass surface of approximately 0.70 square meters and an angle of inclination of approximately 30 degrees. As a result, the interior of a Bugatti heats up more due to higher solar radiation or solar charge. Sky View – the popular glass roof option among Bugatti customers – further increases the level of indoor heat when the sun is shining. To counter this, the Chiron and Divo models have a powerful air conditioning compressor with a cooling capacity of up to 10 kW and two air conditioning condensers – enough to cool an apartment in Europe of around 80 square meters. About 3 kg of coolant per minute can be compressed from a pressure of around 2 bar to a high pressure of up to 30 bar.
In addition, the compressor mounted on the engine is exposed to very high ambient temperatures due to its proximity to the exhaust system, so it is cooled by another sophisticated system. “At first glance, our air conditioning system seems to work like a conventional system. But it is a real challenge to perfectly harmonize the very complex system of a hyper sports car of small series so that it functions flawlessly even at maximum speed and engine load “, explains Julia Lemke. It therefore conducts research and development in terms of maximum cooling capacity as well as efficiency, system acoustics and draft reduction. This includes reducing and refining the refrigerant circuit to minimize the use of refrigerants and energy consumption.
As interior coordinator, she is in charge of all matters relating to the interior of the new Chiron Pur Sport. The different departments work closely together and all employees participate in the further development of products. As an exclusive luxury manufacturer, Bugatti also gives its employees the opportunity to quickly develop and implement ideas. On top of that, there is her main job as the air conditioning system manager: she has to make sure that all the components of the system work reliably and provide pleasant interior comfort in all operating conditions. “Due to the increase in engine speed of the Chiron Pur Sport of up to 6,900 rpm, the emphasis is on the proper functioning of the air conditioning compressor as an engine peripheral. This is why I take part in numerous road tests to guarantee the functioning of my system in all climatic conditions ”, she explains. Julia Lemke naturally manages to drive hyper sports cars herself during the tests. For her, cars in general and the Chiron in particular are a technical masterpiece. “The more I get involved as an engineer, the more I admire what we get overall in the development of these vehicles. The enormous power of the W16 engine and the incredible speed are unique – this is what makes this very complex system different from the others, ”she said.
Her hobbies are her love of cars and technology: racing and racing photography. In her spare time, she enjoys going to auto racing events to take photos. When asked which Bugatti model is her favorite, she answers without hesitation: “The Chiron Super Sport 300+ is my absolute dream car. It has even more power and maximum speed that goes far beyond all of the above, pushing the limits of physics. I have immense respect for all of my colleagues who made this possible. “
Despite the small series of only 500 vehicles planned, Bugatti goes out of its way to achieve perfection. Two test vehicles were available for climatic tests during the development of the Chiron. To make the air currents more visible, Julia Lemke follows the air flow using 3D simulations, smoke lances and even woolen threads. It may sound strange, but the light woolen threads clearly indicate the air flow. Its goal is to continue to refine and adjust the air conditioning system so that the occupants of the vehicle feel comfortable and do not hear or feel any draft. The result is only perfect if they don’t notice anything at all.