Cabin comfort is a given for motorists nowadays. The trend for multizone air-conditioning systems enables automakers to offer more comfort features. Continuing just-auto/QUBE's series of interviews with tier one component suppliers, we spoke to executives of Valeo's Thermal Systems division to learn more about such trends, regulatory drivers and its recent climate control system innovations.

Valeo is an automotive supplier and partner to automakers worldwide. It is structured around four business groups, namely Driver Assistance Systems, Powertrain Systems, Thermal Systems and Visibility Systems. Valeo's Thermal Systems business comprises five product groups, namely Thermal Climate Control; Thermal Powertrain; Thermal Compressor; Thermal Front End; and Thermal Bus. Its Thermal Climate Control product group develops the systems and components required to provide all-season thermal comfort on all kinds of vehicle, with internal combustion, hybrid or electric powertrains. This group also offers active solutions addressing growing concerns on air quality (protection against allergens, fine particles, gas, etc.), and for personalising the cabin with fragrance design. Over the coming months, just-auto/QUBE's interview series will cover Valeo's other business groups.  

As we understand it, automatic control is constantly growing in market share while two or more zone systems are no longer limited to large models or luxury brands. How do you see this trend?

As cars are more and more automated, A/C control is following the same trend.

Cabin comfort is a given for car users; they want to feel as good in their car as at home without worries. And as cars are more and more automated (key-free ignition, automatic headlamps, etc), A/C control is following the same trend. The rate of adoption can, of course, vary by region; but, the overall global trend is that the majority of new vehicles being sold will have automatic air conditioning. At Valeo, we estimate that automatic versions represent already more than 60 per cent of production volume. On mainstream segments (mostly C and D segments), automatic A/C represents more than 75 per cent. 

Regarding zoning, the same trend is valid: occupants look for more individualized comfort, which means two-zone A/C minimum (temperature can be set differently for driver and front passenger). On the mainstream segment, for example (C and D segments), mono-zone HVAC can represent 25 per cent of a platform volume while two-zone could cover roughly 60 per cent and tri-zone 15 per cent. On premium segment, tri- and four-zone systems have become almost a mandatory (more than 65 per cent of a platform volume).

How is demand for multi-zoned air conditioning shaping up in Europe?

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Europe does not differ from the worldwide trend. A/C is a mandatory, even on the small car segment (A segment); two-zone HVAC is becoming a standard on mainstream; three-zone and four-zone a more common feature of premium segments. Indeed the larger the vehicle cabin size and/or the higher the luxury of the car, the more zones are offered (often as an optional feature). For instance, a Peugeot 508 (D segment) is equipped with a full four-zone HVAC (mixing and distribution) since 2010 on its high-end finish.

In what ways have the regulatory forces driven recent innovations from Valeo?

Regulations drive vehicle energy efficiency and exhaust emissions reductions. And Valeo has to take into account new regulations, exactly as OEMs have to.

As far as air conditioning systems are concerned, the main focus is put on CO2 emission reduction. With the implementation of the WLTP (Worldwide Harmonised Light Vehicle Test Procedure) since January 2017 and Real Driving Emissions test, realistic driving conditions have become reality. And the Industry expects a 15 to 20 per cent increase in CO2 emission level value target versus what is estimated today with NEDC (New European driving Cycle) due to this new driving style test. That means that car manufacturers have to increase and accelerate efforts to reduce energy consumption and achieve the stringent target of 95 g CO2/ km by 2021. Since the HVAC is taken into account in this new procedure and because it is an important energy consumer, Valeo is working on new solutions in the following domains: electric consumption reduction and weight reduction.

Valeo proposes new HVAC architectures that could increase air recirculation into the cabin. 

For instance, Valeo proposes new HVAC architectures that could, for example, increase air recirculation into the cabin.  Another possibility is to by-pass partially the evaporator when we need warmer air in the cabin; thus we avoid cooling systematically all the air that will be then warmed-up.

Regulations can also drive the refrigerant choice. Depending on regional regulations, Valeo has to design A/C loop adapted to the mandatory refrigerant: while R-1234yf is now mandatory in Europe, more and more car manufacturers will also use it on their worldwide platforms with production in North America or in Japan. We also adapt our offer to the new demand for R-744 compatible components, whether related to classic A/C loop or to heat pumps system.

And today an additional force is shaping the automotive evolution. In China, for instance, the government, as well as city councils, have put in place new regulations to speed up the electrification of the car fleet, to reduce pollution in the city centres (particle pollution, acoustic pollution, etc). So to further sell cars, OEMs are eager to move into this electrification revolution and very demanding on any new technology that can either reduce energy consumption and acoustics level.

Not so long ago, air conditioning systems used to be noisy. How have you addressed this issue?

Acoustics is becoming a key driver in cabin comfort.

Acoustics is becoming a key driver in cabin comfort. Indeed passengers want to listen nicely to their music or discuss in a quiet environment with friends via Bluetooth, and not hear the engine or HVAC blower motor. So car manufacturers are putting more stringent specifications since a few years: on HVAC for the mainstream segment, for instance, we moved from around 61 dB(A) in  2012 to 58 dB(A) in  2015 to achieve a 55 dB(A) level on upcoming platforms (SOP from 2019). To give you an idea, this level is similar to the level of a conversation at home.

To achieve such low acoustics level, Valeo is working on different solutions. The priority is to avoid noise generation. To do that, Valeo uses a comprehensive set of standards (HVAC design and components integration), as well as computer simulation and predictive tools to optimise the HVAC development.

However, because noise is related to the airflow (generating turbulence) and because we cannot jeopardise system efficiency, we also have to look at solutions that reduce transmission of noise. Historically, the first answer is to avoid noise transfer from the A/C loop to the HVAC by adding foam around the heat exchangers. It is also necessary to reduce the air pressure drop by improving air exchange on exchangers and inside the HVAC. For instance, we can optimise blade shape and blower wheel design to improve air velocity.

On the premium segment, more car manufacturers are choosing to install brushless blower motors to reduce consumption and improve acoustic performance.

Another solution is to implement new, quieter technologies. For instance, on the premium segment, more and more car manufacturers are choosing to install brushless blower motors not only to reduce consumption but also to improve acoustics performance. Valeo is also working on new features that can further reduce noise up to 52 dB(A).

Electric vehicles are gradually gaining momentum. To what extent is there a focus on research to make HVAC systems for these vehicles even quieter?

It is true; this trend is accelerating with the emergence of electrified vehicles. Even if all car players are still experimenting and learning, we see specifications becoming tougher: within one platform generation change, car manufacturers may request additional acoustic improvements to reach 50 dB(A) at HVAC level by 2022.

To achieve this, Valeo implements the same solutions as developed for other vehicles, with the best optimisations.

With the increasing interest in electric and hybrid vehicles from the auto manufacturers what other developments are taking place for HVAC systems in such vehicles and what is Valeo doing in this area?

To complement progress on component performance and integration, Valeo is also innovating in HVAC architecture. Indeed when we look at dedicated BEV (Battery Electric Vehicles) vehicle platforms, we can completely re-think the HVAC design and integration inside the vehicle to relocate some parts in the engine compartment. For instance, with the 'split HVAC' concept, we can move air intake module with blower under-hood.

But if a car manufacturer shares a platform cross powertrain from ICE (Internal Combustion Engine) to Hybrid through 100 per cent BEV, it will prefer not to de-standardise the HVAC. This means that he may keep a standard HVAC positioned under the instrument panel (with potentially a Low Voltage Air PTC Heater – Positive Temperature Coefficient); and in the case of PHEV and BEV models, he will still use  the coolant loop with an additional High Voltage Coolant Heater (outside the HVAC) to ensure passengers comfort. In fact, Valeo and any thermal system supplier has to adapt its product portfolio and architecture offer to answer any demand.

It is especially true when we look at the more global picture: indeed in the case of electrified vehicles, we do not only work on optimised passenger thermal comfort but also on battery conditioning. To ensure the maximum lifetime of the battery, we need to ensure it remains in a range of temperature between 20° and 35°C, this means that we have to optimise the overall thermal management, looking for the best balance between energy consumption and heat recovery from powertrain. And for some customers, heat pump architecture can be a brick to optimise electric consumption of the battery to the benefit of driving range in winter.

How is Valeo reducing HVAC related power consumption?

Reduction of HVAC-related power consumption is linked to noise reduction. If we optimise airflow and lower air pressure drop, we can use reduced power blower motors, where there is less resistance to overcome. On top, we can use PWM (Power Module) power control instead of resistive or linear control, or even more effective, we can implement a brushless motor.

But power consumption is also related to weight: the lighter the car will be, the less the engine will consume. This means that our teams work not only on new plastic material and wall thickness reduction but also on new component generations that are more compact and much lighter than current ones; for instance, our new generation of additional PTC heaters will weigh 25 to 30 per cent less than current competitors' products. Evaporators are also more and more compact: moving from 48-50 mm to 35 -40 mm on new current generations.

To reduce power consumption – as mentioned earlier- we can also work on optimised HVAC architectures. For instance, with the dual layer HVAC architecture, Valeo can increase air recirculation into the cabin. Indeed dual layer HVAC is a simple architecture which separates fresh from recycled air flow in the blower unit to ensure an independent air management in lower/ upper cabin with limited air renewal. This stratification concept has two objectives: It reduces the warm-up time without misting risk and thus improves thermal comfort (3 mn gain). Or it reduces additional heater (PTC) electrical consumption while maintaining the same comfort level (versus a single layer HVAC) without misting risk. In both cases, Air stratification can significantly reduce energy consumption and thus contribute to CO2 emission reduction.

Another example is the bypass evaporator architecture. With an additional duct allowing the air to by-pass the evaporator, this HVAC reduces A/C loop consumption by 10 to 20 per cent at low thermal load conditions without impacting comfort level. It is possible thanks to the active management of the cold storage evaporator operation in phases of charging, and the release of the stored cooling power respectively. It is especially interesting in micro-hybrid vehicles during stop phases.

In the case of electrified vehicles, a heat pump system is another solution: It offers between +14 per cent and + 20 per cent driving range (between -10°C and 0°C), while dividing by 2 electric power consumption in heating mode at -10°C (vs high voltage air heater alone).

To what extent does a vehicle with stop-start impact on the effectiveness of the thermal management system?

Passengers cannot bear being uncomfortable yet don't want to lose the consumption benefit of the stop-start system.

In theory, a vehicle with stop-start is not effective in terms of thermal comfort as we shut off the compressor when the vehicle is stopped. But passengers cannot bear being uncomfortable (and neither wants to lose the consumption benefit of the stop-start system).  The first solution is to install a storage evaporator with Phase Change Material that can maintain an acceptable temperature for a few seconds. Now, to go a step forward, the new challenge is to reduce A/C system's fuel consumption on WLTC or RDE cycle with a system able to optimise ICE efficiency in real time. That means that it optimises the loop functioning in stop/ start, coasting and cruising phases. The new Valeo system enables to store energy during accelerations and regenerative braking, while releasing it to cool down air during coasting and idle (ICE Off).