KULI Agenda​​​​​​​​​​​​​​​​​​​​​

Developing thermal management for BEVs means also to adapt the simulation workflow accordingly. In this sense BMW‘s transition is shown and the role of KULI therein presented. A short outlook to full vehicle simulation with focus on BEVs concludes the way of thermal simulation at BMW in order to be ready for Neue Klasse. 

tbd

Since the last ECS Software Conference, KULI has undergone substantial advancements, incorporating state-of-the-art features designed to optimize thermal management simulations across various applications while enhancing user-friendliness. This presentation will provide a review of the key updates introduced in the latest versions of KULI, highlighting significant improvements in the user interface and simulation accuracy.​​​​​​​

In addition to reviewing recent advancements, this presentation will also explore the current topics driving the future development of KULI. Attendees will gain valuable insights into ongoing research and development efforts, including the integration of innovative technologies and methodologies aimed at further enhancing KULI's capabilities.

Internal Combustion Engine (ICE) trucks require a significant amount of air to the engine to operate efficiently and therefore a turbocharger compressor is needed to increase the intake air. However, the compression process raises the air temperature which must be cooled down by a “Charged Air Cooler” (CAC). Cooling the compressed air allows more oxygen to enter the engine resulting higher engine performance and lower emission. In most trucks, the CAC is typically air- to Air cooler.

In cold climate, when the ambient temperatures are low, the charged air temperature exiting the cooler is also low. If the ambient humidity is high, there is the risk of water condensation at the cooler outlet which can lead to ice formation in the worst case. Ice building is a problem because it causes higher pressure drop inside the CAC, reduce air flow and decrease engine performance. One of the solution which can be used in order to avoid this phenomenon, is installing a so-called “Blind Curtain” on the cooler to reduce the cooler cooling performance slightly and therefore minimize the water condensation (ice forming) after the cooler.Regardless of the curtain type, manual or automatics, the curtain size must carefully selected. 
It should be large enough to prevent ice building but not so large that cases the air to remain extremely hot.

To optimize the curtain size, a simple Kuli model is developed. Due to complexity of the process (transient, mass transfer, phase change, etc.), several simplifications has been considered. First of all, instead of transient calculation (road simulation), a number of steady-state operating points were analyzed. In addition, a block , representing blind curtain with a specified width, was added in front of the cooler in Kuli model. Furthermore, two empirical thermodynamics formulas were applied in order to estimate the maximum possible absolute humidity based on the air pressure and temperature. Using the model, the risk of condensation (ice formation) or evaporation at the CAC outlet was assessed under various conditions including ambient temperature and humidity, the engine load (air temperature, pressure and flow after compressor) and curtain size etc. Finally, it was verified that the curtain did not cause any extreme high temperature on the air and the coolant in the coolant radiator.

The result of the simple Kuli for a specific engine platform shows that without a curtain, the risk for condensation increases at -20°C and rises rapidly all the way up to 0°C. On the other hand, with a medium size blinder, the risk is entirely eliminated as humidity can be evaporated across all the ambient temperatures. However, the result reveals that a bigger size blinder is over dimensioned to only prevent condensation and leads to unacceptable high air temperatures entering the engine. This can trigger the fan unnecessarily, leading to increased energy consumption.

The overall thermal management strategy in electric vehicles can directly or indirectly improve battery efficiency and vehicle range. This study aims to simulate and enhance the performance of BTMS (Battery Thermal Management System) and battery packs developed for an electric bus using 1D computational fluid dynamics models. Simulation studies were conducted for the 18-meter EV Citivolt vehicle of Anadolu Isuzu. Design parameters such as the placement of coolant flow lines and component selection were determined using the 1D models. The final design obtained in the study was validated through vehicle physical tests and simulation studies. The results showed that the components in the coolant line accurately detected the flow rate with a maximum deviation rate of 11%. Additionally, the components on the coolant lines were added to the 1D model through their own characteristic dP-Q curves. This approach demonstrated that these components, which contain complex flow lines, can be represented with unique dP-Q curves. 

The vehicle tests were conducted at the Anadolu ISUZU Test Center, where the 18-meter EV Citivolt vehicle from Anadolu Isuzu was specifically chosen due to its widespread use in urban transportation as an 18m low-floor vehicle. There are six batteries and each of two batteries are mounted one on the top of the other. There are three parallel coolant circuits for all batteries. BTMS aims to all batteries thermally optimal working conditions.  

Flowmeters have been strategically positioned in near of batteries. The selected flowmeter points are located at the inlet and outlet points of each component.Flowrate values were read with the flowmeters in the course of flow test and CAN Bus communication was used to control PWM (Pulse Width Modulation) value of the circulating pump placed in BTMS. 

When choosing the coolant for a bus, it's important to consider corrosion and freezing in the winter. To prevent freezing, it's crucial to include antifreeze, such as glycol, in the coolant mixture. Commercial coolant which is a mixture of 50% Glycol and 50% water, recommended by the BTMS supplier,  

In the initial study, the physical test and KULI results were compared for circulating pump placed in BTMS operating at 100% PWM. It was found that the minimum flow rate in Battery 5 and Battery 6 was not met in the physical test and KULI simulation results.  

It shows KULI simulation and physical test results. It is seen that the deviation of both results accounts for almost 11%. Simulation results showed good agreement with the experimental data. 

As part of the improvement efforts, only changes were made to the pipe diameters to meet the minimum flow requirements. Specifically, the diameter of the pipe going to the 1st and 2nd Battery was reduced from 15 millimeters to 6 millimeters, and the pipe/hose diameter going to the 3rd Battery was reduced from 15 millimeters to 8 millimeters. These mean first four batteries near to BTMS unit has much more flowrate due to low pressure loss. To increase pressure drop for these four batteries, inner diameters connected to these batteries are decreased to have much more drops. These technical variations are adjusted by KULI to improve and optimize each battery coolant line. 

Generally circulating pumps were not preferred to run 100% PWM value because it consumes much more energy and life expectancy parallelly is declined. 100% pwm value only is used for simulation and physical test validation. The maximum pwm value allowed by BTMS supplier is 90%.  

All these changes were implemented on the vehicle, and a new physical flow test was performed again.  

Following circulating pump PWM value was set to 90%, it was observed in the physical test and Kuli simulation results that the minimum flow rate requirement was provided. 

In the rapidly evolving field of thermal management, we encounter various challenges in our daily work as both developers and users of KULI. This presentation will delve into some of the latest enhancements designed to elevate the handling of vehicle simulations. We will showcase improvements that empower users to tackle complex models with greater ease, such as:
 
• Usage of the new Mollier chart
• Controlling mass flow in refrigerant branches
• Usage of refrigerant plate heat exchangers
 
Join us to explore how these new features can simplify your daily work with KULI.

The concept of zero-emission vehicles is highlighted considering concerns regarding fuel efficiency and global emissions. Automobiles are increasingly prioritizing a fully electric future, signifying a shift towards the electrification of road transport. Consequently, the environmentally friendly alternative being promoted is the electric vehicle, aimed at enhancing the health of the planet. Nearly all developed and developing countries are currently transitioning to this Eco-friendly electric vehicle option in order to entice individuals with financial advantages, government subsidies, tax incentives, fuel savings, and reduced maintenance costs.

The design of an electric vehicle must prioritize the battery thermal management system, given that electric vehicles are equipped with battery packs.

In this context, the KULI software, particularly its KULI HVAC feature, is utilized for the simulation of battery thermal management systems in battery packs.

To enhance battery longevity and performance, simulation serves as the most effective method for refining the thermal cooling system. The presentstudy includes a simulation of battery thermal management utilizing active cooling through an air conditioning plate heat exchanger connected with refrigerant circuit. The heat exchange through system then can be determined with the help of simulation.

Location will be announced soon

Vehicle range, driving efficiency, payload and low total costs of ownership belong to the most recognized and requested vehicle key performance indicators (KPIs) of a battery electric truck. This paper focuses on the influence of vehicle thermal and energy management functions to these vehicle targets and the benefits of system-oriented development methodologies.

Especially in hot and cold environments the conditioning of cabin, powertrain and battery has a considerable impact on the total energy consumption and does have potential for optimization. In general, optimization means operating the system close to its limits. Therefore, a deep understanding in both, vehicle and component level, is required. Due to the temperature dependence of powertrain component efficiency, a simple approach, like just limiting heating or cooling, is not sufficient to ensure driving efficiency in most cases. Advanced control functions and waste heat recovery of the electric powertrain show 
promising results. However, especially in the field of thermal comfort, cabin and battery conditioning, the full potential is still not reached. For further optimization a holistic view on the interactions between vehicle, cabin HVAC, powertrain and battery is required to ensure best comfort and lowest energy consumption for different environmental conditions and use cases. These complex interactions and advanced control functions significantly increase the validation and calibration effort. 
Magna developed a system-oriented development method to overcome these challenges and to ensure fast, efficient and cost-effective engineering and reliable software functions for commercial vehicles.

The thermal management strategy in electric buses have a critical role in ensuring battery performance, maintaining thermal stability, and maximizing the range and longevity of the vehicle. Effective thermal management systems prevent critical issues such as overheating, uneven coolant distribution, and thermal imbalances, which can degrade the performance and durability of battery packs. This study focuses on the optimization of the Battery Thermal Management System (BTMS) for a 12-meter electric bus. By employing advanced 1D  simulations, key design parameters such as coolant line configurations, component selection, and thermal load distribution were analyzed to create an efficient and reliable system. 

A significant challenge addressed in this research was the uneven flow distribution among the battery packs, which arises due to differences in pressure drops along the cooling circuit. Battery packs closer to the pump often receive higher flow rates, while those farther away suffer from insufficient cooling, leading to thermal differences. To overcome this issue, adjustments were made to pipe diameters and component placements to equalize pressure drops across the system. Additionally, pressure drop-flow rate (dP-Q) curves were developed for each component, enabling precise representation of their individual flow resistance characteristics. These adjustments ensured that the coolant flow rates to all battery packs remained within the desired operational range, enhancing thermal consistency and overall system performance. 

The optimized BTMS design was validated through physical testing and numerical simulations. Results showed a maximum deviation of 10% between experimental data and simulation predictions, confirming the accuracy and reliability of the proposed system. The validation process also highlighted the importance of combining computational models with experimental methods to develop robust designs capable of meeting physical operational requirements. 

Beyond improving thermal performance, the optimized design significantly enhanced the energy efficiency of the pump by reducing it's a lot operational . By ensuring uniform coolant distribution and eliminating overflows in certain areas, the pump could operate at lower power levels without working system performance also contributed to overall energy savings, which is essential for the sustainability of electric buses. 

This research provides a comprehensive and scalable framework for optimizing thermal management systems in electric vehicles. The findings and methodologies presented in this study offer valuable insights into the development of efficient and reliable cooling systems for next-generation electric buses. By improving battery life, reducing energy consumption, and ensuring consistent performance, this work contributes to the advancement of sustainable public transportation solutions. 

In the current scenario, demand for alternate energy is increasing due to depletion of fossil fuels and countries commitment towards carbon neutrality by 2050. Hydrogen is considered as one of the cleaner fuel and many OEMs across the world started to work on various strategies like hydrogen combustion engine and fuel cell. Passenger vehicles like Buses are at the lookout for fuel cell technology at faster rate than other commercial vehicles. In fuel cell vehicles, cooling system design is critical & complex since it includes fuel cell cooling, Power electronics cooling & battery cooling. In this paper cooling system design of a Fuel cell electric bus for inter-city application is demonstrated. Radiators and Fans are selected based on the overall heat rejection and Coolant inlet temperature requirements of components. Cooling system circuit and pump is decided to meet the coolant flow rate targets. Flow simulation and thermal simulation done using simulation software KULI to predict coolant flow rate and temperature through each components. Fuel cell circuits, Power electronic circuits modelled in KULI with all components in the circuit. KULI predicted results signifies good co-relation with actual results. 

The further development of an existing simulation model, which represents the cooling and air conditioning systems of the Plasser InfraSpector 18.0 track inspection vehicle as realistically as possible, is intended to show the potential of dynamic control of the systems. 

In the existing simulation model, the maximum performance of the charge air cooling and cabin air conditioning was previously taken into account as a constant requirement, regardless of the driving and environmental conditions. The implementation of the charge air temperature control and the dynamic climate control model ensures a more realistic consideration of the interactions within the overall system. 

The simulation study is based on the climatic and route-specific boundary conditions of the high-speed route between Mecca and Medina in Saudi Arabia. The aim is to clarify the effects of the implemented dynamic control concepts on the overall performance of the vehicle and thus on the system efficiency. 

The use of simulation tools in the development of thermal management systems has indeed become a critical aspect of optimizing performance and design. They provide flexibility, enable rapid iteration, and assist in understanding system behavior without the cost and time required for full-scale physical experiments. But to be able to create an appropriate 1D model, experimental data are needed first. 

A compact modular refrigeration circuit serves as a chiller to maintain the temperature of critical components, such as batteries, power electronics, and motors in an electric vehicle (EV) application has been designed by AKG. The compactness is important to fit within the confined space of an electric vehicle. Modular design is advantageous because it allows scalability and easier integration into various vehicle platforms. As chiller and condenser aluminium brazed plate heat exchanger (BPHX) are used.

For further development of the system a 1D-model is created in Kuli-HVAC. Especially the calibration of the heat exchanger models bases on limited set of experimental data. While this can provide good accuracy within the bounds of the calibrated conditions, extrapolating the model to significantly different conditions (such as varying flow rates, or external heat loads) results in less accurate predictions, as validation by experiments shows. 

In this presentation the methodology and applicability of measurement data set for the calibration of 1D model of a BPHX is presented and the validation results discussed

tbd

Efficient heating and cooling of electric and electronic components is one of the key factors of a well-designed electric vehicle. In passenger cars, increasing fast-charging requirements lead to very high battery pack cooling demands and for sports cars critical temperatures can also occur during high performance driving. In commercial vehicle and off-highway equipment applications, very high load-peaks during operation pose significant challenges for battery cooling, too. One solution is to maximize heat transfer coefficients by immersing electric components directly into the cooling fluid. The French company Wattalps has developed such a modular and stackable battery concept. In an ongoing research activity between Wattalps, MAGMA Giessereitechnologie and Engineering Center Steyr  we are working on an efficient development workflow, where a combination of 3D coolant flow simulation (MAGMASOFT) and 1D system simulation (KULI) allows both the optimization of interior battery flow distributions and integration of the battery pack in the overall vehicle cooling system. In our presentation we want to share some first results from this cooperation.

In the highly competitive world of Formula Student racing, cutting every gram and optimizing every component of the racing car is essential for success. Among the critical systems, the cooling system plays a crucial role in ensuring, that every component can be run at its maximum power, without having to worry about overheating and losing power, which would make the car unreliable and consequently loose us points in competitions. Utilizing a cooling system software like KULI is a game-changer for a Formula Student team, enhancing performance, reliability and efficiency.

(Quick introduction about TUfast, How our car looks like, What our goals are, From the project to the real world application)

Cooling System Design and Simulation
KULI allows our team to design and simulate our cooling systems with precision. By creating virtual models of radiators, heat exchangers, cooling ducts, and fluid flow paths, we can analyse and predict how heat will be managed during races and endurance runs and how to optimize its diffusion. This eliminates much of the trial-and-error typically involved in designing a cooling system, saving valuable time and resources, both being very limited in the Formula Student ambient. By analysing real-time data from sensors monitoring temperatures, pressures, and flow rates on the car, the software provides actionable insights. We can adjust cooling strategies dynamically and, on the road, such as modifying fan speeds or redirecting airflow, based on the car’s thermal performance on the track. This adaptability can be crucial during long races or in varying weather conditions, where maintaining constant low temperature for the four wheel-engines and the inverter, as well as the accumulator, is of vital importance for preventing power loss, or mechanical failure. Furthermore, thanks to KULI lab it is possible to quickly export the results of our simulations and graph them in the best optimal way. This allows us to quickly confront small changes done to the system and therefore eases our iteration process. This iterative approach significantly reduces the cost and time of manufacturing and testing physical components. We can therefore explore a wider range of design options and materials, from radiator core thickness to the placement of cooling ducts, to find the optimal configuration.

(I will show our cooling system, Compare it with other teams, Show our iteration process, Our conclusions that we can extrapolate from the excel tables)

Long-Term Benefits for the Team
Beyond immediate performance gains, utilizing an easy to learn, practical and organized cooling system software, such as KULI, enhances the team's understanding of thermal management principles. This knowledge transfer is extremely important, as it enables the future student working on it, to build and edit directly on past projects therefore retuning and improving our design year after year. In addition, getting familiarized with an industry level software prepares us for careers in engineering, where tools like this one are widely implemented.

Conclusion
In conclusion we can safely say, KULI offers TUfast significant advantages, from efficiently planning our cooling system design to real-time performance optimization. Utilising all the tools KULI offers, makes it possible for us to not only achieve better results on the track but also seek a deeper understanding of engineering principles, setting the stage for continued innovation and success.

Formula Student is arguably the most important motorsport competition dedicated to students, in which the universities’ teams must conceive, design and manufacture a Formula-like single-seater to race with. The Technical University of Cluj-Napoca’s team from Romania, named ART TU, is the first one from the country to have ever participated with an electrically powered vehicle. The mission of this team is to create a center of know-how in the domain of electric performance vehicles and to enrich the students with skills and competence which will help them integrate more easily into the automotive sector.

The challenges of an Electric Formula Student team are well known, and they mostly gravitate around getting all the high-voltage safety systems in line with the regulation and passing all technical inspections. Although the team is still viewed as relatively new, with only 3 competition seasons under its belt, it has grown steadily and has obtained more points from the static events each year. This year is the first one when the objective will be to participate in the competitions’ dynamic events.

Despite the project’s challenges and incipient phase, the development of the powertrain’s thermal management has never been a problem, which is largely due to the availability of the KULI software at the university and the pre-existing working experience with it of a few members. 

The powertrain consists of two electric motors, powering the two wheels of the rear axle individually, and their two corresponding controllers. The development of the liquid-based cooling system starts with the motors’ and controllers’ heat generation estimation from KULI, where the input simulation parameters are extracted from an internally developed lap time simulation. These values, together with the average velocity and several ambient temperature and liquid flow rate scenarios create a list of requirements that is sent to our partner, RAAL, who proposes a few custom-made radiator models. Based on the specific 
needs and packaging possibilities one radiator-fan pairing is validated and their corresponding KULI components are provided by RAAL and integrated in the cooling circuit. The complete system and hose routing is modeled in a CAD software, which allows the definition of all tubes and bends in the KULI model, therefore adding all the additional pressure drops that occur in the circuit. Finally, several water pump models were tested, the choice being driven by factors such as the temperature reached in the motor stator and controller, the liquid pressure inside the components’ cooling channels and last but not the
least, the costs.

One important criterion in the choice of the water pump is the possibility to control its speed via a PWM signal. This allows the analysis of several control algorithm combinations between the water pump’s continuously variable speed and the fan’s on/off position to increase the system’s energy efficiency.

Location will be announced soon

Agenda:

• 09:00 - 10:00 | Part 1
• 10:00 - 10:15 | Coffee break
• 10:15 - 12:00 | Part 2
• 12:00 - 12:45 | Lunch break
• 12:45 - 14:30 | Part 3