The range of battery electric vehicles (BEV) is directly proportional to their battery capacity. With the current technology of battery cells on average a range of 6.6 kilometers per 1 kWh of battery capacity is achieved.
In practice the range of a BEV depends on the climate and environmental conditions. A large portion of the battery's power must be used for regulating the temperature in the passenger cabin. Under unfavourable conditions this can lead to a range reduction of up to 40%. For example, during a cold winter day the loss heat of a conventional internal combustion engine is no longer available as a "free" source of energy for heating the cabin.
Thermal analyses of cabin climatization have always been highly important for the layout of HVAC systems in cars. BEVs call for an even more extensive analysis covering the energy balance of the entire thermal system of the car. This necessarily includes the batteries themselves since running within the optimal operating temperature range extends life time and maintains maximum possible capacity. Furthermore, the study has to cover all measures for reducing battery power invested in passenger comfort rather than for the pure purpose of powering the car.
The optimal temperature range for battery electric vehicles is between 20 and 30 °C. Higher temperatures reduce the life expectancy of the battery. Lower temperatures negatively impact the electrical capacity. For that reason alone, during summer a separate cooling mechanism has to be applied to the battery independent of the need for air-conditioning of the passenger cabin. During winter there is no heat loss from the engine available for heating. The heat for regulating the internal battery temperature to an optimal range has to be supplied by the battery itself.
All potential measures listed below can be tested and evaluated by simulations with THESEUS‑FE. Relying on simulations during the early stage of car development drastically reduces the costs for trying out some variations compared to real physical testing. Most importantly these virtual tests can be done even before any prototype of the car exists. The insight gained during this stage can save a lot of money before a wrong decision materializes in a real prototype.
Measures for intelligent, range increasing climatization concepts include:
To cite an example, THESEUS‑FE allows for wavelength-dependent transmission and reflection properties of windows. Several variants of windows and coatings can be simulated with ease to rate their influence on the thermal budget of the car. Simulation results thus give immediate feedback about the effect of the HVAC systems power as well as the thermal comfort of passengers.
As part of the publicly funded BMBF project, E-Komfort involved generating a highly detailed finite element model for simulating the climate control system of the passenger compartment of a Volkswagen e-Golf. A model originally used for crash simulations was used as a basis for developing a cabin model for interior climate control systems. Simulations were performed in an virtual environmental chamber under winter and summer load conditions relevant to vehicle design and range. This work also involved testing and calibrating special lamp models (for simulating sunlight in environmental chambers), and then using these models in the simulation.
The paper (available for download below) describes an initial validation study demonstrating a simulating technique capable of delivering realistic predictions of average and local cabin air temperatures. We illustrate how we extrapolated and calibrated a simplified cabin model (known as a rapid or generator model) from a highly detailed e-Golf simulation model. Doing so allowed us to reduce computing time from several days to a few seconds without compromising the quality of the simulated average temperature of the cabin air.
Using THESEUS‑FE simulations, we were able to demonstrate that employing zonal climate control concepts can massively reduce the amount of energy that the climate control system consumes. Energy can also be conserved through the use of infrared emitters, which were simulated using suitable models and assessed in terms of their impact on local thermal comfort values. Under winter load conditions, e-vehicle range is significantly limited by the amount of energy consumed by the climate control system. As such, heating or cooling passengers only where needed and/or only to a comfortable temperature makes more sense than heating/cooling the entire passenger compartment. Against this backdrop, our simulation also incorporated a thermophysiological model and used the concept of equivalent temperature as a basis for assessing local thermal comfort. The final portion of the paper provides a discussion of motivation and strategies for coupled cabin simulations - in this case coupling THESEUS‑FE and OpenFOAM - as well as the corresponding validation work.
Thermal simulation of a complete vehicle using manikin models
[english, 3.3 MB]
S. Paulke, D. Köster, R. Hass, V. Bader, S. Menzel, A. Gubalke
P+Z Engineering, Volkswagen AG
17. SIMVEC 2014 | November 18-19, 2014 | Baden-Baden, Germany
Thermische Simulationen einer Volkswagen e-Golf-Fahrzeugkabine unter Einbezug von thermischen Menschmodellen
[german, 3.1 MB]
S. Paulke, D. Köster, R. Hass, V. Bader, S. Menzel, A. Gubalke
P+Z Engineering, Volkswagen AG
17. SIMVEC 2014 | November 18-19, 2014 | Baden-Baden, Germany
Thermal Simulations of a Volkswagen e-Golf Cabin Incorporating Human Thermal Comfort Models
[english, 3.3 MB]
S. Paulke, D. Köster, R. Hass, V. Bader, S. Menzel, A. Gubalke
P+Z Engineering, Volkswagen AG
17. SIMVEC 2014 | November 18-19, 2014 | Baden-Baden, Germany
Innovative concepts relating to air-conditioning and thermal comfort, for optimizing the range of electric vehicles (E-comfort)
[english, 0.5 MB]
BmBF
BmBF
Press Announcement | 2011
Be it busses, tramways, metro or passenger trains - THESEUS‑FE can be utilized to solve any thermal problems arising in and around public transportation vehicles. Application cases where THESEUS‑FE really shines are the thermal comfort assessment of passengers and analyzing energetic measures such as different glazings or heat insulation.
An overview of use cases where THESEUS‑FE can help to gain invaluable insight for public transportation:
In a joint project with MAN, Volkswagen, and the University of Applied Sciences, Munich, we have developed a THESEUS‑FE model for predicting the HVAC performance of an MAN A37 City Bus.
Our main focus was on the validation of the THESEUS‑FE model with an existing Excel-based tool developed by F. Artmeier at MAN Truck & Bus.
Aim of the project was to demonstrate the capabilities of THESEUS‑FE for simulating a bus air conditioning system. The main goal of the simulation was to derive the net power of the HVAC system needed to enforce a contant value of 20 °C cabin temperature.
In a first step we validated the Finite Element results of THESEUS‑FE by comparing them with the results obtaining using an MAN in-house tool. The MAN tool, developed and tested by Mr. Felix Artmeier as part of his diploma thesis in 2012, considers energy balances for the bus cabin. In a second step we demonstrated the advantage of employing THESEUS‑FE by creating an extended simulation model also capable of simulating passenger thermal comfort. Finally we validated the THESEUS‑FE prediction of AC power using a Mollier diagram.
THESEUS‑FE permits all kinds of thermal boundary conditions such as conduction, convection, and radiation.
The overall intent of the simulation was to derive the net power of the HVAC system needed to enforce a constant value of 20 °C cabin temperature (Tcabin) typical climate conditions for a summer day in Germany.
For the extended THESEUS‑FE model we added seats and additional heat sources such as passenger metabolism and engine heating.
The project clearly demonstrated that THESEUS‑FE is a useful simulation tool in designing a bus AC system. Environmental conditions for any place on earth are easily integrated into the model. The results were more than satisfactory and confirm the role of THESEUS‑FE as an established and reliable tool in predicting vehicle cabin HVAC parameters.
MAN Bus A37: HVAC Analysis & Benchmark with THESEUS-FE
[english, 3.0 MB]
S. Paulke, F. Artmeier, K.-E. Yildirim, V. Bader, A. Gubner
P+Z Engineering, MAN Truck & Bus AG, Volkswagen AG, TU Munich
Project Report | August 19, 2013
Numerical Simulation of the Air Flow and Thermal Comfort in a Train Cabin
[english, 1.3 MB]
M. Konstantinov, C. Wagner
TU Ilmenau, DLR Göttingen
2014
Contra Vision bus window wraps - HVAC case study using THESEUS-FE
[english, 0.8 MB]
Contra Vision
Contra Vision
November, 2019
The main task of the environmental control system (ECS) of an aircraft is to provide air supply, thermal control and cabin pressurization for the crew and passagers. An amount of 0.55 lb/min of fresh air has to be supplied for each passenger within the following bounds:
The desired cabin pressure is regulated by controlled draining of stale air. Recirculation air and fresh air are mixed in roughly equal proportions.
For the normal flight operation, cabin temperature is regulated to 21-25 °C For cooling down an airplane while on the ground on a hot sunny day, one estimates the necessary cooling power to about 150-200 W per passenger. For a large capacity aircraft with 350 passengers this leads to a required cooling capacity of over 50 kW.
When putting the ECS system into operation, its efficiency is demonstrated with dynamic load cases
The cabin target temperature has to be reached within 30 minutes.
The process of heating up during the winter load case demands for up to 70°C fresh air temperature.
The portion of needed fuel for the environmental control system compared to the total fuel consumption is approximately 5%.
For the summer load case while on the ground, about 25% of the ECS power is used for dehumidification of the air.
Nowadays for that purpose high-pressure water separators are used.
They utilize that fact that air at high pressure absorbs less water than at normal pressure levels.
At any time within an aircraft cabin a suitable temperature has to be set. This depends for example on the typical clothing of the passengers, e.g. is it summer or winter. Furthermore it can depend on the activity level of the passengers - are they awake or sleeping.
Reasons for local discomfort can be:
When designing the cabin ventilation system, in general asymmetric and inhomogeneous thermal conditions should be avoided. To compare local comfort indices of passengers, it is appropriate to do thermal simulations using the thermophysiological human model of THESEUS‑FE coupled with fine-grained CFD simulations. Different variants of climatization concepts can be analyzed easily this way without the need for cost-intensive prototypes.
Examples of industrially relevant turbulent flow simulation with OpenFOAM
[english, 10.5 MB]
M. Konstantinov, K. Weinman, W. P. Wu, T. Köthe, M. Fragner, R. Deiterding, C. Wagner
DLR Göttingen
Project Report | October 09, 2013
Numerical Simulation of the Air Flow and Thermal Comfort in Aircraft Cabins
[english, 0.3 MB]
M. Konstantinov, W. Lautenschlager, A. Shishkin, C. Wagner
DLR Göttingen
2014
Adhesives in Car Body Development. Process Simulation.
[english, 1.1 MB]
M. Eis, S. Paulke
BMW, P+Z Engineering
Paderborner Symposium Fügetechnik | November 29-30, 2006 | Paderborn, Germany
Kleben im Karosseriebau. Prozess-Simulation.
[german, 1.1 MB]
M. Eis, S. Paulke
BMW, P+Z Engineering
Paderborner Symposium Fügetechnik | November 29-30, 2006 | Paderborn, Germany
Numerical prediction of thermal panel distortion incorporating thermal material properties of 6016 aluminum alloy
[english, 1.0 MB]
C. Albiez, M. Liewald, A. Görres, J. Regensburger
Uni Stuttgart, Audi AG
European Aluminium Congress 2011 | November 22, 2011
Digital Paint Process Simulation - E-Coating and Thermomechanic
[english, 2.5 MB]
T. Haberland
Volkswagen AG
MAGNA-Conference on Enhanced Dip Painting Process by Simulation Tools | May 29, 2013 | St. Valentin, Austria
Challenges in developing tools for the Digital Factory
[english, 1.4 MB]
S. Paulke
P+Z Engineering
MAGNA-Conference on Enhanced Dip Painting Process by Simulation Tools | May 29, 2013 | St. Valentin, Austria