Volkwagen's cooling and climatic testing plant, Hall 68 in Wolfsburg
More than ever, the reduction of costs through time-optimised processes during the development of a vehicle is a decisive factor for its success. This also refers to testing the effects of various climatic conditions as they exist in different regions of the earth.
Several years ago, Volkswagen in Wolfsburg, Germany started considerations as to how to minimise expensive prototype testing in different parts of the world by indoor-tests, providing the same climatic conditions in a Laboratory. The aim was furthermore to become independent of seasonal and daytime influences by creating reproducible ambient conditions, to economise travel and transportation costs and to reduce time losses between the test cycles.
The result is a test centre in Wolfsburg, built during 2004 and 2006, in the form of a test plant named Hall 68, where nearly all climatic and environmental conditions occurring in different parts of the world can be simulated. In addition to six temperature or climatic test chambers for complete vehicles, it includes a test chamber for engines.
Part of the vehicle test chambers is equipped with dynamometers and can simulate altitude conditions and the air-flow on vehicles ranging in size from small cars to utility vehicles. In order to utilise the test chambers to their maximum capacity, the vehicles are preconditioned in separate soak boxes. Thereafter they are transferred to the test chambers through the connecting “dry zone”, where the air is constantly maintained at a low dew point to prevent formation of dew, frosting and ice. The tests are coordinated, carried out and monitored from five control rooms.
The provision of the test equipment for a complete test plant of such magnitude was a unique challenge for the engineers at Weiss Umwelttechnik GmbH in Reiskirchen-Lindenstruth. The project was to be implemented within just two years from the date of award of the contract until acceptance through the customer. As its execution required carefully co-ordinated planning and intense co-operation among all departments involved, the responsibilities were split and distributed to three project managers. The engineers had to ensure that the individual test chambers meet the technical requirements and can be integrated into a well-networked overall system. The project management also had to take care of aspects of electrical and control engineering as well as static and logistics.
The requirements of Volkswagen AG were realized by a new 3-storey building where the middle floor houses the test facilities and control rooms. The machinery for refrigeration, fresh air conditioning, etc. is located on the ground floor and the top floor accommodates offices and conference rooms.
The layout and dimension of the test chambers in the middle floor level enables an optimised testing of the whole range of Volkswagen cars from the Fox through to transportation vehicles. In addition, its compact layout simplifies the daily testing procedures and as a result, Hall 68 is an extremely service-friendly facility.
Preconditioning of the cars prior to a test takes place in one of twelve soak boxes. To increase their capacity, parking systems inside the boxes allow the treatment of two cars simultaneously. Thus an additional 20% of tests can be prepared on 24 parking bays in a 2-shift operation every day. The temperatures inside the boxes cover the entire range of the different test chambers.
Vehicle movers are used to transfer the preconditioned vehicles from the soak boxes into the test chambers.
The technical highlight of Hall 68 is the climatic chamber KKL2 which allows the simulation of the influence of temperature, humidity, sunlight, air-flow and pressure (for altitude simulation) simultaneously. It is equipped with a four- wheel dynamometer, and it enables ascent and descent driving combined with sunlight simulation with a radiation level up to 1100 W/m2 and pressure levels from sea level up to 3000 m at velocities up to 180 kph. For exact conditioning even at high levels of humidity and thermal load, the circulation air heat exchanger is tempered indirectly. The coolant is cooled in a reservoir by NH3 refrigeration and maintained at temperatures down to -43°C depending on the operating point of the plant.
In addition to the altitude chamber, there are two further chambers providing various climatic conditions, one of which is equipped with a single-axis dynamometer and an air-flow fan for wind velocities up to 130 kph to test complete vehicles at controlled humidity.
Three cooling/heating chambers, one of which is equipped with a single-axis dynamometer and an air-flow fan, are capable of working in the temperature range of -40 to +20°C, complete the testing capacity for vehicles.
There is another cooling/heating chamber to test engines on a dynamometer at temperatures between -30 and +25°C. The refrigeration system allows the compensation of heat loads from the specimen up to 300 kW.
The ground floor houses 13 additional cabinets and chambers with volumes of 0.5 to 24 m3. These are used for testing components like injection pumps, windscreen wipers or doors under extreme conditions. Operation of the plant began in November 2006 in the presence of 150 guests at the R&D division of Volkswagen factory in Wolfsburg.
“The road test can never be replaced”, said Dr. Jens Pohlmann, the director of the plant, “however this plant takes us to a new level of know-how which earlier we were only able to obtain in different locations of the world. With this new plant, we have set an important milestone in the technological development of Volkswagen. The new test centre will enable us to minimise the development period of our new vehicles because we can now carry out much more tests inside our lab. Our engineers will be able to analyse and optimise the new vehicles much faster.” l