Simulating the desert sun in the hot tunnel
In the hot tunnel, it is possible to generate temperatures in the range from minus 10 to plus 60 degrees Celsius. The facility also includes a system for simulating the sun. Its 32 lamps radiate light with an intensity range equivalent to that of real sunlight. Over an area of 8 by 2.5 metres, it is possible to regulate this intensity to between 200 and 1200 watts per square metre. The higher figure here is comparable with the intensity of the real sun only as experienced in very few places in the world - such as Death Valley in the USA or in one or two remote desert locations. Even there it is only reached around midday when the sun is vertically overhead, corresponding as it does to a temperature of more than 50 degrees Celsius.
In the Mercedes-Benz hot tunnel, the whole sun simulation system can be tilted sideways to as far as just five degrees above the horizon. This makes it possible to imitate very realistically the course of the sun through the day or to conduct meaningful tests in conditions involving strong sunlight from one side.
Even rapid fluctuations of light and temperature, such as those experienced when clouds appear or when driving into a tunnel, can be included in the test programme. Fine mesh panels can be pushed over the front of the lamps to simulate the effect of clouds, while solid covers can be put over the lamps
to imitate the abrupt change of light that comes when entering a tunnel.
A further development tool used in the hot tunnel is the Hot Road, a simulated hot road surface, the temperature of which can be set on a continuously variable scale to between 50 and 70 degrees Celsius. This is used to simulate the heat radiated by a road in summer, as a means, once again, of creating conditions that are as realistic as possible.