TerraXcube investigates the effects of extreme environments
Image credit: Alpitronic
Tucked away in Italy’s mountainous South Tyrol province lies a test centre that studies how organisms and objects react in extreme climate conditions. E&T takes a tour of the facility.
Until recently, the only way to find out what happened to anything in extreme cold, or heat, or at low atmospheric pressures, was to take it somewhere suitably extreme and run tests on site – and this was for large-scale testing. This, however, is expensive, often perilous, and hit-and-miss when it comes to the replication or control of variables.
Although small-scale environmental testing within specially designed chambers has been around for decades, solar panels, technical clothing, drones, bulldozers and even humans, plants and other living things can now all be tested to their limits at a facility in Bolzano in the Italian Tyrol – the terraXcube.
The team at terraXcube can match atmospheric pressures from sea level to the top of Everest, simulate blizzards and torrential rain, high winds, extreme humidity or parched desert dryness, and temperatures from -40°C to +60°C, and combinations of all the above.
Christian Steurer is the director of the centre. “We are unique in the world in that we can run a combination of so many different environmental parameters in a single large chamber. Most of the other facilities similar to ours are commercially restricted to owner operators in the automotive sector. Also, they tend to use separate chambers for different parameters – for example, one for snow, another for temperature. Our big advantage is that we can make wind plus rain or snow, at varying altitudes, simulating storms or typhoons all at once inside a single space.”
On the day that E&T visited the facility, it was 15°C and sunny outside, but -10°C and snowing inside the climate box, with a spot of freezing fog. The terraXcube sits inside an ordinary office building on the Eurac Research campus in Bolzano.
To prevent the entire building from vibrating, and so that the neighbours didn’t complain about the noise, the chamber had to be constructed on a floating floor made of an elastic rubber-like material to dampen the noise and vibration from the multiple pumps and motors of the environmental control systems. The walls of the 12m x 6m x 5m space are constructed of steel and concrete so that the internal pressure can be guaranteed. The structure must be flexible so that at low internal pressures (simulating high altitude), the walls can flex inwards by 1-2cm.
Meanwhile, altitude is simulated in two different ways depending on the nature of the test. For machinery tests at altitude, vacuum pumps suck out the air until the internal pressure is at, for example, 0.33 atmospheres, a third of that at sea level or an equivalent of the atmospheric pressure at 9,000m. If there are humans involved in physiological tests, then the team lower the oxygen partial pressure in the chamber using membrane technology to remove the oxygen, and at the same time replace it with nitrogen to simulate the breathed atmosphere at high altitude, and its effects on the human body.
The set temperature for any trial must be uniform throughout the space, with minimal variation to plus or minus 1°C. To achieve this, air entering the chamber is pre-treated in a 1m space above the chamber itself. A two-stage cooling system is used to pull the chamber down to extremely low temperatures. The first uses a hydrofluoro-olefin gas refrigerant to lower the interior temperature to -10°C. A second is based on carbon dioxide, and allows the chamber to reach its low of -40°C. The pre-treated air flows into the chamber, circulated through tiny perforations in the stainless-steel plates lining the walls to ensure a uniform airflow and an evenness of temperature throughout.
The chamber also has two layered walls with a 20cm airspace between them. This airspace has its own air-conditioning system for both insulation and energy efficiency. Maintaining the air in the gap at around 20°C also prevents condensation on the walls, which would encourage fungal growth to form, which would be detrimental to people working inside.
“The real fun starts when a client needs snow. We are often asked to deposit a certain quantity of snow on equipment under test,” says Steurer. One client, who produces lights for trains, asked terraXcube to simulate a train moving through a snowstorm. There are many different kinds of snow; fluffy flakes with a big structure and volume, for example, will behave quite differently from wet compact snow.
The train lamp systems had a heating and de-icing system; the tests were run to assess the visibility of the lights under differing snow and ice conditions, to confirm that these safety-critical lights could shine through a snowstorm and penetrate their own de-icing system.
Fortunately, terraXcube has an expert snow generation partner in the form of local snow-gun manufacturer Technoalpin – a global player responsible for the snow at the recent Beijing Winter Olympics. The chamber is equipped with two snow guns; one of the future goals is to further refine control over snow quality, quantity and direction within the chamber.
When E&T visited, the snow was falling inside the chamber, as rapid electric vehicle charging company Alpitronic was there to test the performance of two of its hyper chargers under snow, ice, and melting cycles replicating spring mountain days. Hardware engineer Peter Gruber works at the Bolzano-based company, which designs hyper chargers capable of charging an EV at 300kW in 10 minutes, adding 100km of range. “We have our own chamber that will give us the temperature range, but I’m here for the snow,” he said, smiling. “It’s easy to test here, we can set the parameters and are not dependent on God and the weather.”
The company ran a set of tests last year in the terraXcube to check the behaviour of the power electronics from +50°C to -30°C, and from that improved the cooling fan control system. “A quiet fan system is a must – people get mad over persistent noise issues in a neighbourhood, even if it’s only a hum. But today, I’m here to check out the performance of the cable management system in a series of freeze and melt cycles under a deposit of several centimetres of snow,” Gruber explained. Everything is performing well and the BMW i3 in the chamber is receiving the correct charge at -10°C. The hyper-chargers are designed to be sited at petrol stations and are also used to fast-charge new electric vehicles coming off the factory production lines at several top automotive companies.
Beyond snow, the chamber can also create high winds of up to 30m/s, or Beaufort scale 11, equivalent to a violent storm and just below a hurricane, using two wind generator turbines. Combining these very high winds with driven rain has been useful to test the rim permeability of satellite or telecoms dome covers for applications in everything from international shipping and military vehicles to TV receivers on camping caravans. The wind-driven rain has also been used to test antenna design – moisture inhibits radio wave transmission and if it is allowed to freeze, essentially the antenna becomes non-functional. Another use case is the testing of autonomous vehicle sensor designs – water interferes with the effective functioning of lidar, light-based radar systems critical to autonomous vehicle navigation.
Testing interactions with technology in the controllable conditions inside the cube also enables human-machine interfaces to be optimised: can equipment be efficiently operated in extreme conditions, and is it the machine or the operator that needs to be adapted? Buses, tanks, other military and agricultural machinery, and industrial robots have all been put through their paces in the chamber, often at the prototyping phase of design, returning for repeat tests as the designs are amended in response to performance under extreme environmental stressors. Companies often return for final product certification of function in extreme conditions.
Recently there have been many tests of aerial drones, as companies seek to understand the effects of blade icing and high winds on flight systems and have their vehicles certified for flight in sensitive areas.
Clothing and fabric designers also use the box to test everything from high-fashion winter parkas in the cold, to performance cycling clothing in high winds and driving rain – the very worst a cyclist can encounter. In May 2022, D’Air Lab tested a specialist heated suit designed for the worst of Antarctic conditions. The suit must protect the wearer in -40°C with a feels-like wind chill of -70°C.
When models and volunteers are being subjected to these sometimes-brutal conditions, the participants have multiple physiological sensors on their bodies and are monitored continuously for body core temperature, blood pressure, oxygen saturation, heart rate and ECG, with physicians continuously in attendance for safety. Up to 15 people can be accommodated inside the chamber at any one time. There are other environmental chambers, but few are open to all comers, and most are single-parameter uses in the commercially sensitive automotive sector.
The terraXcube is unique in the sheer number of parameters that can be manipulated simultaneously – and everyone loves the snow.
Downstairs from the large chamber at terraXcube are four small chambers specially equipped for plant research. Inside these, combinations of light spectra can be selected from ultraviolet through visible to infrared, and CO2 levels from 400ppm to 1,000ppm, both vital parameters for healthy plant growth. The same plant variety can be stress tested to see how it performs under differing future climate change parameters.
Today’s viticulturists have to make decisions as to which vine variety to plant in new vineyards. But the lifetime of a vineyard is 25-30 years, so it is increasingly important for farmers to consider the future impact of climate change.
Georg Niedrist, a plant scientist at the university campus of Eurac, used the small chambers to test the responses of a grape variety with which we are all familiar – Sauvignon Blanc – to both heat and drought. “The plants were equipped with multiple sensors to measure the physiological stresses,” says Niedrist. “Our work is part of a programme to help viticulturists be prepared for future climate scenarios.”
An Ocean in a Box
The Scripps Ocean Atmosphere Research Simulator, or SOARS, has just opened in San Diego, California. The 36m-long wave tank with a wind tunnel built above it was commissioned in January 2022.
The ocean-atmosphere boundary is a little-understood place where chemical, biological and physical processes occur that can affect the weather, climate change and offshore engineering to name a few.
With the help of piped Pacific Ocean sea water from the nearby Scripps pier, the ‘ocean in a box’ can produce 1.2m waves, air temperatures of between -20°C and +30°C, and storm-force wind speeds of up to 100km/h or 26m/s. At water temperatures of 1°C, sea water will freeze when cold air passes over it, allowing the oceanographers to simulate conditions in the polar regions, producing floating ice. The headspace above it allows researchers to investigate the importance of sea spray and sea-spray aerosols in the form of smog. Two viewing rooms allow direct observations by the scientists. The chamber will also serve as a test bed for marine instrumentation prior to deployment in the open ocean.
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