Posted to News on 24th Nov 2020, 00:00
Innovative field shelter delivers off-grid cooling solution for remote basestation
A field equipment shelter fitted with fault-tolerant cooling is ensuring the reliability of a wireless communications link that connects instrument-ation on a new gas pipeline crossing a Middle Eastern desert to the remote control room. Fabricated from tough glassfibre-reinforced polyester (GRP) materials, the shelter houses a TETRA basestation powered by solar panels – in order to function reliably in an off-grid location some 50 km from the nearest town.
Intertec’s shelter employs a ‘hybrid cooling’ system to safeguard the 56m2 shelter’s electronics equipment, and battery power storage compartment – a Zone 1 area. The system consists of a water-based passive cooler assisted by dual-redundant electrically-powered water coolers. This approach combines the intrinsic reliability of passive cooling with active water refrigeration to increase cooling efficiency on hot days.
The system can handle a cooling load of around 1.9 kW, ensuring that even during this Middle Eastern climate's summer – when ambient temperatures can climb as high as 55°C – interior shelter temperatures will always stay below a worst-case peak of around 35°C. At other times of the year, internal shelter temperatures are maintained far below these levels. The remote location means that the basestation is far from the electricity grid, and must be powered by solar energy. The passive cooling system, based on a water tank with internal and external heat exchangers, exploits the desert climate’s daily temperature swing to store the coolness of the night and use it to moderate internal temperatures during the day. The water circulates around the system by natural convection, without electrical power or moving parts.
This system alone manages the shelter’s cooling needs during the winter months – typically keeping temperatures at around 18-20°C. The two powered water coolers increase the efficiency of the cooling system during the hottest months – operating in an alternating sequence for fault tolerance – typically maintaining temperatures in the 20-30°C range. Even if both water coolers were to fail, Intertec's passive system has enough cool water capacity to maintain low shelter temperatures for many days, giving maintenance staff plenty of time to access the remote site and make repairs.
The water coolers are a new variant of Intertec’s novel Hybricool range that operate directly from a DC power supply, making them an efficient solution for solar-powered installations. These cooling units are specially designed to supplement passive coolers operating in process plants, with a heat exchanger element that can be installed inside the water storage tank of a passive cooling system to decrease temperature. This interior element is isolated from the rest of the externally-mounted refrigeration system, making it both an efficient and economic solution for explosion proof applications.
