A mobile air cooling unit engineered for use in remote underground locations offers significant benefits to mining operations, especially where additional cooling capacity is needed or where existing cooling capacity is not available or inadequate.
Available from Mine Support Products (MSP), a company within the DCD-DORBYL Group, the unit was developed by M-Tech Industrial to provide a more comfortable working environment.
Dion Booyens, of MSP, explains that the unit, designated the Enerflow Modular Underground Air Cooling Unit (ACU), is ideal for providing localised cooling where heat is a problem.
“It has a very high positional efficiency, and is modular and mobile making it easy to transport and install. The dimensions of the unit are such that it will fit very easily into a mine cage, and as mine development expands the unit can easily be moved,” he adds.
M-Tech Industrial’s divisional manager heat pumps – Martin van Eldik says that development on the unit started in 2003 when a need was identified within the market for a cooling unit that could be used in remote underground areas where the ambient temperature is close to the critical 32.5ºC wet bulb. Both international and South African patents are pending on the unit.
The development of the cooling unit was based on field-proven heat pump technology in the commercial sector, one of the core capabilities of M-Tech Industrial. Van Eldik says it is suitable for all remote underground locations with air wet bulb temperatures in the region of 32.5ºC and water inlet temperatures of up to 35ºC.
The unit uses a vapour compression cycle that comprises a compressor, an air evaporator and a water condenser. All components are housed within a single, mobile, modular unit. It can be mounted on a tracked unit, have its own tracked undercarriage or if required could be wheel-mounted.
The unit was designed to allow easy connection of all services including water, electricity and fan. Typically it would be situated in an area where normal ventilation is not sufficient for the cooling needs of the personnel in that section. Hot air is drawn into the unit and cycled through the air evaporator using a standard mine ventilation fan, resulting in cooling down of the hot air and the feeding of this cooled air back into the surrounding area.
“The temperature change on the air side through the unit is between 5 and 10ºC wet bulb, depending on the air volume flow rate through the unit. The system can be customised to accommodate specific mine environmental conditions,” van Eldik says.
The energy extracted from the air is transferred to the water in the condenser via the compressor and this water is then discharged into the mine’s waste water reticulation system. The system design is such that this volume of water is minimal, depending on the specific application circumstances as well as the temperature of the supply water, the flow is typically in the region of 1 litre/second. The maximum flow rate is about 2 litres/second.
Should additional cooling be required, the Enerflow Modular Underground ACU can be installed in series or in parallel. Water connection requires one inlet and one outlet using 50-mm flexible hoses. Electricity supply required is 525 V 40A/phase. Currently a 406-mm mine ventilation fan with a 4 kW capacity or a 572 mm (7.5 kW) fan is used.
This electrically-driven unit has a nominal cooling capacity of 80 kW yet requires only 18 kW electrical input, making it energy efficient. “The cooling capacity of the unit has been kept at 80 kW to enable its modular configuration, however if the heating load is larger then units can be installed in a parallel configuration,” Booyens adds.
Because of its modular construction, the unit can be easily moved from one location to another as the mine progresses. “It is, in fact, not designed to be a fixed unit underground,” van Eldik says. “It is ideal for development work on mining faces and allows very focused cooling in areas where required because of its high positional efficiency.”
“Two prototype units have been in the field for more than 18 months in deep level gold mines,” Booyens says. “Both have been used in development areas within the mines and have significantly reduced ambient temperatures, facilitating a more comfortable working environment.”
The air cooling unit is 2.3 m long x 1.25 m wide x 1.8 m high and has a weight of 2 t. It makes use of R134a – an environmentally friendly refrigerant.
MSP is responsible for the marketing of the Enerflow Modular Underground Air Cooling Unit (ACU). The company was formed as an equal partnership between DCD-DORBYL, the largest mechanical engineering concern in South Africa, and Barloworld’s Robor (Pty) Ltd.
An ISO 9001 accredited company, MSP has received a number of accolades for excellence in safety and technology. These include the Institution of Mechanical Engineering Award for Innovation and Design, and the 5 Gold Star Pro-Risk International Accreditation for compliance with international safety, health and environmental standards.
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