MechChem Africa January-February 2022

Booyco mobile HVAC systems: busting the perception of over-engineering

MechChemAfrica talks to Booyco Engineering’s MD Brenton Spies, along with Grant Miller, executive director, about purpose-engineered HVAC systems that are designed to best suit the harsh operating conditions experienced in the military, rail and mining sectors, where extreme temperatures, vibration and dust make commonly used units functionally inadequate, unreliable and prone to very early failures.

are generally designed for condens- ing temperatures of 60 °C. Therefore a system that is designed for a 35 °C ambient, has a 25 °C temperature dif- ference to enable heat to be rejected from the cabin and into the surrounding environment. This means a much smaller condenser or outside coil can be used. But if operating in a 50 °C ambient temperature with the same condensing temperature of 60 °C, the temperature difference is only 10 °C, hence a much smaller available temperature difference and therefore a much larger condenser coil is required to reject the heat into the hotter surroundings,” he explains, adding that, when it comes to rejecting heat using HVAC systems, it is the differential that matters most: the smaller that differential, the larger the coils, fans and compressors needed to achieve the cooling capacity re- quired. “If you use a system designed for a

temperature by 10°C. In terms of the heat that needs to be rejected, this difference is huge,” explains Miller. In order to eject this additional heat, larger components are needed, such as larger condenser coils and more powerful fans. “While our systems may seem over- sized, they will work in the hot ambient temperatures and off-road environments they are designed for, while cheaper road- based systems will struggle,” he adds. Cooling capacity is specified in terms of kilowatts (kW) of cooling, which often leads to confusion when people compare our systems to conventional HVAC units. If we specify 3.5 kW of cooling capacity for a unit cooling a cabin in a 45 °C ambient down to a 25 °C internal temperature, it is significantly different from a unit deliver- ing 3,5 kW of cooling in a 35 °C ambient to the same 25 °C internal temperature. Getting a little more technical, systems

“T here is a misconception that our mobile HVAC solutions are over-engineered, making them more expensive than they need to be, particularly in comparison to the mass-produced systems designed for use in typical heavy goods vehicles (HGVs). But these vehicles seldom run off motorways and they are typically designed for cooler cli- mates,” beginsGrantMiller, executivedirector of Booyco Engineering. “Our systems are not designed or manu- factured for road transport vehicles,” adds Booyco Engineering’s MD, Brenton Spies. “Those systems can be rapidly assembled in high volumes in factories anywhere in the world, for use by any vehicle OEM looking to minimise the selling cost of their HGVs,” he says. “At Booyco , we have deve l oped a range of purpose-designed HVAC units for the harsher conditions typically found in African mining markets. The first and most important di f ferent iator i s that our systems are rated for use at ambient temperatures of 45 °C to 50 °C, while the road transport units tend to be designed for cooler climates, where 35 °C is seen as the accepted max imum operat i ng temperature. “This makes a huge different to the cooling performance required from the HVAC system. Our systems are designed to cool the cabin down to 25 °C in a 45° to 50°C ambient. To do this in an ambient temperature that is 10 to 15 °C higher, means that the cabin temperature change required from our systems can be as high as 25°C, while the mass-produced units are generally only designed to reduce the

26 ¦ MechChem Africa • January-February 2022