HVAC
EVAPORATIVE
COOLING
ColdAir system performance
in a real industrial shed
CLIENT
Manufacturer of adiabatic evaporative cooling systems for industrial buildings
CHALLENGE
Assess by CFD how a roof-mounted ColdAir system performs, and how outside humidity changes the answer
RESULT
Close to 7°C of cooling in the working zones at 30% relative humidity, and useful cooling even at 70%
01
CHALLENGE
Cooling a large industrial shed through the summer is one of the harder problems in industrial HVAC. Large heat-losing surfaces, solar radiation on the roof and internal thermal loads can push the air temperature very high, which destroys comfort for the people working there and drives the energy cost of cooling up with it.
Adiabatic evaporative cooling has been spreading in recent years as an answer: it cools the air naturally, by evaporating water, and so uses considerably less energy than conventional compression-based air conditioning.
The client asked us for a campaign of CFD simulations to look in detail at how the ColdAir system behaves inside a real industrial shed — the temperature distribution, the relative humidity distribution, and how effective the cooling stays as ambient conditions change.
02
SOLUTION
We built a three-dimensional CFD model of the shed. The ColdAir unit sits on the roof and delivers cooled air through six nozzles angled at 45°, about five metres above the floor, at a total flow rate of 40,000 m³/h.
The simulations account for heat transfer, the buoyancy of the warm air, and the presence of water vapour in the fluid: the air is modelled as a mixture of air and water vapour, which is what makes it possible to represent the evaporative process properly rather than approximate it.
The model also includes the things that decide the answer in a real building — heat loss through the walls, solar radiation on the roof, heat exchange with the ground and natural ventilation through the openings. The domain was discretised with an unstructured mesh of over four million cells, with prism layers at the walls to resolve the thermal boundary layer.
To understand the influence of ambient conditions, three scenarios were run at a constant outside temperature of 35°C with the outside relative humidity set to 30%, 50% and 70%.
03
RESULTS
At 30% relative humidity the system performed best: in the working zones of the shed the air temperature falls to around 27°C, nearly 7°C below the outside air. The simulations also show clearly the pockets of cooler air forming under the supply jets, which is what improves comfort where the work actually happens.
As the outside humidity rises the efficiency of evaporative cooling falls away, exactly as the physics of the process says it must. Even in the most demanding case analysed — 70% relative humidity — ColdAir still delivers a reduction in the perceived temperature inside the building.
The analysis confirmed the effectiveness of this generation of direct adiabatic evaporative cooling in industrial environments: better thermal comfort, lower energy consumption than conventional systems, and effective distribution of the cooled air even across a large space. Against compression-based air conditioning, evaporative technologies cut operating costs by up to 70%, for a significantly lower initial investment and a considerable reduction in CO₂ emissions.
The simulations also gave the client what they needed to optimise the placement and sizing of ColdAir units in future installations.
