Here comes a buyer who is from Miami, Florida, USA, he owns an industrial building with all steel structure, no insulation materials, length 50 meters, width 30 meters and height 10meters, usually 20 workers, power supply 440V/60Hz 3 phase, the highest ambient temperature is 35℃ over the year. This is how we make a solution for him.
1. Cooling Load
Heat transfer load of the envelope structure (wall + roof)
Because it is an all-steel structure without an insulation layer, the heat transfer from the roof and walls is the largest source of heat load.
Roof heat transfer load (steel structure without insulation) : approximately 25 to 30 W/m²
Wall heat transfer load (without insulation) : approximately 15 to 20 W/m²
The industrial building is rectangular with a scale of 30 m × 50 m × 10 m
Roof area: 30 × 50 = 1,500 m²
Wall area: 2×(30+50)×10 = 1,600 m²
Roof load: 1500 × 30 = 45,000 W
Wall load: 1600 × 20 = 32,000 W
Total 77,000W=77kW
2. Workers Heat Load, 150W each person, 20*150W=3,000W=3kW
3. Fresh Air load (ventilation and air exchange)
As per the conventional air change rate of 3 to 5 times per hour in industrial plants, taking 4 times per hour, the volume is 15,000 m³
Air flow rate: 15,000 × 4 = 60,000 m³/h
The cooling load is approximately 60,000 × 1.2 kg/m³ × 1.005 kJ/kg·K × temperature difference (10℃) ÷ 3,600 ≈ 201 kW
(Note: The temperature difference is taken as 35℃ - 25℃ = 10℃, and 1.2 is the air density)
Fresh air cooling load: approximately 200 kW
Estimation of total cooling capacity
Heat transfer of the envelope structure------77kW
Personnel heat dissipation----------------------3kW
Fresh Air Load -------------------------------------200kW
It is recommended to configure an air conditioning system with a cooling capacity of about 300 kW, so we choose a rooftop air conditioning unit,it can be placed either on the rooftop of the building or beside the building on the ground. The users need to do nothing but only connect the air ducts to deliver cold air into the room space.
