Product Overview
Mechanical Cooling Mode (B5)
Mechanical + Free Cooling Mode (B5)
Figure 2-2 Operating Modes (Bottom Supply)
2.1 Free Cooling System
When the operating conditions for free cooling are met, the control system switches the air damper to the free
cooling position. Cooler air from outside is delivered to the shelter by the supply air fan. At the same time, hot
air in the shelter is discharged to the outdoor environment.
2.2 Adaptive Free Cooling
Traditional Wall Packaged Unit control provides a fixed outdoor temperature where free cooling starts based
on indoor setpoint. With adaptive free cooling, the system will automatically learn and remember the optimal
temperatures where free cooling can take over. Adaptive free cooling will continuously optimize toward free
cooling hours with no human adjustment required. This is particularly valuable whenever the site heat load
changes as the system will also adapt to find the new optimal free cooling setpoints.
2.3 Mechanical Cooling System
When the operating conditions for mechanical cooling are met, the control system switches the air damper to
the mechanical cooling position. The compressor compresses the refrigerant gas and sends it to the
condenser. The condenser is a heat exchanger, removing heat from the hot compressed gas and allowing it
to condense into a liquid. The liquid refrigerant is then routed to the thermal expansion valve, which acts as a
restriction device by forcing the refrigerant to go through a small hole. This causes the pressure to drop. Then
the liquid refrigerant is routed to the evaporator. The evaporator is also a heat exchanger, absorbing heat from
the indoor hot air causing the liquid refrigerant to change back into gas. The refrigerant gas is then routed back
to the compressor to complete the cycle. The refrigerant is used repeatedly, absorbing heat from the indoor
environment and discharging heat to the outdoor environment.
2.4 Soft Start
When mechanical cooling is requested, the compressor will ramp up its capacity and continuously modulate it
to match the required site load. This minimizes mechanical stress upon startup, eliminates startup voltage
spikes, and reduces unit noise level
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