CAREL, specialist in humidification and evaporative cooling systems, presents the optiMist, a product to enrich its wide range of solutions for the HVAC/R market.
optiMist is not only a humidifier: this single product, in fact, combines the functions of evaporative cooling (in the Summer) and humidification (in the Winter).
optiMist features a water inlet circuit, a volumetric pump and two solenoid valves to distribute pressurised water (16 bars). The electrical panel includes the power circuit, a programmable electronic controller and an inverter.
It receives the control signal from a remote control unit or directly from the temperature or humidity probes. The electronic controller calculates the flow-rate of atomised water required to meet the evaporative cooling or humidity demand, and signals the required pump speed to the inverter. This ensures linear modulation of water atomisation, avoiding waste.
Specifically, evaporative cooling occurs due to the spontaneous evaporation of the water droplets produced: the change in phase from liquid to vapour subtracts energy from the air, which is consequently cooled. Evaporation of 100 kg/h of water absorbs 69 kW of heat from the air. The exhaust air can be cooled by several degrees without restrictions in terms of humidity level, as it is discharged by the AHU. This cooling capacity can be exploited to cool the fresh inlet air, via a heat exchanger, with efficiency - depending on the heat recovery unit - that easily exceeds 50%. This means the size, capacity and power consumption of the cooling coil and chiller can be reduced.
Special care has been paid to hygiene when designing optiMist, to ensure effective Legionella prevention. In fact, the built-in controller automatically fills the lines only when humidification or evaporative cooling are required; empties the lines when there is no humidification or evaporative cooling demand for some time; periodically washes the lines. The washing cycle is performed using dedicated solenoid valves, and not by spraying the water being drained.
From the point of view of energy efficiency, optiMist does not create additional pressure drop for the fans on the AHU, maintaining constant efficiency over time (unlike evaporative coolers/humidifiers using wet deck technology). Furthermore, it can receive a limit signal directly from the exhaust air fan or from the recirculation damper actuator. This innovation optimises evaporative cooling by ensuring water is not wasted.
Compared to existing systems on the market that use the wetted media technology, optiMist optimises pump operation using an inverter, meaning no energy is wasted.
optiMist guarantees considerable energy savings, providing evaporative cooling in summer and precise air humidity control in winter in a single product, guaranteeing a global energy saving in the management of the Air Handling Units.