The Semco REV 2250 ventilation unit is illustrated in Figure 2.  It integrates a 3000 cfm circulation fan, a 50 kW air based heat pump for cooling/heating, and an active solid desiccant wheel, which can be used for air dehumidification in summer and air heating in winter. Figure 2 Configuration of SEMCO Revolution Unit (courtesy of SEMCO Inc.) The operating principles of this unit are illustrated in Figure 3; and its flow diagram, in Figure 4. Figure 3 Operating Principle of SEMCO Revolution Unit (courtesy of SEMCO Inc.) Figure 4 Flow Diagram of SEMCO REV 2250 This ventilation unit can be operated either as an air conditioning system, recirculating air from the building space and combining it with outside air for cooling/heating/ventilation in the space or as a dedicated outside air system, DOAS, processing only the ventilation air.  For DOAS operation in summer, the outside air, OA, is drawn through the direct expansion, DX, cooling coil, where it is cooled and dehumidified.

If the unit is operated as an air conditioning system, the mixture of outside and recirculation air, RA, shown as the dash line in Figure 4, will be drawn through the DX coil. The air leaving the DX coil, LDX, is then split into two portions: one portion goes into the active desiccant wheel where it is further dehumidified, LDW; another portion bypasses around the wheel through a modulating damper. The warm dry air from the desiccant wheel is then mixed with the cold moist, probably saturated, air bypassing the wheel.  The mixture is ducted into the IW.  The bypass damper is set; the heat pump compressor and the desiccant regeneration air temperature are adjusted in order to obtain the operator specified supply air, SA, temperature and humidity under different outdoor conditions.  This air handling process is represented by the solid lines in the psychrometric chart shown in Figure 5 for a summer design day in Pittsburgh. Figure 5 Psychrometric Representation of Different Air Handling Processes for Pittsburgh Summer Design Day

(solid lines indicate SEMCO approach, dash lines conventional rooftop approach and dotted lines previous desiccant-integrated approach)hvac unit in cars In a conventional rooftop air conditioning unit, the air flow is cooled below its dew point temperature to reduce its moisture content and then is reheated to the desired supply temperature, as indicated by the dashed lines in Figure 5.  8 ton air conditioner costIn prior desiccant integrated systems, all of the air flow first flows through the desiccant wheel to achieve the desired supply humidity, approximately a constant enthalpy process.  central heating air conditioning units pricesA large amount of moisture is adsorbed, and the air temperature leaving the desiccant wheel is high, as shown by the dotted lines in Figure 5.

As seen from Figure 5, the Semco ventilation unit offers the following advantages over conventional rooftop air conditioning units and previous desiccant integrated systems: As mentioned earlier, there are two major components in Semco REV 2250 unit: active desiccant dehumidification module andLOOKING FOR YOUR OWNER’S GUIDE? An owner’s guide can come in handy should you ever need more information about your Trane system. Trane product guides are readilyBut since they are updated often, your local Trane Comfort Specialist is the best source for the most appropriate version for your specific product. Whether searching our online database or contacting your local dealer, be sure to have the INDOOR UNITS - FURNACES & AIR HANDLERS Includes the following products: XC95m, XV95, XT95, XR95, XB90, XC80, XV80, XL80, XT80, XR80, XB80, XV80 Oil, XP80, Hyperion XL, Hyperion XR, Hyperion XB Trane Indoor Units Owner's Guide OUTDOOR UNITS - AIR CONDITIONERS & HEAT PUMPS