A space heating system has a furnace, a humidifier and a preheater. Outdoor air enters the preheating coil at 14°C and essentially 0 percent relative humidity. The outdoor air is then heated to 16°C and mixed with the return air. Then it is heated and humidified to 40°C and 30% relative humidity for supply to the space. 25% (by mass) of supply air is outside air, required for proper ventilation. The building has a total heating load of 145 kW. The sensible heat factor for the space is 0.8 , and the space is to be maintained at 2 celcius C and 30% relative humidity. Saturated steam at 1.2bar is used for humidification.
a. Sketch the system and draw the cycle on the psychrometric chart.
