1- An air handling unit working in the summer is shown in Figure 1. Please respond to the following questions using the psychrometric chart (with Pat= 101.325 kPa). a) Show the psychrometric properties of all the points in Figure 1 (complete Table 1). Attach the chart with the points (please use different colours). (3.5 marks) Outdoor air (OA) Mixed air Air handling unit (MA) Exhaust air (EA) Supply air (SA) Return air (RA) Zone Table 1: Deliverable submission deadline Specific Tab Twb Tdp W Enthalpy volume Name (C) (C) (C) (g/kg da) (%) (kJ/kg) (m/kg) OA 31 60 0.880 MA SA 30 RA 18 7.5 45 51 b) Using what "process" can you decrease the relative humidity of MA to 46% without changing the moisture content (W)? (0.5 marks) c) Calculate the quantity of latent and sensible enthalpy of the air at RA. (1 mark) d) Find the saturated vapor pressure (Pws (kPa)) at OA, when the Pat is 90 kPa. (1 mark) e) What is the increase in the amount of enthalpy if the SA is humidified to 65%? (0.5 mark) f) If the surface temperature of the SA duct is 12 C, will moisture condense on the surface? What is the lowest surface temperature for this duct to avoid condensation? (1 mark) ASHRAE PSYCHROMETRIC CHART NO. 1 NORMAL TEMPERATURE BAROMETRIC PRESSURE SEA LEVEL 101.325 kPa. COPYRIGHT 1992 ASHRAE 100 1.0 08 07 06 50- 05 04 40- 0.3 20 SENSIBLE HEAT SH TOTAL HEAT ENTHALPY HUMIDITY RATIO 30 - AW 1.0 -5.0 20 40 -20 00 0.0 140 -20 -1.0 ASHRAE 80 ENTHALPY) KILOJOULES PER KILOGRAM DRY AIR 60 20 SATURATION TEMPERATURE C 40 15 20 90 25 %06, Y%08 30 100 60% 30 50% 40% 00 25 WET BULB TEMPERATURE 20% 10% RELATIVE HUMIDITY LUME CUBIC METRE LOGR R 30 28 26 120 24 22 110 20 18 100 16- 14 90 0.40 12 80 10 2 30 40 50 70 60 0.60 -0.65 0.70 -0.70 0.80 -0.85 0.90 0.95 1.0