Question

a) what is the physical interpretation of the wet-bulb temperature?

b) during winter time a room is maintained at a steady temperature and humidity by an air-conditionibg system shown. 200 m^3/ min of room return air at 30 c, 50% relative hunidity is first mixed with 40 m^3/min of outdoor at 10 c, 20% relative humidity. the mixed air is then introduced to a heater where the temp of air is raised to 45 c and supplied to the room. ( note that air and the steam in the heater do not mix. Steam simply supplies the heat).

do the following using ASHRAE psychrometric chart only:

1) plot the processed on the ASHRAE chart and submit. Show all the states clearly on the chart.

Determine:

2) the required capacity of the steam heater, kW

3) the relative humidity , of the air supplied to the room, %

4) is the calculated rellative humidity of the supply of air acceptable in common engineering practices? Explain why

5) the required mass flow rate of the steam through the heater if saturated vapor is supplied at 150 kPa and exits the heater as saturated liquid at the same pressure, kg/min

Satvape ISOkPa Sutolige isokpa Mixedair Steam heater X 300287501 001 لا الهما وبا 45 Room 3 4 40 m3/min 10G6=20%

Answer 1