Question

PROBLEM 2. (20 POINTS) A space to be maintained at 25 C dB (dry bulb) temperature and 18°C wB (wet bulb) has a rate of sensible-heat gain of 25 kWand a rate of moisture gain of20 kg/hr. Moist air enters the space at a dry-bulb temperature of 15°C. Outdoor air at 35 C dB temperature and 25 C wB is supplied for ventilation purposes at a rate of 400 Us (litres per second) of standard air. After leaving the room, some of the air exhausts to the outside and the remainder mixes with the ventilation air and then passes through a filter, a cooling coil and a fan. a. Draw a diagram of the system. b. Draw the operating cyele on the psychrometric chart provided. c. Identify each significant point, on the diagram and psych rometric chart, and note for each of these points its dry bulb and wet bulb temperature. d. Calculate the conditions of the air entering the cooling coil (dB and wB) e. Caleulate the capacity of the coil (kW ), apparatus dew point, coil by-pass factor. . Caleulate room sensible heat factor (SHF), and grand sensible heat factor (GSI

Answer 1

resh air 《me' Recirculated air lter b25C cooling Coil 2 3600 RSHF RSH 25 0.9962 25+0 09 44 Assumingヂ Recirculthed air mixed with 4resh air draw Point-3.-as-mixing-Point-ao ! condną air supriring to the rooom point 4) . Oue Point Teno g. Coi) ADP 12-4 By paro ATinaメ ldb-db IST-12 30-12 _

Coolin Capai Coil = a em Chaat S3 0-877 10 116 3.062- TR Cond" ot air enteing cooling co CPoint 3 m the Psic chart rand Sensible heat (GS.Hf) 06

025 SENSIBLE HEAT RAOCai 1 30 035 OUTOKUMPU HEAT TRANSFER PSYCHROMETRIC CHART Normal Temperature St Units SEA LEVEL 040, -34 390 32 0 30 29 C BAROMETRIC PRESSURE: 101.325 kPa 270 022 25 D 020 25 23 0 22 C 20 19 얹 1、OUTSIDE AIR 20 170% 0 85 5 ADP RoOM AIR 90 SUPPLy AiR 80 60 50 30 CRY BULB TENPERATURE "C ENTHALPY - KJ PER KILOGRAMO DRY AIR