Question

CHAPTER 2. SELECTED TOPICS IN THERMODYNAMICS Laboratory Quiz 4 - Psychrometry A new HVAC system is been tested at the laboratory. The experimental data for the humid air at Inlet conditions that include Dry bulb temperature of 33.4°C and Relative humidity of 40% and at Outlet conditions that include Dry bulb temperature of 22.0°C and Dew point temperature of 18.0°C. The mass flow rate of dry air is 100 kg/s. Assume that the temperature of the condensate water is equal to the dew point of the outlet air at the evaporator and assume that conditions are under standard atmospheric pressure. 1. Determine the mass rate of removed in HVAC system in kg/s. 2. Determine the total sensible heat in kW 3. Determine the total latent heat in kW 4. Calculate the total amount of heat transferred in kW 5. For different given conditions, the initial condition includes relative humidity (RH) of 70% and dry-bulb temperature of 33.0°C and final condition includes relative humidity (RH) of 30% and dry-bulb temperature 24.0°C. (a) what is the change in water content (in &/kda)? (b) was water added or removed?

Answer 1

0.20 0.25 SENSIBLE HEAT RATIO = Qs/Qt 0.30 110 0.35 120 UZO 0.40 -34.0 33.0 -320 -310 30 WET BULB TEMPERATURE 126 0.45 -30.0 -290 020 - 25 0.5524.0 019 23,0 ENTHALPY - KJ PER KILOGRAM OF DRY AIR .018 F DRY AIR HON 017 2016 015 IN DEW POINT TEMPERATURE-C u ri o o o o VAPOR PRESSURE - MM OF MERCURY o o THALPY-KI PER U IN 044 reyntynyt 11.0 HUMIDITY RADIO - KILOGRAMS MOISTURE PER KILOGRAM DRY 8/3 SN 18/8 18 18 VITY AD.86 VOLUME - CUBIC/METER PER KG DRY AIR VI HIVHAX GAA SENSIBLE HEAT RATIO - Os / Qt 20% TA WHAVE 20% VA TA 10% RELATIVE HUMIDI A 10 24 15 Chart by: HANDS DOWN SOFTWARE, www.handsdownsoftware.com 92.24 3086 35 DRY BULB TEMPERATURE - C 3304 ENTHALPY-KJ PER KILOGRAM OF DRY AIR

Ins As it is As it is clear that states DBT = 33.4°C & RH = 40% and DBT-230 & OPT=18& Ire on some specific humidity line and no condensation occurs. mass rate of removed to & Sensible heat = m (hi-h2) = luo ( 67.5-553) Sensible Heat = 1220kW Conly approximate as calculated using Psychrometric chart Total Laptent heat =ofelal since humidity ratio is maltered 4 Total amount of heat fromsferred = 1220 kW 5 line 3-4 represents this process. change in walter content = (W3-04) = (0,0226-006056) change inwater content = 0.017 kg of water vapors (eg of de In air since humidity ratio is decreasing, it meme water is being removed,
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