Question

On the psychrometric chart provided mark clearly the point for air with a
dry bulb temperature of 30^oC and a Percentage Saturation of 80%.
At this air condition, by referring to the same chart, what are the values of
wet bulb temperature, specific volume, moisture content in kg/kg (dry air)
and enthalpy.

If the air is air-conditioned to 15^oC dry bulb and a Percentage Saturation of
60, what is the associated enthalpy drop.

NAT BEBE Reduced scale CIBSE psychrometric chart by spermission of CIBSE) 120 125 130 140 80 70 00 PERCENTAGE SATURATION SO 40 PANIFCEE 30 20 CIBSE PSYCHROMETRIC CHART 0-030 EFEL 4-0-029 i 0020 30 2 027 +0070 +0-025 BASED ON A BAROMETRIC PRESSURE OF 101-325 kPa -0-024 0.1 0.2 -0-023 09 0.4 4-0-022 0-5 -0-021 25 -0020 07 FO-019 -09 SENSIBLE/TOTAL HEAT -10RATIO TOR WATER -DO ADDED AT 30C -0-8 -0% SPECIFIC ENTHALPY kJ/kg -0019 SPECIFIC VOLUME m/ kg O-017 0-85 -0-6 0-016 20.! -0015 0-014 0:3 0-1 10-013 -0.012 0-011 WET - BULB TEMPERATURE *C (SLING) Ho-010 -0.009 15.2 Specific humidity, relative humidity, and percentage saturation -0.008 13 0-30 -0-007 -0-006 8 -0.005 -0-004 -0.003 0-002 -10 0-001 -10 10 +0-000 60 45 SO 55 25 35 DRY - BULB TEMPERATURE °C ASSASS 45 30 35 AS -10 SPECIFIC ENTHALPY kJ/kg 539 0 CBSE LONDON 1987

Answer 1

= 80% After ₂ bulb temperature =27.087 C GIVEN : 1.) Initial drybulb temperature = 30°c 2.) Percentage saturation air-conditi conditioning 3.) Final dry bulb temperature = 15°c 4.) percentage Saturation = 604. SOLUTION; (PART-I The given psychrometric Chart {approx.) In psychrometric chart, go 80 simply draw from 30% such that give us moisture it will cut 80%. percentas saturation line, will give us Now, draw a temperature horizontal line tos o 5 10 15 20 25 30 35 40 45 from the given chart, uring the Wet Chart Specific volume moisture content in kg/kg = 0.02166 kg / kg da. enthalpy = 85.527 ao c014 0.013 0.012 Fooll To.oos horizontal line from that point will a line -0.008 to.007 content. Inclined line 0.00 0.005 toooy f0.003 wet-bulb Jo.002 Fooool Toooo = 0.889 m²/kg kJ kg.

PART-2 air-conditioning process will be represented 0 5 10 15 20 25 30 35 40 B Soss 45 line 1-2 will represent the given air conditioning process. So from the chart, At 15c bulb temperature and 60% relative humidity , we have; 15c dry chart Enthalpy = = 31.193 kJ/kg. [using • Associated o Enthalpy drop = hi ha - 85.527 – 3193 =54.334 kJ/kg. [h, 85 ser from previous part