TUGAS OPERASI TEKNIK KIMIA II

SOAL-SOAL DEHUMIDIFIKASI

Oleh :

Kelompok 5

Kelas B

INGET YESTER YUNANDA (1007121587)

LAILA KUSMIATI (1007121535)

FITRI AFRIANI SUSANTI (1007121668)

NIRMALA SARI (1007121611)

NOFERI YANLI (1007121556)

PROGRAM SARJANA TEKNIK KIMIA

FAKULTAS TEKNIK UNIVERSITAS RIAU

PEKANBARU

2012

1. Air having a dry bulb temperature of 37,8oC and wet bulb of 26,7oC is to be dried by first cooling to 15,6oC to condense water vapor and then heating to 23,9oC. (Geankoplis:Problem 9.3.9)a. Calculate the initial humidity and percentage humidityb. Calculate the final humidity (hint: locate the initial point on the

humidity chart. Then go horizontally (cooling) to the 100 % saturation line. Follow this line to 15,6oC. Then go horizontally).

Solution :

HandBook Munters DH The Dehumidification Handbook second Edition

A. Initial humidity: 0,0397 kg H2O/kg dry air percentage humidity : 40 %B. Entalpy 15,6oC= 27 btu/lb

ΔH= cp.ΔT=0,240 btu/lb F x (75,02-60,08)oF=3,58 btu/lb

Entalpy 23,9oC= (27 + 3,58)btu/lb=30,58 btu/lbHumidity 23,9oC=0,0252 kg H2O/kg dry airFinal humidity := (0,0397-0,0282) kg H2O/kg dry air= 0,0057 kg H2O/ kg dry air

2. Air entering an adiabatic cooling chamber has a temperature of 32,2oC and a percentage humidity of 65%. It is cooled by a cold and heated to 23,9oC. The final air has a percentage humidity of 40%.(Geankoplis:Problem 9.3.10)a. What initial humidity of the airb. What is the final humidity after heating

Solution:

HandBook Munters DH The Dehumidification Handbook second Edition

A. Initial humidity : 0, 0419 kg H2O/kg dry air

B. final humidity : 0,0187 kg H2O/kg dry air

3. Udara akan didinginkan dan didehumidifikasi melalui kontak lawan-arah dengan air didalam menara isian. Menara tersebut dirancang sebagai berikut: suhu dry bulb udara masuk 28oC, suhu wet bulb udara masuk 25oC, laju alir udara masuk 700 kg/jam udara kering, suhu air masuk 10oC, dan suhu air keluar 24oC. Persen humidity keluar 70 %.

a. Untuk udara masuk tentukan kelembaban, persen kelembaban relatif,dan titik embun

b. Berapakah ΔHR ?

Solution:

HandBook Munters DH The Dehumidification Handbook second Edition

A. Initial humidity : 0,11 kg H2O/ kg dry airpercentage humidity : 90%dew point : 770 F / 10,7oC

B. h1 = cp1. (T1-Tref)=1,0019 cal/g.C (10-0)C

h2 =cp2. (T2-Tref)=0,9993 cal/g.C (24-0)C=23,98 cal/g

Δh = h2-h1 =13,9642 cal/g=25,135 btu/lb

h2 = h1- Δh=(43-25,135)btu/lb=17,86 btu/lb

Final humidity : 0,0187 kg H2O/kg dry airΔHR = (0,11-0,0187) kg H2O/kg dry air

=0,091 kg H2O/kg dry air

4. Moist air at 50°C dry bulb temperature and 32%relative humidity enters the coolingcoil of a dehumidification kiln heat pump system and iscooled to a temperature of 18°C. If the drying rateof 6 m3 of red oak lumber is 4 kg/hour,determine the kW of refrigeration required.

Solution:

HandBook Munters DH The Dehumidification Handbook second Edition

∆HR = (25.2- 12.9) g water/ kg dry air

= 12.3 g water/ kg dry air

Wa¿drying rate

∆ HR

= 4 kg/h

0.0123 kg H 2O /kgdryair

= 325.2 kg dryair/h

∆h = (115.7 – 50,8) kj/kg dry air

= 64.9 kj/kg dry air

q = (∆h)(Wa)

= [64.9kj

kg dry air ][325.2kgdry air

h ] = 21105.7 kj/h = 5.9 kW

5. Udara dimasukkan dalam suatu proses mempunyai suhu bola kering 30 oC dan RH 40%. Proses terdiri dari pendinginan, dehumidifikasi, dan pemanasan kembali. Udara masuk pendinginan pada Tdb 35 oC dan RH 70% dengan laju alir 1 m3/s pada 1 atm. Tentukan laju panas yang dikeluarkan dalam pendinginan dan dehumidifikasi!

Solution:

Entalphy awal pemanasan (h1) = 58 kJ/kg

Entalphy akhir pemanasan (h2) = 63 kJ/kg

Entalphy awal pendinginan (h3) = 91 kJ/kg

Entalphy akhir pendinginan (h4) = 85 kJ/kg

Volume spesifik awal (V2) = 0,59 m3/kg. UK

Volume spesifik (V3) = 0,91 m3/kg. UK

laju pendinginan=h awal−h akhirvolume spesifik

x laju alir volum

¿ h 3−h 4V 3

x q

¿ 91−850.91

x1 m3 /s

= 6.5934 kJ/s