Tugas Akhir Konversi Energi DAFTAR ISI
DAFTAR ISI
JUDUL LEMBAR PENGESAHAN KATA PENGANTAR ......................................................................................... i ABSTRAK......................................................................................................... iv DAFTAR ISI ..................................................................................................... vi DAFTAR GAMBAR ......................................................................................... xi DAFTAR GRAFIK.............................................................................................xiii DAFTAR TABEL ........................................................................................... xv NOMENCLATURE ....................................................................................... xvi
BAB 1 PENDAHULUAN 1.1. Latar Belakang ....................................................................................... 1 1.2. Perumusan Masalah ................................................................................ 5 1.3. Batasan Masalah ..................................................................................... 6 1.4. Tujuan Penelitian .................................................................................... 7 1.5. Manfaat Penelitian.......................................................................................8 1.6. Metode Penelitian ....................... ..............................................................8 1.7. Sistematika Penulisan ............................................................................ .9 BAB 2 TINJAUAN PUSTAKA 2.1. Penelitian-Penelitian Terdahulu ............................................................ 11 2.2. Mekanisme Perpindahan Panas ............................................................. 20 Teknik Mesin FTI – ITS
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Tugas Akhir Konversi Energi DAFTAR ISI
2.2.1. Perpindahan Panas Konduksi..........................................................21 2.2.2. Perpindahan Panas Radiasi..............................................................22 2.2.3. Perpindahan Panas Konveksi..........................................................23 2.2.3.1. Perpindahan Panas Konveksi Bebas..................................25 2.4. Mekanisme Perpindahan Panas Kondensor .......................................... 29 2.4.1. Perpindahan Panas Dalam Enclosure .......................................... 29 2.4.2. Perpindahan Panas Pada Pelat Datar Vertikal .............................. 32 2.4.3. Effectiveness .............................................................................. 35 BAB 3 METODE PENELITIAN 3.1. Variabel Penelitian ............................................................................... 38 3.2. Instalasi Percobaan ............................................................................... 41 3.3. Karakteristik Fluida Kerja.........................................................................43 3.4. Spesifikasi Alat Ukur................................................................................45 3.5. Prosedure Eksperimen...............................................................................49 3.6. Parameter Percobaan ……………………………………………………50 3.7. Prosedure Penelitian..................................................................................51 3.8. Flowchart Eksperimen...............................................................................52 3.9. Flowchart Perhitungan..............................................................................54 BAB 4 ANALISA DAN DISKUSI 4.1. Data Hasil Percobaan ........................................................................... 56 4.2. Contoh Perhitungan .............................................................................. 59 4.2.1. Perhitungan Sistem Refrigerasi.......................................................60 4.3. Analisa Dan Evaluasi Grafik ................................................................ 64 Teknik Mesin FTI – ITS
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4.3.1. Pengaruh Perubahan Gap Ratio (S/D) .......................................... 64 A. Analisa Sistem Refrigerasi Terhadap Kerja Kompresor..................... 64 B. Terhadap Laju Perpindahan Panas Evaporator.....................................66 C. Terhadap Coefficient Of Performance ( COP )………………………67 D. Terhadap Temperatur Tube Kondensor...............................................68 E. Terhadap Laju Perpindahan Panas Kondensor.....................................70 F. Terhadap Temperatur Pelat...................................................................71 G. Terhadap Laju Perpindahan Panas Pelat..............................................72 H. Rayleigh Number......….......................................................................74 I. Nusselt Number.........………………………………………………...75 J. Koefisien Konveksi rata – rata....……….………………………….....77 K. Grafik ε = f ( S / D) …………………....…………………………….78 4.3.2. Pengaruh Perubahan Panjang Pipa Kapiler.....................................79 A. Analisa Sistem Refrigerasi Terhadap Kerja Kompresor..................... 79 B. Terhadap Laju Perpindahan Panas Evaporator ....................................81 C. Terhadap Coefficient Of Performance ( COP )………………………82 D. Terhadap Temperatur Tube Kondensor...............................................83 E. Terhadap Laju Perpindahan Panas Kondensor.....................................84 F. Terhadap Laju Perpindahan Panas Pelat...............................................85 BAB 5 KESIMPULAN DAN SARAN 5.1. Kesimpulan ........................................................................................... 86 DAFTAR PUSTAKA ...................................................................................... 88
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LAMPIRAN
LAMPIRAN A DATA PERCOBAAN Tabel A-1. Data percobaan pipa kapiler 2.5 m ............................................. 89 Tabel A-2. Data percobaan pipa kapiler 3.0 m ............................................. 90 Tabel A-3. Data percobaan pipa kapiler 3.5 m ............................................. 91 LAMPIRAN B PROPERTIS DATA Tabel B-1. Properties data untuk pipa kapiler 2.5 m .................................... 92 Tabel B-2. Properties data untuk pipa kapiler 3.0 m .................................... 93 Tabel B-3. Properties data untuk pipa kapiler 3.5 m .................................... 94 LAMPIRAN C PERHITUNGAN DATA Tabel C-1. Perhitungan data untuk pipa kapiler 2.5 m ................................. 95 Tabel C-2. Perhitungan data untuk pipa kapiler 3.0 m ................................. 95 Tabel C-3. Perhitungan data untuk pipa kapiler 3.5 m ................................. 96 LAMPIRAN D DISTRIBUSI TEMPERATUR PELAT Grafik D-1. Distribusi Temperatur pelat untuk pipa kapiler 2.5 m.................97 Grafik D-2. Distribusi Temperatur pelat untuk pipa kapiler 3.0 m.................99 Grafik D-3. Distribusi Temperatur pelat untuk pipa kapiler 3.5 m...............101 Grafik D-4. Temperatur pelat rata-rata= f(S/D)............................................103 Teknik Mesin FTI – ITS
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LAMPIRAN E DISTRIBUSI TEMPERATUR TUBE Grafik E-1. Distribusi Temperatur Tube untuk pipa kapiler 2.5 m..............104 Grafik E-2. Distribusi Temperatur Tube untuk pipa kapiler 3.0 m..............106 Grafik E-3. Distribusi Temperatur Tube untuk pipa kapiler 3.5 m..............108 Grafik E-4. Grafik T tube,rerata = f(S/D)...........................................................110 Grafik E-5. Grafik T tube,rerata = f(panjang pipa kapiler).................................110 Tabel E-6. Tabel pipa kapiler.......................................................................111 Tabel E-7. Tabel Properties Refrigeran R-12...............................................112 Tabel E-8. Parameter Percobaan.................................................................. 114 Tabel E-9. Properties udara pada tekanan atmosfer.....................................115 LAMPIRAN F DIAGRAM P-h Grafik F-1. Grafik P-h Diagram dengan variasi pipa kapiler........................116 Grafik F-2. Grafik P-h Diagram untuk panjang pipa kapiler 2.5m...............117 Grafik F-3. Grafik P-h Diagram untuk panjang pipa kapiler 3.0m...............118 Grafik F-4. Grafik P-h Diagram untuk panjang pipa kapiler 3.5m...............119 Tabel F-5. Variabel Penelitian......................................................................120 Lampiran F-6. Perhitungan Perancangan Sistem Refrigerasi.......................128
BIOGRAFI PENULIS.......................................................................................131
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Tugas Akhir Konversi Energi DAFTAR ISI
DAFTAR GAMBAR
Gambar 1.1. Sistem Refrigerasi Kompresi Uap Sederhana.....................................1 Gambar 1.2. Model Proses Siklus Kompresi Uap Sederhana ................................ 2 Gambar 1.3. Susunan Wire and Tube Standart ..................................................... 3 Gmabar 1.4. Refrigerator Model Sekarang………………………..........................4 Gambar 1.5. Model Alat penukar panas yang diuji..................................................5 Gambar 2.1. Model CRCP milik Conroy & Mumma. ......................................... 11 Gambar 2.2. Kontur Temperatur dalam Sistem Enclosure ................................. 12 Gambar 2.3. Vertikal Enclosure milik Ahmed dan Yovanovich. ......................... 16 Gambar 2.4. Conduction, convection, and radiation heat transfer modes ............ 21 Gambar 2.5. Gradien temperatur perpindahan panas konduksi satu dimensi ....... 21 Gambar 2.6. Lokal and total convection heat transfer ......................................... 23 Gambar 2.7. Lapisan batas pada bidang vertikal dipanaskan............................... 25 Gambar 2.8. Konveksi bebas dalam rongga persegi............................................ 29 Gambar 2.9. Aliran fluida dalam enclosure rongga horizontal ............................ 30 Gambar 2.10. Sirkulasi fluida dalam rongga vertikal .......................................... 31 Gambar 2.11. Garis Temperatur pada Enclosure ................................................ 31 Gambar 2.12. Perpindahan panas total melalui pelat........................................... 32 Gambar 2.13. Perpindahan panas melalui pelat datar............................................33 Gambar 2.14. Control volume penukar panas........................................................37 Teknik Mesin FTI – ITS
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Gambar 3.1. Skema instalasi peralatan pengujian sistem refrigerasi ................... 41 Gambar 3.2. Instalasi pengujian ........................................................................ 42 Gambar 3.3. Skema penempatan termokopel pada kondensor ............................ 43 Gambar 3.4. Digital thermometer display ........................................................... 46 Gambar 4.1. Skema model proses sistem pendingin pada variasi gap rasio untuk panjang pipa kapiler 3 m...................................................................65 Gambar 4.2. Fenomena aliran udara disekitar tube kondensor ............................ 69 Gambar 4.3. Fenomena aliran enclosure................................................................70 Gambar 4.4. Fenomena aliran dalam enclosure.....................................................73 Gambar 4.5. Diagram P-V ................................................................................. 80 Gambar 4.6. Skema model proses sistem pendingin pada variasi panjang pipa kapiler................................................................................................81
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Tugas Akhir Konversi Energi DAFTAR ISI
DAFTAR GRAFIK
Grafik 2.1. Grafik fungsi temperatur terhadap tinggi box pada sistem enclosure...............................................................................................12 Grafik 2.2. Grafik fungsi Nusselt Number terhadap tinggi box pada sistem enclosure..............................................................................................13 Grafik 2.3. Grafik kecepatan rata-rata terhadap lebar box dalam sistem enclosure..............................................................................................14 Grafik 2.4. Rasio Nu / Ra1 / 4 sebagai fungsi dari rasio jarak (S/D).......................16 Grafik 2.5. Grafik Nu = f(Ra) dengan 3 letak heater.............................................17 Grafik 2.6. Grafik hubungan antara Effisiensi Overall fungsi Gap Ratio..............18 Grafik 2.7. Grafik hubungan antara Effisiensi Overall fungsi Gap Ratio..............20 Grafik 4.1. Grafik Distribusi temperatur pelat.......................................................61 Grafik 4.2. Grafik Wcomp. = f ( S / D) .....................................................................64 Grafik 4.3. Grafik Qevap. = f ( S / D) .......................................................................66 Grafik 4.4. Grafik COP = f ( S / D) .......................................................................67 Grafik 4.5. Grafik Ttube = f ( S / D) ........................................................................68 Grafik 4.6. Qkond = f ( S / D) ..............................................................................70 Grafik 4.7. Grafik T p = f ( S / D) ………………………………………………..71 Grafik 4.8. Grafik Q pelat = f ( S / D) ......................................................................72 Teknik Mesin FTI – ITS
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Tugas Akhir Konversi Energi DAFTAR ISI
Grafik 4.9. Grafik Wcomp. = f (Panjang pipa kapiler)...............................................74 Grafik 4.10. Grafik Q evap = f (Panjang pipa kapiler).............................................75 Grafik 4.11. Grafik COP = f (Panjang pipa kapiler)..............................................77 Grafik 4.12. Grafik Ttube = f (Panjang pipa kapiler)..............................................78 Grafik 4.13. Grafik Q kond. = f(Panjang pipa kapiler)..............................................79 Grafik
4.14.
Grafik
Q pelat
=
f(Panjang
pipa
kapiler)..............................................81 Grafik 4.15. Grafik Ra = f ( S / D) ……………………………………………….82 Grafik 4.16. Grafik Nu = f ( S / D) ……………………………………………....83 Grafik 4.17. Grafik h = f ( S / D) ………………………………………………..84 Grafik 4.18. Grafik ε = f ( S / D) ………………………………………………...85
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DAFTAR TABEL
Tabel 3.1. Parameter Bebas ............................................................................... 38 Tabel 3.2. Parameter Percobaan.............................................................................50 Tabel 3.3. Urutan perubahan parameter pada eksperimen ................................... 51
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NOMENCLATURE
ρ
= Densitas fluida (kg/m3)
α
= Diffusivitas
ε
= Effectiviness
β
= Koefisien ekspansi volumetrik (K-1)
V
= Laju alir volume (L/s)
m
= Mass flow rate (kg/s)
δ
= Tebal boundary layer
T∞1
= Temperatur udara di dalam enclosure (oC)
T∞ 2
= Temperatur udara ruangan (oC)
µ
= Viskositas dinamik
υf
= Volume spesifik fluida (L/kg)
ν
= Viskositas kinematik
Ap
= Luas pelat dinding konveksi (m2)
C
= Kapasitas panas
Cp
= Koefisien perpindahan panas specifik (kJ/kg.K)
D
= Diameter tube (m)
g
= gaya gravitasi (m/s2)
Gr
= Grashoff number
h
= Koefisien perpindahan panas konveksi (W/m2.K)
H
= Tinggi enclosure (m)
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hi
= entalphy inlet (kJ/kg)
ho
= entalphy outlet (kJ/kg)
k
= konduktivitas udara (W/m.K)
L
= Jarak antara tube (m)
Nu
= Nusselt number
P
= Tekanan (kPa)
Pr
= Prandlt number
q
= laju perpindahan panas (W)
Ra
= Rayleigh number
S
= Jarak antara dinding adiabatis dengan dinding konveksi (m)
T
= Temperatur (oC)
W
= Lebar enclosure (m)
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