Karakteristik Aliran Dan Perpindahan Panas Simulasi Finned Tube 3 Dimensi High Pressure Evaporator HRSG Di PT. PJB Gresik

Ramadhi, Rizza (2014) Karakteristik Aliran Dan Perpindahan Panas Simulasi Finned Tube 3 Dimensi High Pressure Evaporator HRSG Di PT. PJB Gresik. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

HRSG merupakan pembangkit gabungan (siklus Brayton
dan siklus Rankine) dimana gas buang atau exhaust gas yang
masih panas dari siklus Brayton dimanfaatkan kembali oleh HRSG
untuk memanasi fluida water sehingga nantinya uap panas
digunakan untuk memutar turbin uap (siklus Rankine).
Pada penelitian tugas akhir ini dilakukan simulasi numerik
tiga dimensi pada circular finned tube. Variasi kecepatan fluida
pada velocity inlet 4m/s, 9m/s, 24m/s, temperatur dinding steel
yaitu 613K, temperatur flue gas (udara) 743K. Metode simulasi
dari ketiga variasi tersebut menggunakan software computational
fluid dynamic gambit 2.4.6 dan fluent 6.3.26.
Hasil yang didapatkan dari penelitian ini adalah dengan
kecepatan inlet 4m/s, 9m/s, 24m/s bahwa temperatur fin tertinggi
terdapat pada fin row 2 yaitu untuk Re 2500 (kecepatan 4m/s), T =
680.058K; Re 5622 (kecepatan 9m/s), T = 694.631K; Re 15000
(kecepatan 24m/s), T = 712.837K. Nilai Nusselt Number
maksimum terdapat pada tube row 2 yaitu untuk Re 2500
(kecepatan 4m/s), Nu = 54.149 pada sudut teta (θ) 64.28o; Re 5622
(kecepatan 9m/s), Nu = 74.2616 pada sudut teta (θ) 64.28o; Re
15000 (kecepatan 24m/s), Nu = 150.814 pada sudut teta (θ) 64.28o.
Effectiveness fin maksimum terdapat pada Re 2500, untuk posisi C
= 4.23, posisi B = 3.45, dan posisi A = 3.27. Effectiveness fin
maksimum terdapat pada Re 2500, untuk posisi C = 4.14, posisi B
= 3.38, dan posisi A = 3.09. Effectiveness fin maksimum terdapat
pada Re 2500, untuk posisi C = 4.39, posisi B = 3.92, dan posisi A= 3.86. Bahwasannya Reynolds Number sangat berpengaruh
terhadap karakteristik perpindahan panas. Nusselt Number akan
meningkat seiring bertambahnya Reynolds Number. Effectiveness
fin akan menurun seiring bertambahnya Reynolds Number, hal ini
disebabkan Tf (temperatur rata-rata fin) akan meningkat seiring
bertambahnya nilai Re maka ΔT akan menurun. Effectiveness fin
atau fin performance pada setiap posisi (a, b, c) untuk masingmasing
Reynolds Number sangat memenuhi karena nilai dari Ef ≥
2 apabila Ef ≤ 2 maka desain fin tersebut kurang baik.

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HRSG is combined cycle powerplant (Brayton cycle and
Rankine Cycle) in which the exhaust gases are still hot from the
Brayton cycle is recovered by HRSG to warm the fluid water, so
that the steam can be used to turn the steam turbine (Rankine
cycle).
In this thesis three-dimensional numerical simulations
performed on circular finned tube. Variation of fluid velocity in the
inlet velocity of 4m/s, 9m/s, 24m/s, steel wall temperature is 613K,
the temperature of the flue gas (air) 743K. Simulation method of
the three variations using software computational fluid dynamic
gambit 2.4.6 and fluent 6.3.26.
The results obtained from this study is the inlet velocity of
4m/s, 9m/s, 24m/s that the temperature is highest fin on fin row 2
ie for Re 2500 (speeds of 4m/s), T = 680.058K; Re 5622 (speed
9m/s), T = 694.631K; Re 15000 (speed of 24m/s), T = 712.837K.
The maximum value of Nusselt Number contained in the tube row
2 ie for Re 2500 (speeds of 4m /s), Nu = 54.149 at an angle theta
(θ) 64.28o; Re 5622 (speed 9m/s), Nu = 74.2616 at an angle theta
(θ) 64.28o; Re 15000 (speed of 24m/s), Nu = 150.814 at an angle
theta (θ) 64.28o. Maximum fin effectiveness are at Re 2500, for the
position of C = 4.23, B = 3.45 position, and the position of A =
3.27. Maximum fin effectiveness are at Re 2500, for the position of
C = 4.14, B = 3.38 position, and the position of A = 3.09. Maximum
fin effectiveness are at Re 2500, to the position of the C = 4.39,
position B = 3.92, and the position of A = 3.86. Reynolds Number greatly affect the heat transfer characteristics. Nusselt Number will
increase with Reynolds Number. Fin effectiveness decreases with
increasing Reynolds Number, this is due to Tf (average fin
temperature) will increase with increasing Re, the ΔT value will
decrease. Effectiveness fin or fin performance at each position (a,
b, c) is suitable for each of the Reynolds Number because the value
of Ef ≥ 2 if Ef ≤ 2 then the fin design is not good.

Item Type:	Thesis (Undergraduate)
Uncontrolled Keywords:	HRSG; circular finned tube; metode numerik; perpindahan panas; numerical simuation method; heat transfer.
Subjects:	T Technology > TJ Mechanical engineering and machinery
Divisions:	Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Anis Wulandari
Date Deposited:	24 May 2017 06:55
Last Modified:	27 Dec 2017 02:33
URI:	http://repository.its.ac.id/id/eprint/41367

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