ANALISIS PERUBAHAN EFEKTIVITAS THERMAL PADA SHELL AND TUBE HEAT EXCHANGER 211-E-9 BERDASARKAN PENGGANTIAN MATERIAL TUBE

ANGGA PRIWICAKSONO, Harjono, S.T., M.T.

2016 | Tugas Akhir | D3 TEKNIK MESIN SV

INTISARI Air laut yang melewati material tube 70-30 CuNi dalam jangka waktu yang lama, menyebabkan tube pada shell and tube heat exchanger 211-E-9 mengalami korosi. Atas dasar itu maka diambil kebijakan untuk melakukan penggantian material 70-30 CuNi menjadi duplex stainless steel. Standar Birmingham Wire Gage (B.W.G) dan laju perpindahan kalor pada heat exchanger dijadikan acuan dalam menentukan nilai ketebalan tube duplex stanless steel yang tepat. Perbandingan nilai tahanan thermal konduksi dan ketebalan tube dari masing-masing material dijadikan acuan untuk menentukan material mana yang memiliki efektivitas thermal lebih baik. Hasil perhitungan menunjukkan laju perpindahan kalor pada setiap tube sebesar 784,186 Watt, dengan laju perpindahan kalor tersebut diperoleh nilai ketebalan tube untuk material duplex stainless steel sebesar B.W.G 19 atau 1,067 mm. Nilai ketebalan tersebut mampu mengakomodir temperatur operasi rata-rata yang terjadi pada tube, yaitu sebesar 34 Celcius. Dari segi efektivitas thermal, material duplex stainless steel jauh lebih baik dibandingkan dengan 70-30 CuNi, karena memiliki nilai ketebalan tube dan tahanan thermal konduksi yang lebih kecil daripada 70-30 CuNi. Nilai ketebalan tube dan tahanan thermal konduksi material duplex stainless steel secara berturut-turut sebesar 1,067 mm dan 1,53x10-4 Celcius per Watt , sedangkan pada material 70-30 CuNi masing-masing sebesar 2,108 mm dan 1,61x10-4 Celcius per Watt.

ABSTRACT Sea water passing through the tube with CuNi 70-30 material in the long term could make a tube leak caused by corrosion at shell and tube 211-E-9, based of this reason, CuNi 70-30 tube would be replaced by duplex stainless steel material. The heat transfer rate occurred in each tube and standard of Birmingham Wire Gage (B.W.G) were used as reference to decide the value of final thickness that correct and commercially available. The comparison of conduction's thermal resistance and tube thickness of each material were used as reference to decide the material that had a better thermal effectiveness. The result of calculation showed rate of heat transfer of each tube was 784,186 W. Based from it was obtained the value of tube thickness for duplex stainless steel 1,067 mm (B.W.G 19), it could accommondate an average temperature in the tube that was equal to 34 Celcius. Duplex stainless steel had better thermal effectiveness than CuNi 70-30, because the tube thickness and conduction thermal resistance of duplex stainless were smaller than CuNi 70-30. The thickness tube and conduction thermal resistance of duplex stainless steel were 1,067 mm and 1,53x10-4 Celcius per Watt. The tube thickness and conduction thermal resistance of CuNi 70-30 were 2,108 mm and 1,61x10-4 Celcius per Watt.

Kata Kunci : Rate of heat transfer, tube thickness, thermal effectiveness