Perpindahan panas pada kolektor surya bentuk plat menggunakan pantulan sinar lampu
BETANURSANTI, Ida, Ir. Supranto, MSc.,PhD
2001 | Tesis | S2 Teknik KimiaPemanfaatan energi surya untuk pengeringan hasil-hasil pertanian di Indonesia masih dilakukan secara tradisionil. Diperlukan area yang luas, bahan mudah terkontaminasi, proses sulit dikendalikan, sehingga kualitas hasil rendah. Pengering energi surya tertutup dengan konsentrator energi dan sistem pengendalian proses perlu dikembangkan untuk meminimalkan kekurangan pengering energi surya tradisionil. Penelitian ini bertuj uan untuk mendapatkan formulasi pengaruh kecepatan alir udara dan intensitas radiasi terhadap koefisien transfer panas konveksi dan koefisien absorbansi kolektor. Secara aplikatif, didapatkan formulasi pengaruh jenis logam dan warna logam kolektor terhadap unjuk kerja plat kolektor. Nilai koefisien transfer panas konveksi dan absorbansi diperoleh dari data periodik suhu udara dan suhu kolektor sampai tercapai kondisi steady stute pada kecepatan alir udara, intensitas radiasi, dan kolektor tertentu. Digunakan jenis kolektor alumunium, kuningan, dan tembaga, warna lvariasi dilapis cat hitam dan tanpa cat. Pengaruh kecepatan alir udara dan intensitas radiasi pada koefisien perpindahan panas konveksi ditunjukkan oleh korelasi bilangan Nusselt (Nu), bilangan Pecklet (Pe), dan perbandingan antara kekentalan udara suhu bulk dengan kekentalan pada suhu kolektor (pdk) berikut ini. Nu =9,05.Pe0,29.(~pw)07’4.(D/L)*’pada kisaran bilangan Pecklet antara 0,0035 dan 0,0088, kisaran perbandingan kekentalan udara antara 0,974 dan 1,023, dan kesalahan rerata 6,11 %. Koefisien absorbansi kolektor tanpa lapis cat sebesar lxlO-’ % dan koefisien absorbansi kolektor bercat hitam antara 86% dan 99,99%. Kolektor yang baik adalah kolektor yang berwarna hitam
Solar energy has been used for drying crops in Indonesia using a traditional technique. It needs wide area, mostly contaminated, and uncontrolled processes, in which affected to the quality of the dried product crops. Open air solar dryer with energy concentrator and controlled process system must be developed to reduce the disadvantage of the traditionally solar drylng method. The objective of this research is to formulate the influence of the linear velocity of air, and the radiation intensity to the heat transfer coefficient of convection and the coeficient absorptive of the collector. The effect of materials and the color of collector to the performance of the collector had been studied. Temperatures of the collector and air were measured periodically to obtain the heat transfer coefficient of convection and the coefficient absorptive values up to steady state condition with the variation of linear velocity of air, the radiation intensity, the kinds of materials, and the color of the collector. The kinds of materials of the collector are alumunium, brass, and cooper. The variations of collector’s color were the black painted and the original color of metal. The effects of the linear velocity of air and the radiation intensity to the heat transfer coefficient are showed by the correlation of the Nusselt number (Nu), the Pecklet number (Pe), and the ratio of the air viscosity (pJpw) as: Nu = 9.05.Pe02 9.(pJp,v)01 4.(D/L)1’3T.h e Pecklet number in the experiment was between 0.0035 and 0.0088, the ratio of air viscosity was between 0.974 and 1.023, and the error average was 6.1 1 %. The absorptive coefficient of the original color of metal was lx lo-’% and the black painted collector was between 86 % and 99.99 %. The collector with a black painted has the best performance.
Kata Kunci : Perpindahan Panas,Kolektor Surya Bentuk Plat,Pantulan Sinar Lampu, solar energy, collector, convection, and absorptive
