scholarly journals Analisis Perpindahan Panas Pada Heat Exchanger Di Furnace Boiler Circulating Fludizing Bed Unit 1 Pltu Nagan Raya 2 X 110 Mw

Author(s):  
Maidi Saputra ◽  
Ari Ferdian

Sistem tenaga listrik terdiri atas pembangkitan, penyaluran dan distribusi. Salah satu jenis pembangkit adalah Pembangkit Listrik Tenaga Uap (PLTU). Komponen–komponen utama dalam PLTU adalah ketel uap (Boiler), Turbin Uap, Kondenser dan Generator sinkron. Perpindahan panas yang terjadi di dalam beberapa Heat Exchanger pada Furnace Boiler Ciruculating Fludizing Bed (CFB) terjadi dengan Konduksi, Konveksi maupun Radiasi. Tujuan penelitian ini untuk menghitung dan membandingkan nilai Koefisien Perpindahan Panas dan banyaknya Kalor yang Diserap selama proses penelitian atau Nilai Aktual dengan proses Komisioning pada Heat Exchanger di Furnace Boiler (Wall tube atau HE1, Evaporator atau HE2, dan Platen Superheater atau HE3). Pengumpulan data dilakukan dengan metode observasi. Pengolahan data untuk menghitung nilai Koefisien Perpindahan panas dan banyaknya kalor yang diserap terlebih dahulu dengan menghitung beda temperatur dengan metode Log Mean Difference Temperature (LMDT) dan juga bilangan Nusselt dan Reynold untuk masing-masing Heat Exchanger pada kondisi Aktual dan komisioning. Selanjutnya didapatkan nilai perhitungan untuk Koefisien Perpindahan Panas pada HE1 Aktual dan komisioning sebesar 0,598 W/m2 0c, pada HE2 Aktual dan Komisioning sebesar 0,829 W/m2 0c, pada HE3 Aktual sebesar 0,779 W/m2 0c dan Komisioning sebesar 0,8 W/m2 0c, dan banyaknya kalor yang diserap pada HE1 Aktual sebesar 88,515 KJ/Kg dan Komisioning sebesar 11,99 KJ/Kg, pada HE2 Aktual sebesar 1,73 KJ/Kg dan Komisioning sebesar 1,44 KJ/Kg, pada HE3 Aktual sebesar 271,06 KJ/Kg dan Komisioning sebesar 72,82 KJ/Kg.  

Author(s):  
R. W. Anderson ◽  
D. L. Senecal

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.


1971 ◽  
Vol 68 (3) ◽  
pp. 451-457 ◽  
Author(s):  
Helen E. A. Farran ◽  
Christine Haiste ◽  
R. Hoffenberg

ABSTRACT Serum PBI and thyroxine iodine (T4I) levels have been compared in a large series of patients. A mean difference of 0.35 μg/100 ml was found in euthyroid subjects, but a much greater difference obtained when both values were high, whether the elevation resulted from hyperthyroidism, pregnancy or the administration of thyroxine or oestrogen. This discrepancy was greater in a group of patients with diffuse goitre than in those with nodular glands. A circulating non-thyroxine iodinated compound is thought to account for this discrepancy, the origins of which could lie in the thyroid gland, although peripheral deiodination of thyroxine seems more likely.


2020 ◽  
Vol 46 (3) ◽  
pp. 182-189 ◽  
Author(s):  
Davide Farronato ◽  
Mattia Manfredini ◽  
Michele Stocchero ◽  
Mattia Caccia ◽  
Lorenzo Azzi ◽  
...  

The aim of this study was to evaluate the influence of bone quality, drilling technique, implant diameter, and implant length on insertion torque (IT) and resonance frequency analysis (RFA) of a prototype-tapered implant with knife-edge threads. The investigators hypothesized that IT would be affected by variations in bone quality and drilling protocol, whereas RFA would be less influenced by such variables. The investigators implemented an in vitro experiment in which a prototype implant was inserted with different testing conditions into rigid polyurethane foam blocks. The independent variables were: bone quality, drilling protocol, implant diameter, and implant length. Group A implants were inserted with a conventional drilling protocol, whereas Group B implants were inserted with an undersized drilling protocol. Values of IT and RFA were measured at implant installation. IT and RFA values were significantly correlated (Pearson correlation coefficient: 0.54). A multivariable analysis showed a strong model. Higher IT values were associated with drilling protocol B vs A (mean difference: 71.7 Ncm), implant length (3.6 Ncm increase per mm in length), and substrate density (0.199 Ncm increase per mg/cm3 in density). Higher RFA values were associated with drilling protocol B vs A (mean difference: 3.9), implant length (1.0 increase per mm in length), and substrate density (0.032 increase per mg/cm3 in density). Implant diameter was not associated with RFA or IT. Within the limitations of an in vitro study, the results of this study suggest that the studied implant can achieve good level of primary stability in terms of IT and RFA. A strong correlation was found between values of IT and RFA. Both parameters are influenced by the drilling protocol, implant length, and substrate density. Further studies are required to investigate the clinical response in primary stability and marginal bone response.


2014 ◽  
Vol 6 (4) ◽  
pp. 285-300 ◽  
Author(s):  
Venkataram Krishna ◽  
S. Spoorthi ◽  
Pradeep G. Hegde ◽  
K. N. Seetharamu
Keyword(s):  

Sign in / Sign up

Export Citation Format

Share Document