Determination of the Reference Temperature for a Convective Heat Transfer Coefficient in a Heated Tube Bank

Abstract

The paper presents a theoretical analysis of heat transfer in a heated tube bank, based on the Nusselt number computation as one of the basic dimensionless criteria. To compute the Nusselt number based on the heat transfer coefficient, the reference temperature must be determined. Despite the value significance, the quantity has several different formulations, which leads to discrepancies in results. This paper investigates the heat transfer of the inline and staggered tube banks, made up of 20 rows, at a constant tube diameter and longitudinal and transverse pitch. Both laminar and turbulent flows up to Re = 10,000 are considered, and the effect of gravity is included as well. Several locations for the reference temperature are taken into consideration on the basis of the heretofore published research, and the results in terms of the overall Nusselt number are compared with those obtained by the experimental correlations. This paper provides the most suitable variant for a unique reference temperature, in terms of a constant value for all tube angles, and the Reynolds number ranges of 100–1000 and 1000–10,000 which are in good agreement with the most frequently used correlating equations.

Heat Transfer and Thermal Efficiency in Oxy-Fuel Retrofit of 0.5 MW Fire Tube Gas Boiler

“…When substituting the burner in a natural-gas-fueled fire tube industrial boiler with an oxy-fuel burner, a comparable level of heat absorption occurs within the combustion chamber, enabling retrofitting. With this modification, oxy-fuel with flue gas The Zhukauskas correlation (Equation ( 6)), primarily developed for bare tube banks [32], is commonly used in economizer designs [33] that include finned tubes [34].…”

“…This increase in the heat transfer coefficient is notably more pronounced during condensation compared to the single phase, as depicted in Figure 11. The Zhukauskas correlation (Equation ( 6)), primarily developed for bare tube banks [32], is commonly used in economizer designs [33] that include finned tubes [34]. 𝑁𝑢 0.686 𝑅𝑒 .…”

Analisis Kinerja Termal Penukar Kalor Tube Bank Bare in-Line Aliran Silang Sebagai Pemulihan Limbah Panas Pengering Konvektif Rumput Laut

“…Penukar kalor tube bank aliran silang digunakan dalam banyak aplikasi, seperti industri ketenagaan, biomedis, sistem pendinginan udara (economizer dan evaporator), pemrosesan polimer, dan sistem biologis [71]. Kinerja termal dari penukar kalor tube bank dipengaruhi oleh parameter geometris yakni pitch tube (L) [72], ukuran tube, transverse pitch tube (ST), longitudinal pitch tube (SL), panjang tube (H) [73], konfigurasi tube (Kim, 2013).…”

“…Kajian koefisien perpindahan panas sebagai fungsi dari posisi tube dan penurunan tekanan untuk pernukar kalor tube bank bare in-line, ternyata koefisien perpindahan panas sebagai fungsi posisi dan bilangan Reynolds dimana bilangan Nusselt meningkat sebesar 12,49% untuk kolom pertama ke kolom kedua, 11,85% kolom kedua ke kolom ketiga, 5,27% dari kolom ketiga ke kolom keempat [79]. Kajian efektivitas penukar kalor tube bank bare in-line terpasang pada porous burner dengan udara sebagai fluida kerja dan LPG sebagai bahan bakar, ternyata efektivitas maksimum pada rasio ekuivalen (Φ) = 0,75, kecepatan campuran gas volumetrik (Vmix) =30 m 3 /jam, dan laju aliran udara (QAH) = 42 m 3 /jam [80] dan penentuan temperatur referensi untuk koefisien perpindahan panas konveksi pada penukar kalor tube bank bare in-line terdiri dari 20 baris dengan diameater tube, ST/D sama dengan SL/D = 2, dimana temperatur referensi berada pada di setengah inlet subdomain adalah suhu referensi yang paling tepat untuk bilangan Reynolds di kisaran 10 2 dan 10 3 , serta koefisien perpindahan panas maksimum; tube I   = 0, tube II   = 65, sedangkan tube III -XIX   = 60 [71]. Berdasarkan berbagai studi penukar kalor tube bank bare in-line, belum ada informasi terkait penerapan penukar kalor tube bank bare in-line sebagai pemulihan limbah panas pada pengering konvektif.…”

Thermal Performance of Staggered Bare Tube Bank Heat Exchanger as Air Pre-Heater for Seaweed Convective Dryer

“…In contrast, cold fluid flows externally outside the tube, so heat exchange occurs in cross-flow over the tube [80]. Crossflow tube bank heat exchangers are used in many applications, such as the power industry, biomedicine, air cooling systems (economizers and evaporators), polymer processing, and biological systems [81]. The thermal performance of a tube bank heat exchanger is influenced by geometric parameters, namely tube pitch (L) [82], tube size, transverse pitch tube (ST), longitudinal pitch tube (SL), tube length (H) [83], tube configuration (in-line and staggered) [84].…”