Investigation of Flow of the Disc-and-Doughnut Baffles and 40% Cut Segmental Baffles

Abstract

Heat exchanger is usually used in manufacturing process. At present, many researchers have efforts to increase the performance of the heat exchanger with less of the cost. This research discussed about the performance of heat exchanger using 40% cut segmental baffles compared with modified double segmental baffles disc-and-doughnut type. In this study, the investigation of the computational results consisted of heat flux, velocity profile along the heat exchanger, pressure distribution and, theoretical heat transfer coefficient and heat exchanger effectiveness. The model was calculated using finite difference method forward modeling with Multiphysics Software and focuses on the performance evaluation of the small shell-and-tube heat exchanger (STHE) – laboratory type. The tubes are composed of 14 tubes with 0.583 m length, triangular 30° rotated pitch. The pipe radius of shell and tube are 0.055 m and 0.00635 m, respectively. The baffle radius of disc and doughnut are 0.055 m and 0.025 m, respectively, and the baffle radius of 40% cut segmental baffles are 0.055 m. Both types of the baffle have a distance of 0.116 m which is evenly distributed along the shell. The generalized minimal residual (GMRES) method for the fluid flow case used as an iterative method for solving some of the complex linear equations shows good performance as in reliability and validity. For the 40% cut segmental baffles, fluid flow makes a zigzag pattern, an Eddy or swirling of a fluid, and there was some back mixing of fluid stream which caused several dead zones along the shell. The occurrence of the dead zones caused the heat transfer to be ineffective and gave lower value compared to the double segmental disc-and-doughnut baffles. The 40% cut segmental baffles was also seen to have a higher pressure at the outlet region than the double segmental disc-and-doughnut baffles. The disc-and-doughnut baffles leads to a turbulent fluid flow which causes an increase in heat transfer characteristics and also lower pressure drop than the 40% cut segmental baffles. Based on the theoretical, both types of disc-and-doughnut baffles and the 40% cut segmental baffles of heat exchanger investigated have highest effectiveness at the lowest mass flow rate of the hot fluids (tube).

Analisis Aliran Udara dan Kenyamanan Termal di Laboratorium Perpindahan Panas dan Massa menggunakan Metode Computational Fluid Dynamics (CFD)

“…Udara yagn yang digunakan pada proses simulasi diasumsikan sebagai fluida gas 1 fasa seperti Tabel 5. Selain propertis dari masing-masing material yang digunakan, pengaturan juga dilakukan terhadap boundary condition dari masing-masing inlet dan outlet, seperti kecepatan udara, tekanan, dan temperatur (Rønneseth dkk., 2019;Tanujaya dan Darmawan, 2021). Untuk kisi AC, digunakan kecepatan udara sesuai dengan variasi kecepatan udara pada kisi AC seperti yang dijelaskan pada Tabel 4 dengan temperatur sebesar 293 K (20 ºC) yang diukur berdasarkan pengaturan kecepatan AC, tingkat 1-4.…”

Komparasi Simulasi CFD Pada Turbin Cross-Flow Dengan Model Turbulen k-ε STD dan RNG k-ε

“…berwarna transparan, sehingga pola alirannya tidak dapat dilihat langsung tanpa beberapa metode khusus (Mukhlisin, Erwin dan Wiyono, 2022). Rumitnya aliran pada bagian dalam runner turbin cross-flow membutuhkan suatu analisis dengan menggunakan metode Computational Fluid Dynamics (CFD) untuk dapat mencapai hasil yang optimal (Tanujaya dan Darmawan, 2021).…”