Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
CHARACTERIZATION OF THE ROUGHNESS PATTERN AND REYNOLDS NUMBER EFFECTS ON THE SCALE DEPOSITS IN PIPE FLOWS
Submission Author:
Tiago Nascimento , RJ
Co-Authors:
Tiago Nascimento , Adão Souza Gonçalves, Juliana Loureiro
Presenter: Adão Souza Gonçalves
doi://10.26678/ABCM.ENCIT2022.CIT22-0514
Abstract
The formation of scale on the internal surfaces of ducts, valves or heat exchangers is the main reason for the loss of efficiency in many industrial applications. The development of mitigation technologies becomes crucial for a long-term successful operation. However, the methodology currently employed, i.e., the injection of chemical inhibitors or mechanical removal, are costly and ineffective. In order to advance new understanding with regard to this problem, an experimental campaign was carried out to investigate the influence of flow dynamics on the deposition of calcium carbonate (CaCO3) in circular ducts. Within the scope of this work, the calcium carbonate deposition rate was measured for different Reynolds numbers and test times. The experiments have been conducted at the Multipurpose Flow Loop, which operates in open circuit and is equipped with 70 m long pipes of different inner diameters. Four different total flow rates were investigated: 300, 450, 600 and 750 litres per hour. Each experimental run lasted for 90 minutes, after which the test sections were dried at ambient temperature and the cleaning solution was pumped into the flow loop. The scaling thickness along the tube was measured and the deposits characterized by the scanning electron microscope (SEM). The work also discusses the joint contributions for the measured pressure drop along the pipe as a result of three different effects: i) the increase in surface roughness due to the calcium carbonate deposition, ii) the decrease in the effective diameter of the tube, which varies along the pipe, iii) and the additional drag imposed by precipitated solid particles in suspension in the bulk flow.. The type of roughness created by the deposition process is also investigated, as well as its growth. The experimental results allow the characterization of the changes in the friction factor with the increase in the number of Reynolds. The calculated roughness factors have been related to the saturation indexes along the pipe.
Keywords
scaling, turbulent pipe flow, magnetic field, Experiments
