Friction losses in valves and fittings for power-law fluids

Abstract

-Data on pressure drop were obtained in stainless steel, sanitary fittings and valves during laminar and turbulent flow of aqueous solutions of sucrose and xanthan gum, which were selected as model fluids. The rheological properties of these solutions were determined and the power-law model provided the best fit for experimental data. Friction losses were measured in fully and partially open butterfly and plug valves, bends and unions. Values of loss coefficients (k f ) were calculated and correlated as a function of the generalized Reynolds number by the two-k method. The model adjustment was satisfactory and was better in the laminar flow range (0.976 ≤ r 2 ≤ 0.999) than in the turbulent flow range (0.774 ≤ r 2 ≤ 0.989). In order to test the adequacy of the results for predicting loss coefficients during flow of real fluids, experiments were conducted with coffee extract. Comparison between experimental and predicted loss coefficients showed very good agreement.

Non-newtonian flow and pressure drop of pineapple juice in a plate heat exchanger

“…Shear rate range was 0.5 to 300 s -1 and both upward and downward tests were performed in duplicate for each temperature and soluble solids content combination. The experimental procedure was previously tested by a rheological study of ethylene glycol and chlorobenzene (Telis-Romero et al, 2005;Polizelli et al, 2003).…”

Local resistance characteristics of highly concentrated coal-water slurry flow through fittings

“…The empirical correlation for resistance coefficient K with Reynolds Number for non-Newtonian suspension flowing through local fittings is given by Eq. (11), which is suitable for different fittings [9][10][11][12]. The results for gradual contraction are listed in Table 2:…”

“…Many scholars have investigated the local resistance characteristics of different non-Newtonian fluids flowing through the sudden enlargements, sudden contractions, bends, valves and other parts of the local fittings, and have arrived at several empirical formulas [5][6][7][8][9]. Turian et al reported the resistance coefficient for laminar flow of non-Newtonian fluids was dependent on the size of different fittings [10].…”

Forced convection to laminar flow of liquid egg yolk in circular and annular ducts

“…The performance of the apparatus was checked using a CMC solution (1% w/w), which was pumped through the equipment at 68 different flow rates in the laminar range. At each flow rate, inlet and outlet temperatures in a straight pipe section of 1.80 m were measured with ten repetitions made at fiveminute intervals, in a procedure similar to that used by Polizelli et al (2003) and Telis-Romero et al (2005) when investigating friction losses in fittings during non-Newtonian fluid flow. The thermophysical properties of CMC solution were obtained from the work of Carezzato et al (2007).…”