Oil fouling in double‐pipe heat exchanger under liquid‐liquid dispersion and the influence of copper oxide nanofluid

Abstract

Dispersions of oil in water are encountered in a variety of industrial processes leading to a reduction in the performance of the heat exchangers when thermally treating such two phase fluids. This reduction is mainly due to changes in the thermal and hydrodynamical behavior of the two phase fluid. In the present work, an experimental investigation was performed to study the effects of light oil fouling on the heat transfer coefficient in a double-pipe heat exchanger under turbulent flow conditions. The effects of different operating conditions on the fouling rate were investigated including: hot fluid Reynolds number (the dispersion), cold fluid Reynolds number, and time. The oil fouling rate was analyzed by determining the growth of fouling resistance with time and through pressure drop measurements. The influence of copper oxide (CuO) nanofluid on the fouling rate in the dispersion was also determined. It was found that the presence of dispersed oil causes a reduction in heat transfer coefficient by percentages depending on the Reynolds number of both cold and hot fluids and the concentration of oil. In addition, the time history of fouling resistance exhibited different trends with the flow rates of both fluids and its trend was influenced appreciably by the presence of CuO nanofluid. K E Y W O R D S copper oxide, dispersion, double-pipe heat exchanger, fouling, heat transfer, nanofluid, oil Heat Transfer-Asian Res.

Study on oil fouling in a double pipe heat exchanger with mitigation by a surfactant

“…It is evident that the U o increases linearly with Re h for all Rec. It has been demonstrated in part 1 4 that the experimental results of single phase agree very well with Friend and Mitzner 17 . Figure 2 also shows that the U o is higher for higher Re c .…”

“…It is evident that the R f increases asymptotically with time due to the deposition of oil on the inside surface. The accumulation of oil increases the thermal resistance to heat transfer due to the lower thermal conductivity of oil than water (the physical properties of oil and water are presented in Table 2 in part 1 4 ). Figure 3 also indicates that for a higher temperature of dispersion fluid, the asymptotic value of R f is lower.…”

“…The experimental apparatus has been described in the authors’ previous work 4 . It is shown schematically in Figure 1.…”

“…Schematic of the experimental setup. 1, Double pipe heat exchanger; 2, agitated hot fluid tank; 3, coiled heater (±1°C); 4, agitator motor; 5, temperature data logger; 6, centrifugal pump; 7, control gate valve; 8, flow meter (rotameter); 9, water chiller; 10, thermocouples (±0.1°C); 11, blade impeller 4 [Color figure can be viewed at wileyonlinelibrary.com]…”

“…The Reynolds number of the dispersion (hot fluid), Re h , was calculated by considering the physical properties of continuous phase 15,16 . The uncertainty analysis has been presented in part 1 4 …”