# Modeling of particle agglomeration in nanofluids

## Abstract

Agglomeration strongly influences the stability or shelf life of nanofluid. The present computational and experimental study investigates the rate of agglomeration quantitatively. Agglomeration in nanofluids is attributed to the net effect of various inter-particle interaction forces. For the nanofluid considered here, a net inter-particle force depends on the particle size, volume fraction, pH, and electrolyte concentration. A solution of the discretized and coupled population balance equations can yield particle sizes as a function of time. Nanofluid prepared here consists of alumina nanoparticles with the average particle size of 150 nm dispersed in de-ionized water. As the pH of the colloid was moved towards the isoelectric point of alumina nanofluids, the rate of increase of average particle size increased with time due to lower net positive charge on particles. The rate at which the average particle size is increased is predicted and measured for different electrolyte concentration and volume fraction. The higher rate of agglomeration is attributed to the decrease in the electrostatic double layer repulsion forces. The rate of agglomeration decreases due to increase in the size of nano-particle clusters thus approaching zero rate of agglomeration when all the clusters are nearly uniform in size. Predicted rates of agglomeration agree adequatemore »

- Authors:

- Department of Mechanical Engineering and Mechanics, Lehigh University, 19W Memorial Dr, Bethlehem, Pennsylvania 18015 (United States)
- Dynalene Inc., 5250W Coplay Rd, Whitehall, Pennsylvania 18052 (United States)

- Publication Date:

- OSTI Identifier:
- 22413215

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 9; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABUNDANCE; AGGLOMERATION; ALUMINIUM OXIDES; COLLOIDS; CONCENTRATION RATIO; ELECTROLYTES; MATHEMATICAL MODELS; MATHEMATICAL SOLUTIONS; NANOFLUIDS; NANOPARTICLES; PARTICLE SIZE; PH VALUE; STORAGE LIFE; TIME DEPENDENCE

### Citation Formats

```
Krishna, K. Hari, Neti, S., Oztekin, A., and Mohapatra, S.
```*Modeling of particle agglomeration in nanofluids*. United States: N. p., 2015.
Web. doi:10.1063/1.4913874.

```
Krishna, K. Hari, Neti, S., Oztekin, A., & Mohapatra, S.
```*Modeling of particle agglomeration in nanofluids*. United States. doi:10.1063/1.4913874.

```
Krishna, K. Hari, Neti, S., Oztekin, A., and Mohapatra, S. Sat .
"Modeling of particle agglomeration in nanofluids". United States.
doi:10.1063/1.4913874.
```

```
@article{osti_22413215,
```

title = {Modeling of particle agglomeration in nanofluids},

author = {Krishna, K. Hari and Neti, S. and Oztekin, A. and Mohapatra, S.},

abstractNote = {Agglomeration strongly influences the stability or shelf life of nanofluid. The present computational and experimental study investigates the rate of agglomeration quantitatively. Agglomeration in nanofluids is attributed to the net effect of various inter-particle interaction forces. For the nanofluid considered here, a net inter-particle force depends on the particle size, volume fraction, pH, and electrolyte concentration. A solution of the discretized and coupled population balance equations can yield particle sizes as a function of time. Nanofluid prepared here consists of alumina nanoparticles with the average particle size of 150 nm dispersed in de-ionized water. As the pH of the colloid was moved towards the isoelectric point of alumina nanofluids, the rate of increase of average particle size increased with time due to lower net positive charge on particles. The rate at which the average particle size is increased is predicted and measured for different electrolyte concentration and volume fraction. The higher rate of agglomeration is attributed to the decrease in the electrostatic double layer repulsion forces. The rate of agglomeration decreases due to increase in the size of nano-particle clusters thus approaching zero rate of agglomeration when all the clusters are nearly uniform in size. Predicted rates of agglomeration agree adequate enough with the measured values; validating the mathematical model and numerical approach is employed.},

doi = {10.1063/1.4913874},

journal = {Journal of Applied Physics},

number = 9,

volume = 117,

place = {United States},

year = {Sat Mar 07 00:00:00 EST 2015},

month = {Sat Mar 07 00:00:00 EST 2015}

}