Acknowledgements

Having obtained dimensionless concentration distribution (n) along the dimensionless separation distance (H) in Eq. (6), the particle deposition flux to the channel surface can be found as

Here, J<sup>0</sup> is the particle number flux at H ¼ H0. The negative sign on the right hand side of Eq. (9) indicates that the particle number flux is toward the solid surface. Moreover, the dimensionless particle deposition rate onto the channel surface can be quantified by the

<sup>¼</sup> <sup>f</sup> <sup>1</sup>ð Þ <sup>H</sup><sup>0</sup>

The thermal effects on the particle deposition rate (i.e., Sherwood number) are influenced by the temperature dependences of all the forces (Fvdw, Fedl, FG, and FL) acting on the particles. For van der Waals force, the Hamaker constant is a temperature dependent parameter. For EDL force, EDL thickness, zeta potential, and relative dielectric constants of materials are varied with the temperature. For gravity and hydrodynamic lift forces, the magnitude of forces is changed due to the variations of density and viscosity of liquid. Details of the calculations for

For the first time, based on the DLVO theory with considering the temperature-dependent interactions, a simplified one-dimensional mass transport model was developed and it can serve as a semi-quantitative approach for describing particle deposition phenomena in

Particle deposition and particulate fouling have been ubiquitous phenomena in natural and industry processes. Thermal effects (i.e., temperature and temperature gradient) on particle deposition are important but always 'ignored' in literatures. Most of the published research works about micro-/nanoparticles deposition in a microchannel were conducted in the room temperature environment, seldom with consideration of elevated bulk temperature or temperature gradient, which is a crucial factor for thermal driven fouling phenomena in reality. Especially, the microscale mechanism of particle deposition in microchannel at elevated temperature was still in its infancy. In this chapter, researches on particle deposition and particulate fouling on surfaces have been extensively reviewed both theoretically and experimentally from the published works. This chapter has summarised relevant concepts of particle deposition, key parameters, and experimental techniques (e.g., device design) as well as theoretical methodologies (e.g., modelling). The physics of particle deposition phenomena under different parametric influences has been discussed in detail. The authors have presented a new microfluidic temperature-gradient device that can be used to directly observe particle deposition

dn dH 

H¼H<sup>0</sup>

dn dH 

H¼H<sup>0</sup>

: (19)

: (20)

J<sup>0</sup> ¼ �f <sup>1</sup>ð Þ H<sup>0</sup>

0 D∞n∞,p=ap

Shnum ¼ � <sup>j</sup>

the temperature dependences can be found in [71, 73].

microchannel flows at elevated temperatures.

6. Summary and future prospects

Sherwood number

128 Microfluidics and Nanofluidics

This work has been partially supported by the National Key Research & Development Program of China (2016YFB0401502), the National Natural Science Foundation of China (61574065, 51561135014, and U1501244), Science and Technology Planning Project of Guangdong Province (2016B090906004), Special Fund Project of Science and Technology Application in Guangdong (2017B020240002), PCSIRT Project No. IRT\_17R40, the National 111 Project, the MOE International Laboratory for Optical Information Technologies, and the Cultivation Project of National Engineering Technology Center of Optofluidic Materials and Devices (2017B090903008). Zhibin Yan also acknowledges the financial support by the Foundation for Distinguished Young Talents in Higher Education of Guangdong, China and the Research and Cultivation Fund for Young Faculty supported by South China Normal University (SCNU). Xiaoyang Huang and Chun Yang appreciate the financial support from the Ministry of Education of Singapore under Grant No. RG80/15 and RG97/13, respectively.
