5. Conclusions

(9)

<sup>2</sup> (10)

∂2 T ∂x<sup>2</sup> þ

8 >><

Figure 7. Two-dimensional heat conduction model with nodal network [66].

>>:

where α<sup>w</sup> is the thermal diffusivity.

rwcwΔl 2

" #

TtþΔtð Þ¼ <sup>i</sup>; <sup>j</sup> <sup>1</sup> � <sup>2</sup>Δt kð Þ <sup>x</sup> <sup>þ</sup> kz

72 Microfluidics and Nanofluidics

at the node (i, j) after Δt:

rwCwΔl

4.5. Precise control of temperature field

transmitted into the workpiece surface.

TtþΔtð Þ¼ <sup>i</sup>; <sup>j</sup> <sup>Δ</sup><sup>t</sup>

∂2 T <sup>∂</sup>z<sup>2</sup> <sup>¼</sup> <sup>1</sup> α<sup>w</sup> ∂T ∂t

<sup>α</sup><sup>w</sup> <sup>¼</sup> kw rwcw

Difference in the equation of various nodes in internal grids can be obtained based on (9):

As for boundary conditions analysis in grinding zone, coordinate node (i, j) on the workpiece surface is taken as an example. According to energy conservation law [67, 68], the temperature

The temperature field at different times during the steady process can be obtained by solving the difference Eq. (11). Figure 8 shows the temperature isoline under NMQLC at different times and the corresponding time-space distribution of surface temperature. It can be seen that the grinding process can be divided into three stages, namely, cut-in, steady state, and cut-out [66]:

Cut-in: when abrasive grains start to contact and cut the workpiece, the undeformed chip thickness increases gradually and the heat generated on the grinding interface begins to be

Steady state: the undeformed chip thickness kept at the mean value and workpiece surface

Cut-out: the undeformed chip thickness decreases gradually in the cut-out region. According to the theory of heat transfer, the heat conduction in the cut-out region is reduced considering the

temperature stops increasing. The temperature field reaches the steady state.

Ttð Þ� <sup>i</sup>; <sup>j</sup> <sup>Δ</sup>t kf g <sup>x</sup> � <sup>½</sup>T ið Þþ ; <sup>j</sup> <sup>þ</sup> <sup>1</sup> T ið Þ ; <sup>j</sup> � <sup>1</sup> � þ kz � ½ � T ið Þþ <sup>þ</sup> <sup>1</sup>; <sup>j</sup> T ið Þ � <sup>1</sup>; <sup>j</sup> rwcwΔl

<sup>2</sup> f g k � ½T ið Þþ � 1; j T ið Þþ þ 1; j T ið Þ þ 1; j -3T ið Þ ; j � þ ½q � h Tð Þ <sup>t</sup> � Ta � � Δl þ T ið Þ ; j (11)

This chapter has presented a review of published researches in the application of NMQLC during grinding. The following conclusions may be drawn from the present literature review:


5. The lubricating performance of oil-based nanofluid is better than that of water-based nanofluid and the cooling effect is just reverse.

hBN hexagonal boron nitride

MWCNTs multi-walled carbon nanotubes MQL minimum quantity lubrication

UAG ultrasonic-assisted grinding

, Changhe Li<sup>1</sup>

Astronautics, Nanjing, China

Author details

Min Yang<sup>1</sup>

USA

References

NMQLC nanofluid minimum quantity lubrication cooling

\*, Yanbin Zhang<sup>1</sup>

\*Address all correspondence to: sy\_lichanghe@163.com

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Thermodynamic Mechanism of Nanofluid Minimum Quantity Lubrication Cooling Grinding and Temperature Field…

1 School of Mechanical Engineering, Qingdao University of Technology, Qingdao, China

2 Department of Biomedical Engineering, University of Southern California, Los Angeles, CA,

3 College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and

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