**4. Principles of EMbaffle® technology**

To overcome the lower performance in heat transfer, intrinsic of the longitudinal flow design when compared to cross flow, EMbaffle® technology makes use of the rhombus-like shape of the expanded metal baffle mesh to promote turbulence. The two tube pitches defined by the layout are named "long way of the diamond" (LWD) and "short way of the diamond" (SWD) (**Figures 3** and **4**).

Essentially, the baffle grids generate a local turbulence whose longitudinal extension and amplitude, other than by the fluid properties, are determined by the peculiar geometry of the grid mesh (**Figure 5**).

In **Figures 6** and **7**, the turbulence kinetic energy, as a measurement of the turbulence grade, is shown for different type of grid mesh shape with a specified grid span. The turbulence amplitude and extension are quite different for the different grids type.

Imposing a higher order of magnitude to the tube side heat transfer coefficient, the effect of the grids on the global heat transferred is studied by CFD analysis. As reported in **Figure 8** the heat transfer coefficient development substantially replicates the local turbulence peak at the grid, but the decay slope is significantly lower granting the maintenance of a quite homogeneous value from grid to grid.

Grid mesh shape also allows for different tube count to be allocated within the same shell diameter, determining the total available heat exchange surface and the mean average flow velocity that governs the longitudinal contribution to the HTC. Finally, increase or reduction in baffles span contributes, further to stronger or lighter tubes confinement, to the overall shell side HTC, with reversed impact on

*CFD analysis of turbulent kinetic energy generated by different grid types, gas case [3].*

*EMbaffle® – Local flow velocity profile governed by the grid mesh shape induced turbulence.*

The selection of grid type and grids span shall therefore be guided by the relevant boundary conditions as higher turbulence means higher pressure drops and overall HTC, while lower turbulence means lower pressure drops and lower total

pressure drops.

**Figure 6.**

**Figure 4.**

**Figure 5.**

*EMbaffle® – Typical rhombus-like shape of grid mesh [3].*

*EMbaffle® Heat Transfer Technology Step-Up in CO2 Reduction*

*DOI: http://dx.doi.org/10.5772/intechopen.96253*

heat transferred.

**329**

**Figure 3.** *EMbaffle® –typical tube layout.*

*EMbaffle® Heat Transfer Technology Step-Up in CO2 Reduction DOI: http://dx.doi.org/10.5772/intechopen.96253*

**Figure 4.**

vibration issues govern, with performance increasing under increased process

• Further, by making use of the reduced fouling accumulation and so the better use of the available pressure drops to improve global Heat Transfer Coefficient, the technology can replace in several processes different standard TEMA segmental baffle exchangers granting same/improved performances with

Plant data and case studies will be proposed to offer a general view of EMbaffle

To overcome the lower performance in heat transfer, intrinsic of the longitudinal flow design when compared to cross flow, EMbaffle® technology makes use of the rhombus-like shape of the expanded metal baffle mesh to promote turbulence. The two tube pitches defined by the layout are named "long way of the diamond"

Essentially, the baffle grids generate a local turbulence whose longitudinal extension and amplitude, other than by the fluid properties, are determined by the

In **Figures 6** and **7**, the turbulence kinetic energy, as a measurement of the turbulence grade, is shown for different type of grid mesh shape with a specified grid span. The turbulence amplitude and extension are quite different for the

granting the maintenance of a quite homogeneous value from grid to grid.

Imposing a higher order of magnitude to the tube side heat transfer coefficient, the effect of the grids on the global heat transferred is studied by CFD analysis. As reported in **Figure 8** the heat transfer coefficient development substantially replicates the local turbulence peak at the grid, but the decay slope is significantly lower

design performance advantages when replacing traditional TEMA solutions.

(LWD) and "short way of the diamond" (SWD) (**Figures 3** and **4**).

flow rates within the same shell diameter constraints.

*Heat Transfer - Design, Experimentation and Applications*

reduced capex/opex costs.

**4. Principles of EMbaffle® technology**

peculiar geometry of the grid mesh (**Figure 5**).

different grids type.

**Figure 3.**

**328**

*EMbaffle® –typical tube layout.*

*EMbaffle® – Typical rhombus-like shape of grid mesh [3].*

**Figure 5.**

*EMbaffle® – Local flow velocity profile governed by the grid mesh shape induced turbulence.*

**Figure 6.**

*CFD analysis of turbulent kinetic energy generated by different grid types, gas case [3].*

Grid mesh shape also allows for different tube count to be allocated within the same shell diameter, determining the total available heat exchange surface and the mean average flow velocity that governs the longitudinal contribution to the HTC.

Finally, increase or reduction in baffles span contributes, further to stronger or lighter tubes confinement, to the overall shell side HTC, with reversed impact on pressure drops.

The selection of grid type and grids span shall therefore be guided by the relevant boundary conditions as higher turbulence means higher pressure drops and overall HTC, while lower turbulence means lower pressure drops and lower total heat transferred.

The correction factor *Ft* ranges from 0 to 1. Typically, values smaller than 0.8 indicate close temperature approaches and therefore an inadequate design for the given process conditions; the design may be easily improved by increasing the

EMbaffle® allows to achieve a 100% counter-current configuration thanks to its pure longitudinal flow, maximizing the correction factor *Ft* to 1 and making the exchanger extremely performing where very tight temperature approaches are

In EMbaffle® technology, the shell-side HTC is calculated using the following correlations for the Nusselt number in case of laminar and turbulent flow respectively:

<sup>0</sup>*:*<sup>6</sup>*Pr*<sup>0</sup>*:*<sup>4</sup> *<sup>μ</sup><sup>b</sup>*

<sup>0</sup>*:*<sup>8</sup>*Pr*<sup>0</sup>*:*<sup>4</sup> *<sup>μ</sup><sup>b</sup>*

The geometry coefficient functions, *CL* and *CT*, account for the enhancement due to the cross flow at the shell entrance and exit conditions. The Reynolds number

> *Reh* <sup>¼</sup> *<sup>ρ</sup>VSDh μb*

> > <sup>2</sup> � *NTDo*

The characteristic diameter is four times the nominal flow area divided by the

<sup>2</sup> <sup>ð</sup>*LWD* � *SWD*Þ � *<sup>π</sup>*

<sup>2</sup> *πDo*

<sup>2</sup> (6)

<sup>4</sup> *Do*

where *VS* is the shell-side velocity and *Dh* is the characteristic diameter. The shell-side velocity is calculated with the continuity equation, using the

> *As* <sup>¼</sup> *<sup>π</sup>* 4 *Ds*

*Dh* <sup>¼</sup> <sup>4</sup> <sup>1</sup>

*μw* <sup>0</sup>*:*<sup>14</sup>

*μw* <sup>0</sup>*:*<sup>14</sup> (3)

(4)

(5)

(7)

correction factor *Ft* switching to a counter-current type exchanger.

*EMbaffle® Heat Transfer Technology Step-Up in CO2 Reduction*

*DOI: http://dx.doi.org/10.5772/intechopen.96253*

*Nu* ¼ *CLReh*

*Nu* ¼ *CTReh*

following expression for the shell-side flow area:

*Measured Nusselt number as a function of Reynolds number.*

specified.

**5.1 Heat transfer correlations**

is calculated as follows:

wetted perimeter:

**Figure 9.**

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#### **Figure 7.**

*CFD analysis of turbulent kinetic energy generated by different grid spans, liquid case [3].*

**Figure 8.** *From turbulence to heat transfer – Plot of HTC generated by different grid types [3].*
