**5. Thermal Performance Comparison of Combining Jute into the (Active Cooling) Air-Based Cooling Strategy and (Passive Cooling) PCM-Assisted Cooling Strategy**

#### *5.1. Temperature Development*

Figure 11 compares the changes in the average battery surface temperatures measured by thermocouples under different cooling conditions. The thermal schematic shows that the battery temperature reached the highest value, around 48 ◦C, in natural air convection with no cooling (NC). The temperature increment decreased by applying different cooling strategies: cooling with fans (active cooling), evaporative cooling (EC) with combined jute, and passive cooling assisted with PCM. Comparing active cooling and EC, EC with wet jute obtained a relatively close result to active cooling with four fans, but with less equipment, weight, and power consumption. Moreover, comparing EC with passive cooling, an additional reduction in temperature occurred with passive cooling integrated with jute. It can be concluded that jute had a positive impact on both environmental aspects and temperature enhancement for cooling strategy optimization.

## *5.2. Uniformity*

According to Figure 12, the use of the PCM+jute technique decreased the temperature uniformity more than the rest of the cooling strategies. However, with the use of jute integrated into the active cooling with fans, the uniformity was enhanced, and an improvement in temperature distribution was achieved.

#### *5.3. Efficiency*

In Figure 13, all the performed characterizations are abbreviated to a single plot, which describes and compares the efficiency for every cooling scenario. Maximum temperature (*Tmax*) and Δ*T* efficiency were generally achieved under most of the cooling strategies, but integrating jute with PCM led to the highest *Tmax* and Δ*T* efficiency at 23% and 60%, respectively. Uniformity efficiency was not accomplished under most of the cooling strategies, excepting PCM and EC with wet jute. Therefore, it can be concluded that jute had a


remarkable impact on the cooling efficiency in terms of *Tmax*, Δ*T*, and uniformity and could be integrated into BTMS design optimization.

**Figure 11.** Comparison of the average surface temperature rise for all the discussed cooling strategies.


**Figure 12.** Comparison of nonuniformity temperature distributions for all the discussed cooling strategies.

**Figure 13.** Efficiency comparison for cooling strategies: (1) PCM, (2) PCM+jute, (3) 2 fans, (4) 4 fans, (5) EC with jute, (6) EC with wet jute.

#### **6. Experimental Uncertainty Analysis**

Using the method presented by Moffat [56], the experiment error analysis was estimated. Assuming that the result, S, of the experiment is acquired from a set of measurements as follows:

$$\mathbf{S} = \mathbf{S}(\mathbf{x}\_1, \mathbf{x}\_2, \mathbf{x}\_3, \dots, \mathbf{x}\_{\prime}, \mathbf{x}\_n)$$

The uncertainty is specified by the following equation:

$$\delta S = \left\{ \sum\_{k=1}^{n} \left( \frac{\partial R}{\partial \mathbf{x}\_k} \delta \mathbf{x}\_k \right)^2 \right\}^{1/2} \tag{4}$$

where *δS* is the total uncertainty and *δxk* is the uncertainty of every singular measurement. The uncertainties of experimental equipment were assumed as the absolute bias given by the aperture specification and described in Section 2.1. However, the uncertainty of the average temperature measurement was acquired based on the average temperature of the thermocouples attached to the cell. Thus, the total uncertainties were calculated following Equation (5) and estimated as 3.6%.

$$\frac{\Delta T\_R}{\mathbf{T}\_R} = \sqrt{\sum\_{i=1}^{4} \left(\Delta T\_{Ri}/T\_{Ri}\right)^2} \tag{5}$$

#### **7. Conclusion and Future Work**

This study attempted to investigate and analyze a novel and environmental optimization for LIB thermal management systems by integrating jute fiber with an active cooling strategy and a passive cooling strategy with PCM. It concluded with interesting results, which are summarized as follows:

1. Integrating jute fabrics with PCM (passive cooling strategy) achieved the desired effect on the battery thermal behavior and enhanced the cooling efficiency; temperature difference (Δ*T*) efficiency was enhanced by 60%. Furthermore, less PCM and

nonenvironmental cooling material was used. Therefore, system weight reduction and environmental material enhancement were achieved.


**Author Contributions:** Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data Curation, Writing—Original Draft, Visualization, and Writing—Review & Editing, R.Y.; Writing—Review & Editing, M.S.H.; Writing—Review & Editing, J.H.; Supervision & Project administration, M.A.-S.; Supervision & Project administration, J.V.M.; Supervision & Project administration, M.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** European Union Horizon 2020 research and innovation program under Grant Agreement No. 824311, the study was mainly developed within the framework of the ACHILES project.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** This study was mainly developed within the framework of the ACHILES project, which has received the funding from the European Union Horizon 2020 research and innovation program under Grant Agreement No. 824311. The authors also wish to acknowledge Flanders Make for support to the MOBI research group.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

