Performance and Parameter Sensitivity Analysis of the PEMFC Flow Channel with Porous Baffles

Round 1

Reviewer 1 Report

The manuscript introduces a numerical approach to optimize the performance of PEMFC using porous material as a flow channel baffle. Numerical simulation using COMSOL were conducted, which showed that the porous baffle channel is mostly sensitive to the thickness.

The manuscript is well written and useful. There are few items that I recommend to address :

• The sensitivity analysis in Fig 10 shows low dependency on the baffle porosity for values above 0.5. What is the performance of lower porosity (<0.5) ?
• Define the range of “i” in Eq. 3, also specify the range of “k” in Eq. 4.
• Maxwell-Stefan model is used for the multicomponent diffusion. The authors need to explain how the diffusion coefficients are calculated. Is cross-phase diffusion considered? Is there effect of uphill diffusion (i.e. off-diagonal diffusion coefficients ?). The authors may site this paper that details with the effect of Maxwell and Fickian diffusions
• Hoteit, Modeling diffusion and gas–oil mass transfer in fractured reservoirs, Journal of Petroleum Science and Engineering, 2013, https://doi.org/10.1016/j.petrol.2013.03.007.

Author Response

Thank you for your review of my manuscript. The performance of the baffle below 0.5 (0.4,0.3) is simulated, and the relevant data are supplemented and shown in Figure 10. When the porosity is below 0.5, the effect of porosity change on the performance of PEMFC changes with the change of baffle thickness，When the thickness of the baffle is 1.28 mm, and the porosity of the baffle increases from 0.3 to 0.8, the average current density of the PEMFC increases from 1.238 A/cm2 to 1.298 A/cm2, i.e., an increase of 7.428 %. This part is added to lines 276-279 of the article.

“I” represents the material type, the anode represents H2, H2O, and the cathode represents O2, N2, H2O; “K” represents the type of non-I material, the anode represents H2, H2O, and the cathode represents O2, N2, H2O; Relevant explanations are added to subscriptions.

Thank you for the literature you provided. Referring to the literature you mentioned, "the system is ideal and binary" is added to the model hypothesis as a hypothesis. Under this hypothesis, the diffusion coefficient of Maxwell Stefan model is the same as that of Fick model under multicomponent, which can be expressed as formula 5. At the same time, the relevant diffusion rate under Fick diffusion refers to the data in the follow literature.

Cai G , Liang Y , Liu Z , et al. Design and optimization of bio-inspired wave-like channel for a PEM fuel cell applying genetic algorithm[J]. Energy, 2020, 192(Feb.1):116670.1-116670.11.

Reviewer 2 Report

The article by Cong Chen et al. is devoted to the very urgent problem of finding the optimal performance of PEMFC, which is one of the very promising sources of recyclable energy. Based on the literature data, which are sufficiently well covered in the Introduction, the authors suggest the using of PEMFC with four porous baffles flow channels. A number of parameters of the proposed model were analyzed, such as thickness and quantity of porous baffles as well as the sensitivity analysis. Some parameters were compared with basic model of flow channel. The results show an improvement in some indicators. The conclusions are quite well formulated. I believe that the article is relevant, suitable for publication in a special issue of the Applied Sciences and can be published after minor revision.

For non-specialists in this field, could the authors formulate in a more general way how significant are your improvements? Do these improvements pay off the complexity of the design compared to the basic model? Or with other models that you describe in the Introduction?

There are also some minor typos:

1. In the subscripts part after ch – The channel, for l – there is no explanation
2. In the Figure 2. CathOde GDL must be Cathode
3. In the beginning of 3.3 part “A The” should be The?
4. In 3.5 part, first sentence, after “numerical model” “The” must be “the”
5. The titles of Table 3 and Figure 7 - it should be with a capital letter
6. Line 270 after “the PEMFC is not obvious” - there should be a dot.
7. The name of the ordinate axis in Figure 11 should be capitalized.

Author Response

Thank you for your review of my manuscript.The channel design used in this paper improves the performance of the PEMFC.At the same time, compared with the baffle channel and bionic channel mentioned in the introduction, the channel design parameters (porosity, thickness, baffle number) used are less and simpler, and the channel advantages are added in this paper.This section was added to lines 98-99 of the article.Thanks for your careful discovery.I apologize for the inconvenience caused by my carelessness.I have corrected these errors you mentioned and carefully examined elsewhere.