Thermal management studies for a high temperature proton exchange membrane fuel cell stack

Ellamla, H R (2013) Thermal management studies for a high temperature proton exchange membrane fuel cell stack. PhD thesis, IIT Hyderabad.

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Abstract

High temperature proton exchange membrane fuel cells (HT-PEMFCs) operate in the temperature range of 100 to 200oC and offer several advantages compared to the better known low temperature proton exchange membrane fuel cells (LT-PEMFCs) which typically operateattemperaturesbelow100oC. During the operation of a HT-PEMFC stack, heat is generated in the electrodes and electrolyte of each cell, and this heat must be effectively removed without creating any hot or cold spots. Proper thermal management of the HT-PEMFCs stack is required to ensure that the cell temperature is neither too low (which would lead to low cell efficiency) nor too high(which would damage the materials of the stack).The high heat generation rate in HT-PEMFCs, especially at high current densities where it can exceed the total electric power output, poses a challenge to the thermal management of HT-PEMFC stacks. Against this background, the objective of the present work is to systematically study the thermal management of an HT-PEMFC stack and quantify the effect of various stack cooling strategies on the overall performance of the stack using a multi-scale computational fluid dynamics (CFD) model. The stack model couples the flow and temperature fields with the electrochemistry using an empirical cell polarization curve to capture local current density – a function of local temperature within the active regions of each cell. This approach greatly reduces computational effort and time while retaining the essential physics and the coupling between the temperature and current density fields, thus enabling studies that clarify thermal management at the stack level: the focus of this study. A specific goal of this study is to investigate stack cooling methods that enable as high an average stack temperature as possible while ensuring that the temperature does not exceed 200oC anywhere in the stack. The thermal management techniques investigated in this work are: i) integrated cathode air cooling, ii) external air flow over the hot stack, iii) coupling a H2 storage system to the cathode air cooling system, iv) the use of liquid coolants in a separate cooling circuit.Integrated cathode air cooling uses excess air directed through cooling channels between cells to remove heat from the stack before directly introducing this air into the channels feeding air to the cell.

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IITH Creators:
IITH CreatorsORCiD
Item Type: Thesis (PhD)
Uncontrolled Keywords: Thermal management, polymer electrolyte membrane fuel cells, high temperature operation, temperature mapping, computational fluid dynamics, hydrogen storage, current density, pressure drop, flow distribution, TD79
Subjects: Chemical Engineering
Divisions: Department of Chemical Engineering
Depositing User: Mr. Siva Shankar K
Date Deposited: 17 Sep 2014 06:18
Last Modified: 13 Nov 2015 04:31
URI: http://raiith.iith.ac.in/id/eprint/2
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