processes Review A Review on Temperature Control of Proton Exchange Membrane Fuel Cells Qinghe Li 1, Zhiqiang Liu 1, Yi Sun 2, Sheng Yang 1,* and Chengwei Deng 2,* 1 School of Energy Science and Engineering, Central South University, Changsha 410083, China; [email protected] (Q.L.); [email protected] (Z.L.) 2 Space Power Technology State Key Laboratory, Shanghai Institute of Space Power-Sources, Shanghai 200245, China; [email protected] * Correspondence: [email protected] (S.Y.); [email protected] (C.D.) Abstract: This paper provides a comprehensive review of the temperature control in proton exchange membrane fuel cells. Proton exchange membrane (PEM) fuel cells inevitably emit a certain amount of heat while generating electricity, and the fuel cell can only exert its best performance in the appropriate temperature range. At the same time, the heat generated cannot spontaneously keep its temperature uniform and stable, and temperature control is required. This part of thermal energy can be classified into two groups. On the one hand, the reaction heat is affected by the reaction process; on the other hand, due to the impedance of the battery itself to the current, the ohmic polarization loss is caused to the battery. The thermal effect of current generates Joule heat, which is manifested by an increase in temperature and a decrease in battery performance. Therefore, it is necessary to design and optimize the battery material structure to improve battery performance and adopt a suitable cooling system for heat dissipation. To make the PEM fuel cell (PEMFC) universal, some extreme situations need to be considered, and a cold start of the battery is included in the analysis. In this paper, the previous studies related to three important aspects of temperature control in proton exchange membrane fuel cells have been reviewed and analyzed to better guide thermal management Citation: Li, Q.; Liu, Z.; Sun, Y.; of the proton exchange membrane fuel cell (PEMFC). Yang, S.; Deng, C. A Review on Temperature Control of Proton Keywords: proton exchange membrane fuel cell; temperature control; cold start; temperature Exchange Membrane Fuel Cells. distribution; cooling system Processes 2021, 9, 235. https:// doi.org/10.3390/pr9020235 Academic Editor: Alfredo Iranzo 1. Introduction Received: 29 December 2020 As a kind of high efficiency and environmental protection energy device, fuel cells Accepted: 24 January 2021 Published: 27 January 2021 have been highly expected and have a broad application prospect. In particular, as the problems of environmental pollution and the energy crisis are becoming more and more Publisher’s Note: MDPI stays neutral serious, green renewable energy has become an urgent demand in today’s society. Because with regard to jurisdictional claims in fuel cells are highly efficient and environmentally-friendly green-energy technologies, they published maps and institutional affil- have developed very rapidly. To date, there are many types of fuel cells, including proton iations. exchange membrane (PEM), solid oxide (SO), alkaline, direct methanol (DM), phosphoric acid (PC), and molten carbonate (MC) fuel cells, each has its own advantages. As a current research hotspot, proton exchange membrane fuel cells do not involve the combustion process of hydrogen and oxygen during power generation, so they are not limited by the Carnot cycle and have a high energy conversion rate. In addition, the proton exchange Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. membrane fuel cell does not produce pollution during power generation. The system This article is an open access article unit is modular, with high reliability, and is easy to assemble and maintain. Compared distributed under the terms and with traditional power generation devices, it does not produce noise; the working tem- conditions of the Creative Commons perature is lower; the startup response faster, etc. [1,2]. These advantages make it stand Attribution (CC BY) license (https:// out among many fuel cells. In recent years, PEM fuel cells (PEMFCs) have developed creativecommons.org/licenses/by/ very rapidly and have made tremendous progress and breakthroughs. They have been 4.0/). successfully applied in some fields, such as portable power supplies, transportation, and Processes 2021, 9, 235. https://doi.org/10.3390/pr9020235 https://www.mdpi.com/journal/processes Processes 2021, 9, x FOR PEER REVIEW 2 of 21 Processes 2021, 9, 235 2 of 21 have been successfully applied in some fields, such as portable power supplies, transpor‐ aerospacetation, and equipment aerospace [equipment3]. Despite [3]. this, Despite there are this, still there some are technical still some barriers technical that barriers restrict its commercialthat restrict its application. commercial application. The PEMFCPEMFC generatesgenerates electricityelectricity and and releases releases heat heat simultaneously simultaneously in in the the electrochemi- electro‐ calchemical reaction reaction process. process. The local The and local overall and overall current current density density distribution distribution of the stackof the is stack closely relatedis closely to related the temperature to the temperature distribution. distribution. The current The densitycurrent relateddensity torelated the reactant to the reac supply‐ strategytant supply directly strategy affects directly the temperature affects the temperature distribution distribution inside the stack,inside andthe stack, the temperature and the affectstemperature the stack affects performance the stack performance by controlling by controlling the electrochemical the electrochemical reaction rate. reaction In addition rate. toIn relyingaddition on to the relying stack, on the the stable stack, operation the stable of operation the fuel cell of the system fuel requirescell system a corresponding requires a subsystemcorresponding to form subsystem a balance to form of plant,a balance which of plant, mainly which includes: mainly Oxidantincludes: subsystem,Oxidant sub fuel‐ subsystem,system, fuel cooling subsystem, subsystem, cooling electricalsubsystem, subsystem, electrical subsystem, and control and subsystem. control subsystem. For the tem- peratureFor the temperature control of fuel control cells, of thefuel cooling cells, the subsystem cooling subsystem is critical. is Generally,critical. Generally, the hydrogen the energyhydrogen utilization energy utilization of PEMFCs of isPEMFCs shown is in shown Figure in1. Figure In addition 1. In addition to the generated to the generated electrical energy,electrical the energy, heat generated the heat generated is also considerable, is also considerable, which is which equivalent is equivalent to 45% to to 60% 45% of to the total60% of hydrogen the total energyhydrogen entering energy the entering battery the [4 battery]. However, [4]. However, the exhaust the temperatureexhaust temper of‐ the fuelature cell of isthe relatively fuel cell lowis relatively (including low the (including evaporative the evaporative heat absorption heat of absorption the product of the water, thisproduct part water, of the this energy part is of affected the energy to ais certain affected extent to a certain by the extent temperature by the temperature of the operating of point),the operating the heat point), taken the away heat by taken the exhaust away by is only the exhaust about 3%, is only and theabout proportion 3%, and ofthe radiation pro‐ heatportion dissipation of radiation and heat natural dissipation convection and natural of air isconvection very small. of air Most is very of the small. heat Most needs of to bethe taken heat needs away to by be an taken additional away by cooling an additional system. cooling Itis necessary system. to Itis carry necessary out temperature to carry controlout temperature and optimized control design and optimized of the cooling design subsystem of the cooling for the subsystem proton exchange for the membrane proton fuelexchange cell to membrane ensure the fuel efficient cell to andensure stable the operationefficient and of stable the fuel operation cell [5]. of PEMFC the fuel thermal cell management[5]. PEMFC thermal can be management divided into can two be processes: divided into Temperature two processes: control Temperature and heat control recovery. Theand humidityheat recovery. of the The proton humidity exchange of the membraneproton exchange is more membrane sensitive is to more temperature. sensitive to Too hightemperature. or too low Too temperature high or too andlow humiditytemperature have and a directhumidity impact have on a thedirect performance impact on the of the membraneperformance and of stack.the membrane A reasonable and stack. choice A of reasonable a cooling systemchoice of is a required. cooling system On the is basis re‐ of ensuringquired. On the the efficient basis of and ensuring stable the operation efficient of and the stable stack, operation the excess of wastethe stack, heat the is removed,excess andwaste at heat the same is removed, time, the and temperature at the same distributiontime, the temperature is uniform distribution and stable. is Heat uniform recovery and is basedstable. on Heat the recovery control of is thebased entire on the stack control of waste of the heat entire recovery stack of and waste reuse. heat Depending recovery and on the application,reuse. Depending the stack on canthe useapplication, waste heat the cooling, stack can heating, use waste or power heat cooling, generation heating,