Proton Exchange Membrane Fuel Cell Temperature Research Articles

Investigation of the geothermal flash cycle developed by a thermoelectric generator and PEMFC: 3E analysis and optimization

Investigations have revealed that geothermal organic Rankine cycles (ORCs) have a low efficiency and high exergy destruction rate, especially in the heat exchangers network, which drastically reduces the whole system's performance. To tackle this problem, in the present research, the effects of employing thermoelectric generators (TEG) and proton exchange membrane fuel cell (PEMFC) on the performance of a geothermal ORC will be discussed from thermodynamic and economic points of view. In this study, three geothermal flash cycles are investigated. The first system, GFC, is a geothermal flash cycle. The second system is the GFC boosted by a TEG thermoelectric generator, which is applied instead of the condenser (GFTC). The third system is GFTC, developed using a PEMFC (GFTPC) before the evaporator. These systems are compared from energy, exergy, and economic perspectives. Parametric analysis is conducted for the system with the best performance and the effects of the evaporator temperature, evaporator quality, flash temperature, and PEMFC temperature on the system performance. Based on the results, the net power outputs of the GFTC and GFTPC are 10.21 % and 40.49 % higher than those of the GFC, respectively. GFTC and GFTPC have higher energy and exergy efficiencies and lower LCOE and payback period than GFC. In the GFTPC, a 32.86 % increase in the net power output, 20.81 % enhancement in the energy efficiency, and 0.22 % increase in the exergy efficiency are observed with an increase in the PEMFC temperature from 75 to 115 °C. Moreover, The PEMFC temperature increment reduces the LCOE and payback period of the GFTPC system. Also, the multi-objective optimization for GFTPC design with three decision variables has been done.

Modeling and optimization of a residential PEMFC-based CHP system under different operating modes

Proton exchange membrane fuel cell (PEMFC)-based combined heat and power (CHP) system can improve the system overall efficiency. In this study, with the electrical and thermal demand curves from a survey of 500 households as the input, a residential PEMFC-based CHP system is numerically studied to explore the system operating characteristics under different operating modes, including constant-power output, electrical-led output, and stepped electrical-led output. Effects of structural and operating parameters, such as tank volume, tank temperature, PEMFC temperature, and environmental temperature, are studied. The system performance is evaluated based on CHP efficiency, matching degree, and hydrogen consumption. The results show that while the optimal CHP efficiency is higher under the constant-power output mode, the corresponding matching degree is lower and the hydrogen consumption rate is higher. A new hybrid mode is proposed to combine the advantages of different modes, achieving both higher efficiency and matching degree. Additionally, the CHP system is compared with a conventional energy supply system in terms of carbon emission and operating costs. The critical hydrogen price for a more cost-effective CHP system than the conventional system is calculated. Furthermore, a dataset is utilized to establish the relationship between CHP efficiency and key input parameters, and an artificial neural network (ANN) model is developed to predict CHP efficiency. The ANN model demonstrates a high accuracy of 98.5% and is coupled with the genetic algorithm to optimize the system, leading to the final CHP efficiency of 95.62%.

Waste heat recovery from exhausted gas of a proton exchange membrane fuel cell to produce hydrogen using thermoelectric generator

Proton exchange membrane fuel cell (PEMFC) is an efficient (40–50%) carrier to utilize hydrogen, which means around 50–60% of waste heat dissipates into ambience. To recover waste heat, advance hydrogen production and system efficiency, a novel integrated system with power generation and hydrogen production is proposed in this paper. The system includes a PEMFC, the thermoelectric generator (TEG) modules and a water electrolysis cell. The effects of cooling-method, electrical array configuration, the outlet temperature of PEMFC on the output power, system efficiency, hydrogen production rate and payback period have been investigated by means of a sensitivity analysis. The life cycle climate performance method is applied to evaluate the environmental performance. The results show that the hydrogen production rate of the water-cooling method is 31.4–44.8% larger than that of the air-cooling method. The electrical array configuration has no obvious effect on system performance. Additionally, the outlet temperature of PEMFC has positive effect on hydrogen production per module, while TEG module number is opposed. Furthermore, for optimizing the system, six different objection functions have been developed and compared. After optimization, the optimal height, area and volume of the thermoelectric leg are 1.01–1.3 mm, 2.52–3.28 mm2 and 3.08–4.26 mm3 at range of outlet temperature within 50–100 °C. The net output power, system efficiency and hydrogen production are 31.8–39.4%, 3.7–31.5% and 22.1–34.5% higher than that of the commercial module. The payback period and the year achieving zero carbon emissions are 15.0–34.3% and 17.8–36.8% lower than that of commercial module.

Development of practical empirically and statistically-based equations for predicting the temperature characteristics of PEMFC applied in the CCHP system

In this study, we investigate the temperature characteristics of a proton exchange membrane fuel cell (PEMFC) stack applied to a combined cooling, heating and power (CCHP) system for achieve a suitable operating temperature range of PEMFCs and meeting the requirements associated with the heat source temperature of the CCHP system. The functional relationships between the current density, cooling water flow rate, number of single cells, PEMFC temperature, and the cooling water outlet temperature in stacks composed of 5–30 single cells are analyzed. There is a current density interval for each cooling water flow rate that meets the requirements of both the PEMFC and cooling water outlet temperature, which decreases with an increase in the cooling water flow rate. The coefficients of determination (R2) of the equations are all greater than 0.997. The reliability of the equations is verified on a stack composed of 50 single cells, and the error between the predicted and actual results is less than 0.5%. Based on empirical equations, the recommended cooling water flow rate interval is obtained at each current density, and the recommended operating current density should be less than or equal to 1.1 A·m−2.

The Impact of Hydrogen Energy Storage on the Electricity Harvesting

The economics, infrastructure, transportation, and level of living of a country are all influenced by energy. The gap between energy usage and availability is a global issue. Currently, all countries rely on fossil fuels for energy generation, and these fossil fuels are not sustainable. The hydrogen proton exchange membrane fuel cell (PEMFC) power system is both clean and efficient. The fuel delivery system and the PEMFC make up the majority of the PEMFC power system. The lack of an efficient, safe, and cost-effective hydrogen storage system is still a major barrier to its widespread use. Solid hydrogen storage has the large capacity, safety and good reversibility. As a hydrogen source system, the hydrogen supply characteristics affect the characteristics of the PEMFC at the output. In this paper, a mathematical model of a hydrogen source reactor and PEMFC based on chemical absorption/desorption of solid hydrogen storage is established, and a simulation model of a PEMFC power system coupled with solid hydrogen storage is established using MATLAB/SIMULINK software, and the hydrogen supply of the reactor is analyzed in detail. The influence of prominent factors is evaluated. The research results show that the proposed method improved the system performance. At the same time, increasing the PEMFC temperature, increasing the area of the proton exchange membrane and the oxygen supply pressure can increase the output power of the power system.

Comparison of organic coolants for boiling cooling of proton exchange membrane fuel cell

Cooling and temperature homogeneity are the key technical problems for the proton exchange membrane fuel cell (PEMFC) thermal management. In this paper, a one-dimensional model of a PEMFC with phase-change cooling (flow boiling cooling) is proposed for PEMFC thermal management, and the heat transfer of microchannel flow boiling is integrated with PEMFC cooling. Five organic coolants (Novec 649, HFC-365mfc, HFE-356mec, HFE-347pcf2, and HFE-7100) and single-phase water are compared by the PEMFC average temperature of the catalyst layer (ATCL) and temperature difference of the catalyst layer (TDCL). The PEMFC temperature characteristics with organic coolant are investigated in detail. The results indicate that HFE-7100 exhibited the lowest ATCL and minimum TDCL among the coolants. The maximum TDCL of HFE-7100 is 5.5 K at current density of 1.2 A/cm2, which can completely keep the PEMFC operating temperature at proper and uniform conditions. The minimum ATCL of Novec 649 is over 353 K, which dissatisfies the cooling demand. The TDCLs of PEMFCs with different organic coolants have a minimum value when the coolant outlet vapour mass fraction is 0.4. Temperature uniformity should be the most important factor for mass flow control in PEMFCs using organic coolants.

VALIDATION OF SEMI-EMPIRICAL TEMPERATURE MODEL OF PEMFC USING ATOM SEARCH OPTIMIZATION ALGORITHM

Proton Exchange Membrane Fuel Cell (PEMFC) has unique thermal characteristics. The change in PEMFC temperature directly effects the PEMFC performance. The voltage and temperature of PEMFC at different loading/ambient conditions is not easy to predict. In this work a newly developed semi-empirical model is used and the parameters of the model are optimized for single cell PEMFC (base-case) by using atom search optimization. The semi-empirical model was developed and tested for stack PEMFC system but any model developed for PEMFC cannot be validated unless it is effective for single-cell PEMFC system. The new parameters show promising results and hence the model works is considered as good model. Previously due to unknown base-case parameters the ranges selected for parameters are extremely large. In this model by considering the base-case parameters and previously extracted parameters the new short ranges for parameters are given so that in future the optimization of parameters will take less time and this increases the chances of this model to be used in online prediction of PEMFC temperature.

A novel electrochemical refrigeration system based on the combined proton exchange membrane fuel cell-electrolyzer

This study presents an electrochemical cooling system consisting of a proton exchange membrane fuel cell (PEMFC) and a proton exchange membrane electrolyzer cell (PEMEC) based on a continuous thermally regenerative electrochemical refrigerator (TRER) cycle. The three-dimensional model of the PEMFC and PEMEC are numerically simulated. The cooling system performance was investigated in terms of coefficient of performance (COP), cooling capacity, and external added power. The practical limits of operating current density for the cooling system are extracted. Moreover, the effects of the operating temperature and pressure on the cooling system performance are investigated. Results showed that the COP and cooling capacity of the system increase with increasing the temperature of PEMEC while the consumed power by the system decreases. The PEMFC temperature had a reverse effect on the COP and cooling capacity and consumed power. Also, higher operating pressure increases the COP while decreasing the cooling capacity and consumed power. The COP to Carnot COP of the integrated cooling system is about 0.017–0.067. Furthermore, the cooling system is compared with other cooling technologies. Considering that the efficiency and cost of the PEMFCs and PEMECs are expected to improve drastically over time, this system could be a promising option for cooling applications.

Three‐dimensional simulations for counter‐flow proton exchange membrane fuel cells with thin catalyst‐coated membrane cooled by liquid water

Three-dimensional simulations were performed for proton exchange membrane fuel cell (PEMFC) with thin catalyst-coated membrane (CCM) regarding liquid water cooling design. The studied PEMFC follows a counter-flow pattern for the H2 and air stream, which is commonly adopted in today's automotive PEMFCs. For the thermal modeling of the liquid water, conjugate heat transfer model is used. The cooling flow inlet temperature between 60 and 75°C, direction, flow rate between 0.08 and 0.32 L s−1 m−2 as well as the cooling channel number are investigated, specifically. It is found that the cooling inlet temperature directly determines the working temperature of PEMFC under the same cooling flow rate. It means that increasing the cooling inlet temperature can lift the PEMFC operating temperature. The co-direction for the liquid flow and the air stream is found to be better for PEMFC as it can suppress the liquid water formed near cathode outlet. It is then pointed out that the cooling flow rate would determine the along-channel temperature non-uniformity in PEMFC and moderate flow rate is preferred. Reducing the number of the cooling channels while assigning higher flow rate for each channel will slightly lift the PEMFC temperature overall, but this strategy will result in more pumping power loss.

Temperature and humidity management of PEM fuel cell power system using multi-input and multi-output fuzzy method

• A PEMFC temperature and humidity transient synergy control strategy is proposed. • This method can improve the stack dynamic response capability and power density. • The control performance of this method is verified by experiments. Dynamic hydrothermal management is the critical issue for improving the performance of Proton exchange membrane fuel cell (PEMFC). In this study, a multi-input and multi-output (MIMO) fuzzy control method is proposed for the hydrothermal management of PEMFC in real time. For PEMFC, stack temperature and relative humidity at cathode are chosen as the control objectives, and the cooling water flow rate and inlet gas humidity at cathode are set as the control variables. To establish the transient synergy control of temperature and humidity, a fuzzy logic controller is constructed. The input parameters of controller include the errors of temperature, humidity and their derivatives. The dynamic performances of temperature and humidity transient synergy control under the disturbance of load current and operating parameters are analyzed. The results show that the temperature and humidity transient synergy control based on MIMO fuzzy method presents faster response speed and better control performance than traditional Proportion Integration Differentiation (PID) control. The output voltage of the proposed control method is 3.14% and 4.21% higher than that of traditional PID controllers. Furthermore, the power density of THTSc is 9.37% higher than that of PID controller.

Temperature and voltage dynamic control of PEMFC Stack using MPC method

Proton Exchange Membrane Fuel Cell (PEMFC) is a multi-parameter and strongly coupled complex system, efficient and smooth operation is beneficial to the efficiency and stability of PEMFC. In this paper, aiming at improve the temperature and voltage management in PEMFC, a stack model is established, and a PEMFC temperature and voltage dynamic management controller based on Model Predict Control method (MPC) is proposed. The working temperature and output voltage are controlled by the mass flow rate of cooling water and hydrogen gas, respectively. The performances of PEMFC under different controller including MPC and traditional PID controllers are analyzed. Due to the optimization of future time step in MPC controller, the measured value will move close to the set value faster. The response time and overshoots of temperature and voltage are remarkably reduced. Compared with PID controller, MPC temperature control has smaller overshoot and faster response time, Moreover, with step current change, voltage overshoot of MPC controller is less than 1.2% which is better than other controllers.

Investigation of optimal operating temperature for the PEMFC and its tracking control for energy saving in vehicle applications

The operating temperature, as one of the key factors influencing the system efficiency is very critical for the proton exchange membrane fuel cell (PEMFC). However, the specific relationship between the operating temperature of PEMFC and its efficiency remains unclear, which further challenge the high-efficiency operation of the PEMFC in the fuel cell vehicle (FCV). This paper aims to decouple the operating temperature from the complicated driving conditions of the FCV, and find the mapping relationship between the operating temperature and PEMFC output power, hence to improve the efficiency by the optimal control of PEMFC system. A temperature control model of the PEMFC cooling system is established and enhanced by a series of experiments under different power levels against different temperature. The mapping relationship between the optimal operating temperature and the PEMFC power is obtained by the experiments. Then, a predictive control with the function of tracking the optimal operating temperature is developed and verified under NEDC and CHTC-HT driving cycles. Simulation results show that compared with constant temperature control and the traditional rule-based temperature control, under the optimal temperature tracking control, the PEMFC efficiency is improved by 15% and 18.2%, 25.6% and 28.7% respectively in the two driving cycles.

Experimental Investigation on the Operating Characteristics of Flat-Plate CLPHP for PEMFC Cooling

Proton exchange membrane fuel cell (PEMFC) generates electricity through hydrogen and oxygen chemical reaction with the generation of much heat. According to the working temperature of PEMFC, the thermal resistance and internal relative pressure change of the flat-plate micro closed-loop pulsating heat pipe (CLPHP) are tested and analyzed at different filling ratios, vacuum degrees, and inclination angles, whose working medium is binary methanol-deionized water with a mass ratio of 5:1. The experiment results show that the higher the vacuum degree is, the better the startup and heat transfer performance of CLPHP become; the thermal resistance is less sensitive to inclination angle except for horizontal placement; the 40% volume-filling ratio can effectively avoid dry-out at high temperature. When 80 °C is the ideal working temperature of PEMFC, the thermal resistance of CLPHP is 0.093°C/W; the heat transfer heat flux is 1.59 W/cm2, and the temperature fluctuation is small. Therefore, flat-plate CLPHP has great application potential for PEMFC cooling.

Temperature and Voltage Dynamic Control of PEMFC Stack Using MPC Method

Proton Exchange Membrane Fuel Cell (PEMFC) is a multi-parameter and strongly coupled complex system, efficient and smooth operation is beneficial to the efficiency and stability of PEMFC. In this paper, aiming at improve the temperature and voltage management in PEMFC, a stack model is established, and a PEMFC temperature and voltage dynamic management controller based on Model Predict Control method (MPC) is proposed. The working temperature and output voltage are controlled by the mass flow rates of cooling water and hydrogen gas, respectively. The performances of PEMFC under different controller including MPC and traditional PID controllers are analyzed. The results show that the MPC controller can remarkably reduce the response time and overshoots of temperature and voltage. The temperature overshoot of MPC controller is lower than 1.1 K, and the response time is less than traditional PID controllers. Moreover, with step current change, voltage overshoot of MPC controller is less than 0.6V which is better than other controllers.

Thermal management of open-cathode proton exchange membrane fuel cell stack with thin vapor chambers

Proton exchange membrane fuel cell (PEMFC) is one of the most promising electricity-generating devices with zero pollution. However, a large amount of waste heat will be generated during the operation. The waste heat must be dissipated in time to prevent performance deterioration and irreversible damage. In this paper, a novel cooling strategy is proposed and implemented. Five thin vapor chambers (VCs) are integrated into a 10-cell open-cathode PEMFC stack to enhance its heat dissipation effect. PEMFC stack with VCs has been successfully fabricated and tested experimentally. Results show that VCs can effectively reduce the operating temperature of PEMFC and the minimum in-plane temperature difference can be reduced to 0.5 °C, which provides a reliable and stable thermal environment for safe operation. The effects of VCs on the through-plane and in-plane temperature distribution is studied and analyzed in detail. In addition, when the cathode air flow is small, the thermal management of the stack is significantly affected by the inclination angle. This study has fully demonstrated the feasibility of integrating VCs in PEMFC stack to improve thermal management, and provides guidance for designing and developing a better cooling system of PEMFC stack.

Effect of superior mesenteric artery branch structure-based flow field on PEMFC performance

The flow field structure of a proton exchange membrane fuel cell (PEMFC) is a key factor that affects its performance. In this study, based on the structural characteristics of the superior mesenteric artery and branches of the human body, a new type of bionic flow field was designed for a PEMFC. The effects of the conventional serpentine flow field (CSFF) and new bionic flow field (NBFF) on fuel cell performance were studied via simulation and experiment. Compared with the CSFF, the NBFF significantly improves droplet dynamic transmission characteristics, reduces droplet aggregation at bends, shortens the retention time of droplets in the flow field, and increases the droplet removal rate by 36.3%. The output performance of the NBFF-based fuel cell is the best under an air flow rate of 4 L/min and a hydrogen flow rate of 2.5 L/min. The NBFF exhibits better heat dissipation than the CSFF does. When the current density is high and the operating temperature exceeds 50 °C, the performance of the NBFF fuel cell is improved by 30.03% compared with that of the CSFF-best fuel cell. Moreover, the actual working temperature of PEMFC is 60–80 °C. Therefore, the NBFF can enhance the practicability of fuel cells.

Model Predictive Control With Lifetime Constraints Based Energy Management Strategy for Proton Exchange Membrane Fuel Cell Hybrid Power Systems

In this article, a model predictive control (MPC) energy management strategy is proposed to distribute power flows of proton exchange membrane fuel cell (PEMFC)-based hybrid power systems consisting of PEMFC, battery, and waste heat recovery system such as TEG and CHP. To optimally meet the demand of load power balancing as well as protect PEMFC from lifetime degradation, a novel objective function by considering fuel consumption, state-of-charge (SOC) of battery, as well as power slope and temperature of PEMFC is constructed and solved in the states prediction horizon within the defined lifetime constraints and SOC limitations. In particular, temperature effects are newly introduced by adding a state-variable to the energy management model and formulating a penalty function. Simulations with mobility and stationary application scenarios are presented. In the automobile case, the hydrogen consumption of the constraints MPC is reduced by 9.98% compared with the rule-based strategy, and the same results can be achieved in the household application. A hardware in the loop experiment was carried out to verify the real-time performance of the MPC strategy which occupied a 2.21% average CPU load rate. The proposed MPC strategy has a promising fuel consumption optimization, lifetime extension, and real-time capability.

Comprehensive influences measurement and analysis of power converter low frequency current ripple on PEM fuel cell

To deeply understand the influences of power converter's low frequency current ripple (LFCR) and harmonics on a proton exchange membrane fuel cell (PEMFC) in its power conditioning system (PCS), a comprehensive measurement and analysis of the influences of LFCR and harmonics on PEMFC's performance and durability is investigated in this paper. Based on an equivalent circuit model of PEMFC stack and a mechanism model for evaluating the LFCR effects on the PEMFC, this paper studies primarily and systematically the comprehensive influences of LFCR and harmonics on PEMFC performances and durability, such as (1) degrading the PEMFC performance, (2) shortening the lifetime of PEMFC, (3) reducing the stack output power, (4) lowing its availability efficiency, (5) producing more heat and raising the PEMFC temperature, (6) consuming more fuel, and (7) decreasing the fuel utilization. Finally, a Horizon 300 W PEMFC stack is implemented and tested.

Material behavior of rubber sealing for proton exchange membrane fuel cells

Reliable sealing is necessary for the stable operation of proton exchange membrane fuel cell (PEMFC). In practical application, various materials have been tried in PEMFC sealing. However, the mechanical properties of these sealing materials, which play a key role in the sealing stability, have not been fully understood in PEMFC environment, especially after long-term operation. In this paper, according to the operating environment of PEMFC, sealing material experiments are carried out to explore the differences in mechanical behaviors of sealing materials, including silicone rubber (SR), fluororubber (FR), nitrile rubber (NBR) and ethylene-propylene-diene-terpolymer rubber (EPDM) and the variation of mechanical properties of these sealing materials is predicted as time goes on. The results indicate that compression rate has a great influence on sealing contact stress. SR and EPDM, with the variation of 0.15 MPa and 0.45 MPa in stress, show the best and worst mechanical stability at different compression rates, respectively. In terms of temperature, it is found that SR can adapt to different operating temperature of PEMFC and only 18% variation is found from 20 °C to 100 °C. Finally, based on Time-Temperature Superposition (TTS), high temperature experiments are conducted to predict long-term relaxation stress under PEMFC working condition. The analysis results are beneficial for choosing suitable sealing material, and it can also be applied to predict sealing ability in PEMFC.

Development of a PEMFC dynamic model and the application to the analysis of fuel cell vehicle performance

In order to investigate basic output performances of PEMFC (Proton Exchange Membrane Fuel Cell) stack, a dynamic model of PEMFC stack has been developed by combining electrochemical sub-model and thermodynamic sub-model. With necessary validation, it demonstrates that modelling results and experimental data are in very good agreement in terms the U-I curve and power output. By applying the dynamic model to analyse performance outputs of PEMFC stack and applying the model for FC-Hybrid vehicle powertrain configuration, it demonstrates that improved PEMFC quality with increased maximum current density could increase the peak power output and also increase the working efficiency, although the increase of peak power is not linear relation with the increase of maximum current density. Higher working temperature of PEMFC would benefit the increases of both peak power output and efficiency. Compared to working temperature, ambient temperature’s increase could also make positive influence on power output and efficiency, though the influence is weak. Coupling the dynamic model with a powertrain model of FC-Electric hybrid vehicle, the analysis suggests that both PEMFC stack and battery stack should have similar size for general driving condition. Too big either PEMFC stack or battery stack would increase the total weight then contaminate the fuel/energy economy.