Thermoelectric Module Integrated Fuel Cell in a Liquid Desiccant-Assisted Air-Conditioning System

Abstract

This study aims to estimate the energy performance of a liquid desiccant and evaporative cooling-assisted 100% outdoor air system (LD-IDECOAS) combined with a thermoelectric module integrated proton exchange membrane fuel cell (TEM-PEMFC). During the cooling season, recovered heat from the PEMFC was reclaimed to heat a weak desiccant solution and the generated electricity was used to operate the LD-IDECOAS. The TEM was operated as an auxiliary heater for heating the weak desiccant solution. In the off-cooling season, the PEMFC was operated to generate electricity and the recovered heat was also used to generate electricity using TEMs. In this study, a detailed energy simulation model was developed to estimate the energy savings potentials of the proposed system compared with the conventional LD-IDECOAS that uses a gas boiler and grid power without TEM-PEMFC. The result shows that TEMs can operate with a mean coefficient of performance of 2.0 when utilized for auxiliary heater in the cooling season. In addition, TEMs generate additional electricity with a mean power generation efficiency of 0.9%. Finally, the proposed system can save the 10.6% of annual primary energy compared with the conventional LD-IDECOAS. Therefore, the advantages of using TEM-PEMFC as heating and energy harvesting components were verified.     

Multi-stack coupled energy management strategy of a PEMFC based-CCHP system applied to data centers

Aiming at the power fluctuation and mismatch of the combined cooling, heating, and power (CCHP) system based on proton exchange membrane fuel cells (PEMFCs) and adsorption chiller, this study proposes a multi-stack coupled power supply strategy. The PEMFC stacks are divided into types Ⅰ, Ⅱ, and Ⅲ to meet the electric load and cooling load of the data center, and the heat requirements of the system. Meanwhile, economic analysis is conducted on the single-stack energy supply strategy and the multi-stack coupled energy supply strategy. The results show that with the multi-stack coupling power supply strategy, the cooling power and electric power almost completely match the load of the data center, without power fluctuations and overshoot. By smoothing the PID control results of the current of the stacks-Ⅲ, the heating power fluctuation is significantly reduced, and the maximum overshoot does not exceed 0.5 kW. Therefore, the strategy is conducive to the stable operation of the PEMFC stack and improves the lifetime of the system. Considering investment costs, maintenance costs, hydrogen costs, and electricity benefits, the multi-stack coupled energy supply strategy can save about 6.1 × 10⁵ $ per year. In summary, the multi-stack coupled energy supply strategy has advantages in system lifetime, operational stability, and economy.     

Analysis on a hybrid desiccant air-conditioning system

Hybrid desiccant-assisted preconditioner and split cooling coil system, which combines the merits of moisture removal by desiccant and cooling coil for sensible heat removal, is a potential alternative to conventional vapor compression cooling systems. In this paper, experiments on a hybrid desiccant air-conditioning system, which is actually an integration of a rotary solid desiccant dehumidification and a vapor compression air-conditioning unit, had been carried out. It is found that, compared with the conventional VC (vapor compression) system, the hybrid desiccant cooling system economizes 37.5% electricity powers when the process air temperature and relative humidity are maintained at 30 °C, and 55% respectively. The reason why the hybrid desiccant cooling system features better performance relative to the VC system lies in the improvement brought about in the performance of the evaporator in VC unit due to desiccant dehumidification. A thermodynamic model of the hybrid desiccant system with R-22 as the refrigerant has been developed and the impact of operating parameters on the sensible heat ratio of the evaporator and the electric power saving rate has been analyzed. It is found that a majority of evaporators can operate in the dry condition even if the regeneration temperature is lower (i.e. 80 °C).     

Assessment and optimization of an integrated energy system with electrolysis and fuel cells for electricity,cooling and hydrogen production using various optimization techniques

In this research study, a novel integrated solar based combined, cooling, heating and, power (CCHP) is proposed consisting of Parabolic trough solar collectors (PTSC) field, a dual-tank molten salt heat storage, an Organic Rankine Cycle (ORC), a Proton exchange membrane fuel cell (PEMFC), a Proton exchange membrane electrolyzer (PEME), and a single effect Li/Br water absorption chiller. Thermodynamics and economic relations are used to analyze the proposed CCHP system. The mean of Tehran solar radiation as well as each portion of solar radiation during 24 h in winter is obtained from TRNSYS software to be used in PTSC calculations. A dynamic model of the thermal storage unit is assessed for proposed CCHP system under three different conditions (i.e., without thermal energy storage (TES), with TES and with TES + PEMFC). The results demonstrate that PEMFC has the ability to improve the power output by 10% during the night and 3% at sunny hours while by using TES alone, the overnight power generation is 86% of the power generation during the sunny hours. The optimum operating condition is determined via the NSGA-II algorithm with regards to exergy efficiency and total cost rate as objective functions where the optimum values are 0.058 ($/s) and 80%, respectively. The result of single objective optimization is 0.044 ($/s) for the economic objective in which the exergy efficiency is at its lowest value (57.7%). In addition, results indicate that the amount of single objective optimization based on exergetic objective is 88% in which the total cost rate is at its highest value (0.086 $/s). The scattered distribution of design parameters and the decision variables trend are investigated. In the next step, five different evolutionary algorithms namely NSGA-II, GDE3, IBEA, SMPSO, and SPEA2 are applied, and their Pareto frontiers are compared with each other.     

Thermodynamic and economic assessment of a PEMFC-based micro-CCHP system integrated with geothermal-assisted methanol reforming

A micro-combined cooling heating and power (CCHP) system integrated with geothermal-assisted methanol reforming and incorporating a proton exchange membrane fuel cell (PEMFC) stack is presented. The novel CCHP system consists of a geothermal-based methanol steam reforming subsystem, PEMFC, micro gas turbine and lithium bromide (LiBr) absorption chiller. Geothermal energy is used as a heat source to drive methanol steam reforming to produce hydrogen. The unreacted methanol and hydrogen are efficiently utilized via the gas turbine and PEMFC to generate electricity, respectively. For thermodynamic and economic analysis, the effects of the thermodynamic parameters (geothermal temperature and molar ratio of water to methanol) and economic factors (such as methanol price, hydrogen price and service life) on the proposed system performance are investigated. The results indicate that the ExUF (exergy utilization factor the exergy utilization factor), TPES (trigeneration primary energy saving) and energy efficiency of the novel system can be reached at 8.8%, 47.24% and 66.3%, respectively; the levelized cost of energy is 0.0422 $/kWh, and the annual total cost saving ratio can be reached at 20.9%, compared with the conventional system. The novel system achieves thermodynamic and economic potential, and provides an alternative and promising way for efficiently utilizing abundant geothermal energy and methanol resources.     

High efficiency micro trigeneration systems

This work focuses on micro polygeneration research in three areas: prime movers, cooling devices, and novel system integration options. An original analysis of matching prime mover heat sources to thermally-driven devices is presented, and waste heat for eight prime movers used in micro CHP is characterized using a T-Q diagram. “Micro” is roughly defined as 1–50 kW electric, and an emphasis is placed on systems of <5 kW electric. With regard to cooling technologies, the increasing demand for tight control of humidity and ventilation represents distinct opportunities for integrated energy systems. Polygeneration can provide efficient ways to accomplish better comfort, such as by separating sensible and latent cooling loads. The increasing legislation dealing with GWP of refrigerants for vapor compression systems also provides a driving force for thermally-activated cooling. Advances are being made both for vapor compression and thermally-activated cooling cycles, and a review is provided of research in the areas of transcritical cycles, subcooling, adsorption cooling, desiccant dehumidification, and integrated systems. Many new adsorbent working pairs and desiccant dehumidification materials have driving temperatures low enough to utilize heat from reciprocating engine coolant or even a vapor compression condenser. This enables smaller installations to benefit from combined cooling, heating and power; and opens new possibilities for separating sensible and latent cooling to extend the operating range of sorption-based heat pumps and improve solar cooling efficiency.     

Performance comparison between a solar driven rotary desiccant cooling system and conventional vapor compression system (performance study of desiccant cooling)

Solar driven rotary desiccant cooling systems have been widely recognized as alternatives to conventional vapor compression systems for their merits of energy-saving and being eco-friendly. In the previous paper, the basic performance features of desiccant wheel have been discussed. In this paper, a solar driven two-stage rotary desiccant cooling system and a vapor compression system are simulated to provide cooling for one floor in a commercial office building in two cities with different climates: Berlin and Shanghai. The model developed in the previous paper is adopted to predict the performance of the desiccant wheel. The objectives of this paper are to evaluate and compare the thermodynamic and economic performance of the two systems and to obtain useful data for practical application. Results show that the desiccant cooling system is able to meet the cooling demand and provide comfortable supply air in both of the two regions. The required regeneration temperatures are 55 °C in Berlin and 85 °C in Shanghai. As compared to the vapor compression system, the desiccant cooling system has better supply air quality and consumes less electricity. The results of the economic analysis demonstrate that the dynamic investment payback periods are 4.7 years in Berlin and 7.2 years in Shanghai.     

Cooling potential of ventilated PV façade and solar air heaters combined with a desiccant cooling machine

Thermal energy collected from a PV-solar air heating system is being used to provide cooling for the Mataro Library, near Barcelona. The system is designed to utilise surplus heat available from the ventilated PV facade and PV shed elements during the summer season to provide building cooling. A desiccant cooling machine was installed on the library roof with an additional solar air collector and connected to the existing ventilated PV façade and PV sheds. The desiccant cooling cycle is a novel open heat driven system that can be used to condition the air supplied to the building interior. Cooling power is supplied to the room space within the building by evaporative cooling of the fresh air supply, and the solar heat from the PV-solar air heating system provides the necessary regeneration air temperature for the desiccant machine. This paper describes the system and gives the main technical details. The cooling performance of the solar powered desiccant cooling system is evaluated by the detailed modelling of the complete cooling process. It is shown that air temperature level of the PV-solar air heating system of 70 °C or more can be efficiently used to regenerate the sorption wheel in the desiccant cooling machine. A solar fraction of 75% can be achieved by such an innovative system and the average COP of the cooling machine over the summer season is approximate 0.518.     

Micro tri-generation system for indoor air conditioning in the Mediterranean climate

Mediterranean countries show two specific features regarding air-conditioning of buildings: a high—and growing—cooling load and high relative humidity, at least in coastal zones. In this contribution we report on the development of an innovative micro scale tri-generation system (power + heating + cooling), equipped with a rotor based desiccant system adapted to the Mediterranean conditions which receives heat for the desiccant regeneration from a combined heat and power (CHP) cycle.The paper presents the design of the advanced desiccant air handling unit which uses a high efficient combination of a vapor compression chiller working at a high evaporator temperature and a desiccant wheel (silica gel). The electricity of the chiller is supplied by the CHP system and the heat to regenerate the desiccant is the waste heat of the CHP. System simulations have been used to optimize the hydraulic design and the operation strategy in order to minimize operation costs and maximize energy savings. Some new component models, e.g. for the advanced desiccant cycle were developed for this purpose. The final design of the entire system consisting of the CHP system, the vapor compression chiller, the advanced desiccant air handling unit and the load system is described. The load system is composed of an air duct network with induction units and a chilled water network with fan-coils in the office rooms.Regarding energy performance results indicate an electricity saving >30% in comparison to state-of-the-art solutions based on conventional technology.     

Engine-driven hybrid air-conditioning system

A hybrid air-conditioning system that combines an engine-driven chiller with desiccant dehumidification was configured and experimentally tested to provide reliable data for energy consumption and operation cost. The engine performance and the desiccant wheel performance were measured and a numeric model previously set up for dehumidification capacity prediction was validated. For a reference building, the results based upon measured data show that under present electricity/gas price ratio, more than 40% of operation cost can be saved by the hybrid system.     

Use of desiccant dehumidification to improve energy utilization in air-conditioning systems in Beirut

Humidity and indoor moist surrounding affect air cleanliness and protects harmful microorganisms when relative humidity is above 70%. In humid climates, the humidity issues are a major contributor to energy inefficiency in HVAC devices. The use of liquid desiccant dehumidification systems of supply air is a viable alternative to reduce the latent heat load on the HVAC system and improve efficiency. Thermal energy, at a temperature as low as 40–50°C, required for the operation of a liquid desiccant hybrid air conditioner can be efficiently obtained using a flat-plate solar collector. In this work a model of a solar-operated liquid desiccant system (using calcium Chloride) for air dehumidification is developed. The system utilizes packed beds of counter flow between an air stream and a solution of liquid desiccant for air dehumidification and solution regeneration. The desiccant system model is integrated with a solar heat source for performance evaluation at a wide range of recorded ambient conditions for Beirut city. Standard mass and energy balances are performed on the various components of the system and a computer simulation program is developed for the integrated system analysis. The desiccant system of the current study replaces a 3 TR (10.56 kW) vapour compression unit for a typical house as low latent load application, and is part of a hybrid desiccant–vapour compression system for a high latent load application, namely a small restaurant with an estimated cooling load of 11.39 TR (40 kW), including reheat. The relevant parameters of the desiccant system are optimized at peak load, and it is found out that there is an important energy saving if the ratio of the air flow rate in the regenerator to that in the dehumidifier is about 0.3 to 0.4. The COP of the desiccant unit is 0.41 for the house, and 0.45 for the restaurant. The size of the vapor compression unit of the restaurant is reduced to 8 TR when supplemented by a desiccant system. The performance is studied of the desiccant system integrated with a solar collector system and an auxiliary natural gas heater to heat the regenerator. The transient simulation of the solar desiccant system is performed for the entire cooling season. The solar fraction for the house is equal to 0.25, 0.47, and 0.68 for a collector area of 28.72, 57.44, and 86.16 m², respectively. The solar fraction for the restaurant is 0.19, 0.38, and 0.54, for the same collector areas. The life cycle savings for the house run solely on desiccant system were positive only if natural gas is available at a cheap price. For the restaurant, the economic benefit of the desiccant system is positive, because the need for reheat in the vapor compression system is eliminated. For a gas price of 0.5638 $/kg, the payback period for the restaurant turned out to be immediate if the energy is supplied solely by natural gas, and 11 years if an 86.16 m² solar collector is implemented to reduce the fuel consumption. Copyright © 2003 John Wiley & Sons, Ltd.     

Solar hybrid air-conditioning system for high temperature cooling in subtropical city

Although solar energy is able to power the heat-driven refrigeration, its contribution is quite limited due to the conventional cooling requirement. In building air-conditioning, it is common to supply low temperature chilled water, usually in 5–7 °C. If this temperature can be elevated, it would enhance the effectiveness to harness solar energy and minimize auxiliary heating. Solar refrigeration would then be more effective through high temperature cooling, by providing 15–18 °C chilled water instead. In such provision, radiant ceiling cooling can be coupled to handle the space cooling load, particularly space sensible load. And the space latent load and ventilation load are handled by a separate dehumidification provision, like the heat-driven desiccant dehumidification. Therefore, a solar hybrid air-conditioning system is formulated, using adsorption refrigeration, chilled ceilings and desiccant dehumidification. In this study, the year-round performances of the proposed solar hybrid air-conditioning systems were evaluated for two typical office types. The performance metrics include the solar fraction, coefficient of performance, solar thermal gain, primary energy consumption and indoor conditions. Comparative study was conducted for the hybrid air-conditioning system worked with the three common types of chilled ceilings, namely the chilled panels, passive chilled beams and active chilled beams. The solar hybrid air-conditioning system was also benchmarked with the conventional vapour compression refrigeration for office use. It is found that the proposed solar hybrid air-conditioning system is technically feasible through high temperature cooling. Among the three types of chilled ceilings, the passive chilled beams is the most energy-efficient option to work with the solar adsorption refrigeration for space conditioning in the subtropical city.     

Study of a solar powered solid adsorption–desiccant cooling system used for grain storage

A hybrid solar cooling system, which combines the technologies of rotary desiccant dehumidification and solid adsorption refrigeration, has been proposed for cooling grain. The key components of the system are a rotary desiccant wheel and a solar adsorption collector. The former is used for dehumidification and the later acts as both an adsorption unit and a solar collector. The heating load from sunshine can thus be reduced to a greater extent since the solar adsorption collector is placed on the roof of the grain depot. Compared with the solid adsorption refrigeration system alone, the new hybrid system performs better. Under typical conditions, the coefficient of performance of the system is >0.4 and the outlet temperature is <20°C. It is believed that the system can be used widely in the regions with abundant solar resources due to such advantages as environmental protection, energy saving and low operation costs. Additionally, some parameters, for example, ambient conditions, the effectiveness of the heat exchanger and evaporative cooler, mass air-flow rate, etc., which affect system performance, are also analyzed.     

Comprehensive assessment on a hybrid PEMFC multi-generation system integrated with solar-assisted methane cracking

A hybrid proton exchange membrane fuel cell (PEMFC) multi-generation system model integrated with solar-assisted methane cracking is established. The whole system mainly consists of a disc type solar Collector, PEMFC, Organic Rankine cycle (ORC). Methane cracking by solar energy to generate hydrogen, which provides both power and heat. The waste heat and hydrogen generated during the reaction are efficiently utilized to generate electricity power through ORC and PEMFC. The mapping relationships between thermodynamic parameters (collector temperature and separation ratio) and economic factors (methane and carbon price) on the hybrid system performance are investigated. The greenhouse gas (GHG) emission reductions and levelized cost of energy (LCOE) are applied to environmental and economic performance evaluation. The results indicate that the exergy utilization factor (EXUF) and energy efficiency of the novel system can reach 21.9% and 34.6%, respectively. The solar-chemical energy conversion efficiency reaches 40.3%. The LCOE is 0.0733 $/kWh when the carbon price is 0.725 $/kg. After operation period, the GHG emission reduction and recovered carbon can reach 4 × 10⁷ g and 14,556 kg, respectively. This novel hybrid system provides a new pathway for the efficient utilization of solar and methane resources and promotes the popularization of PEMFC in zero energy building.     

Comparative study between parallel and counter flow configurations between air and falling film desiccant in the presence of nanoparticle suspensions

A comparative numerical study is employed to investigate the heat and mass transfer between air and falling film desiccant in parallel and counter flow configurations. Nanoparticles suspensions are added to the falling film desiccant to study heat and mass transfer enhancements. The numerical results show that the parallel flow channel provides better dehumidification and cooling processes of the air than counter flow configuration for a wide range of pertinent parameters. Low air Reynolds number enhances the dehumidification and cooling rates of the air and high air Reynolds number improves the regeneration rate of the liquid desiccant. An increase in the channel height results in enhancing the dehumidification and cooling processes of air and regeneration rate of liquid desiccant. The dehumidification and cooling rates of air are improved with an increase in the volume fraction of nanoparticles and dispersion factor. Copyright © 2003 John Wiley & Sons, Ltd.     

Opportunities and challenges for thermally driven hydrogen production using reverse electrodialysis system

Ongoing and emerging renewable energy technologies mainly produce electric energy and intermittent power. As the energy economy relies on banking energy, there is a rising need for chemically stored energy. We propose heat driven reverse electrodialysis (RED) technology with ammonium bicarbonate (AmB) as salt for producing hydrogen. The study provides the authors’ perspective on the commercial feasibility of AmB RED for low grade waste heat (333 K–413 K) to electricity conversion system. This is to our best of knowledge the only existing study to evaluate levelized cost of energy of a RED system for hydrogen production. The economic assessment includes a parametric study, and a scenario analysis of AmB RED system for hydrogen production. The impact of various parameters including membrane cost, membrane lifetime, cost of heating, inter-membrane distance and residence time are studied. The results from the economic study suggests, RED system with membrane cost less than 2.86 €/m², membrane life more than 7 years and a production rate of 1.19 mol/m²/h or more are necessary for RED to be economically competitive with the current renewable technologies for hydrogen production. Further, salt solubility, residence time and inter-membrane distance were found to have impact on levelized cost of hydrogen, LCH. In the present state, use of ammonium bicarbonate in RED system for hydrogen production is uneconomical. This may be attributed to high membrane cost, low (0.72 mol/m²/h) hydrogen production rate and large (1,281,436 m²) membrane area requirements. There are three scenarios presented the present scenario, market scenario and future scenario. From the scenario analysis, it is clear that membrane cost and membrane life in present scenario controls the levelized cost of hydrogen. In market scenario and future scenario the hydrogen production rate (which depends on membrane properties, inter-membrane distance etc.), the cost of regeneration system and the cost of heating controls the levelized cost of hydrogen. For a thermally driven RED system to be economically feasible, the membrane cost not more than 20 €/m²; hydrogen production rate of 3.7 mol/m²/h or higher and cost of heating not more than 0.03 €/kWh for low grade waste heat to hydrogen production.     

Investigation of electricity,and hydrogen generation and economical analysis of PV-T depending on different water flow rates and conditions

In this paper, the electricity and hydrogen generation performance of a system contains a cooled photovoltaic-thermal (PV-T) panel, a parabolic trough solar collector (PTSC), and a proton exchange membrane (PEM) for investigation thermodynamically. The proposed system is also evaluated with respect to energetic and exergetic efficiency. Meanwhile, the water, whose temperature rises by cooling the PV-T, is sent to the PTSCs to reach a higher temperature. Then, it is stored in a storage tank for domestic use. This parametric study is carried out for two different operating conditions. Firstly, the flow rate of the water used to cool the PV-T is gradually increased from 5 g/s to 50 g/s and the simulations are made according to these mass flow rates. Also, an economical analysis of the PV-T is found for these ten mass flow rates, Secondly, the efficiency of the system is determined by changing the ambient temperature from 0 °C to 30 °C under 400 W/m² solar radiation and by fixing the cooling water flow rate to 50 g/s. All the analyses of the system are made utilizing the Engineering Equation Solver. It is aimed to enhance the hydrogen production performance of the system by increasing the electricity production of the PV-T by removing the excess heat of the solar cells with the water flow. As the flow rate of the cooling water increased, the electrical energy generated by the PV-T increased, so the highest electricity production is achieved when the flow rate was 50 g/s. Also, while the cooling mass flow rate is increased from 5 g/s to 50 g/s, the payback time of PV-T decreases from 8.093 to 7.734 years. The electricity produced is delivered to PEM and hydrogen was produced by electrolysis of water heated by PTSC. As a result, it is obtained that the electricity and hydrogen generation of the system is higher in the summer months than in the other nine months. Accordingly, it is found that while 351.1 g of hydrogen is produced in July, only 144.1 g of hydrogen could be produced in January. On the other hand, it is found that the amount of electricity and hydrogen produced by the system decreases as the ambient temperature increases. However, it was found that the electricity and hydrogen production performance of the system increased when the wind energy coming to the PV-T's surface increased from 1 m/s to 5 m/s.     

Thermodynamic analysis and assessment of novel ORC- DEC integrated PEMFC system for liquid hydrogen fueled ship application

Proton-exchange membrane fuel cell (PEMFC) and liquid hydrogen are gaining attention as a power generation system and alternative fuel of ship. This study proposes a novel PEMFC system, integrated with the organic Rankine cycle–direct expansion cycle (ORC-DEC), which exploits cold exergy from liquid hydrogen and low temperature waste heat generated by the PEMFC for application in a liquid hydrogen fueled ship. A thermodynamic model of each subsystem was established and analyzed from the economic, energy, and exergy viewpoints. Moreover, parametric analysis was performed to identify the effects of certain key parameters, such as the working fluid in the ORC, pressure exerted by the fuel pump, cooling water temperature of the PEMFC, and the stack current density on the system performance. The results showed that the proposed system could generate 221 kW of additional power. The overall system achieved an exergy and energy efficiency of 43.52 and 40.45%, respectively. The PEMFC system had the largest exergy destruction, followed by the cryogenic heat exchanger. Propane showed the best performance among the several investigated ORC working fluids and the system performance improved with the increase in the cooling water temperature of the PEMFC. The economic analysis showed that the average payback time of ORC-DEC was 11.2 years and the average net present value (NPV) was $295,268 at liquid hydrogen costing $3 to $7, showing the potential viability of the system.     

Technical development of rotary desiccant dehumidification and air conditioning: A review

Rotary desiccant air conditioning system, which combines the technologies of desiccant dehumidification and evaporative cooling, is advantageous in being free from CFCs, using low grade thermal energy and controlling humidity and temperature separately. Compared with conventional vapor compression air conditioning system, it preserves the merits of environment-friendly, energy saving, healthy, comfortable, etc. Ongoing research and development works suggest that new desiccant materials and novel system configurations have significant potential for improving the performance and reliability and reducing the cost and size of rotary desiccant dehumidification and air conditioning system, thereby increasing its market competitiveness and breaking out the current fairly small niche market. For the purpose of providing an overview of recent efforts on these issues and showing how rotary desiccant air conditioning systems can be designed and coupled to available thermal energy, this paper presents and analyzes the status of rotary desiccant dehumidification and air conditioning in the following three aspects: the development of advanced desiccant materials, the optimization of system configuration and the utilization of solar energy and other low grade heat sources, such as solar energy, district heating, waste heat and bioenergy. Some key problems to further push forward the research and development of this technology are also summarized.     

Tuning of PEM fuel cell model parameters for prediction of steady state and dynamic performance under various operating conditions

Many models are available with various degrees of complexity to study the behaviour of Proton Exchange Membrane Fuel Cells (PEMFC) under varying operating conditions. To our knowledge no model has been developed from single cells to multiple cells with increased electrode area for PEMFC stacks along with power conditioners, by considering the dynamic characteristics of the fuel cells under the influence of stoichiometry, humidity ratio and their response during their integration with power conditioners. We have developed a model using Matlab to study the transient response of the cell for 30 cm², which has been extended to a multicell stack of 1.2 kW capacity of electrode area 150 cm². The developed model has been validated using PEMFC single cells and stacks, by considering partial pressure of hydrogen, oxygen, and water as three states, anode fuel utilization and all three losses. This model is proposed to evaluate the transient response of all the stacks developed at Centre for Fuel Cell Technology (CFCT) ranging from a few watts to 10 kW that are integrated with various power conditioners depending on the applications.