Enhancement of the Electrical Efficiency of Commercial Fuel Cell Units by Means of an Organic Rankine Cycle: A Case Study

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Carlo De Servi ◽  
Stefano Campanari ◽  
Alessio Tizzanini ◽  
Claudio Pietra
Keyword(s):  
Fuel Cell ◽  
Power Output ◽  
High Performance ◽  
Waste Heat ◽  
Electrical Power ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Molten Carbonate ◽  
Levelized Cost Of Electricity ◽  
Electrical Efficiency

Among the various fuel cell (FC) systems, molten carbonate fuel cells (MCFC) are nowadays one of the most promising technologies, thanks to the lower specific costs and a very high electrical efficiency (net low heating value (LHV) electric efficiency in the range 45%–50% at MWel scale using natural gas as fuel). Despite this high performance, MCFC rejects to the ambient almost half of the fuel energy at about 350–400 °C. Waste heat can be exploited in a recovery Rankine cycle unit, thereby enhancing the electric efficiency of the overall system. Due to the temperature of the heat source and the relatively small power capacity of MCFC plants (from few hundred kWel to 10 MWel), steam Rankine cycle technology is uneconomical and less efficient compared to that of the organic Rankine cycle (ORC). The objective of this work is to verify the practical feasibility of the integration between a MCFC system (topping unit) and an ORC turbogenerator (bottoming unit). The potential benefits of the combined plant are assessed in relation to a commercial MCFC stack. In order to identify the most suitable working fluids for the ORC system, organic substances are considered and compared. The figure of merit is the maximum net power of the overall system. Finally, the economical benefits of the integration are determined by evaluating the levelized cost of electricity (LCOE) of the combined plant, with respect to the standalone MCFC system. In order to assess the economic viability of the bottoming power unit, two cases are considered. In the first one, the ORC power output is approximately 500 kWel; in the latter, about 1 MWel. Results show that the proposed solution can increase the electrical power output and efficiency of the plant by more than 10%, well exceeding 50% overall electrical efficiency. In addition, the LCOE of the combined power plant is 8% lower than the standalone MCFC system.

Installation and Performance Analysis of 125 kW Organic Rankine Cycle for Stationary Fuel Cell Power Plant

2016 ◽  
Author(s):  
Kwanghak Huh ◽  
Parsa Mirmobin ◽  
Shamim Imani
Keyword(s):  
Renewable Energy ◽  
Fuel Cell ◽  
Power Plant ◽  
Performance Analysis ◽  
Power Plants ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Molten Carbonate ◽  
And Performance

Installation and performance analysis of Thermapower™ 125MT Organic Rankine Cycle (ORC) System for recovery of waste heat from an existing Molten Carbonate Fuel Cell (MCFC) plant are presented. Over the last three years, about 100 MWe of new FC stationary power plants are in operation in Korea and more FC stationary power plants are on order and planned. The success of these fuel cell plants is their capability to supply both electricity and heat to customers. In order to promote renewable energy in Korea, the Korean Government is enforcing large power plants to supply electricity generated by renewable energy. The Korea Power Exchange (KPX) buys fuel cell generated electricity as renewable energy with higher price than other fossil fuel power plants [1]. Most of these FC plants supply electricity to power companies with their full capability, however valuable heat is wasted due to the limited demand, especially in summer season and off working hours or lack of heat pipe infrastructures. Due to the recent decrease in electricity price for renewable energy in Korea, the need for efficient utilization of waste heat is ever more demanding. In this study, 125 kWe ORC system is installed to 11.2 MWe FC power plant to demonstrate cost saving benefits. This FC Power plant has 4 units of 2.8 MWe fuel cell in operation and has capacity of producing 6.0 ton/h of 167°C steam. In order to install an ORC system to existing FC plant, their Balance of Plant (BoP) has to be modified since only excess steam is allow to be utilized by the ORC system, after supplying steam to their prime customer. Furthermore, site has distinctly hot and cold seasons, thus affecting condensing conditions and therefore ORC performance. Design considerations to accommodate varying ambient conditions as well as steam flow rate variation are presented and discussed.

scholarly journals Modeling and Simulation of a Proton Exchange Membrane Fuel Cell Alongside a Waste Heat Recovery System Based on the Organic Rankine Cycle in MATLAB/SIMULINK Environment

2021 ◽  
Vol 13 (3) ◽  
pp. 1218
Author(s):  
Sharjeel Ashraf Ansari ◽  
Mustafa Khalid ◽  
Khurram Kamal ◽  
Tahir Abdul Hussain Ratlamwala ◽  
Ghulam Hussain ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Waste Heat Recovery ◽  
Proton Exchange Membrane ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Proton Exchange ◽  
Waste Heat Recovery System ◽  
Recovery System ◽  
Exchange Membrane

The proton exchange membrane fuel cell (PEMFC) is the fastest growing fuel cell technology on the market. Due to their sustainable nature, PEMFCs are widely adopted as a renewable energy resource. Fabricating a PEMFC is a costly process; hence, mathematical modeling and simulations are necessary in order to fully optimize its performance. Alongside this, the feasibility of a waste heat recovery system based on the organic Rankine cycle is also studied and power generation for different operating conditions is presented. The fuel cell produces a power output of 1198 W at a current of 24A. It has 50% efficiency and hence produces an equal amount of waste heat. That waste heat is used to drive an organic Rankine cycle (ORC), which in turn produces an additional 428 W of power at 35% efficiency. The total extracted power hence stands at 1626 W. MATLAB/Simulink R2016a is used for modeling both the fuel cell and the organic Rankine cycle.

Waste Heat Recovery in a Cruise Vessel in the Baltic Sea by Using an Organic Rankine Cycle: A Case Study

2015 ◽  
Author(s):  
Fredrik Ahlgren ◽  
Maria E. Mondejar ◽  
Magnus Genrup ◽  
Marcus Thern
Keyword(s):  
Power Output ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Maritime Transportation ◽  
Working Fluid ◽  
Net Power Output

Maritime transportation is a significant contributor to SOx, NOx and particle matter emissions, even though it has a quite low CO2 impact. New regulations are being enforced in special areas that limit the amount of emissions from the ships. This fact, together with the high fuel prices, is driving the marine industry towards the improvement of the energy efficiency of current ship engines and the reduction of their energy demand. Although more sophisticated and complex engine designs can improve significantly the efficiency of the energy systems in ships, waste heat recovery arises as the most influent technique for the reduction of the energy consumption. In this sense, it is estimated that around 50% of the total energy from the fuel consumed in a ship is wasted and rejected in fluid and exhaust gas streams. The primary heat sources for waste heat recovery are the engine exhaust and the engine coolant. In this work, we present a study on the integration of an organic Rankine cycle (ORC) in an existing ship, for the recovery of the main and auxiliary engines exhaust heat. Experimental data from the operating conditions of the engines on the M/S Birka Stockholm cruise ship were logged during a port-to-port cruise from Stockholm to Mariehamn over a period of time close to one month. The ship has four main engines Wärtsilä 5850 kW for propulsion, and four auxiliary engines 2760 kW used for electrical consumers. A number of six load conditions were identified depending on the vessel speed. The speed range from 12–14 knots was considered as the design condition, as it was present during more than 34% of the time. In this study, the average values of the engines exhaust temperatures and mass flow rates, for each load case, were used as inputs for a model of an ORC. The main parameters of the ORC, including working fluid and turbine configuration, were optimized based on the criteria of maximum net power output and compactness of the installation components. Results from the study showed that an ORC with internal regeneration using benzene would yield the greatest average net power output over the operating time. For this situation, the power production of the ORC would represent about 22% of the total electricity consumption on board. These data confirmed the ORC as a feasible and promising technology for the reduction of fuel consumption and CO2 emissions of existing ships.

Thermodynamic and Performance Study of Solar Regenerative Organic Rankine Cycle System for Use in Residential Micro-Combined Heat and Power Generation

2019 ◽  
Author(s):  
Wahiba Yaïci ◽  
Evgueniy Entchev
Keyword(s):  
Power Generation ◽  
Energy Demand ◽  
Waste Heat ◽  
Residential Buildings ◽  
Electrical Power ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Heat And Power ◽  
Energy Sources ◽  
Performance Study

Abstract A continued increase in both energy demand and greenhouse gas emissions (GHGs) call for utilising energy sources effectively. In comparison with traditional energy set-ups, micro-combined heat and power (micro-CHP) generation is viewed as an effective alternative; the aforementioned system’s definite electrical and thermal generation may be attributed to an augmented energy efficiency, decreased capacity as well as GHGs percentage. In this regard, organic Rankine cycle (ORC) has gained increasing recognition as a system, which is capable for generating electrical power from solar-based, waste heat, or thermal energy sources of a lower quality, for instance, below 120 °C. This study focuses on investigating a solar-based micro-CHP system’s performance for use in residential buildings through utilising a regenerative ORC. The analysis will focus on modelling and simulation as well as optimisation of operating condition of several working fluids (WFs) in ORC in order to use a heat source with low-temperature derived from solar thermal collectors for both heat and power generation. A parametric study has been carried out in detail for analysing the effects of different WFs at varying temperatures and flowrates from hot and cold sources on system performance. Significant changes were revealed in the study’s outcomes regarding performance including efficiency as well as power obtained from the expander and generator, taking into account the different temperatures of hot and cold sources for each WF. Work extraction carried out by the expander and electrical power had a range suitable for residential building applications; this range was 0.5–5 kWe with up to 60% electrical isentropic efficiency and up to 8% cycle efficiency for 50–120 °C temperature from a hot source. The operation of WFs will occur in the hot source temperature range, allowing the usage of either solar flat plate or evacuated tube collectors.

scholarly journals Regression Models for the Evaluation of the Techno-Economic Potential of Organic Rankine Cycle-Based Waste Heat Recovery Systems on Board Ships Using Low Sulfur Fuels

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1378 ◽  
Author(s):  
Enrico Baldasso ◽  
Maria E. Mondejar ◽  
Ulrik Larsen ◽  
Fredrik Haglind
Keyword(s):  
Heat Recovery ◽  
Energy Production ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Levelized Cost Of Electricity ◽  
Cost Of Electricity ◽  
Levelized Cost ◽  
Low Sulfur

When considering waste heat recovery systems for marine applications, which are estimated to be suitable to reduce the carbon dioxide emissions up to 20%, the use of organic Rankine cycle power systems has been proven to lead to higher savings compared to the traditional steam Rankine cycle. However, current methods to estimate the techno-economic feasibility of such a system are complex, computationally expensive and require significant specialized knowledge. This is the first article that presents a simplified method to carry out feasibility analyses for the implementation of organic Rankine cycle waste heat recovery units on board vessels using low-sulfur fuels. The method consists of a set of regression curves derived from a synthetic dataset obtained by evaluating the performance of organic Rankine cycle systems over a wide range of design and operating conditions. The accuracy of the proposed method is validated by comparing its estimations with the ones attained using thermodynamic models. The results of the validation procedure indicate that the proposed approach is capable of predicting the organic Rankine cycle annual energy production and levelized cost of electricity with an average accuracy within 4.5% and 2.5%, respectively. In addition, the results suggest that units optimized to minimize the levelized cost of electricity are designed for lower engine loads, compared to units optimized to maximize the overall energy production. The reliability and low computational time that characterize the proposed method, make it suitable to be used in the context of complex optimizations of the whole ship’s machinery system.

Radial Turboexpander Optimization Over Discretized Heavy-Duty Test Cycles for Mobile Organic Rankine Cycle Applications

2016 ◽  
Author(s):  
Miles C. Robertson ◽  
Aaron W. Costall ◽  
Peter J. Newton ◽  
Ricardo F. Martinez-Botas
Keyword(s):  
Power Output ◽  
System Performance ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Heavy Duty ◽  
Design Code ◽  
Duty Cycles ◽  
Thermodynamic Conditions ◽  
Operating Points

Mobile organic Rankine cycle (MORC) systems represent a candidate technology for the reduction of fuel consumption and CO2 emissions from heavy-duty vehicles. Through the recovery of internal combustion engine waste heat, energy can be either compounded or used to power vehicle ancillary systems. Waste heat recovery systems have been shown to deliver fuel economy improvements of up to 13% in large diesel engines [1]. Whilst the majority of studies focus on individual component performance under specific thermodynamic conditions, there has been little investigation into the effects of expander specification across transient test cycles used for heavy-duty engine emission certification. It is this holistic approach which will allow prediction of the validity of MORC systems for different classes of heavy-duty vehicle, in addition to providing an indication of system performance. This paper first describes a meanline (one-dimensional simulation along a mean streamline within a flow passage) model for radial ORC turbines, divided into two main subroutines. An on-design code takes a thermodynamic input, before generating a candidate geometry for a chosen operating point. The efficacy of this design is then evaluated by an off-design code, which applies loss correlations to the proposed geometry to give a prediction of turbine performance. The meanline code is then executed inside a quasi-steady-state ORC cycle model, using reference emission test cycles to generate exhaust (heat source) boundary conditions, generated by a simulated 11.7L heavy-duty diesel engine. A detailed evaporator model, developed using the NTU-effectiveness method and single/two-phase flow correlations, provides accurate treatment of heat flow within the system. Together, these elements allow estimation of ORC system performance across entire reference emission test cycles. In order to investigate the limits of MORC performance, a Genetic Algorithm is applied to the ORC expander, aiming to optimize the geometry specification (radii, areas, blade heights, angles) to provide maximal time-averaged power output. This process is applied across the reference duty cycles, with the implications on power output and turbine geometry discussed for each. Due to the large possible variation in thermodynamic conditions within the turbine operating range a typical ideal-gas methodology (generating a single operating map for interpolation across all operating points) is no longer accurate — a complete off-design calculation must therefore be performed for all operating points. To reduce computational effort, discretization of the ORC thermodynamic inputs (temperature, mass flow rate) is investigated with several strategies proposed for reduced-order simulation. The paper concludes by predicting which heavy-duty emission test cycles stand to benefit the most from this optimization procedure, along with a comparison to existing transient results. Duty cycles containing narrow bands of operation were found to provide optimal performance, with a Constant-Speed, Variable-Load cycle achieving an average power output of 4.60 kW. Consideration is also given to the effectiveness of the methodology contained within the paper, the challenges of making ORC systems viable for mobile applications, along with suggestions for future research developments.

scholarly journals Configuration Selection of the Multi-Loop Organic Rankine Cycle for Recovering Energy from a Single Source

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1435
Author(s):  
Youyi Li ◽  
Tianhao Tang
Keyword(s):  
Heat Source ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Optimal Solution ◽  
Rankine Cycle ◽  
Optimal Number ◽  
Exergy Efficiency ◽  
Working Fluid ◽  
Levelized Cost Of Electricity ◽  
Multi Objective

The Organic Rankine Cycle (ORC) is a well-established way to recover energy from a single waste heat source. This paper aims to select the suitable configuration, number of loops, and working fluids for the Multi-Loop ORC (MLORC) by using multi-objective optimization. The thermodynamic and economic performance of MLORC in three various configurations was analyzed. Multi-objective optimizations of the series and parallel MLORC using different working fluid groups were conducted to find the optimal configuration, number of loops, and working fluid combination. The analysis results show that the series–parallel MLORC performed the worst among the three configurations. The optimization results reveal that series MLORC has a higher exergy efficiency than the parallel MLORC. The exergy efficiency of the optimal solution in series dual-loop, triple-loop, and quadruple-loop ORC is 9.3%, 7.98%, and 6.23% higher than that of parallel ORC, respectively. Furthermore, dual-loop is the optimal number of cycles for recovering energy from a single heat source, according to the grey relational grade. Finally, the series dual-loop ORC using cyclohexane\cyclohexane was the suitable configuration for utilizing a single waste heat source. The exergy efficiency and levelized cost of electricity of the series dual-loop ORC with the optimal parameters are 62.18% and 0.1509 $/kWh, respectively.

scholarly journals A Comprehensive Perspective of Waste Heat Recovery Potential from Solar Stirling Engines

2021 ◽  
Vol 313 ◽  
pp. 06001
Author(s):  
Siddharth Ramachandran ◽  
Naveen Kumar ◽  
Venkata Timmaraju Mallina
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Payback Period ◽  
Stirling Engine ◽  
Economic Feasibility ◽  
Levelized Cost Of Electricity ◽  
Stirling Engines

Despite the higher efficiency advantage, the cost reduction of PV technology has been more successful compared to the dish Stirling engine (DSE) due to the large market volume and sturdy competition. Irrespective of the types of source, there exists a potential of waste heat recovery from Stirling engines operating at higher temperature regime. Accordingly, to make DSE commercially viable and efficient, innovative ways such as hybridization (combing a bottoming cycle), Co-generation, Tri-generation etc. need to be explored. In this paper, the techno-economic feasibility of hybridization of a typical solar DSE with a bottoming organic Rankine cycle (ORC) via. a heat recovery vapour generator (HRVG) is explored. The overall energetic and exergetic efficiency of the DSE has been improved by 5.79% and 5.64% while recovering the waste heat through a bottoming ORC. The design and effective incorporation of the HRVG with cooler side of the Stirling engine is identified to be crucial for the overall exergetic performance of solar Stirling-ORC. Further, the economic feasibility of a solar String-ORC combination is evaluated in terms of levelized cost of electricity (LCOE) and payback period. Both LCOE and payback period are found to be in comparable range with the PV technology.

scholarly journals Exergy and Exergoeconomic Analyses of a Combined Power Producing System including a Proton Exchange Membrane Fuel Cell and an Organic Rankine Cycle

2019 ◽  
Vol 11 (12) ◽  
pp. 3264 ◽  
Author(s):  
S. M. Seyed Mahmoudi ◽  
Niloufar Sarabchi ◽  
Mortaza Yari ◽  
Marc A. Rosen
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Cell System ◽  
Exergy Efficiency ◽  
Proton Exchange ◽  
Operating Pressure ◽  
Cost Rate

Comprehensive exergy and exergoeconomic assessments are reported for a proposed power producing system, in which an organic Rankine cycle is employed to utilize the waste heat from the fuel cell stack. A complete mathematical model is presented for simulating the system performance while considering water management in the fuel cell. The simulation is performed for individual components of the fuel cell system, e.g., the compressor and humidifiers. A parametric study is conducted to evaluate the effects on the system’s thermodynamic and economic performance of parameters, such as the fuel cell operating pressure, current density, and turbine back pressure. The results show that an increase in the fuel cell operating pressure leads to a higher exergy efficiency and exergoeconomic factor for the overall system. In addition, it is observed that the overall exergy efficiency is 4.16% higher than the corresponding value that is obtained for the standalone fuel cell for the same value of fuel cell operating pressure. Furthermore, the results indicate that the compressor and condenser exhibit the worst exergoeconomic performance and that the exergoeconomic factor, the capital cost rate and the exergy destruction cost rate for the overall system are 40.8%, 27.21 $/h, and 39.49 $/h, respectively.

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