Integration of solid-oxide fuel cells and absorption refrigeration for efficient combined cooling, heat and power production

Abstract Combined cooling, heating and power (CCHP) systems are characterized by a substantially higher energy-utilization efficiency compared to standalone systems. In this study, an integrated system comprising a solid-oxide fuel cell (SOFC), hot-water storage tank (HWST) and absorption refrigeration (AR) cycle is considered. The SOFC model was developed in Aspen Plus®. It was used to determine the thermodynamic properties of the exhaust gas that was then used to provide heat for the HWST and to drive the AR cycle. Thermodynamic models for the AR cycles were developed in Engineering Equation Solver, considering LiBr–H2O and NH3–H2O as working fluids. The sensitivity analysis of a number of SOFC output parameters has been carried out. The most optimal case was characterized with the coefficient of performance (COP) and CCHP efficiency of 0.806 and 85.2% for the LiBr–H2O system, and 0.649 and 83.6% for the NH3–H2O system, respectively. Under such optimal operating conditions, the SOFC was characterized by the net electrical efficiency of 57.5% and the net power output of 123.66 kW. Data from the optimal solution were used to perform the thermodynamic study and sensitivity analysis to assess the influence of different absorption cycle operating conditions and to identify possible applications for the considered integrated systems.

Download Full-text

Performance Analysis of a Small-Scale Biogas-Based Trigeneration Plant: An Absorption Refrigeration System Integrated to an Externally Fired Microturbine

Energies ◽

10.3390/en12203830 ◽

2019 ◽

Vol 12 (20) ◽

pp. 3830 ◽

Cited By ~ 1

Author(s):

Villarroel-Schneider ◽

Malmquist ◽

Araoz ◽

Martí-Herrero ◽

Martin

Keyword(s):

Performance Analysis ◽

Primary Energy ◽

Hot Water ◽

Energy Utilization ◽

Coefficient Of Performance ◽

Small Scale ◽

Absorption Refrigeration ◽

Refrigeration System ◽

Absorption Refrigeration System ◽

A Performance

Trigeneration or combined cooling, heat and power (CCHP) systems fueled by raw biogas can be an interesting alternative for supplying electricity and thermal services in remote rural areas where biogas can be produced without requiring sophisticated equipment. In this sense, this study considers a performance analysis of a novel small-scale CCHP system where a biogas-fired, 5 kWel externally fired microturbine (EFMT), an absorption refrigeration system (ARS) and heat exchangers are integrated for supplying electricity, refrigeration and hot water demanded by Bolivian small dairy farms. The CCHP solution presents two cases, current and nominal states, in which experimental and design data of the EFMT performance were considered, respectively. The primary energy/exergy rate was used as a performance indicator. The proposed cases show better energy performances than those of reference fossil fuel-based energy solutions (where energy services are produced separately) allowing savings in primary energy utilization of up to 31%. Furthermore, improvements in electric efficiency of the EFMT and coefficient of performance (COP) of the ARS, identified as key variables of the system, allow primary energy savings of up to 37%. However, to achieve these values in real conditions, more research and development of the technologies involved is required, especially for the EFMT.

Download Full-text

A 2-D model for Intermediate Temperature Solid Oxide Fuel Cells Preliminarily Validated on Local Values

Catalysts ◽

10.3390/catal9010036 ◽

2019 ◽

Vol 9 (1) ◽

pp. 36 ◽

Cited By ~ 9

Author(s):

Bruno Conti ◽

Barbara Bosio ◽

Stephen John McPhail ◽

Francesca Santoni ◽

Davide Pumiglia ◽

...

Keyword(s):

Fuel Cells ◽

Operating Conditions ◽

Solid Oxide ◽

Intermediate Temperature ◽

Physical Parameters ◽

Local Concentration ◽

Oxide Fuel ◽

Molten Carbonate ◽

Experimental Apparatus ◽

Set Up

Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC) technology offers interesting opportunities in the panorama of a larger penetration of renewable and distributed power generation, namely high electrical efficiency at manageable scales for both remote and industrial applications. In order to optimize the performance and the operating conditions of such a pre-commercial technology, an effective synergy between experimentation and simulation is fundamental. For this purpose, starting from the SIMFC (SIMulation of Fuel Cells) code set-up and successfully validated for Molten Carbonate Fuel Cells, a new version of the code has been developed for IT-SOFCs. The new release of the code allows the calculation of the maps of the main electrical, chemical, and physical parameters on the cell plane of planar IT-SOFCs fed in co-flow. A semi-empirical kinetic formulation has been set-up, identifying the related parameters thanks to a devoted series of experiments, and integrated in SIMFC. Thanks to a multi-sampling innovative experimental apparatus the simultaneous measurement of temperature and gas composition on the cell plane was possible, so that a preliminary validation of the model on local values was carried out. A good agreement between experimental and simulated data was achieved in terms of cell voltages and local temperatures, but also, for the first time, in terms of local concentration on the cell plane, encouraging further developments. This numerical tool is proposed for a better interpretation of the phenomena occurring in IT-SOFCs and a consequential optimization of their performance.

Download Full-text

Numerical investigations to determine the optimal operating conditions for 1 kW-class flat-tubular solid oxide fuel cell stack

Energy ◽

10.1016/j.energy.2017.09.082 ◽

2017 ◽

Vol 141 ◽

pp. 673-691 ◽

Cited By ~ 9

Author(s):

Kashif Rashid ◽

Sang Keun Dong ◽

Muhammad Taqi Mehran

Keyword(s):

Fuel Cell ◽

Solid Oxide Fuel Cell ◽

Operating Conditions ◽

Solid Oxide ◽

Oxide Fuel ◽

Optimal Operating ◽

Fuel Cell Stack ◽

Numerical Investigations

Download Full-text

Studying a Hybrid System Based on Solid Oxide Fuel Cell Combined With an Air Source Heat Pump and With a Novel Heat Recovery

Journal of Electrochemical Energy Conversion and Storage ◽

10.1115/1.4041864 ◽

2018 ◽

Vol 16 (2) ◽

Author(s):

Giulio Vialetto ◽

Marco Noro ◽

Masoud Rokni

Keyword(s):

Fuel Cell ◽

Solid Oxide Fuel Cell ◽

Electric Power ◽

Heat Pump ◽

Heat Recovery ◽

Research Work ◽

Solid Oxide ◽

Coefficient Of Performance ◽

Oxide Fuel ◽

Air Source Heat Pump

In this paper, a new heat recovery for a microcogeneration system based on solid oxide fuel cell and air source heat pump (HP) is presented with the main goal of improving efficiency on energy conversion for a residential building. The novelty of the research work is that exhaust gases after the fuel cell are first used to heat water for heating/domestic water and then mixed with the external air to feed the evaporator of the HP with the aim of increasing energy efficiency of the latter. This system configuration decreases the possibility of freezing of the evaporator as well, which is one of the drawbacks for air source HP in Nordic climates. A parametric analysis of the system is developed by performing simulations varying the external air temperature, air humidity, and fuel cell nominal power. Coefficient of performance (COP) can increase more than 100% when fuel cell electric power is close to its nominal (50 kW), and/or inlet air has a high relative humidity (RH) (close to 100%). Instead, the effect of mixing the exhausted gases with air may be negative (up to −25%) when fuel cell electric power is 20 kW and inlet air has 25% RH. Thermodynamic analysis is carried out to prove energy advantage of such a solution with respect to a traditional one, resulting to be between 39% and 44% in terms of primary energy. The results show that the performance of the air source HP increases considerably during cold season for climates with high RH and for users with high electric power demand.

Download Full-text

Calculation algorithm for operating parameters of steam-compressive chilling machine with adsorptive chillling unit

Computer modeling analysis control optimization ◽

10.32434/2521-6406-2020-8-2-3-9 ◽

2020 ◽

Vol 8 (2) ◽

pp. 3-9

Author(s):

E.A. Belyanovskaya ◽

◽

G.M. Pustovoy ◽

A.I. Sklyarenko ◽

M.P. Sukhyy ◽

...

Keyword(s):

Silica Gel ◽

Thermal Energy ◽

Sodium Acetate ◽

Operating Conditions ◽

Energy Utilization ◽

Coefficient Of Performance ◽

Adsorptive Capacity ◽

Operating Parameters ◽

Adsorption Refrigeration ◽

Refrigeration Unit

The work is focused on the development of an effective algorithm for calculating the operational characteristics of a steamcompressive chilling machine with an adsorptive chilling unit, which involves a cold box, an adsorber, an evaporator and a condenser, water being used as a refrigerant. An algorithm for calculating the operating parameters of the adsorptive chilling unit has been developed, which includes the determination of the cooling capacity of the steam compressor refrigeration unit, the heat load on the condenser, the power consumed by the compressor, the coefficient of performance of the steam compressor refrigeration unit, as well as the calculation of the mass of water, the mass of the adsorbent, the refrigerating capacity, the coefficient of performance of the adsorptive chilling unit and the coefficient of useful energy utilization of a steam compressive chilling machine with an adsorption chilling unit. The chilling capacity and the coefficient of performance of the adsorption chilling unit are estimated under the operating conditions of a typical steam compression chilling machine. The crucial factors affecting the efficiency of the adsorptive chilling unit are analyzed. It has been established that the chilling capacity, the coefficient of performance of the adsorption refrigeration module and the energy efficiency of the installation are determined by the thermal load on the condenser, and, therefore, by the mass of water that is desorbed and evaporated. The coefficient of performance of the adsorption chilling unit and the efficiency of the steam compressor chilling machine with the adsorptive chilling unit are estimated to be 0.878 and 4.64. The criteria for the selection of adsorbents for the adsorption module are analyzed. The temperature of regeneration is determined by the temperatures in the condenser, and the limit adsorption affects the mass of the adsorbent and the size of the adsorber. A comparison of the efficiency of adsorptive chi l l ing uni t based on silicoaluminophosphates and composite adsorbents «silica gel – sodium acetate» is carried out. The prospects of using composites «silica gel – СН3СООNa» are shown. The optimal composition of the composite was established, which corresponds to the minimal size of the adsorber, (80% sodium acetate and 20% silica gel). The prospects of using adsorptive conversion of thermal energy for utilization of low-potential thermal energy during the operation of steam compressive chilling machine are shown. Keywords: adsorptive conversion of heat energy, composite adsorbent, steam compressive chilling unit, adsorption, adsorptive capacity.

Download Full-text

1D thermodynamic modeling for a solid oxide fuel cell stack and parametric study for its optimal operating conditions

Energy Conversion and Management ◽

10.1016/j.enconman.2020.112614 ◽

2020 ◽

Vol 209 ◽

pp. 112614 ◽

Cited By ~ 3

Author(s):

Gyubin Min ◽

Young Joon Park ◽

Jongsup Hong

Keyword(s):

Fuel Cell ◽

Solid Oxide Fuel Cell ◽

Thermodynamic Modeling ◽

Parametric Study ◽

Operating Conditions ◽

Solid Oxide ◽

Oxide Fuel ◽

Optimal Operating ◽

Fuel Cell Stack

Download Full-text

An experimental investigation of solid oxide fuel cell performance at variable operating conditions

Thermal Science ◽

10.2298/tsci130617019t ◽

2016 ◽

Vol 20 (5) ◽

pp. 1421-1433 ◽

Cited By ~ 3

Author(s):

Ismet Tikiz ◽

Imdat Taymaz

Keyword(s):

Fuel Cell ◽

Flow Rate ◽

Operating Conditions ◽

Solid Oxide ◽

Cell Performance ◽

Oxide Fuel ◽

Nitrogen Flow ◽

Cell Temperature ◽

Hydrogen Flow ◽

Fuel Cell Performance

Cell temperature and selection of the reactant gases are crucial parameters for the design and optimization of fuel cell performance. In this study, effect of operating conditions on the performance of Solid Oxide Fuel (SOFC) has been investigated. Application of Response Surface Methodology (RSM) was applied to optimize operations conditions in SOFC. For this purpose, an experimental set up for testing of SOFC has been established to investigate the effect of Hydrogen, Oxygen, Nitrogen flow rates and cell temperature parameters on cell performance. Hydrogen flow rate, oxygen flow rate, nitrogen flow rate and cell temperature were the main parameters considered and they were varied between 0.25 and 1 L/min, 0.5 and 1 L/min, 0 and 1 L/min and 700-800 oC in the analyses respectively. The maximum power density was found as 0.572 W/cm2 in the experiments.

Download Full-text

A Simulation of the Solid Oxide Fuel Cell Electrochemical Light Off Phenomenon

Heat Transfer: Volume 4 ◽

10.1115/ht2005-72845 ◽

2005 ◽

Author(s):

Comas L. Haynes ◽

J. Chris Ford

Keyword(s):

Fuel Cell ◽

Thermal Cycling ◽

Solid Oxide Fuel Cell ◽

Heat Generation ◽

Operating Conditions ◽

Solid Oxide ◽

Oxide Fuel ◽

Cell Potential ◽

Start Up ◽

Electrochemical Transport

During latter-stage, “start-up” heating of a solid oxide fuel cell (SOFC) stack to a desired operating temperature, heat may be generated in an accelerating manner during the establishment of electrochemical reactions. This is because a temperature rise in the stack causes an acceleration of electrochemical transport given the typical Arrhenius nature of the electrolyte conductivity. Considering a potentiostatic condition (i.e., prescribed cell potential), symbiosis thus occurs because greater current prevalently leads to greater by-product heat generation, and vice versa. This interplay of the increasing heat generation and electrochemistry is termed “light off”, and an initial model has been developed to characterize this important thermal cycling phenomenon. The results of the simulation begin elucidating the prospect of using cell potential as well as other electrochemical operating conditions (e.g., reactants utilization) as dynamic controls in managing light off transients and possibly mitigating thermal cycling issues.

Download Full-text