Marcin Wołowicz

Variant Analysis of the Structure and Parameters of SOFC Hybrid Systems

The paper presents a variant analysis of the structure of SOFC hybrid system. The systems are divided into two gropus: atmospheric and pressurized. The main parameter of such systems are indicated and commented. The comparison of various configurations is shown in a view of efficiency obtained. The ultra high efficiency (65% HHV, 72% LHV) of electricity production seems to be possible by systems like these.

Boosting the Efficiency of an 800 MW-Class Power Plant through Utilization of Low Temperature Heat of Flue Gases

This article presents an analysis on possible ways of utilizing low-temperature waste heat. If well-designed, this could contribute to increasing the efficiency of power plants without introducing many complex changes to the whole system. The main analysis focuses on the location of the regenerative heat exchanger in the facility. This could differ with varying temperatures of working media in the system. The base for investigations was a 800 MW-class power unit operating in off-design conditions and supplied with steam from an BB2400 boiler. Modifications to the model were made using commercially available software and by applying the Stodola equation and the SCC method. It allowed to determine the most suitable position for installing the low-temperature heat exchanger. Calculations for off-design conditions show that, after making some modifications to the system, both heat and electricity generation could be increased through the addition of a low-temperature heat exchanger.

Seasonal Thermal Energy Storage - A Size Selection

The paper presents a theoretical investigation of using a Seasonal Thermal Energy Storage facility (STES) to cover the heat demand of a complex of four buildings. The STES is placed in the ground and connected to both the local district heating network and solar panels. A number of scenarios were investigated to find an adequate size of the STES (tank size and solar panel area.) The results obtained show that the use of a STES could reduce heat consumption by 22100% depending on the architecture solution chosen.

Experimental Investigation of CO2 Separation from Lignite Flue Gases by 100 cm2 Single Molten Carbonate Fuel Cell

The paper presents an experimental investigation of using a Molten Carbonate Fuel Cell (MCFC) for reducing CO2 emission from the flue gas of a lignite boiler. The MCFC is placed in the flue gas stream and separates CO2 from the cathode side to the anode side. As a result, a mixture of CO2 and H2O is obtained; from which pure CO2 can be obtained by cryogenic condensation of water and carbon dioxide. The main advantages of this solution are: additional electricity generated, reduced CO2 emissions and higher system efficiency. The results obtained show that the use of an MCFC could reduce CO2 emissions by 90% with over 30% efficiency in additional power generation.

Experimental Investigation of CO2 Separation from Hard Coal Flue Gases by 100 cm2 Molten Carbonate Fuel Cell

The paper presents an experimental investigation of using a Molten Carbonate Fuel Cell (MCFC) for reducing CO2 emission from the flue gas of a hard coal fired boiler. The MCFC is placed in the flue gas stream and separates CO2 from the cathode side to the anode side. As a result, a mixture of CO2 and H2O is obtained; from which pure CO2 can be obtained by water condensation. The main advantages of this solution are: additional electricity generated, reduced CO2 emissions and higher system efficiency. The results obtained show that the use of an MCFC could reduce CO2 emissions by 90% with over 35% efficiency in additional power generation.

Working fluid model for supercritical Co2 Brayton cycle

Since carbon dioxide used as a working fluid in both supercritical and transcritical power cycles operates mostly in the supercritical area, the ideal gas model cannot be applied to obtain the working parameters and the cycle performance. In this paper some equations of state and their modifications that are usually recommended in the literature are presented. In the high-precision equations the maximum relative error can reach approximately 20% in the near critical region. That is why some of the authors using corrections. The corrected equations can precisely predict the density of supercritical CO2, and the average relative error can be restricted to within 1.5%. The Lee-Kesler equation of state is recommended for further calculations owing to its good performance and availability in the software application to design a supercritical CO2 cycle.

Mathematical modelling and analysis of recompression supercritical CO2 Brayton cycle in terms of maximum pressure and temperature at turbine inlet

In this paper, a supercritical CO2 cycle concept is investigated in terms of possible use as a power conversion cycle. Three types of most popular modifications of simple Brayton cycle (pre-compression, partial cooling and recompression) are described. As the most efficient, a recompression cycle was chosen for further investigation. The model of the recompression supercritical carbon dioxide Brayton cycle was created using GateCycle software. The results of simulation performed in GateCycle software show that the cycle achieves efficiency of 44% for CO2 turbine inlet conditions of 550°C and 20 MPa. Comparison of optimum turbine inlet pressure for cycle efficiency and net output power at turbine inlet is presented.

Impact of selected parameters on the performance of compressed natural gas energy storage using cavern gag storage system

In the article the new method of energy storing, using cavern gas storage system is presented. The idea drew from the Compressed Air Energy Storage systems, but use natural gas stored in salt caverns as a medium, so can be called the Compressed Natural Gas Energy Storage (CNGES). The concept of the store charging is to pump the gas from lower pressure cavern to the higher pressure one by an electric powered compressor. In the discharging mode the gas expands through the expander connected with the generator, from the high pressure cavern to the lower pressure one with the electricity production.The paper covers the dynamic model of CNGES implemented in Aspen Hysys numerical environment. The main aim of the simulation was to determine the influence of selected parameters of the store (gas initial and terminal temperature and pressure). The article covers main model assumptions, implemented methodology description, results analysis and conclusions.In the article the new method of energy storing, using cavern gas storage system is presented. The idea drew from the Compressed Air Energy Storage systems, but use natural gas stored in salt caverns as a medium, so can be called the Compressed Natural Gas Energy Storage (CNGES). The concept of the store charging is to pump the gas from lower pressure cavern to the higher pressure one by an electric powered compressor. In the discharging mode the gas expands through the expander connected with the generator, from the high pressure cavern to the lower pressure one with the electricity production.The paper covers the dynamic model of CNGES implemented in Aspen Hysys numerical environment. The main aim of the simulation was to determine the influence of selected parameters of the store (gas initial and terminal temperature and pressure). The article covers main model assumptions, implemented methodology description, results analysis and conclusions.

Operational Characteristics of Coin Type Molten Carbonate Fuel Cell Fueled by Ash Free Coal

The paper presents behavior of molten carbonate fuel cell fueled by ash free coal. Comparison between AFC and hydrogen as a fuel for MCFC is presented. Then, simulation gases expected from gasified ash free coal were investigated. The simulations were provided for different composition of gases based on results of AFC gasification. Current-voltage curves for investigated cases are presented as well as results are discussed.

Determination of Electronic Conductance of 100 cm2 Single Molten Carbonate Fuel Cell

This work considers electronic conductance in a molten carbonate fuel cell and consequences of its existence. The voltage characteristics of cells show differences between a theoretical maximum circuit voltage and open circuit voltage (OCV). A relationship is assumed between the OCV value and electronic conductance. Based on experimental measurements an appropriate mathematical model was created. The model is used to calculate the temperature dependence of electronic conductance for the most popular types of electrolyte: Li2CO3/K2CO3. The results obtained point to the possible existence of a very close relationship between electronic conductance and open circuit voltage. This relationship enables OCV to be calculated when electronic conductance is known. Appropriate formulae can be determined. Temperature is one of the factors affecting electronic conductance. Other influencing factors do exist, but their impact on OCV is not well known. This article mentions some of them.