Search

The wide use of fuel cells in mobile applications carries significant risks caused by accompanying vibrations, the origin of which can be found in the interaction of the ground or other vibration-generating components. The classical approach treated vibration and creep as two separate phenomena. One generated pulses, and the other caused durable deformations under the influence of temperature and static loads. This work combines both phenomena, describing the impact of vibrations on the material's structure and estimating the magnitude of durable deformations caused by the aggregation of alloy inclusions and dislocations in the material mesh. The Norton creep model and the failure model described by Kachanov were used for this. In addition, Stobyriev's reduced stresses were used to reflect the failure spectrum of the material: from brittle to ductile. • The previous approach treated vibration and creep as two separate phenomena. • A material with brittle deformation showed a high affinity for Vibro-creep. • Ductile materials exhibit low Vibro-creep values. • Martensitic α phase in austenite structure increases Vibro-creep. • The phenomenon of creep-fatigue reduced the life of the weld joint. [ABSTRACT FROM AUTHOR]

Poland continues to rely heavily on coal and fossil fuels for household heating, despite efforts to reduce Particulate Matter (PM) levels. The availability of reliable air quality data is essential for policymakers, environmentalists, and citizens to advocate for cleaner energy sources. However, Polish air quality monitoring is challenging due to the limited coverage of reference stations and outdated equipment. Here, we report the results of a study on the spatio-temporal variability of Particulate Matter in Legionowo, Poland, using residents' network of low-cost sensors. Along with identifying the hotspots of household-emitted PM, (1) we propose a data quality assurance scheme for PM sensors, (2) suggest an approach for estimating the Relative Humidity-induced uncertainty in the sensors without co-location with reference instruments, and (3) develop an interpretable Machine Learning (ML) model, a Generalized Additive Model (RMSE = 6.16 μg m−3, and R 2 = 0.88), for unveiling the underlying relations between PM 2.5 levels and other environmental parameters. The results in Legionowo suggest that as air temperature and wind speed increase by 1 °C and 1 km h−1, PM 2.5 would respectively decrease by 0.26 μg m−3 and 0.14 μg m−3 while PM 2.5 increases by 0.03 μg m−3 as RH increases by 1%. • PM variability is analyzed using residents' network of low-cost sensors. • A data quality assurance scheme for PM sensors is proposed. • Relative Humidity-induced uncertainty of PM sensors is estimated using a new approach. • PM 2.5 and environmental settings relations are explored with an explainable ML model. • Sensors identify fossil-fuel-induced air pollution hotspots. [ABSTRACT FROM AUTHOR]

The operation of a fuel cell poses significant problems related to local current density and the failure rate of components. The issue results from high flow resistance and stresses that guarantee the tightness of the stack. Low flow resistance allows the stack to be used in Hybrid Energy Storage. This study shows that the selection of the best variant of the channel shape in a fuel cell should be based on more than just observing electrochemical performance. Increasing the current density flux can lead to faster component degradation. Older material degradation models based on the strain tensor will only accurately identify some risks. Thanks to the use of Perzyna's viscoplastic model, it was possible to protect the fuel cell from premature failure. Earlier studies did not indicate how the changes in the shape introduced, improving the electrochemical properties, impacted the component's service life during cyclic loads. [Display omitted] • Sinusoidal channels showed a higher power density than the parallel channel. • The sinusoidal wave generates an additional convective mass flux. • The shape canal change did not affect the time to mixed-type fracture. • The use of Perzyna's model showed a cyclical increase in strain energy. • The cyclic increase in plastic strain describes the ratcheting phenomenon. [ABSTRACT FROM AUTHOR]

In an era of changes in the electricity market, where the share of renewable energy sources is increasing and moving away from conventional coal-based energy, the electricity used for heating is gaining importance, for example to power heat pumps. They currently are one of the most common ways for heating buildings as an alternative to fossil fuels and biomass. In this article, the authors present an analysis aimed at answering the question whether using the concept of microgrids in Polish realities provides a feasible solution. Within the framework of this article, analyses were carried out by assuming the electrification of the heating installation of users in a local microgrid located in a selected location of the Polish low-voltage distribution network. The increase in electricity demand needed to generate the corresponding amount of heat was then estimated, and subsequently the impact of this demand on the microgrid was determined. In addition, in the article, the authors estimate the production of a prosumer PV installation at the selected location and analyze the level of autoconsumption of the generated electricity in the PV installation by the heat pump. [ABSTRACT FROM AUTHOR]

The compliance with international standards does not necessarily ensure a long-term reliability of photovoltaic modules. Field tests are required to make the standard tests more adjusted to the evaluation of new concepts. Numerous researches focus on long-term performance of standard modules, but only few studies are dedicated to lightweight modules. Therefore, the field operation of a PV system consisting of 28 lightweight modules of 4 different types (denoted as P1, P2, P3 and P4) has been being monitored for a year in warm temperate climate conditions. Over this period, the modules were tested by visual inspection, thermography and electroluminescence imaging and their electrical parameters were measured to compare results with the outcome of simulations in PVsyst. Visual inspections revealed yellowing and delamination of a few P2 and P4 modules because of issues with EVA foil. Thermography exposed many hot spots and failure of substrings in case of P2 modules. Also, the electroluminescence imaging showed numerous defects, mostly various micro cracks, which affected all modules' types. Nevertheless, excluding P2 modules, the others generated higher yield than estimated by the simulations. Analysing year-to-year degradation, results for P3 and P4 were in line with results predicted for standard PV modules in similar climates. [ABSTRACT FROM AUTHOR]

HVAC systems use a substantial part of the whole energy usage of buildings. The optimizing of their operation can greatly affect the power use of a building, making them an interesting subject when trying to save energy. However, this should not affect the comfort of the people inside. Many approaches aim to optimize the operation of the heating and cooling system; in this paper, we present an approach to steer the heat pumps to reduce energy usage while aiming to maintain a certain level of comfort. For this purpose, we employ a market-based distributed method for power-balancing. To maintain the comfort level, the market-based distributed system assigns each device a cost-curve, parametrized with the current temperature of the room. This allows the cost to reflect the urgency of the HVAC operation. This approach was tested in a real-world environment: we use 10 heat pumps responsible for temperature control in 10 comparable-sized rooms. The test was performed for 3 months in summer. We limited the total peak power, and the algorithm balanced the consumption of the heat pumps with the available supply. The experiments showed that the system successfully managed to operate within the limit (lowering peak usage), and - to a certain point - reduce the cost without significantly deteriorating the working conditions of the occupants of the rooms. This test allowed us to estimate the minimal peak power requirement for the tested set-up that will still keep the room temperatures in or close to comfortable levels. The experiments show that a fully distributed market-based approach with parametrized cost functions can be used to limit peak usage while maintaining temperatures. [ABSTRACT FROM AUTHOR]

The operation of a fuel cell (PEMFC) is associated with severe problems related to individual components' local power density and durability. The problem arises from the unsatisfactory distribution of the H2 and O 2 reaction components and the high flow resistance. To find an answer to the problem posed, we tested nine variants of open anode/cathode channels dedicated to subsequent 3D printing. We have compared the obtained current-voltage characteristic curves with the experimental data of the fuel cell for which the new channels were dedicated. Each of the newly designed open flow channels had better current characteristics. Subsequently, we have compared selected cell properties between the best variants from the section. The final shape of the open channel ensured a high value of the current flux and local power density in the entire operating range of the fuel cell. Also, it generated low flow resistance allows for building a stack of cells. [Display omitted] • The size of the mesh determines the value of current-voltage characteristics. • The open porous channel was dedicated to the PEM fuel cell. • The complicated shape of the channel made it difficult to distribute the fluid. • A better distribution of the fluid components increased the current density. [ABSTRACT FROM AUTHOR]

Adsorption cooling and desalination technologies have recently received more attention. Adsorption chillers, using eco-friendly refrigerants, provide promising abilities for low-grade waste heat recovery and utilization, especially renewable and waste heat of the near ambient temperature. However, due to the low coefficient of performance (COP) and cooling capacity (CC) of the chillers, they have not been widely commercialized. Although operating in combined heating and cooling (HC) systems, adsorption chillers allow more efficient conversion and management of low-grade sources of thermal energy, their operation is still not sufficiently recognized, and the improvement of their performance is still a challenging task. The paper introduces an artificial intelligence (AI) approach for the optimization study of a two-bed adsorption chiller operating in an existing combined HC system, driven by low-temperature heat from cogeneration. Artificial neural networks are employed to develop a model that allows estimating the behavior of the chiller. Two crucial energy efficiency and performance indicators of the adsorption chiller, i.e., CC and the COP, are examined during the study for different operating sceneries and a wide range of operating conditions. Thus this work provides useful guidance for the operating conditions of the adsorption chiller integrated into the HC system. For the considered range of input parameters, the highest CC and COP are equal to 12.7 and 0.65 kW, respectively. The developed model, based on the neurocomputing approach, constitutes an easy-to-use and powerful optimization tool for the adsorption chiller operating in the complex HC system. [ABSTRACT FROM AUTHOR]

The fuel cell operation is associated with significant current density and durability problems, among other anode collectors. We used a numerical model based on flows with chemical reactions in a porous medium to solve these problems. We tested four variants of the anode channels. In the shape of the anode channel, we introduced changes to improve the current density. We also examined the influence of the channel shape on the stress field and rheological processes in the casing material. We verified the numerical model on the experimental data. Furthermore, we corrected the amount of the hydrogen stream and the produced water in the whole range of the cell's operation. The test results show that it is possible to increase the current density in all operating fields of the fuel cell while maintaining a low mechanical load on graphite elements and their safe operation time. [ABSTRACT FROM AUTHOR]

• The European Union trends create an opportunity for geothermal power plants. • The combine analysis of heat source, Organic Rankine Cycle and turbine were done. • The binary geothermal power plant can obtain approximately 2 MW of power output. • The parameters of a low-temperature heat source for Polish conditions are determined. • Designed the two-stage axial turbine reached the internal efficiency of 79%. In recent years, pressure has been growing to increase the share of renewable energy sources in electricity generation, which may offer opportunities for the development of geothermal energy in regions that have been so far considered unprofitable in this respect. One such country currently undergoing an energy transition is Poland in which low-temperature geothermal resources are currently used for district heating and recreation purposes. Nevertheless, research on the possibilities of using geothermal energy for electricity production is ongoing. The objective of this paper was to perform a comprehensive analysis of a binary power plant construction in relation to low-temperature petro-geothermal resources. The potential binary power plant is located in the area characterized by temperature of 120 °C at depths of 5000 m. About half of Poland's area, especially the regions of western and central Poland, has these characteristics. It was assumed that brine at volume flow rate of 400 m3/h is a heat source for the Organic Rankine Cycle with isobutane as a working medium. The thermal efficiency based on the First Law of Thermodynamics and the power output were estimated at 10.5% and 1.79 MW e , respectively. In addition, the thermal efficiency based on the Second Law of Thermodynamics was calculated at 29.0%. For the calculated cycle parameters, a preliminary design of a two-stage axial turbine was constructed. All results were compared to the other binary power plants and they confirm that establishing the binary power plant in Poland would be thermodynamically justified. The main novelty of the present work is the combination of three issues, namely the selection of the low- temperature heat source, the design and analysis of the cycle together with a turbine adapted to these conditions. [ABSTRACT FROM AUTHOR]

Dynamic growth of photovoltaic capacity in Poland encourages many entities to invest in photovoltaic systems. However, in the case of buildings with low roof-bearing capacity it can be problematic or even impossible to mount conventional PV modules due to their relatively high weight. Hence, the use of lightweight PV modules is a potential solution. In this paper four different prototype silicon lightweight modules of novel structure manufactured by the Xdisc S.A have been investigated in terms of their electrical and thermal features. The measurements showed that all prototypes have efficiency exceeding 19.5% and power in range of 214 to 242 Wp at standard test conditions. Their area density is about 3.5 kg/m2 which is typical for lightweight modules. In turn, the Power-to-Weight Ratio exceeds 40 W/kg threshold and in one case reaches almost 58 W/kg. Thanks to the measurements, the prototypes could be modelled in PVsyst (PVsyst SA, Satigny, Switzerland). The performed simulations of an example PV system revealed that installations based on prototypes have comparable performance to a conventional installation. Nevertheless, at current prices they are less profitable than the standard system and it shows the need for future cost reductions in the manufacturing process. The proposed materials selection may be the starting point for search of inexpensive substitutes of these materials which still conserve modules high performance. A system based on the prototypes can still prove advantageous when simplicity and promptness outweigh higher initial costs. [ABSTRACT FROM AUTHOR]

In the article, the method and algorithm for a control strategy of the operation of a micro combined heat and power (mCHP) unit and for reducing the power consumption peaks (peak shaving) are proposed and analyzed. Two scenarios of the mCHP's operation, namely with and without the control strategy, are discussed. For calculation purposes, a boiler fired with wood pellets coupled with a Stirling engine, manufactured by ÖkoFEN, was used. These results were used to analyze two scenarios of the control strategy. In this study, the operation of mCHP was simulated using the energyPRO software. The application of this control strategy to dispersed mCHP systems allows for a very effective "peak shaving" in the local power grid. The results of calculation using the new algorithm show that the electricity generated by the mCHP system covers the total demand for power during the morning peak and reduces the evening peak by up to 71%. The application of this method also allows for a better reduction of the load of conventional grids, substations, and other equipment. [ABSTRACT FROM AUTHOR]