Ireneusz Szczygieł

This work presents a thermodynamic analysis of a six-stroke cycle implemented in Spark-Ignition (SI) engines. The cycle configuration comprises two distinct combustion phases: (1) initial combustion of a methane-hydrogen mixture under fuel-lean conditions (λ > 1), yielding exhaust gases containing residual oxygen, followed by (2) secondary hydrogen injection during the expansion phase to facilitate complete utilization of the remaining oxidizer. The investigation evaluates the system's thermodynamic performance through parametric variation of both the fuel composition (CH₄/H₂ ratio) and the equivalence ratio during primary combustion. The results obtained indicate that the changes in the peak temperature of the second part of the cycle are small, up to 60K relative to the mean value. The fuel mix with =3.0 showed the highest cycle efficiency at 50.73%, indicating the best performance among all cases. According to the data, better performance can be achieved by optimizing cycle parameters such as regeneration, intercooling, pressure ratios, and component efficiency in addition to raising the maximum temperature. In conclusion, better outcomes are not always guaranteed by higher temperatures. Increasing thermal input alone is not as important as designing and optimizing cycles efficiently.

Between February 2024 and February 2025, 27public buildings, selected to be representative of the region, located in the Silesia region of Poland and comprising schools, offices, and cultural facilities, were equipped with advanced measuring systems that allowed the measurement of energy consumption for the purposes of heating and the powering of electrical devices. Thermal and energy data were logged in one minute intervals. After the measurement campaign, the buildings were subjected to multi-variant analysis for the possibility of generating sufficient energy on-site to cover the energy needs of the buildings. Four different photovoltaic panel technologies and three different heat sources were modeled for each building, using the real measurement data. The effects of energy storage were also evaluated. It was determined that despite the diversity of the buildings, and despite the assumption of no further thermal modernization in the buildings other than on the side of the supply, the results are generally favorable.

The topic of this research was an answer to questions about economical advantages and disadvantages of an Electric Vehicle usage in Poland. Analysis done in this paper was based on current economical situation of automotive market. All the data collected for the purpose of comparison was obtained from manufacturers, government institutions or professional literature to ensure the quality of every calculation. Main concerns were covered by the comparison such as: usage of photovoltaic system to power electric vehicle, time of journey to the most popular destinations chosen by Polish citizens, cost of driving for internal combustion engines and electric vehicles. Research brought an answer that the cost of using an electric vehicle is highly dependent of electricity source. It can be also said, that not every region of Poland can guarantee a reasonable payback time when it comes to photovoltaic system and usage of electric vehicle in short distance regime.

This paper presents the computational fluid dynamics (CFD) model of small-scale α-type Stirling engine. The developed mathematical model comprises of unsteady Reynolds averaged Navier–Stokes set of equations, i.e., continuity, momentum, and energy equations; turbulence was modeled using standard κ–ω model. Moreover, presented numerical model covers all modes of heat transfer inside the engine: conduction, convection, and radiation. The model was built in the framework of the commercial CFD software ANSYS fluent. Piston movements were modeled using dynamic mesh capability in ANSYS fluent; their movement kinematics was described based on the crankshaft geometry and it was implemented in the model using user-defined functions written in C programming language and compiled with a core of the ANSYS fluent software. The developed numerical model was used to assess the performance of the analyzed Stirling engine. For this purpose, different performance measures were defined, including coefficient of performance (COP), exergy efficiency, and irreversibility factor. The proposed measures were applied to evaluate the influence of different heating strategies of the small-scale α-type Stirling engine.