Municipal solid waste management has become a critical global issue due to the rapid increase in waste generation driven by urbanization and population growth. This surge in waste poses significant environmental, social, and health challenges, exacerbated by inefficient recycling and waste-to-energy facilities. Effective waste management requires comprehensive strategies encompassing waste reduction, efficient collection, sorting systems, and advanced recycling and energy recovery technologies. This study highlights the potential of incineration as a waste-to-energy solution, specifically focusing on Kuwait. By analyzing various waste management technologies and their applicability, this study emphasizes the role of incineration in transforming municipal solid waste into electricity, thereby reducing landfill use and environmental impacts. The research includes a detailed review of the existing technologies, a case study on Kuwait’s waste management practices, and an evaluation of the economic and environmental benefits of implementing waste-to-energy incineration. The findings underscore the importance of tailored waste management solutions to address specific regional challenges, promote sustainability, and enhance public health and well-being.

In modern steam boilers, flue gas recirculation (FGR) is generally adopted as a temperature control method for reheated steam. Some research suggests that FGR does not affect the thermal performance of steam boilers, while other studies report enhanced thermal performance. This investigation aims to enhance energy efficiency by using an iterative calculation approach to provide a thorough energy evaluation of a steam boiler with an integrated FGR system. The research applies thermodynamic and heat transfer principles to model combustion characteristics, radiative heat transfer in the furnace waterwall, and convective and inter-tube radiative heat transfer in the economizer, superheaters, and reheater. The model is validated using specifications from an existing power plant boiler and a parametric analysis to examine the effects of varying FGR rates on heat distribution and thermal performance at full and partial loads. The results show that radiative heat accounts for an average of 45% of the total heat supplied, with up to 10% in the heat recovery section. As the FGR rate increases, radiative heat in the heat recovery section decreases by 50%, while the convective heat transfer increases then drops. The model shows that the ideal FGR is bounded between 0.3 at 50% boiler load and 0.4 at full load. An analysis of the impact of FGR on the various parts of the boiler reveals that the economizer experiences the most significant net change in heat gain, followed by the reheater. The effect of gas recirculation on the economizer can be nearly twice as great as on the reheater, indicating that FGR has substantial influence on components beyond the reheater. The findings indicate that reducing excessive heat in the economizer and reheater can be accomplished under different load conditions by regulating the fuel consumption rate according to the analysis of the effects of FGR on radiative and convective heat transfer across various components.

This research investigates how slitted beams fitted with piezoelectric transducers (PZTs) behave when generating energy from environmental vibrations. By changing slit widths, slit lengths, and tip masses, we investigated the frequency response of these beams using analytical methods and finite element analysis (FEA). The obtained results demonstrate that resonance peaks are brought closer together, and coupling between vibrational modes is enhanced by larger slit spacing, whether or not anti-resonance dips are present, though the magnitudes of these peaks are affected by the width of the slits. The possibility of energy harvesting can be enhanced when resonance peaks are shifted and amplified by heavier tip masses. The FEA results support the analytical model, showing other characteristics such as sharp dips or anti-resonance troughs. This work provides valuable information for future design improvements by highlighting the significance of optimizing slit parameters and tip masses to enhance the efficiency of piezoelectric energy harvesters. This study demonstrates the benefits of using slitted beams with piezoelectric energy harvesting and provides recommendations for their efficient design.

Over the past decade, various researchers have shown the practicality of extracting electrical energy from vibrating structures. The primary objective of this research was to optimize the parameters of a basic cantilever harvester to maximize the energy production of electricity from surrounding mechanical energy. A distributed parameter model and its modal solution were utilized to determine the design variables via a parametric investigation. It is important to ensure sufficient power generation when there is a wide range of frequencies being excited, without any specific frequency being emphasized. The cost function for the optimization problem was defined as the average power within a specific frequency range, considering geometric and physical restrictions. It was discovered that different parameters’ values can be utilized to generate varying maximum power levels for different frequency ranges. Furthermore, a comparative analysis was performed between the finite element method (FEM) using ANSYS and the current harvesting model. The comparison demonstrated a high level of concordance, enabling the utilization of the finite element method (FEM) for subsequent investigation.

The results obtained from the exergoeconomic and exergy analysis of a model of a generic air conditioning (A/C) system without and with an air membrane exchanger using three commercially available refrigerants: R410A, R407C, and R134a, are reported. The model used specialized software that was validated against recently published data and showed good agreement. A/C systems are energy intensive and consume a significant portion of global electricity. Improving their efficiency by even a small amount will produce considerable savings, reduce running costs, and lower pollution emissions. The efficiency of the same A/c system without and with a membrane was investigated for different ambient temperatures, relative humidities (RHs), and pressure ratios of the compressor. It was shown that the inclusion of a membrane improved the efficiency of the system for all three refrigerants tested, particularly at higher ambient temperature. Both the coefficient of performance and exergetic efficiency reduced with the increase in the pressure ratio due to increasing fuel exergy and losses. In all system components except one, it was found that the source of the cost is inefficiencies; hence, increasing the efficiency at the expense of the non-exergy cost will improve the cost effectiveness of the entire system.

A piezoelectric cantilever with a longitudinal slit splits one bending resonance into two closely spaced peaks. This is attractive for two-frequency sources. However, existing models fit, rather than predict, the resonances. We develop a predictive branched-beam model where the harvester consists of a full-width root splitting into two prongs with independent tip masses. The two resonances are the roots of a closed-form characteristic equation without fitted parameters, the anti-resonance is the transmission zero of the same branched model, and the formulation reduces to the classical cantilever in the no-slit limit. The second (anti-symmetric) mode is weakly tunable and is located near 45 Hz; the inversion leaves the first resonance free and pins the second effectively. It is predictive and inverted to size the tip masses. Three-dimensional finite-element analysis, which tracks 27.2 → 22.3 Hz (against a finite-element 28.9 → 23.5 Hz as the mass doubles) within about 6%, and the prong kinematics, confirm the tip-mass trend. The anti-resonance is called the charge cancellation effect and can be controlled by wiring the electrodes. For a two-line source (25/45 Hz), the design, tuned to the two lines, yields up to about 1.9× the power of a size-matched single-peak beam with two matched lines (1.6× when the second dominates, ≈1× for broadband), with the second peak being intrinsically smaller. A Monte-Carlo study shows a power coefficient of variation of about 72% with manufacturing and damping scatter, the two layer thicknesses accounting for about 83% of the variance, motivating post-fabrication tip-mass trimming. The model is rigorously validated against three-dimensional electromechanical finite-element analysis; experimental validation on a physical prototype is identified as the essential next step. This work transforms the slitted harvester into a designable monolithic dual-frequency device.