Band 12, Heft 1

Purpose The purpose of this study is to critically analyze various parameters that improve the latent heat transfer in heat exchangers. There has been a continuous increase in greenhouse gases because of industrial activities across the world. Consequently, it has become critical to harness renewable energy as a powerful substitute for meeting future energy needs. Thus, phase change materials (PCM) and heat transfer fluids have been instituted as alternatives for activities related to heat transfer enhancement employing heat exchangers with different fin configurations. Methodology The present work deals with the comparative analysis of thermal performance of longitudinal and circular finned heat exchangers. For creating a detailed summary of various computational cum experimental endeavours, efforts have been made to compile a refined picture of design variations and thermal performances of PCM-based latent thermal energy storage system (PCM – LTESS). Findings The comparative analysis of longitudinal as well as circular finned tube arrangement revealed that the latter has better thermal characteristics. However, various fin arrangements have also been explored as part of this review. Originality A significant improvement in heat transfer is observed when heat sinks clubbed with PCM-based arrangement are integrated with pin fins. These are frequently instituted for heat transfer enhancement or thermal energy management of various electronic goods with optimum number and size of fins.

This research shows the operational aspects of an autonomous electrical system that incorporates power-to-gas (PtG) technology. PtG technology plays a crucial role in energy storage by utilizing stored gas to power reserve generators during critical supply-demand situations. The primary focus of this study is to minimize fuel costs for the generators, which serves as an economic indicator, while simultaneously maximizing the system’s reliability index, which is a technical indicator. To achieve these objectives, the particle swarm optimization algorithm is employed to determine the optimal levels of the objectives. Finally, various approaches are employed to validate the effectiveness of the proposed model and the utilization of PtG storage technology.

A pint-sized cross-coupled differential-driven rectifier (CCDDR) circuit with wide power dynamic range (PDR), and high power conversion efficiency (PCE) for 2.48 GHz LS-band RF energy harvesting is proposed. By building two novel functional modules of dynamic body-biasing assist (DBBA) and diode feedback biasing compensation (DFBC) into core rectifier, reverse leakage current while variation on gate potential and threshold voltage of core rectifier transistors can be effectively contained. Using 180 nm/1.8V RF-CMOS technology, the circuit design and layout are implemented. Followed by simulation-based performance comparison, the experimental results demonstrate that the proposed rectifier achieves a higher PCE of 77.8% at a lower input power of − 12.5 dBm -12.5\hspace{0.33em}{\rm{dBm}} in 2.48 GHz frequency band. Additionally, benefiting from wider input PDR of 26 dB compared with other design cases, a single-stage topology rectifier can sufficiently yield a stable output supply voltage of high to 642.46 mV with the sensitivity at 1 V of − 12 dBm -12\hspace{0.33em}{\rm{dBm}} , while the FoM value can be reached up to 54.52 dB, which can provide strong support for realizing source-free near-zero-energy-consumption IoT communication systems.

Today, ultrasonic transducers are commonly used in various industries. Most of the ultrasonic transducers used in industry are of the longitudinal and piezoelectric type. With the development of the application of these transducers in recent years, the need for small-sized transducers has arisen. In the present research, the vibration behavior of the Langevin transducer with four piezoelectric layers is studied using the simple theory and finite element model. For this purpose, by extracting the governing equations and the corresponding boundary conditions, the characteristic equation of the system is derived, and the effect of various parameters on the natural frequency of the system is studied analytically. Through the finite element simulation analysis of the modal, natural frequencies, frequency response, and vibration mode shapes of the transducer are obtained. Finally, the optimal values are determined to achieve the minimum length for the transducer. The results show that in the case of using aluminum electrode layers, the minimum transducer length of 87.47 mm is achieved with the electrode thickness equivalent to 6 mm. It is about 6% shorter than the corresponding transducer length with a copper electrode. Aluminum electrodes in the Langevin transducer under study achieve the optimal size for the transducer.