Current Issue : April-June Volume : 2025 Issue Number : 2 Articles : 5 Articles
With the severe challenge of global climate change and the increasing energy crisis, the construction industry, as one of the main sources of global energy consumption and greenhouse gas emissions, has become particularly critical. Therefore, exploring how to achieve building energy savings through renewable energy has become an urgent and farreaching research topic. This study aims to discuss the current state, challenges, and potential applications of renewable energy in the building field, by reviewing existing literature and case studies. Additionally, it explores strategies to promote the application of renewable energy in building energy conservation through technological innovation and policy support. After analyzing the existing literature and cases, it is found that the application of renewable energy technologies such as solar, wind, and geothermal energy in buildings can significantly save energy, reduce dependence on fossil fuels, and reduce carbon emissions. Optimizing buildings, including passive design and active system integration, is critical to improving energy efficiency without compromising residential comfort. The intelligent energy management system further improves energy efficiency through real-time monitoring and automatic regulation. Policy and economic incentives have played a key role in promoting the use of renewable energy technologies in buildings....
RF energy harvesting converts ambient signals into electrical power, providing a sustainable energy source. This study demonstrates the use of a piezoelectric transformer for efficient RF energy harvesting. In this work, a piezoelectric transformer (PT) is employed as a high-gain, efficient inverting amplifier to enhance RF wireless energy harvesting. The PT, composed of lead zirconate titanate (PZT), is placed after the receiving loop antenna, with its output connected to an AC-to-DC converter circuit. Maximum harvested power was observed at the PT’s resonance frequency of 50 kHz, with an optimal load of 40 kΩ. The system, comprising the antenna, transformer, and rectifier circuit, continues to resonate at 50 kHz, as confirmed by input impedance measurements, demonstrating stable and effective performance. The overall system efficiency was characterized to be 88%....
In this study, a novel solar-assisted heat pump (SAHP) system with hybrid thermal energy storage is proposed. The system can address the problems of large space requirements and the unstable heating of solar heating systems and tackle the energy-efficient degradation of air source heat pumps (ASHPs) in winter. This study utilized TRNSYS18 software to establish a dynamic simulation model of the system, including the system’s model construction and the control scheme’s design. This performance study focused on analyzing the effects of the collector area and thermal energy storage (TES). The results show that with the increase in the collector area, the collector and power generation efficiencies decrease, and the system performance coefficient improves; the rise in the volume of TES leads to the collector and power generation efficiencies first increasing, and then they tend to stabilize, and the performance coefficient shows a trend of firstly increasing, and then decreasing. In terms of parameter optimization, a target optimization scheme and an evaluation model are constructed. The results indicate that the heating demand for a 116-square-meter building in the Tianjin area is met. The equivalent annual cost (EAC) of the system cost is the lowest, which is CNY 3963, when the collector area of the system is 31 square meters, the heat storage tank (HST) volume is 0.4 cubic meters and the phase-change energy storage (PCES) volume is 0.2 cubic meters. The payback period of the system is 10.59 years, which was compared to that of the ASHP. The further comparison of the economic feasibility of the system in the Lhasa, Shenyang, and Tianjin regions shows that the Lhasa region has the lowest EAC and payback period of CNY 1579 and 8.53 years, respectively, while the payback periods of Tianjin and Shenyang are 10.59 and 10.3 years, with EACs of CNY 3963 and CNY 5096, respectively....
Using hybrid energy storage systems, we propose a power mode partitioning control strategy for AC/DC microgrids that effectively mitigates frequency and voltage fluctuations. By incorporating composite virtual impedance, we categorize the state of charge (SOC) into five distinct operational modes. Supercapacitors, known for their dynamic response, are prioritized to counteract power fluctuations. We assign these operational modes to the AC and DC subnetworks based on real-time changes in frequency and voltage. When significant fluctuations occur, coordinated power transmission between the subnetworks and support from the energy storage system ensure that frequency and voltage remain within acceptable limits. Simulations conducted in MATLAB/Simulink confirmed that this control strategy stabilized power fluctuations and addressed the challenges of overcharging and overdischarging in storage batteries....
This article presents a detailed method for reactive power valuation exclusively from the generator-side point of view. This study is performed on a 1.5 MVA doubly-fed induction generator and two main generator-side parameters are introduced as the effective variables. These variables include power loss and active power capacity. In this article, in constant apparent power, the produced/consumed reactive power of the generator in exchange with the power grid is studied in detail and the operational characteristics of the generator including active/reactive power, power factor, and efficiency are reported. Using these functional characteristics, the power loss increment factor and the active power capacity reduction factor are proposed. Finally, the reactive power valuation factor that is the main output of this article is presented and the results are compared with the current reactive power pricing method in Iran. The results show that the proposed method can be useful for a more accurate analysis of reactive power valuation problem from the generator point of view....
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