Linlan Chang¹, Win-Jet Luo^1,2, Indra Permana², Bowo Yuli Prasetyo³, Alya Penta Agharid¹, Fujen Wang^2,*

Energy Engineering, Vol.122, No.5, pp. 1771-1787, 2025, DOI:10.32604/ee.2025.062209 - 25 April 2025

Abstract Heating, Ventilation, and Air Conditioning (HVAC) systems are critical for maintaining thermal comfort in office environments which also crucial for occupant well-being and productivity. This study investigates the impact of integrating ceiling fans with higher air conditioning setpoints on thermal comfort and energy efficiency in office environments. Field measurements and questionnaire surveys were conducted to evaluate thermal comfort and energy-saving potential under varying conditions. Results show that increasing the AC setpoint from 25°C to 27°C, combined with ceiling fan operation, reduced power consumption by 10%, achieving significant energy savings. Survey data confirmed that 85% of… More >

Yining Zhou¹, Yufeng Li², Chen Zhang², Tao Wu¹, Jingru Zhang², Bowen Yun², Rui Tan², Wei Yan^2,*

Energy Engineering, Vol.122, No.5, pp. 1823-1837, 2025, DOI:10.32604/ee.2025.062199 - 25 April 2025

Abstract This study investigated the micro-sliding frictional behavior of shale in fracturing fluids under varying operational conditions using Chang 7 shale oil reservoir core samples. Through systematic micro-sliding friction experiments, the characteristics and governing mechanisms of shale friction were elucidated. Complementary analyses were conducted to characterize the mineral composition, petrophysical properties, and micromorphology of the shale samples, providing insights into the relationship between microscopic structure and frictional response. In this paper, the characteristics and variation law of shale micro-sliding friction under different types of graphite materials as additives in LGF-80 (Low-damage Guar Fluid) oil flooding recoverable… More >

Feng Guo, Chen Yang^*, Dezhong Xia, Jingxiang Xu

Energy Engineering, Vol.122, No.5, pp. 1975-1999, 2025, DOI:10.32604/ee.2025.062035 - 25 April 2025

Abstract Short-term photovoltaic (PV) power forecasting plays a crucial role in enhancing the stability and reliability of power grid scheduling. To address the challenges posed by complex environmental variables and difficulties in modeling temporal features in PV power prediction, a short-term PV power forecasting method based on an improved CNN-LSTM and cascade learning strategy is proposed. First, Pearson correlation coefficients and mutual information are used to select representative features, reducing the impact of redundant features on model performance. Then, the CNN-LSTM network is designed to extract local features using CNN and learn temporal dependencies through LSTM,… More > Graphic Abstract

Steffen Schedler^1,*, Michael Bareev-Rudy¹, Stefanie Meilinger², Tanja Clees^1,3

Energy Engineering, Vol.122, No.5, pp. 1755-1770, 2025, DOI:10.32604/ee.2025.061962 - 25 April 2025

Abstract Germany aims to achieve a national climate-neutral energy system by 2045. The residential sector still accounts for 29% of end energy consumption, with 74% attributed to the direct use of fossil fuels for heating and hot water. In order to reduce fossil energy use in the household sector, great efforts are being made to design new energy concepts that expand the use of renewable energies to supply electricity and heat. One possibility is to convert parts of the natural gas grid to a hydrogen-based gas grid to deliver and store energy for urban quarters of… More >

Yong Sun¹, Haifeng Zhang^1,2, Xiaozhe Song¹, Yifu Zhang^1,2, Song Gao^1,2, Jiayang Zhang^3,*

Energy Engineering, Vol.122, No.5, pp. 1863-1885, 2025, DOI:10.32604/ee.2025.061940 - 25 April 2025

Abstract Aiming at the problems of large fluctuation of output active power and poor control performance in the process of frequency support of an energy-storage-type static-var-generator (ESVG), the adaptive adjustment control method for its active-loop parameters is used to realize the wind-farm frequency support, which has become the current research hotspot. Taking the ESVG with a supercapacitor on the DC side as the research object, the influence trend of the change of virtual rotation inertia and virtual damping coefficient on its virtual angular velocity and power angle is analyzed. Then, the constraint relationship between the equivalent… More >

Danijel Pavković^*, Pietro Kristović, Mihael Cipek, Dragutin Lisjak

Energy Engineering, Vol.122, No.5, pp. 1669-1696, 2025, DOI:10.32604/ee.2025.061916 - 25 April 2025

Abstract In deep drilling applications, such as those for geothermal energy, there are many challenges, such as those related to efficient operation of the drilling fluid (mud) pumping system. Legacy drilling rigs often use paired, parallel-connected independent-excitation direct-current (DC) motors for mud pumps, that are supplied by a single power converter. This configuration results in electrical power imbalance, thus reducing its efficiency. This paper investigates this power imbalance issue in such legacy DC mud pump drive systems and offers an innovative solution in the form of a closed-loop control system for electrical load balancing. The paper… More > Graphic Abstract

Daixuan Zhou¹, Zhichao Wang¹, Kaile Xi², Chong Zuo³, Yan Jia^2,*

Energy Engineering, Vol.122, No.5, pp. 2119-2153, 2025, DOI:10.32604/ee.2025.061712 - 25 April 2025

Abstract HOMER (Hybrid Optimization Model for Electric Renewables) is an effective simulation and optimization platform for hybrid renewable energy. By inputting specific users’ energy resource data (such as wind speed, solar radiation, etc.) and load data, and by determining the types and models of components selected by the user, HOMER calculates and simulates the operational status of each component at every time step. Ultimately, it computes the energy balance of the system within specified constraints to simulate the overall system operation. This approach enables the reasonable determination of system component capacities, the evaluation of system feasibility,… More > Graphic Abstract

Ameer H. Hamzah¹, Abdulrazzak Akroot¹, Hasanain A. Abdul Wahhab^2,*

Energy Engineering, Vol.122, No.5, pp. 2059-2075, 2025, DOI:10.32604/ee.2025.061592 - 25 April 2025

Abstract The current work includes a numerical investigation of the effect of biodiesel blends with different aluminum oxide nanoparticle concentrations on the combustion process in the cylinder of a diesel engine. IC Engine Fluent, a specialist computational tool in the ANSYS software, was used to simulate internal combustion engine dynamics and combustion processes. Numerical analysis was carried out using biodiesel blends with three Al₂O₃ nanoparticles in 50, 100, and 150 ppm concentrations. The tested samples are called D100, B20, B20A50, B20A100, and B20A150 accordingly. The modeling runs were carried out at various engine loads of 0, 100,… More >

Malik A. Faisal^*, Alireza Saraei

Energy Engineering, Vol.122, No.5, pp. 2099-2117, 2025, DOI:10.32604/ee.2025.061569 - 25 April 2025

Abstract Performance enhancement of flat plate solar collectors is an endless research direction as it represents the most used solar technology. The enhancement could be achieved via design alteration, absorber-installed protrusions, and integration with thermal energy storage. The objective of the current research is to evaluate a compacted solar collector integrated with octadecane organic paraffin PCM (phase change materials) as a thermal energy storage medium. The investigations have been performed numerically utilizing ANSYS software. Thermal storage contains the PCM securely encased behind the absorbent plate of the collector in four packing containers. The investigations have been… More >

Chenyang Fu^*, Xinghua Wang, Zilv Li, Xixian Liu, Xiongfei Zhang, Zhuoli Zhao

Energy Engineering, Vol.122, No.5, pp. 1805-1821, 2025, DOI:10.32604/ee.2025.061172 - 25 April 2025

Abstract With the large-scale promotion of distributed photovoltaics, new challenges have emerged in the photovoltaic consumption within distribution networks. Traditional photovoltaic consumption schemes have primarily focused on static analysis. However, as the scale of photovoltaic power generation devices grows and the methods of integration diversify, a single consumption scheme is no longer sufficient to meet the actual needs of current distribution networks. Therefore, this paper proposes an optimal evaluation method for photovoltaic consumption schemes based on BASS model predictions of installed capacity, aiming to provide an effective tool for generating and evaluating photovoltaic consumption schemes in… More > Graphic Abstract