Article
Materials Science, Multidisciplinary
T. Jothi Saravanan
Summary: This paper investigates the propagation of elastic stress waves in the axisymmetric circular cross-section of a high strength steel wire with cylindrical waveguide using a semi-analytical finite element method. The study proposes a method for improving frequency accuracy and discusses the use of higher-order elements for lower computational burden in solving eigenvalue problems.
MECHANICS OF ADVANCED MATERIALS AND STRUCTURES
(2022)
Article
Construction & Building Technology
Wenzhe Wei, Long Ni, Qian Dong, Wei Wang, Jiayu Ye, Laifu Xu, Yahua Yang, Yang Yao
Summary: During the defrosting process in cold regions, injecting medium-pressure vapor refrigerant into the compressor of an air source heat pump can effectively improve defrosting efficiency. Experimental results show that an optimal opening of the injection electronic expansion valve exists, leading to reduced defrosting time, power consumption, and improved defrosting efficiency.
ENERGY AND BUILDINGS
(2022)
Article
Thermodynamics
Wenyi Wang, Qun Zhou, Guanyu Tian, Yikai Wang, Zhongfan Zhao, Feng Cao
Summary: Defrosting is crucial for restoring heating capacity in ASHP systems during winter, but current time-based methods relying on external conditions may lead to mal-defrosting. This study introduces a novel CNN-based defrosting control strategy that accurately predicts frosting and makes correct defrosting initiation decisions.
INTERNATIONAL JOURNAL OF REFRIGERATION
(2021)
Article
Thermodynamics
Ping Jiang, Yu Zhang, Hongxiu Fan, Qi Jin, Yanshun Yu
Summary: Air source heat pumps are widely used due to their efficiency, energy-saving, and environmentally friendly nature. However, frost accumulation on heat exchanger surfaces limits their application in low-temperature and high-humidity regions. This study presents a defrosting solution rooted in the chemical potential theory, which utilizes sodium formate solution to effectively eliminate exchanger frost. Results show that sustaining air circulation, increasing spray flow rate, temperature, and solution concentration can all shorten the defrosting time.
APPLIED THERMAL ENGINEERING
(2024)
Article
Construction & Building Technology
Guoyuan Ma, Tianyu Lu, Fusheng Liu, Jianhui Niu, Shuxue Xu
Summary: This paper designed and built an experimental ASHP system with multiple outdoor units connected in parallel to study the efficient defrosting technology for continuous heating. The experimental results showed that the hot liquid subcooling defrosting (HLSD) enabled the heat pump to complete rotational defrosting with good defrosting effect, and the heating capacity and energy efficiency ratio could be increased by 10% to 20% compared with the hot gas bypass defrosting (HGBD).
ENERGY AND BUILDINGS
(2023)
Article
Thermodynamics
Yoong Chung, Sun-Ik Na, Jin Woo Yoo, Min Soo Kim
Summary: A novel determination method of defrosting start time based on frost accumulation amount tracking (FAAT) is proposed for air source heat pump systems, which predicts the volumetric blockage ratio in real-time. The method shows a root mean square error of 6.2% on a time basis and 5.1% on a capacity basis, demonstrating reliability and robustness. Additionally, the method is shown to be robust under varying frost non-uniformity on the evaporator.
APPLIED THERMAL ENGINEERING
(2021)
Article
Thermodynamics
Yanhua Guo, Shuangquan Shao, Xudong Geng, Hao Li, Zhichao Wang, Nevzat Akkurt
Summary: An efficient and innovative demand-based defrosting initiation strategy is proposed in this paper, based on the learned the degradation of heating capacity (DHC) method using data-driven model. By utilizing sensor data and a neural network model, the strategy effectively reduces defrosting frequency, heating loss, and power consumption while ensuring the efficiency of demand-based control. The results demonstrate a significant improvement in defrosting control efficiency.
APPLIED THERMAL ENGINEERING
(2023)
Article
Construction & Building Technology
Zhanli Xi, Runming Yao, Jinbo Li, Chenqiu Du, Zixian Yu, Baizhan Li
Summary: A novel intelligent control strategy based on hot gas bypass defrosting was proposed for ASHP system, achieving accurate operation under different outdoor temperature ranges. Compared with the conventional system, the hot gas bypass defrosting method increased heating capacity and overall energy efficiency, while reducing fluctuations in indoor air temperature and outlet air temperature.
JOURNAL OF BUILDING ENGINEERING
(2021)
Article
Green & Sustainable Science & Technology
Yaxiu Gu, Guixiang He, Shuaipeng Li, Weiqi Ding, Hanlin Li, Jiahui Duan
Summary: This study prepared a superhydrophobic aluminum surface with a contact angle of 158.3 degrees to solve the frosting problem of air source heat pump outdoor heat exchange under low-temperature and low-humidity conditions. The characteristics of droplet condensation and freezing process on the superhydrophobic surface were revealed through experiments and analysis. Additionally, the frost-suppression effect of the superhydrophobic aluminum-based surface was explored, showing that the condensed droplets appeared late and their quantity was low, resulting in a lower freezing rate and frosting amount compared to the bare aluminum-based surface.
Article
Construction & Building Technology
Chunling Wu, Zhichao Wang, Xiaofeng Li, Zhaowei Xu, Ce Xu, Yingxia Yang, Wenyuan Zhao, Yichao Wang
Summary: The use of frequency conversion technology in air source heat pumps can effectively extend the frost-free period and shorten the defrosting period, thereby improving the overall performance of the units.
JOURNAL OF BUILDING ENGINEERING
(2023)
Article
Thermodynamics
Shengyu Li, Jun Lu, Wuyan Li, Yunqian Zhang, Sheng Huang, Liu Tian, Yifei Lv, Yafei Hu, Yijiang Zeng
Summary: This study proposes an improved dual-temperature air source heat pump cycle with a self-defrosting method and an ejector. Through thermodynamic modeling and simulation analysis, the results show a significant improvement in the heating coefficient and exergy efficiency in the new system compared to the standard system, with the eco-friendly refrigerant R600a exhibiting the best performance.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Jiacheng Ma, Donghun Kim, James E. Braun, W. Travis Horton
Summary: Frost accumulation on evaporator coil surfaces can greatly affect the performance of air-source heat pump systems. This paper presents a dynamic modeling framework that can simulate the behavior of ASHP systems during frost and defrost cycles, and experimental validations show that the model accurately captures the cycling behaviors and is reliable.
Article
Acoustics
Mohammad Mehrabi, Mohammad Hossein Soorgee, Hossein Habibi, Vassilios Kappatos
Summary: This work presents a simple and low-cost method to determine the damping property of a viscoelastic coating layer through experiments. The experimental results were validated by numerical simulations. This technique is suitable for cases that require excitation in a wide frequency range, but precision depends on several factors.
Article
Engineering, Mechanical
Xiaocen Wang, Min Lin, Jian Li, Junkai Tong, Xinjing Huang, Lin Liang, Zheng Fan, Yang Liu
Summary: In this paper, a rapid guided wave imaging method based on convolutional neural network (CNN) is proposed for quantitative evaluation of corrosion damage. The method involves offline training and online imaging, and has shown excellent imaging performance and high success rate in numerical experiments.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2022)
Article
Green & Sustainable Science & Technology
Yunhai Li, Zhaomeng Li, Yi Fan, Cheng Zeng, Yu Cui, Xudong Zhao, Jing Li, Ying Chen, Jianyong Chen, Chao Shen
Summary: Heat pumps (HPs) are important for global carbon reduction and carbon neutrality, but they have performance issues in cold climates. A two-stage heat recovery heat pump (THRHP) was developed to improve COP and energy consumption during defrosting. The optimized THRHP prototype achieved a heating capacity of 32.3 kW, generated 4 m3/h hot water at 55 degrees C with COP of 2.57 at outdoor temperature of 0 degrees C, and consumed only 0.46 kW and 4 mins during defrosting at -6 degrees C. This research provides insights and optimal control strategies for better THRHP performance, promoting the adoption of HPs and carbon-neutrality goals.
Article
Thermodynamics
Hai Zhao, Puzhen Gao, Xiaochang Li, Ruifeng Tian, Hongyang Wei, Sichao Tan
Summary: This study numerically investigates the interaction between flow-induced vibration and forced convection heat transfer in a tube bundle. The results show that the impact of flow-induced vibration on heat transfer varies in different flow velocity regions.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
Rohit Chintala, Jon Winkler, Sugirdhalakshmi Ramaraj, Xin Jin
Summary: The current state of fault detection and diagnosis for residential air-conditioning systems is expensive and not suitable for widespread implementation. This paper proposes a cost-effective solution by introducing an automated fault detection algorithm as a screening step before more expensive tests can be conducted. The algorithm uses home thermostats and local weather information to identify thermodynamic parameters and detect high-impact air-conditioning faults.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
A. Azimi, N. Basiri, M. Eslami
Summary: This paper presents a novel optimization algorithm for improving the water-film cooling system of photovoltaic panels, resulting in a significant increase in net energy generation.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
Duc-Thuan Phung, Chin-Hsiang Cheng
Summary: In this study, a novel CFDMD model is used to analyze and investigate the behavior of thermal-lag engines (TLE). The study shows that the CFDMD model effectively captures the thermodynamic behavior of the working gas and the dynamic behavior of the engine mechanism. Additionally, the study explores the temporal evolution of engine speed and the influence of various parameters on shaft power and brake thermal efficiency. The research also reveals the existence of a thermal-lag phenomenon in TLE.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
Haiying Yang, Yinjie Shen, Lin Li, Yichen Pan, Ping Yang
Summary: The purpose of this article is to find a measure to improve the interfacial thermal transfer of graphene/silicon heterojunction. Through molecular dynamics simulation, it is found that surface modification can significantly reduce the thermal resistance, thereby improving the thermal conductivity of the graphene/silicon interface.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
Qiong Wu, Yancheng Wang, Haonan Zhou, Xingye Qiu, Deqing Mei
Summary: This article introduces a visible methanol steam reforming microreactor, which uses an optical crystal as an observation window and measures the reaction temperature in real-time using infrared thermography. The results show that under lower oxygen to carbon ratio conditions, the microreactor has a higher heating rate and a stable gradient in temperature distribution.
APPLIED THERMAL ENGINEERING
(2024)
Review
Thermodynamics
Giulia Manco, Umberto Tesio, Elisa Guelpa, Vittorio Verda
Summary: In the past decade, there has been a growing interest in studying energy systems for the combined management of power vectors. Most of the published works focus on finding the optimal design and operations of Multi Energy Systems (MES). However, for newcomers to this field, understanding how to achieve the desired optimization details while controlling computational expenses can be challenging and time-consuming. This paper presents a novel approach to analyzing the existing literature on MES, with the aim of guiding practical development of MES optimization. Through the discussion of six case studies, the authors provide a mathematical formulation as a reference for building the model and emphasize the impact of different aspects on the problem nature and solver selection. In addition, the paper also discusses the different approaches used in the literature for incorporating thermal networks and storage in the optimization of multi-energy systems.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
Xuepeng Yuan, Caiman Yan, Yunxian Huang, Yong Tang, Shiwei Zhang, Gong Chen
Summary: In this study, a multi-scale microgroove wick (MSMGW) was developed by laser irradiation, which demonstrated superior capillary performance. The surface morphology and performance of the wick were affected by laser scan pitch, laser power, repetition frequency, and scanning speed. The MSMGW showed optimal capillary performance in alumina material and DI water as the working fluid.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
Maofei Mei, Feng Hu, Chong Han
Summary: This paper proposes an effective local search method based on detection of droplet boundaries for understanding the dynamic process of droplet growth during dropwise condensation. The method is validated by comparing with experimental data. The present simulation provides an effective approach to more accurately predict the nucleation site density in future studies.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
Rahul Kumar Sharma, Ashish Kumar, Dibakar Rakshit
Summary: The study explores the use of phase change materials (PCM) as a retrofit with Heating Ventilation and Air-conditioning systems (HVAC) to reduce energy consumption and improve air quality. By incorporating PCM with specific thickness and fin configurations, significant energy savings can be achieved in comparison to standard HVAC systems utilizing R134a. This research provides policymakers with energy-efficient and sustainable solutions for HVAC systems to combat climate change.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
Zhenhua Ren, Xiangjin Meng, Xingang Qi, Hui Jin, Yunan Chen, Bin Chen, Liejin Guo
Summary: This paper investigates the heat transfer mechanism and factors influencing thermal radiation in the process of supercritical water gasification (SCWG) of coal, and proposes a comprehensive numerical model to simulate the process. Experimental validation results show that thermal radiation accounts for a significant proportion of the total heat exchange in the reactor and a large amount of radiant energy exists in the important spectral range of supercritical water. Enhancing radiative heat transfer can effectively increase the temperature of the reaction medium and the gasification rate.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
Mauro Abela, Mauro Mameli, Sauro Filippeschi, Brent S. Taft
Summary: Pulsating Heat Pipes (PHP) are passive two-phase heat transfer devices with a simple structure and high heat transfer capabilities. The actual unpredictability of their dynamic behavior during startup and thermal crisis hinders their large-scale application. An experimental apparatus is designed to investigate these phenomena systematically. The results show that increasing the number of evaporator sections and condenser temperature improves the performance of PHP. The condenser temperature also affects the initial liquid phase distribution and startup time.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
Ke Gan, Ruilian Li, Yi Zheng, Hui Xu, Ying Gao, Jiajie Qian, Ziming Wei, Bin Kong, Hong Zhang
Summary: A 3-dimensional enhanced heat pipe radiator has been developed to improve heat dissipation and temperature uniformity in cooling high-power electronic components. Experimental results show that the radiator has superior heat transfer performance compared to a conventional aluminum fin radiator under different heating powers and wind speed conditions.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
Xinyi Zhang, Shuzhong Wang, Daihui Jiang, Zhiqiang Wu
Summary: This study focuses on recovering waste heat from blast furnace slag using dry centrifugal pelletizing technology. A comprehensive two-dimensional model was developed to analyze heat transfer dynamics and investigate factors influencing heat exchange efficiency. The findings have important implications for optimizing waste heat recovery and ensuring safe operations.
APPLIED THERMAL ENGINEERING
(2024)
Article
Thermodynamics
Xincheng Wu, An Zou, Qiang Zhang, Zhaoguang Wang
Summary: The boosting heat generation rate of high-performance processors is challenging traditional cooling techniques. This study proposes a combined design of active jet intermittency and passive surface modification to enhance heat transfer.
APPLIED THERMAL ENGINEERING
(2024)