Applied Thermal Engineering最新文献

{"title":"Novel fabrication of polyethylene glycol/ceramic composite pellets with an excellent phase change shape stable trait and their potential applications for greenhouse insulation","authors":"Zhiye Ma,&nbsp;Qian Zhang,&nbsp;Xuechun Wang,&nbsp;Shichao Zong,&nbsp;Bo Bai","doi":"10.1016/j.applthermaleng.2024.125096","DOIUrl":"10.1016/j.applthermaleng.2024.125096","url":null,"abstract":"<div><div>Organic solid–liquid phase change materials (PCMs) face challenges in practical applications due to their susceptibility to leakage during phase transitions. To address this issue, we constructed the polyethylene glycol (PEG)/ceramic pellets (CPs) composite phase change shape stable materials (PCSHs) with thermal energy storage capability, thermal stability, and a firm texture using the melting impregnation method. The PCSHs exhibit remarkable shape stability in the leakage test due to the capillary action and surface tension generated by the micropore structure on their surface. They also can convert light energy into heat and store it as latent heat, achieving an optimal photothermal conversion efficiency of 45.21 % and a maximum melting enthalpy of 13.33 kJ/kg at a PEG loading of ∼ 12 %. An outdoor greenhouse insulation simulation experiment confirmed that the PCSHs can maintain soil temperatures above 30 °C for over 30 min after illumination ceases. This work presents a facile synthesis strategy for shape-stable PCMs with potential applications in greenhouse insulation.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"261 ","pages":"Article 125096"},"PeriodicalIF":6.1,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142756551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental and numerical research on a C-type heat exchanger in duct air conditioner under non-uniform airflow","authors":"Bin Luo ,&nbsp;Feng Li ,&nbsp;Siyuan Wu ,&nbsp;Kewei Shi ,&nbsp;Yunxiao Ding ,&nbsp;Rijing Zhao ,&nbsp;Dong Huang ,&nbsp;Wenxing Shi","doi":"10.1016/j.applthermaleng.2024.125097","DOIUrl":"10.1016/j.applthermaleng.2024.125097","url":null,"abstract":"<div><div>The indoor unit of duct air conditioner typically employs an A-type heat exchanger (HX), but non-uniform airflow within the duct significantly degrades heat transfer performance. The current study proposes a C-type HX to accommodate the non-uniform airflow better. Experiments are conducted to compare the C-type and A-type HXs under varying conditions, including air volume flow rate, air velocity non-uniformity, inlet air temperature, and condensing temperature. Results indicate that as the non-uniformity of inlet air velocity increases, the heat transfer capacity of A-type HX decreases obviously. In contrast, the C-type is insensitive to the non-uniform air velocity distribution, which consistently outperforms the A-type in terms of heat transfer capacity throughout various operating conditions. Additionally, a numerical model is developed to compare the local parameters of the two HX types. The C-type demonstrates a more uniform outlet air temperature and exhibits a heat transfer capacity that is 19.1% higher than the A-type, while maintaining the identical heat transfer area and size parameters.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"261 ","pages":"Article 125097"},"PeriodicalIF":6.1,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance of a greenhouse heating system utilizing energy transfer between greenhouses based on the dual source heat pump","authors":"Baochang Zhou ,&nbsp;Weituo Sun ,&nbsp;Wenzhong Guo ,&nbsp;Wengang Zheng ,&nbsp;Mei Qu","doi":"10.1016/j.applthermaleng.2024.125088","DOIUrl":"10.1016/j.applthermaleng.2024.125088","url":null,"abstract":"<div><div>High energy consumption challenges the multi-span greenhouse industry in China. To address this, a greenhouse heating system utilizing energy transfer between greenhouses based on the dual source heat pump (ETGHP) was designed in our previous research. However, its performance in practical application remains largely unexplored. This study conducted a field test to comprehensively assess this system. Results showed stable heating effects, and the heat collection of the system in Chinese solar greenhouse (CSG) air source heating mode accounted for 2.1% to 28.2% of the total, validating the feasibility of energy transfer between greenhouses. The use of CSG air source increased heating capacity by 27% and coefficient of performance (COP) by 23% for air source heat pumps. Then the dual source configuration achieved a 10.8% increase in heat collection and a 7.9% improvement in COP compared with the single air source. During the test, the COP of the system achieved 2.8 during heat collection and 2.5 for heating the multi-span greenhouse. Outdoor weather, greenhouse structures and management were found to influence system operation. This study also conducted performance comparation and explored the economic and environmental benefits for the system, proving it to be an efficient solution for multi-span greenhouse heating.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"261 ","pages":"Article 125088"},"PeriodicalIF":6.1,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142758988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of cooling performances and energy saving potential for separator enhanced thermosiphon/vapor compression hybrid system","authors":"Lin Zhu,&nbsp;Yang Qin,&nbsp;Chunyang Chen,&nbsp;Yu Zhao","doi":"10.1016/j.applthermaleng.2024.125095","DOIUrl":"10.1016/j.applthermaleng.2024.125095","url":null,"abstract":"<div><div>With the advancement of technology, the energy consumption of data centers has dramatically increased. Among them, the energy consumption of cooling equipment accounts for more than 40% of the total energy consumption of data centers. To reduce energy consumption and enhance performance, A novel separator enhanced thermosiphon/Vapor compression hybrid cooling system (STPVC) has been proposed. The cooling performances of the STPVC system are assessed through experimental test and comparisons in the conventional hybrid system (CTPVC) are shown in this paper as well. The experimental results indicate that compared to the CTPVC, the STPVC system can achieves a maximum improvement of 30.91% in thermosiphon mode and 19.3% improvement in vapor compression mode Additionally, to evaluate the energy saving potential of the STPVC, the annual energy efficiency ratios (AEER) of the system in various latitude cities of China have been theoretically calculated. A high AEER of the system about 15.3 can be achieved in the high latitude area. Even in the low-latitude region, the system also can gain the value of AEER about 5.45. The results of this paper are expected to provide a direction of performances enhancement and energy consumption reduction of the cooling equipment in the data center.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"261 ","pages":"Article 125095"},"PeriodicalIF":6.1,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Naturally circulated system under low to moderate heating condition with supercritical fluid: A comprehensive investigation of loop orientation and Ledinegg instability","authors":"Tanuj Srivastava ,&nbsp;Ashok Kumat Gond ,&nbsp;Dipankar N. Basu","doi":"10.1016/j.applthermaleng.2024.125035","DOIUrl":"10.1016/j.applthermaleng.2024.125035","url":null,"abstract":"<div><div>Out of the two stability characteristics i.e. static and dynamics, static instability has hardly been explored in such systems due to mathematical complexity and absence of explicit boundary conditions. Present numerical investigation deals with the 1D numerical framework analyzing the steady-state and static instability of the loop under different loop orientation i.e., horizontal heater horizontal cooler (HHHC), vertical heater horizontal cooler (VHHC), horizontal heater vertical cooler (HHVC) and vertical heater vertical cooler (VHVC). The range of heating power considered is applicable in the low to moderate heating condition such as in solar heater and electronic chip cooling. Due to uneven generation of buoyancy and friction throughout the flow path, occurrence of FiHTD is also dependent on it, with best and worst thermalhydraulic characteristics for HHHC and VHVC respectively. For every condition, the appearance of static instability was found to be within the heating power limit. For <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>∞</mi></mrow></msub></math></span> = 295 K it spanned over 1050 W for HHHC orientated loop which got decreased by 9.5%, 23.8% and 65.7% for VHHC, HHVC and VHVC respectively. Under the condition of increased of <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>∞</mi></mrow></msub></math></span> = 300 K the same was found within the limit of 575 W and got decreased by 13%, 21.7% and 64.3% for cases mentioned above insequential manner. Stability maps drawn using well known non-dimensional numbers holds a good qualitative behavior of static instability. Dynamic instability is well explored for HHHC combination has throughly done previously by various authors and hence, has not been considered here. The authors believe that dynamic instability will not be much more prominant due to predefined flow direction and can be explored as a future work.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"260 ","pages":"Article 125035"},"PeriodicalIF":6.1,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An investigation on the thermo-hydraulic and electrochemical performance of a novel vanadium-based embedded cooling system for synergistic energy supply and heat dissipation","authors":"Jiale Zhu,&nbsp;Muxing Zhang,&nbsp;Qiang Li","doi":"10.1016/j.applthermaleng.2024.125094","DOIUrl":"10.1016/j.applthermaleng.2024.125094","url":null,"abstract":"<div><div>Miniaturization and integration of electronics require advanced heat dissipation techniques and efficient power interconnections. Integrating energy supply and heat dissipation into one fluidic network presents a viable approach to support compact, highly integrated chip designs. This study introduces an innovative microfluidic system that utilizes embedded cooling with vanadium electrolytes, enabling synergistic near-junction thermal management and power generation. The thermo-hydraulic and electrochemical performance of the system was evaluated under various conditions and subsequently applied to a real GaN chip. Results indicated that the system effectively dissipated a heat flux up to 317.06 W/cm² at a flow rate of 15 mL/min and an inlet temperature of 20 °C. When the flow rate was 2 mL/min, the system’s COP reached 113368. After heat absorption by the coolant, the system’s output power increased by 11.74 % with the temperature rise. High-temperature coolant enhanced ion transport and electrochemical kinetics, demonstrating the system’s potential for waste heat recovery. Upon integration with the GaN semiconductor, the system achieved power supply via waste heat recovery, reducing the hot spot temperature by 70.18 % and increasing the output current signal by 4.75 % compared to the thermally insulated devices.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"261 ","pages":"Article 125094"},"PeriodicalIF":6.1,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142758998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical study of water droplets in hydrogen recirculation ejectors for proton exchange membrane fuel cells","authors":"Jiangkun Zou ,&nbsp;Jing Li ,&nbsp;Gerald Singer ,&nbsp;Li Zhang ,&nbsp;Pingwen Ming","doi":"10.1016/j.applthermaleng.2024.125084","DOIUrl":"10.1016/j.applthermaleng.2024.125084","url":null,"abstract":"<div><div>Gas ejectors play a vital role in recirculating anode hydrogen within proton exchange membrane fuel cells. Previous studies primarily use single-phase flow computational fluid dynamics to design ejectors, neglecting water phase changes and compromising accuracy. Here, we develop a two-phase flow model incorporating droplet injection in the secondary flow and a water condensation model to analyze the ejector’s behavior. Validated by previous experiments in six different conditions, our two-dimensional model captures dynamic interactions between the gas and liquid water phases, leading to predict entrainment ratio more accurately, with an average deviation of 3.08% compared to 24.04% for the single-phase model. Additionally, simulations have been done for six different cases comparing different degrees of humidification of the secondary hydrogen flow. Water droplet growth increases gas temperature and pressure in the mixing chamber while reducing velocity, lowering the entrainment ratio by over 30%. Injecting a certain amount of droplets into the secondary flow can effectively improve the efficiency of the mixing chamber. Integrating a heat exchanger in the hydrogen supply line increases overall temperature and decreases water condensation. This study provides an in-depth understanding of water phase behavior, further optimizes the hydrogen ejector, and improves the accuracy of its simulation.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"261 ","pages":"Article 125084"},"PeriodicalIF":6.1,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal-mechanical behavior of deeply buried pipe energy pile group in sand obtained from model test","authors":"Jianghuai Yuan ,&nbsp;Zhi Chen ,&nbsp;Henglin Xiao ,&nbsp;Lifei Zheng ,&nbsp;Wentao Li ,&nbsp;Xugen Song","doi":"10.1016/j.applthermaleng.2024.125078","DOIUrl":"10.1016/j.applthermaleng.2024.125078","url":null,"abstract":"<div><div>One practical and effective method for shallow geothermal development is energy piling. This research presents the deeply buried pipe energy pile (DBP-EP), which has a wide range of potential applications and can collect deeper geothermal heat from the pile toe. This work conducts a model test investigation of the thermal–mechanical behavior of the DBP-EP group in sandy soil because the construction of the former differs from that of the common inside buried pipe energy piles (IBP-EP). The findings indicate that the heat exchanger tube at the pile toe of DBP-EP will be extended outward for heat exchange with the soil, in contrast to IBP-EP, and that the temperature change at the pile toe is greater than that of the whole. The pile cross-section strain decreases gradually from inside to outside along the radial direction. The axial earth pressure change rule around the pile is larger at both ends and small in the middle. For every 1℃ that the inlet temperature raises, the pile top’s final displacement increases by roughly 0.11‰<span><math><mrow><mi>D</mi></mrow></math></span>. At various inlet temperatures, the DBP-EP group heat transfer rate per meter drops by 8% − 23% when compared to the single pile’s. The average axial earth pressure difference surrounding the pile gradually rises when the pile top is not loaded, while the pile side friction difference of the pile group reduces in comparison to that of the single pile. The variations in pile side friction, axial earth pressure surrounding the pile, and pile top displacement of the pile group are reduced when the pile top is loaded because of the dense effect between the pile and the soil. This study contributes to the theoretical understanding of the design and practical implementation of DBP-EP structures.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"261 ","pages":"Article 125078"},"PeriodicalIF":6.1,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142756563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel determination method for thermal boundary conditions during permafrost simulation","authors":"Wen-zhen Tang,&nbsp;Xiao-kang Li,&nbsp;Xu Li","doi":"10.1016/j.applthermaleng.2024.125080","DOIUrl":"10.1016/j.applthermaleng.2024.125080","url":null,"abstract":"<div><div>Boundary conditions are crucial for simulating the thermal status of permafrost soils, impacting the assessment of infrastructure stability and permafrost degradation. Field measurement and the boundary layer theory are two principal methods to determine the thermal boundary conditions, while parameters in these methods are empirical. This study proposed a novel method to determine the thermal boundary conditions, utilizing the known active layer thickness (ALT) and the depth of permafrost base. Firstly, the accuracy of equations for estimating ALT and the depth of permafrost base was validated using observed data. Next, a numerical model was built to investigate the impact of changes in ALT and the depth of permafrost on its thermal state. And then, the major influencing parameters of ALT and the depth of permafrost were determined. The results indicated that: (1) The maximum relative error between the observed and the estimated ALT is 15 %, and ALT can be reasonably estimated by the extended Stefan equation for multi-layered soils; (2) The maximum relative error between the observed and the estimated depth of permafrost is 4.9 %, and the depth of permafrost base can be estimated by the newly modified equation; (3) As two crucial indicators to judge the reliability of thermal boundary conditions, ALT and the depth of permafrost base needs to be appropriately set to avoid unacceptable deviations in numerical simulation. In this study, the relative error between the numerically inversed and the observed temperature was only 5.4 %, with an appropriate ALT of 2.5 m and a depth of 44.52 m for the permafrost base; (4) ALT is mainly governed by surface thawing index and water content, while the depth of permafrost base is mainly governed by geothermal gradient and mean annual ground temperature (MAGT). Based on the results, a method for determining the upper temperature and the lower heat flux boundary is proposed for permafrost simulation. The findings can guide the design and numerical simulation of geotechnical engineering in permafrost regions.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"261 ","pages":"Article 125080"},"PeriodicalIF":6.1,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142758997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-criteria sensitivity study and optimization of a two-stage preheated SOFC system considering thermal characteristics","authors":"Kui Xu ,&nbsp;Liyun Fan ,&nbsp;Jinwei Sun ,&nbsp;Haibo Huo ,&nbsp;Zejun Jiang ,&nbsp;Chongchong Shen ,&nbsp;Yunpeng Wei","doi":"10.1016/j.applthermaleng.2024.125090","DOIUrl":"10.1016/j.applthermaleng.2024.125090","url":null,"abstract":"<div><div>At present, the pivotal challenges hindering the commercialization of the Solid Oxide Fuel Cell (SOFC) lie in system design and matching, thermal management safety, and performance optimization. To address these issues, a SOFC system-level model for the optimal control is proposed, integrating a two-stage preheater design, the electrochemical reaction mechanisms, and the influence of thermoelectric coupling effects on electrode temperature distributions. Furthermore, a comprehensive multi-criteria sensitivity analysis is conducted, incorporating thermodynamic, economic, and environmental indicators. The research demonstrates that there exist distinct mechanisms underlying the impact of varying trends in fuel utilization ratio and excess air ratio on the performance indicators of the SOFC system. Then, a detailed sensitivity analysis is undertaken, exploring the response trends of performance indicators under varying parameters. To validate the dynamic behavior of the objective functions, an intelligent learning approach based on the Artificial Neural Network is proposed. Additionally, a Multi-Objective Grey Wolf Optimization process is introduced, aimed at enhancing the comprehensive performance of the SOFC system. The results of this study demonstrate that the proposed multi-objective optimization strategy achieves a reduction of 12.12% in maximum temperature gradient, 28.00% in Levelized Cost of Energy, and 4.76% in Mass Specific Emission at the optimal operating point. This underscores the effectiveness of the approach in balancing and optimizing the trade-offs between thermal stability, economic feasibility, and environmental impact of the SOFC system.</div></div>","PeriodicalId":8201,"journal":{"name":"Applied Thermal Engineering","volume":"261 ","pages":"Article 125090"},"PeriodicalIF":6.1,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142758990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}