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Journal of Thermal Science 2022年第3期31卷 650-662页

作者： GE Yi han jitian ZHU Xiaoxuan School of Energy and Power Engineering Shandong UniversityJi’nan250061China

The basic organic Rankine cycle(BORC)and ORC with an internal heat exchanger(IHORC)are studied with different working fluids under a given heat source condition to analyse the thermodynamic performances and net power *** results demonstrate that the external exergy efficiency of IHORC is lower than that of BORC while the internal exergy efficiency is on the opposite with the same overall exergy efficiencies.A multi-objective optimization model with inlet pressure and temperature of expander as independent parameters and exergy and heat recovery efficiencies as objective functions is solved by NSGA-II(the second non-dominated sorting genetic algorithm).The Pareto optimal solutions are obtained by the optimization *** calculation with the optimum conditions,it is determined that R236ea has the best comprehensive performance with exergy efficiencies being 40.69%and 41.38%,and heat recovery efficiencies being 83.2%and 75.6%in IHORC and BORC,*** evaporators occupy the maximum exergy destruction,which can be reduced by decreasing pinch point temperatures and increasing evaporation pressures.

关键词： ORC working fluids exergy analysis multi-objective optimization exergy destruction

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环形热电制冷器支腿几何形状与结构优化

低温与超导 2024年第4期52卷 1-8页

作者：苏炎梅吴若芸杨金文韩吉田山东大学能源与动力工程学院济南250061

环形热电制冷器可以消除平板热电制冷器冷却圆形热源时由于几何形状不匹配而产生的接触热阻。本文采用三维有限元法对变形状支腿的环形热电制冷器进行了数值模拟,研究了支腿形状、体积、电流、环角比例系数、高度等对制冷性能的影响。... 详细信息

环形热电制冷器可以消除平板热电制冷器冷却圆形热源时由于几何形状不匹配而产生的接触热阻。本文采用三维有限元法对变形状支腿的环形热电制冷器进行了数值模拟,研究了支腿形状、体积、电流、环角比例系数、高度等对制冷性能的影响。结果表明,X、Y环形支腿比传统梯形的最大温差分别提升了0.71%和0.74%,同时可节省约25%、38%的热电材料,相同体积下,优化后的结构可使冷端温度降低2.5 K。此外,当环角比例系数θr从1减小至0.15、支腿高度从1 mm增加至2 mm时,制冷性能分别提高了0.66%和0.72%。

关键词：环形热电制冷器支腿形状制冷性能结构优化有限元法

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新型圆锥Ⅰ型热电制冷器的性能优化研究

低温与超导 2024年第3期52卷 1-7页

作者：吴若芸苏炎梅杨金文韩吉田山东大学能源与动力工程学院济南250061

本文通过COMSOL建立了新型圆锥Ⅰ型热电制冷元件的三维模型,采用有限元法对改变热电支腿结构和I型支腿尺寸时热电制冷性能进行了优化研究,分析了在不同热端温度下采用分段式支腿结构对热电制冷元件制冷性能的影响。研究结果表明,圆锥Ⅰ... 详细信息

本文通过COMSOL建立了新型圆锥Ⅰ型热电制冷元件的三维模型,采用有限元法对改变热电支腿结构和I型支腿尺寸时热电制冷性能进行了优化研究,分析了在不同热端温度下采用分段式支腿结构对热电制冷元件制冷性能的影响。研究结果表明,圆锥Ⅰ型支腿最低冷端温度可达235.48 K,在相同电流下比传统、圆柱和圆锥X型支腿冷端温度分别下降了8.47 K、8.46 K和1.77 K。增大圆锥Ⅰ型支腿的高度与冷热端接触面积、减小圆柱段截面积和采用分段式热电结构均能提高热电制冷性能。

关键词：热电制冷 Ⅰ型结构优化制冷性能

Investigation on the Performance of the Pump-Free Double Heat Source Ejector Refrigeration System with R1234yf

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Journal of Thermal Science 2022年第5期31卷 1452-1464页

作者： YU Meihong ZHAO Hongxia WANG Xinli han jitian LAI Yanhua School of Energy and Power Engineering Shandong UniversityJi’nan250061China School of Control Science and Engineering Shandong UniversityJi’nan250061China

A pump is needed in an ejector refrigeration system,which makes the system high cost and complicated and hinders its application.A pump-free double heat source ejector refrigeration system using R1234yf as working fluid is proposed in which an injector driven by another heat source replaces the liquid circulating pump,making the system more affordable,simpler and more *** effect of different operation conditions on entrainment ratios and the influence of different factors on system performance are analyzed on the basis of mass,momentum and energy conservation *** influence degree of each factor on system performance is investigated by the orthogonal test *** condenser temperature has the largest effect on system *** pressure drop in the suction chamber of gas-liquid injector has the least impact on system *** COP can reach about 0.35 under a certain working *** system can be driven by two different temperature heat sources with no electricity needed,and it is a good choice for places with abundant heat resources or lack of electricity.

关键词： ejector refrigeration system injector entrainment ratio coefficient of performance(COP)

Performance Study and Multi-Objective Optimization of a Two-Temperature CO_(2) Refrigeration System with Economizer Based on Energetic, Exergetic and Economic Analysis

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Journal of Thermal Science 2022年第5期31卷 1416-1433页

作者： LIU Guangdi ZHAO Hongxia WANG Zheng ABDULWAHID Alhasan Ali han jitian School of Energy and Power engineering Shandong UniversityJi’nan250061China

A two temperature CO_(2) refrigeration system with economizer is proposed and compared with the traditional dual-temperature CO_(2) refrigeration system based on energy consumption,exergy and economic *** genetic algorithm multi-objective optimization method,taking the COP,exergy loss and total economic cost as the objective functions to find the best design conditions of the two *** Pareto fronts are obtained at different ambient *** for order preference by similarity to an ideal solution decision-making method is adopted to determine the optimum state *** simulation results show that when operating at different ambient temperatures,the introduction of economizer can improve COP,reduce exergy loss and the overall economic cost rate of the two-temperature CO_(2) refrigeration *** addition,economic analyses take the impact of carbon dioxide emission cost and electricity price into *** results indicate that with the increase of CO_(2) emission cost and electricity price,the hourly economic cost of both systems increases,but the hourly economic cost of the two-temperature CO_(2) refrigeration system with economizer system is always lower than that of conventional two-temperature CO_(2) refrigeration system.

关键词： two-temperature refrigeration CO_(2) multi-objective optimization energy exergetic economic cost

Experimental study on freezing of liquids under static magnetic field

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Chinese Journal of Chemical Engineering 2017年第9期25卷 1288-1293页

作者： Hongxia Zhao Feng Zhang hanqing Hu Sheng Liu jitian han School of Energy and Power Engineering Shandong University Vegetable Research Center Beijing Academy of Agriculture and Forestry Sciences National Engineering Research Center for Vegetables

Freezing processes of several liquids under static magnetic field(SMF) less than 50 mT were investigated. Central temperature of liquid samples held in glass test tubes immersed in a liquid bath was measured and collected. Nucleation temperature and phase transition time were obtained from freezing curves. Normality tests were performed for nucleation temperature of these liquids with/without magnetic field and normality distributions were justified. Analysis of variances was carried out for nucleation temperature of these liquids with magnetic field flux density as the influencing factor. Results showed that no significant difference was found for deionized water with or without SMF. However, differences exist in 0.9% NaCl solution and 5% ethylene glycol solution with and without SMF. Nucleation temperature of 0.9% NaCl with SMF is lower than that without SMF, while its phase transition time is shorter than that without SMF. Nucleation temperature of 5% ethylene glycol with SMF is higher than that without SMF, while its phase transition time is not modified with SMF.

关键词： Liquid Freezing Static magnetic field Nucleation temperature Phase transition time

Synergistic effect of N- and F-codoping on the structure and photocatalytic performance of TiO_2

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Journal of Environmental Sciences 2015年第2期27卷 148-156页

作者： Jiemei Yu Zongming Liu Haitao Zhang Taizhong Huang jitian han Yihe Zhang Daohuang Chong School of Energy and Power Engineering Shandong University School of Chemistry and Chemical Engineering University of Jinan School of Materials Science and Technology China University of Geosciences

Three types of TiO2 nanostructures were synthesized via a facile hydrolysis method at195 °C. Effects of the preparation method and doping with N and F on the crystal structure and photocatalytic performance of TiO2 were investigated. The nanomaterials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller porosimetry, ultraviolet–visible diffuse reflectance spectroscopy and fluorescent emission spectra. Their photo-catalytic activity was examined by the photodegradation of methylene blue in aqueous solution under both ultra-violet and visible light irradiation. The results show that nitrogen and fluorine co-doped anatase TiO2 had the characteristics of a smaller crystalline size, broader light absorption spectrum and lower charge recombination than pure TiO2. Most importantly, more efficient photocatalytic activity under both ultra-violet and visible light was observed. The obtained N–F-TiO2 nanomaterial shows considerable potential for water treatment under sunlight irradiation.

关键词： TiO2hydrolysis Anion doping Photocatalyst Nanoparticle

具有喷射制冷的SOFC/TRCC电冷联供系统4E分析

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东南大学学报（自然科学版） 2023年第4期53卷 682-691页

作者：韩吉田刘财浩葛艺山东大学能源与动力工程学院济南250061

提出了一种通过跨临界CO_(2)循环(TRCC)和喷射制冷循环(ERC)回收固体氧化物燃料电池/燃气轮机(SOFC/GT)余热的新型电冷联供系统.在工程求解器(EES)软件环境下建立了系统的数学模型,从能量、㶲、环境和经济(4E)的角度对系统进行研究,分析... 详细信息

提出了一种通过跨临界CO_(2)循环(TRCC)和喷射制冷循环(ERC)回收固体氧化物燃料电池/燃气轮机(SOFC/GT)余热的新型电冷联供系统.在工程求解器(EES)软件环境下建立了系统的数学模型,从能量、㶲、环境和经济(4E)的角度对系统进行研究,分析了关键参数变化对系统性能的影响.结果表明:联供系统在设计工况下净输出功率为272.874 kW,可向用户提供15.785 kW冷负荷,系统总成本为0.288 8元/(kW·h);系统总发电效率、总㶲效率和能源综合利用效率分别为68.12%、66.60%和72.06%;增加燃料利用率或提高SOFC入口温度和增大TRCC透平入口压力都可提高联供系统的㶲效率,当空燃比达到10.88时,系统㶲效率达到最大值66.94%;增大燃料利用率和SOFC入口温度或降低TRCC透平入口压力可降低系统总成本,在空燃比为10.57时达到最小值0.280 8元/(kW·h).

关键词：固体氧化物燃料电池跨临界二氧化碳循环喷射制冷循环 4E分析

Experimental study of the onset of nucleate boiling in vertical helically-coiled tubes

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Journal of Southeast University(English Edition) 2018年第3期34卷 402-407页

作者： Kong Lingjian han jitian Chen Changnian Liu Zhigang ZEnergy Research Institute of Shandong Academy Sciences Jinan 250014China School of Energy and Power Engineering Shandong UniversityJinan 250061China

The experiments of the onset of nucleate boiling using R134a as working fluid were conducted in vertical helically-coiled tubes. The experiments were carried out with a range of pressure from 450 to 850 kPa, inlet subcooling from 4.7 to 15.0℃, heat flux from 0.11 to 8.9 kW/m2 and mass flux from 218. 2 to 443. 7 kg/（ m2 · s ）. The heat flux, superheat and temperature undershoot at the ONB are analyzed in vertical helically-coiled tubes. Also, the effects of mass flux, system pressure, inlet subcooling and geometric parameters on the ONB are studied. The results demonstrate that the inception heat flux and superheat increase with increasing mass flux and inlet subcooling, but decrease with increasing system pressure and helix diameter. The pitch of the helical coil has a slight effect on the wall superheat and heat flux at the ONB. The correlation of heat flux at the ONB of subcooled flow boiling in helical coil is developed based on the experimental data, and it shows a good agreement with the experimental data.

关键词： two-phase flow subcooled flow boiling onset ofnucleate boiling helical coil

SIMULTANEOUS MEASUREMENT OF THE HEAT AND MASS DIFFUSIVITIES IN UNSATURATED MOIST SOILS USING CONSTANT HEAT FLUX METHOD

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Journal of Hydrodynamics 1998年第2期10卷 87-93页

作者： han, jitian Gui, Keting Shi, Mingheng Gong, Weiping Shandong Univ of Technology Jinan China

The simultaneous measurement of heat and mass diffusivities in unsaturated moist soils was presented by using a constant heat flux method. It can determine the heat and mass diffusivities in a moist soil through only one test. The experimental results show that the developed method is timesaving and has potential applications. It provides a new way for the fast and accurate measurement of heat and mass diffusivities in moist soils and other unsaturated wet porous media.

关键词： Diffusion in solids Heat transfer Mass transfer Moisture Sediment transport