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An investigation into the heat transfer characteristics of spiral wall with internal rib in a supercriticalsliding-pressure operation once-through boiler

TANG Renhu, YIN Fei, WANG Haijun, CHEN Tingkuan

《能源前沿（英文）》 2007年 第1卷 第3期   页码 300-304 doi: 10.1007/s11708-007-0043-5

摘要： Within the pressure range of 9–28 MPa, mass velocity range of 600–1 200 kg/(m · s), and heat flux range of 200–500 kW/m, experiments were performed to investigate the heat transfer to water in the inclined upward internally ribbed tube with an inclined angle of 19.5 degrees, a maximum outer diameter of 38.1 mm, and a thickness of 7.5 mm. Based on the experiments, it was found that heat transfer enhancement of the internally ribbed tube could postpone departure from nucleate boiling at the sub-critical pressure. However, the heat transfer enhancement decreased near the critical pressure. At supercritical pressure, the temperature difference between the wall and the fluid increased near the pseudo-critical temperature, but the increase of wall temperature was less than that of departure from nucleate boiling at sub-critical pressure. When pressure is closer to the critical pressure, the temperature difference between the wall and the fluid increased greatly near the pseudo-critical temperature. Heat transfer to supercritical water in the inclined upward internally ribbed tube was enhanced or deteriorated near the pseudo-critical temperature with the variety of ratio between the mass velocity and the heat flux. Because the rotational flow of the internal groove reduced the effect of natural convection, the internal wall temperature of internally ribbed tube uniformly distributed along the circumference. The maximum internal wall temperature difference of the tube along the circumference was only 10 degrees when the fluid enthalpy exceeded 2 000 J/g. Considering the effect of acute variety of the fluid property on heat transfer, the correlation of heat transfer coefficient on the top of the internally ribbed tube was provided.

关键词： m ·     diameter     critical pressure     sub-critical pressure     maximum    

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Convective heat transfer in helical coils for constant-property and variable-property flows with high Reynolds numbers

Yufei MAO, Liejin GUO, Bofeng BAI, Ximin ZHANG

《能源前沿（英文）》 2010年 第4卷 第4期   页码 546-552 doi: 10.1007/s11708-010-0116-8

摘要： Forced convection heat transfer of single-phase water in helical coils was experimentally studied. The testing section was constructed from a stainless steel round tube with an inner diameter of 10 mm, coil diameter of 300 mm, and pitch of 50 mm. The experiments were conducted over a wide Reynolds number range of 40000 to 500000. Both constant-property flows at normal pressure and variable-property flows at supercritical pressure were investigated. The contribution of secondary flow in the helical coil to heat transfer was gradually suppressed with increasing Reynolds number. Hence, heat transfer coefficients of the helical tube were close to those of the straight tube under the same flow conditions when the Reynolds number is large enough. Based on the experimental data, heat transfer correlations for both incompressible flows and supercritical fluid flows through helical coils were proposed.

关键词： convective heat transfer     helical coils     high Reynolds number     supercritical pressure     variable property    

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Calculation and analysis of sub/supercritical methanol preheating tube for continuous production of biodieselvia supercritical methanol transesterification

Wen CHEN, Weiyong YING, Cunwen WANG, Weiguo WANG, Yuanxin WU, Junfeng ZHANG,

《能源前沿（英文）》 2009年 第3卷 第4期   页码 423-431 doi: 10.1007/s11708-009-0075-0

摘要： Biodiesel is an important renewable energy. Supercritical methanol transesterification for biodiesel has recently been concerned because of its obvious advantages. The tubular reactor is an ideal reactor for continuous preparation of biodiesel via supercritical methanol transesterification. A methanol preheating tube is necessary for the tubular reaction system because the reaction temperature for supercritical methanol transesterification is usually 520―600K. Therefore, in the range of 298―600K, changes of the density, isobaric capacity, viscosity and thermal conductivity of sub/supercritical methanol with temperature are first discussed. Then on the basis of these thermophysical properties, an integration method is adopted for the design of sub/supercritical methanol preheating tube when methanol is preheated from 298K to 600K at 16MPa and the influencing factors on the length of the preheating tube are also studied. The computational results show that the Reynolds number and the local convection heat-transfer coefficient of sub/supercritical methanol flowing in ф6mm×1.5mm preheating tube change drastically with temperature. For the local overall heat transfer coefficient and the average overall heat transfer coefficient , temperature also has an important influence on them when the inlet velocity of methanol is lower than 0.5m/s. But when the inlet velocity of methanol is higher than 0.5m/s, and almost keep invariable with temperature. Additionally, both the outlet temperature and the inlet velocity of methanol are the key affecting factors for the length of the preheating tube, especially when the outlet temperature is over the critical temperature of methanol. At the same time, the increase of tin bath’s temperature can shorten the required length of the preheating tube. At the inlet flow rate of 0.5m/s, the required length of the preheating tube is 2.0m when methanol is preheated from 298K to 590K at 16MPa with keeping the tin bath’s temperature 620K, which is in good agreement with the experimental results.

关键词： sub/supercritical methanol     preheating tube     integration method     biodiesel    

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A review on catalytic & non-catalytic bio-oil upgrading in supercritical fluids

Sainab Omar, Yang Yang, Jiawei Wang

《化学科学与工程前沿（英文）》 2021年 第15卷 第1期   页码 4-17 doi: 10.1007/s11705-020-1933-x

摘要： This review article summarizes the key published research on the topic of bio-oil upgrading using catalytic and non-catalytic supercritical fluid (SCF) conditions. The precious metal catalysts Pd, Ru and Pt on various supports are frequently chosen for catalytic bio-oil upgrading in SCFs. This is reportedly due to their favourable catalytic activity during the process including hydrotreating, hydrocracking, and esterification, which leads to improvements in liquid yield, heating value, and pH of the upgraded bio-oil. Due to the costs associated with precious metal catalysts, some researchers have opted for non-precious metal catalysts such as acidic HZSM-5 which can promote esterification in supercritical ethanol. On the other hand, SCFs have been effectively used to upgrade crude bio-oil without a catalyst. Supercritical methanol, ethanol, and water are most commonly used and demonstrate catalyst like activities such as facilitating esterification reactions and reducing solid yield by alcoholysis and hydrolysis, respectively.

关键词： bio-oil     upgrading     supercritical     review    

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Polydimethylsiloxane assisted supercritical CO

Weixia Wang, Shuai Zhou, Zhong Xin, Yaoqi Shi, Shicheng Zhao

《化学科学与工程前沿（英文）》 2016年 第10卷 第3期   页码 396-404 doi: 10.1007/s11705-016-1577-z

摘要： Foamable high melt strength polypropylene (HMSPP) was prepared by grafting styrene (St) onto polypropylene (PP) and simultaneously introducing polydimethylsiloxane (PDMS) through?a?one-step?melt extrusion process. The effect of PDMS viscosity on the foaming behavior of HMSPP was systematically investigated using supercritical CO as the foaming agent. The results show that the addition of PDMS has little effect on the grafting reaction of St and HMSPP exhibits enhanced elastic response and obvious strain hardening effect. Though the CO solubility of HMSPP with PDMS (PDMS-HMSPP) is lower than that of HMSPP without PDMS, especially for PDMS with low viscosity, the PDMS-HMSPP foams exhibit narrow cell size distribution and high cell density. The fracture morphology of PDMS-HMSPP shows that PDMS with low viscosity disperses more easily and uniformly in HMSPP matrix, leading to form small domains during the extrusion process. These small domains act as bubble nucleation sites and thus may be responsible for the improved foaming performance of HMSPP.

关键词： high melt strength polypropylene (HMSPP)     polydimethylsiloxane (PDMS)     supercritical CO2     foaming behavior    

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Corrosion mechanisms of candidate structural materials for supercritical water-cooled reactor

Lefu ZHANG, Fawen ZHU, Rui TANG

《能源前沿（英文）》 2009年 第3卷 第2期   页码 233-240 doi: 10.1007/s11708-009-0024-y

摘要： Nickel-based alloys, austenitic stainless steel, ferritic/martensitic heat-resistant steels, and oxide dispersion strengthened steel are presently considered to be the candidate structural or fuel-cladding materials for supercritical water-cooled reactor (SCWR), one of the promising generation IV reactor for large-scale electric power production. However, corrosion and stress corrosion cracking of these candidate alloys still remain to be a major problem in the selection of nuclear fuel cladding and other structural materials, such as water rod. Survey of literature and experimental results reveal that the general corrosion mechanism of those candidate materials exhibits quite complicated mechanism in high-temperature and high-pressure supercritical water. Formation of a stable protective oxide film is the key to the best corrosion-resistant alloys. This paper focuses on the mechanism of corrosion oxide film breakdown for SCWR candidate materials.

关键词： supercritical water-cooled reactor     general corrosion     oxide film     corrosion mechanism    

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Development of a supercritical and an ultra-supercritical circulating fluidized bed boiler

Junfu LYU, Hairui YANG, Wen LING, Li NIE, Guangxi YUE, Ruixin LI, Ying CHEN, Shilong WANG

《能源前沿（英文）》 2019年 第13卷 第1期   页码 114-119 doi: 10.1007/s11708-017-0512-4

摘要： The supercritical circulating fluidized bed (CFB) boiler, which combines the advantages of CFB combustion with low cost emission control and supercritical steam cycle with high efficiency of coal energy, is believed to be the future of CFB combustion technology. It is also of greatest importance for low rank coal utilization in China. Different from the supercritical pulverized coal boiler that has been developed more than 50 years, the supercritical CFB boiler is still a new one which requires further investigation. Without any precedentor engineering reference, Chinese researchers have conducted fundamental research, development, design of the supercritical CFB boilers independently. The design theory and key technology for supercritical CFB boiler were proposed. Key components and novel structures were invented. The first 600 MWe supercritical CFB boiler and its auxiliaries were successfully developed and demonstrated in Baima Power Plant, Shenhua Group as well as the simulator, control technology, installation technology, commissioning technology, system integration and operation technology. Compared with the 460 MWe supercritical CFB in Poland, developed in the same period and the only other supercritical one of commercial running in the word beside Baima, the 600 MWe one in Baima has a better performance. Besides, supercritical CFB boilers of 350 MWe have been developed and widely commercialized in China. In this paper, the updated progress of 660 MWe ultra-supercritical CFB boilers under development is introduced.

关键词： supercritical     circulating fluidized bed boiler     development     demonstration    

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Thermo-economic analysis of a direct supercritical CO electric power generation system using geothermal

《能源前沿（英文）》 2022年 第16卷 第2期   页码 246-262 doi: 10.1007/s11708-021-0749-9

摘要： A comprehensive thermo-economic model combining a geothermal heat mining system and a direct supercritical CO2 turbine expansion electric power generation system was proposed in this paper. Assisted by this integrated model, thermo-economic and optimization analyses for the key design parameters of the whole system including the geothermal well pattern and operational conditions were performed to obtain a minimal levelized cost of electricity (LCOE). Specifically, in geothermal heat extraction simulation, an integrated wellbore-reservoir system model (T2Well/ECO2N) was used to generate a database for creating a fast, predictive, and compatible geothermal heat mining model by employing a response surface methodology. A parametric study was conducted to demonstrate the impact of turbine discharge pressure, injection and production well distance, CO2 injection flowrate, CO2 injection temperature, and monitored production well bottom pressure on LCOE, system thermal efficiency, and capital cost. It was found that for a 100 MWe power plant, a minimal LCOE of $0.177/kWh was achieved for a 20-year steady operation without considering CO2 sequestration credit. In addition, when CO2 sequestration credit is $1.00/t, an LCOE breakeven point compared to a conventional geothermal power plant is achieved and a breakpoint for generating electric power generation at no cost was achieved for a sequestration credit of $2.05/t.

关键词： geothermal heat mining     supercritical CO2     power generation     thermo-economic analysis     optimization    

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Production of renewable fuels by blending bio-oil with alcohols and upgrading under supercritical conditions

Sainab Omar, Suzanne Alsamaq, Yang Yang, Jiawei Wang

《化学科学与工程前沿（英文）》 2019年 第13卷 第4期   页码 702-717 doi: 10.1007/s11705-019-1861-9

摘要： The work studied a non-catalytic upgrading of fast pyrolysis bio-oil by blending under supercritical conditions using methanol, ethanol and isopropanol as solvent and hydrogen donor. Characterisation of the bio-oil and the upgraded bio-oils was carried out including moisture content, elemental content, pH, heating value, gas chromatography-mass spectrometry (GCMS), Fourier transform infrared radiation, C nuclear magnetic resonance spectroscopy, and thermogravimetric analysis to evaluate the effects of blending and supercritical reactions. The GCMS analysis indicated that the supercritical methanol reaction removed the acids in the bio-oil consequently the pH increased from 2.39 in the crude bio-oil to 4.04 after the supercritical methanol reaction. The ester contents increased by 87.49% after the supercritical methanol reaction indicating ester formation could be the major deacidification mechanism for reducing the acidity of the bio-oil and improving its pH value. Simply blending crude bio-oil with isopropanol was effective in increasing the C and H content, reducing the O content and increasing the heating value to 27.55 from 17.51 MJ·kg in the crude bio-oil. After the supercritical isopropanol reaction, the heating value of the liquid product slightly further increased to 28.85 MJ·kg .

关键词： bio-oil     blending     supercritical     upgrading     characterisation    

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超临界化——优化我国火电结构应从这里起步

宋之平

《中国工程科学》 2002年 第4卷 第2期   页码 22-27

摘要：

文章认为优化火电结构应放在超临界化上，使超临界机组和超超临界机组在我国火电中占据举足轻重的比例。而且这些机组的主要性能指标以及环保性能等应不逊于同类机组的国际水平。论述了超临界技术在优化火电结构的特殊作用，指出超临界化已被证明是改造和优化火电结构的一种成功的道路，阐明了我国实施这一发展道路的必要性和可能性。

关键词： 火电结构     超临界     超超临界     可持续发展战略    

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Micronization of curcumin with biodegradable polymer by supercritical anti-solvent using micro swirl

Kimthet Chhouk, Wahyudiono, Hideki Kanda, Shin-Ichro Kawasaki, Motonobu Goto

《化学科学与工程前沿（英文）》 2018年 第12卷 第1期   页码 184-193 doi: 10.1007/s11705-017-1678-3

摘要： Curcumin is a hydrophobic polyphenol compound exhibiting a wide range of biological activities such as anti-inflammatory, anti-bacterial, anti-fungal, anti-carcinogenic, anti-human immunodeficiency virus, and anti-microbial activity. In this work, a swirl mixer was employed to produce the micronized curcumin with polyvinylpyrrolidone (PVP) by the supercritical anti-solvent process to improve the bioavailability of curcumin. The effects of operating parameters such as curcumin/PVP ratio, feed concentration, temperature, pressure, and CO flow rate were investigated. The characterization and solubility of particles were determined by using scanning electron microscopy, Fourier Transform Infrared spectroscopy, and ultra-violet-visible spectroscopy. The result shows that the optimal condition for the production of curcumin/PVP particles is at curcumin/PVP ratio of 1:30, feed concentration of 5 mg·mL , temperature of 40 °C, pressure of 15 MPa, and CO flow rate of 15 mL·min . Moreover, the dissolution of curcumin/PVP particles is faster than that of raw curcumin.

关键词： micronization     curcumin     polyvinylpyrrolidone     supercritical anti-solvent     swirl mixer    

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Key problems and solutions in supercritical CO

Haizhu WANG, Gensheng LI, Bin ZHU, Kamy SEPEHRNOORI, Lujie SHI, Yong ZHENG, Xiaomei SHI

《能源前沿（英文）》 2019年 第13卷 第4期   页码 667-672 doi: 10.1007/s11708-019-0626-y

摘要： Supercritical CO fracturing is considered to be a new method for efficient exploitation of unconventional reservoirs, such as shale gas, coal bed methane, and tight sand stone gas. Supercritical CO has many special properties including low viscosity, high diffusion coefficient, and lack of surface tension, which brings about great advantages for fracturing. However, these properties also cause several problems, such as difficulty in proppant transportation, high friction loss, and high pump displacement. In this paper, the above problems were analyzed by combining field test with laboratory study and specific solutions to these problems are given. The high frictionloss in the pipeline could be reduced by developing a new drag reducing agent and selecting large-size casing. Besides, for the problem of poor capacity in proppant carrying and sand plug, the methods of adding tackifier into supercritical CO , increasing pump displacement and selecting ultra-low density proppants are proposed. Moreover, for the problem of fast leak-off and high requirement for pump displacement, the displacement can be increased or the pad fluid can be injected into the reservoir. After solving the above three problems, the field test of supercritical CO fracturing can be conducted. The research results can promote the industrialization process of supercritical CO fracturing.

关键词： supercritical CO2     fracturing     friction loss     proppant carrying     flied test problem    

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A new heat transfer correlation for supercritical fluids

Yanhua YANG, Xu CHENG, Shanfang HUANG

《能源前沿（英文）》 2009年 第3卷 第2期   页码 226-232 doi: 10.1007/s11708-009-0022-0

摘要： A new method of heat transfer prediction in supercritical fluids is presented. Emphasis is put on the simplicity of the correlation structure and its explicit coupling with physical phenomena. Assessment of qualitative behaviour of heat transfer is conducted based on existing test data and experience gathered from open literature. Based on phenomenological analysis and test data evaluation, a single dimensionless number, the acceleration number, is introduced to correct the deviation of heat transfer from its conventional behaviour, which is predicted by the Dittus-Boelter equation. The new correlation structure excludes direct dependence of heat transfer coefficient on wall surface temperature and eliminates possible numerical convergence. The uncertainty analysis of test data provides information about the sources and the levels of uncertainties of various parameters and is highly required for the selection of both the dimensionless parameters implemented into the heat transfer correlation and the test data for the development and validation of new correlations. Comparison of various heat transfer correlations with the selected test data shows that the new correlation agrees better with the test data than other correlations selected from the open literature.

关键词： super critical fluids     heat transfer     circular tubes     prediction method    

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Heat transfer with water flowing upward in a tube for pressures up to supercritical region

Yuzhou CHEN, Chunsheng YANG, Shuming ZHANG, Minfu ZHAO, Kaiwen DU,

《能源前沿（英文）》 2010年 第4卷 第3期   页码 358-365 doi: 10.1007/s11708-009-0071-4

摘要： A heat transfer experiment was conducted in a tube of 6.07mm in diameter with water flowing upward, covering the ranges of pressure of 10―23MPa, mass flux of 288―1298kg/(m·s), local water temperature of 78°C―270°C, heat flux of 0.23―1.18MW/m and Reynolds number of 5.5×10―3.9×10. The experimental results were compared with the predictions of the Dittus-Boelter correlation, Jackson correlation, Bishop correlation, Swenson correlation and Yamagata correlation. Significant deterioration in heat transfer was observed in both subcritical and supercritical region due to the effect of buoyancy force, but it was not predicted reasonably by the existing correlations.

关键词： heat transfer     deterioration     buoyancy     supercritical water    

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Simulation analysis of methanol flash distillation circulation process in biodiesel production with supercritical

Zhengjiao TANG, Cunwen WANG, Weiguo WANG, Jia GUO, Yuanxin WU, Jinfang CHEN, Yigang DING

《能源前沿（英文）》 2011年 第5卷 第1期   页码 93-97 doi: 10.1007/s11708-010-0028-7

摘要： High methanol-to-oil ratio is required to obtain a high conversion of oil for the production of biodiesel with supercritical methanol. Recovering the methanol of a stream issuing from a transesterification supercritical reactor by flash distillation instead of evaporation was analyzed. The one-stage and two-stage flash distillation processes were presented and compared. The difference of the recovery percentage of methanol of the above two flash processes is less than 0.5% and the methanol concentration in the vapor for the one-stage process decreases rapidly when feed temperature increases. The process in which the product of transesterification of soybean oil with supercritical methanol is cooled to an appropriate temperature (about 240°C) first and then flashed was put forward. The effect of cooling temperature, feed pressure and flash pressure on methanol concentration and recovery percentage was investigated. According to this study, when the feed pressure range is 15–30 MPa, the flash pressure equals 0.4 MPa, and cooling temperature range is 240°C–250°C, the recovery percentage of methanol is not less than 85%, and the concentration of the vapor in mass fraction of methanol is approximately 99%. Thus, the vapor leaving the flash tank can be directly circulated to the transesterification reactor.

关键词： supercritical methanol     biodiesel     recovery     flash distillation    

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标题 作者 时间 类型 操作

An investigation into the heat transfer characteristics of spiral wall with internal rib in a supercriticalsliding-pressure operation once-through boiler

TANG Renhu, YIN Fei, WANG Haijun, CHEN Tingkuan

期刊论文

Convective heat transfer in helical coils for constant-property and variable-property flows with high Reynolds numbers

Yufei MAO, Liejin GUO, Bofeng BAI, Ximin ZHANG

期刊论文

Calculation and analysis of sub/supercritical methanol preheating tube for continuous production of biodieselvia supercritical methanol transesterification

Wen CHEN, Weiyong YING, Cunwen WANG, Weiguo WANG, Yuanxin WU, Junfeng ZHANG,

期刊论文

A review on catalytic & non-catalytic bio-oil upgrading in supercritical fluids

Sainab Omar, Yang Yang, Jiawei Wang

期刊论文

Polydimethylsiloxane assisted supercritical CO

Weixia Wang, Shuai Zhou, Zhong Xin, Yaoqi Shi, Shicheng Zhao

期刊论文

Corrosion mechanisms of candidate structural materials for supercritical water-cooled reactor

Lefu ZHANG, Fawen ZHU, Rui TANG

期刊论文

Development of a supercritical and an ultra-supercritical circulating fluidized bed boiler

Junfu LYU, Hairui YANG, Wen LING, Li NIE, Guangxi YUE, Ruixin LI, Ying CHEN, Shilong WANG

期刊论文

Thermo-economic analysis of a direct supercritical CO electric power generation system using geothermal

期刊论文

Production of renewable fuels by blending bio-oil with alcohols and upgrading under supercritical conditions

Sainab Omar, Suzanne Alsamaq, Yang Yang, Jiawei Wang

期刊论文

超临界化——优化我国火电结构应从这里起步

宋之平

期刊论文

Micronization of curcumin with biodegradable polymer by supercritical anti-solvent using micro swirl

Kimthet Chhouk, Wahyudiono, Hideki Kanda, Shin-Ichro Kawasaki, Motonobu Goto

期刊论文

Key problems and solutions in supercritical CO

Haizhu WANG, Gensheng LI, Bin ZHU, Kamy SEPEHRNOORI, Lujie SHI, Yong ZHENG, Xiaomei SHI

期刊论文

A new heat transfer correlation for supercritical fluids

Yanhua YANG, Xu CHENG, Shanfang HUANG

期刊论文

Heat transfer with water flowing upward in a tube for pressures up to supercritical region

Yuzhou CHEN, Chunsheng YANG, Shuming ZHANG, Minfu ZHAO, Kaiwen DU,

期刊论文

Simulation analysis of methanol flash distillation circulation process in biodiesel production with supercritical

Zhengjiao TANG, Cunwen WANG, Weiguo WANG, Jia GUO, Yuanxin WU, Jinfang CHEN, Yigang DING

期刊论文