Parametric study on flow and heat transfer characteristics of porous wick evaporator based on AMTEC

Shuang-Ying Wu,Bao-Xi Cao,Lan Xiao,You-Rong Li 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.3

By establishing an axial symmetric invariable temperature phase change interface model of porous wick evaporator based on alkali metal thermal-to-electric converter (AMTEC), a parametric study has been implemented to explore the impact of effective thermal conductivity model, working fluid, wick material, porosity and particle size of porous wick on the flow and heat transfer characteristics. The results indicate that the inner surface temperature profile of wick is closely dependent on effective thermal conductivity models; it is the minimum for series model while the highest for parallel model. The inner surface temperature of wick with Na-K alloy as working fluid is obviously lower than that with sodium or potassium as working fluid. The wick made of refractory ceramics makes the minimum of inner surface temperature, while the one with nickel appears the highest temperature. Increasing the porosity can reduce the pressure drop in the wick, but also increases the temperature of evaporator.

Exergo-economic analysis of finned tube for waste heat recovery including phase change heat transfer

Shuang-Ying Wu,Jing-Rui Jiu,Lan Xiao,You-Rong Li,Chao Liu,Jin-Liang Xu 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.11

In this paper, an exergo-economic criterion, i.e. the net profit per unit transferred heat load, is established from the perspective of exergy recovery to evaluate the performance of finned tube used in waste heat recovery. Also, the dimensionless exergy change number is introduced to investigate the effect of the flow (mechanical) exergy loss rate on the recovered thermal exergy. Selecting R245fa as a working fluid and exhaust flue gas as a heat source, the effects of the internal Reynolds number Rei, the external Reynolds number Reo, the unit cost of thermal exergy εq, the geometric parameter of finned tube ηoβ and the phase change temperature Tv etc. on the performance of finned tube are discussed in detail. The results show that the higher Tv and ηoβ, and lower Rei may lead to the negligible flow (mechanical) exergy loss rate. There exists an optimal value of Rei where the net profit per unit transferred heat load peaks, while the variations of Reo, εq and Tv cause monotonic change of the net profit per unit transferred heat load. The phase change temperature exerts relatively greater influence on the exergo-economic performance of finned tube in comparison with other parameters. And there exists a critical phase change temperature, where the net profit per unit transferred heat load is equal to zero.

Experimental study of natural convection heat transfer from a nonuniformly heated flat plate simulating PV panel

Shuang-Ying Wu,Ying-Ying Wu,Lan Xiao,Zhen Yang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.1

In view of the characteristic of Photovoltaic (PV) conversion, an experimental study has been conducted to investigate the natural convection heat transfer from a flat plate. In order to simulate the real PV cells, three electrical heating circuits were employed to achieve a linear nonuniform heat flux boundary condition. The major parameters, such as the gradient parameter of heat flux k, tilt angle θ and heat flux q w were introduced to analyze their influence on heat transfer ability. Both the local temperature distribution and the overall trend of Nusselt number have been presented. Comparing with the uniform thermal boundary condition, the results show that the local convection heat transfer coefficient is fluctuated at the positions where heat flux has changed. When gradient parameter of heat flux increases, the difference of local convection heat transfer coefficient at the top of the plate between tilt angle θ = 0° and 90° becomes smaller. Moreover, it is observed that the gradient parameter of heat flux has a promotion effect on average convection Nusselt number at larger tilt angle, but the effect becomes complex as tilt angle is smaller. Finally, a correlation combining all significant factors has been put forward to estimate the natural convection heat transfer.

Effect of thermal radiation on convection heat transfer in cooling channel of photovoltaic thermal system

Shuang-Ying Wu,Ying-Ying Wu,Lan Xiao 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.8

The effect of thermal radiation on convection heat transfer in flat-box type cooling channel of photovoltaic thermal system with tilt angleof 30 degree was studied by 3D numerical simulation under constant heat flux boundary condition. The temperature contours andvelocity fields of fluid near the outlet were obtained. The variations of wall temperature and convection Nusselt number along flow directionfor all the separate walls composing the cooling channel were compared and analyzed. The results show that due to thermal radiation,the deflection of the maximum velocity region to heated top wall, together with the asymmetry of temperature field is weakened. Fornatural convection, radiation promotes the formation of multi-vortices. For mixed convection, heat transfer on all the cooling channelwalls is enhanced under the condition of lower heat flux while heat transfer on heated top wall is deteriorated when the heat flux is relativehigh. Also, pressure re-rising is promoted by thermal radiation.

The role of outlet temperature of flue gas in organic Rankine cycle considering low temperature corrosion

Shuang-Ying Wu,Chun Li,Lan Xiao,You-Rong Li,Chao Liu 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.12

This paper gives a special focus on the role of outlet temperature of flue gas (Tgo) in organic Rankine cycle (ORC) system for low temperatureflue gas waste heat recovery. The variations of performance indicators: net work (Wnet), exergy efficiency (ηex) and levelizedenergy cost (LEC) versus Tgo are discussed. Considering the corrosion of low temperature flue gas, the necessity and reasonability oflimiting Tgo at its minimum allowed discharge temperature (355.15 K) are analyzed. Results show that there exist optimal Tgo (Tgo,opt) forWnet and LEC, while Tgo,opt for ηex does not appear under the investigated range of Tgo. Moreover, the Tgo,opt for Wnet is always lower than355.15 K, the Tgo,opt for LEC, despite being greater than the one for Wnet, is just slightly higher than 355.15 K when the inlet temperatureof flue gas varies from 408.15 K to 463.15 K. For the waste heat recovery of low temperature flue gas, it is reasonable to fix Tgo at 355.15K if Wnet or LEC is selected as primary performance indicator under the pinch point temperature difference of evaporator (ΔTe) below 20K.

Upregulation of PITX2 Promotes Letrozole Resistance Via Transcriptional Activation of IFITM1 Signaling in Breast Cancer Cells

Ying-ying Xu,Hai-ru Yu,Jia-yi Sun,Zhao Zhao,Shuang Li,Xin-feng Zhang,Zhi-xuan Liao,Ming-ke Cui,Juan Li,Chan Li,Qiang Zhang 대한암학회 2019 Cancer Research and Treatment Vol.51 No.2

Purpose Although the interferon  (IFN) signaling and the paired-like homeodomain transcription factor 2 (PITX2) have both been implicated in the progression of breast cancer (BCa), it remains obscure whether these two pathways act in a coordinated manner. We therefore aimed to elucidate the expression and function of PITX2 during the pathogenesis of endocrine resistance in BCa. Materials and Methods PITX2 expression was assessed in BCa tissues using quantitative reverse transcription polymerase chain reaction (RT-qPCR) and immunohistochemistry and in experimentally induced letrozole-resistant BCa cells using RT-qPCR and immunoblotting. Effects of PITX2 deregulation on BCa progression was determined by assessing MTT, apoptosis and xenograft model. Finally, using multiple assays, the transcriptional regulation of interferon-inducible transmembrane protein 1 (IFITM1) by PITX2 was studied at both molecular and functional levels. Results PITX2 expression was induced in letrozole-resistant BCa tissues and cells, and PITX2 induction by IFN signaling powerfully protected BCa cells against letrozole insult and potentiated letrozole-resistance. Mechanistically, PITX2 enhanced IFN-induced AKT activation by transactivating the transcription of IFITM1, thus rendering BCa cells unresponsive to letrozoleelicited cell death. Additionally, ablation of IFITM1 expression using siRNA substantially abolished IFN-elicited AKT phosphorylation, even in the presence of PITX2 overexpression, thus sensitizing BCa cells to letrozole treatment. Conclusion These results demonstrate that constitutive upregulation of PITX2/IFITM1 cascade is an intrinsic adaptive mechanism during the pathogenesis of letrozole-resistance, and modulation of PITX2/IFITM1 level using different genetic and pharmacological means would thus have a novel therapeutic potential against letrozole resistance in BCa.

Numerical investigation on developing laminar forced convective heat transfer and entropy generation in an annular helicoidal tube

Shuang-Ying Wu,Su-Jun Chen,Lan Xiao,You-Rong Li 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.6

In this study, numerical investigations are conducted for forced convective heat transfer in an annular helicoidal tube under uniform wall temperature condition for laminar flow including developing region. The numerical computations reveal the developments and distributions of heat transfer and flow fields in the annular helicoidal tube when the outer tube wall is heated and the inner tube wall is insulated. The effects of Reynolds number, curvature ratio, and coil pitch on the circumferential average friction factor and Nusselt number at different axial locations, and the non-dimensional entropy generation number of laminar convection in an annular helicoidal tube are investigated. In addition, the differences of flow and heat transfer characteristics between the annular helicoidal tube and circular helicoidal tube are also described.

Time-Dependent Changes in the Bladder Muscle Metabolome After Traumatic Spinal Cord Injury in Rats Using Metabolomics

Ying-Hao Liu,Qian Gong,Yi-Kai Wang,Wei-Bing Shuang 대한배뇨장애요실금학회 2023 International Neurourology Journal Vol.27 No.2

Purpose: The main treatment options of neurogenic bladder remains catheterization and long-term oral medications. Metabolic interventions have shown good therapeutic results in many diseases. To date, no studies have characterized the metabolites of the detrusor muscle during neurogenic bladder. Using metabolomics, new muscle metabolomic signatures were identified to reveal the temporal metabolic profile of muscle during disease progression. Methods: We used 42 Sprague-Dawley rats (200±20 g, males) for T10 segmental spinal cord injury modeling and collected detrusor tissue and performed nontargeted metabolomics after sham surgery, 30-minute, 6-hour, 12-hour, 24-hour, 5-day, and 2-week postmodelling, to identify the dysregulated metabolic pathways and key metabolites. Results: By comparing mzCloud, mzVault, MassList, we identified a total of 1,271 metabolites and enriched a total of 12 metabolism-related pathways with significant differences (P<0.05) based on Kyoto Encyclopedia of Genes and Genomes analysis. Metabolites in several differential metabolic pathways such as ascorbate and aldarate metabolism, Steroid hormone biosynthesis, and carbon metabolism are altered in a regular manner before and after ridge shock. Conclusions: Our study is the first time-based metabolomic study of rat forced urinary muscle after traumatic spinal cord injury, and we identified multiple differential metabolic pathways during injury that may improve long-term management strategies for neurogenic bladder and reduce costs in long-term treatment.

An Improved Predictive Functional Control with Minimum-Order Observer for Speed Control of Permanent Magnet Synchronous Motor

Shuang Wang,Junyong Fu,Ying Yang,Jian Shi 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.1

In this paper, an improved predictive functional control (PFC) scheme for permanent magnet synchronous motor (PMSM) control system is proposed, on account of the standard PFC method cannot provides a satisfying disturbance rejection performance in the case of strong disturbances. The PFC-based method is first introduced in the control design of speed loop, since the good tracking and robustness properties of the PFC heavily depend on the accuracy of the internal model of the plant. However, in orthodox design of prediction model based control method, disturbances are not considered in the prediction model as well as the control design. A minimumorder observer (MOO) is introduced to estimate the disturbances, which structure is simple and can be realized at a low computational load. This paper adopted the MOO to observe the load torque, and the observations are then fed back into PFC model to rebuild it when considering the influence of perturbation. Therefore, an improved PFC strategy with torque compensation, called the PFC+MOO method, is presented. The validity of the proposed method was tested via simulation and experiments. Excellent results were obtained with respect to the speed trajectory tracking, stability, and disturbance rejection.

Influence of non-Gaussian characteristics of wind load on fatigue damage of wind turbine

Ying Zhu,Miao Shuang 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.31 No.3

Based on translation models, both Gaussian and non-Gaussian wind fields are generated using spectral representation method for investigating the influence of non-Gaussian characteristics and directivity effect of wind load on fatigue damage of wind turbine. Using the blade aerodynamic model and multi-body dynamics, dynamic responses are calculated. Using linear damage accumulation theory and linear crack propagation theory, crack initiation life and crack propagation life are discussed with consideration of the joint probability density distribution of the wind direction and mean wind speed in detail. The result shows that non-Gaussian characteristics of wind load have less influence on fatigue life of wind turbine in the area with smaller annual mean wind speeds. Whereas, the influence becomes significant with the increase of the annual mean wind speed. When the annual mean wind speeds are 7 m/s and 9 m/s at hub height of 90 m, the crack initiation lives under softening non-Gaussian wind decrease by 10% compared with Gaussian wind fields or at higher hub height. The study indicates that the consideration of the influence of softening non-Gaussian characteristics of wind inflows can significantly decrease the fatigue life, and, if neglected, it can result in non-conservative fatigue life estimates for the areas with higher annual mean wind speeds.