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Micro/nanofluidics-enabled energy conversion and its implemented devices

Yang YANG, Jing LIU

《能源前沿(英文)》 2011年 第5卷 第3期   页码 270-287 doi: 10.1007/s11708-010-0126-6

摘要: Most people were not aware of the role of energy as a basic force that drives the development and economic growth of the world until the two great oil crises occurred. According to the conservation law, energy not only exists in various forms but is also capable of being converted from one form to another. The common forms of energy are mechanical energy, chemical energy, internal energy, electrical energy, atomic energy, and electromagnetic energy, among others. The fluids in nature serve as the most common carriers and media in the energy conversion process. Following the rapid development of microelectromechanical systems (MEMS) technology, the energy supply and conversion issue in micro/nano scale has also been introduced in research laboratories worldwide. With unremitting efforts, great quantities of micro/nano scale energy devices have been investigated. Micro/nanofluid shows distinct features in transporting and converting energy similar to their counterpart macroscale tasks. In this paper, a series of micro/nanofluid-enabled energy conversion devices is reviewed based on the transformation between different forms of energy. The evaluation and contradistinction of their performances are also examined. The role of micro/nanofluid as media in micro/nano energy devices is summarized. This contributes to the establishment of a comprehensive and systematic structure in the relationship between energy conversion and fluid in the micro/nano scale. Some fundamental and practical issues are outlined, and the prospects in this challenging area are explored.

关键词: micro/nanofluid     different energy forms     energy conversion     medium role    

Spatial distribution of phosphorus forms in sediments with different distances to the estuary of the

Shaoyong LU, Xiangcan JIN, Fengchang WU, Jing SI, Jianning GUO,

《环境科学与工程前沿(英文)》 2010年 第4卷 第3期   页码 295-300 doi: 10.1007/s11783-010-0231-0

摘要: Effects of human activity on the distribution of phosphorus (P) forms were investigated for the sediments and porewaters in Daqinghe Estuary of Dianchi Lake, China. The concentrations of total P (TP), inorganic-P (I-P), and organic-P (Org-P), and the ratio of iron-bound P (Fe-P)/calcium-bound P (Ca-P) in the sediments decreased with the increasing distance from the sampling site to the estuary. This is probably due to the flocculant materials, e.g., ferric and aluminous salts, usually being added in the wastewater treatment processes. The concentration of ammonia in the sediment porewaters significantly decreased with the increasing distance from the sampling site to the estuary. Both concentrations of total nitrogen and nitrogen in the sediment porewaters decreased to some content with the increasing distance from the sampling site to the estuary. However, the concentrations of nitrate, dissolved total P (DTP), and TP did not have strong relationship with the distances from the sampling sites to the estuary. Pollution load and water quantity also had an important influence on the concentrations of P in sediments and its interstitial water in estuary sedimentary area.

关键词: estuary sedimentary area     phosphorus (P)     spatial distribution     human activity     the Dianchi Lake    

Comparison and analysis of energy consumption of energy-efficient office buildings in different climate

Ke ZHANG, Neng ZHU

《能源前沿(英文)》 2013年 第7卷 第3期   页码 399-405 doi: 10.1007/s11708-013-0260-z

摘要: The purpose of this paper is to analyze the energy consumption (EC) and find out the determining factors of energy-efficient office building cases according to specific case studies in typical cities of different climate zones in China. The investigated building cases were located in four cities (Beijing, Ningbo, Nanjing and Shenzhen) of three architecture thermotechnical design zones (cold zone, hot summer and cold winter zone, hot summer and warm winter zone). The analysis indicates that the energy consumption index (ECI) of these four cases ranges from 41.06 to 74.23 kW·h/(m ·a). Besides, the outdoor climate can change the EC of air conditioning/heating systems, and further determine the monthly volatility of the total EC of the whole building.

关键词: energy-efficient building     breakdown energy consumption (EC)     energy consumption index (ECI)     different climate zone    

Multiple regression models for energy consumption of office buildings in different climates in China

Siyu ZHOU, Neng ZHU

《能源前沿(英文)》 2013年 第7卷 第1期   页码 103-110 doi: 10.1007/s11708-012-0220-z

摘要: The energy consumption of office buildings in China has been growing significantly in recent years. Obviously, there are significant relationships between building envelope and the energy consumption of office buildings. The 8 key building envelope influencing factors were found in this paper to evaluate their effects on the energy consumption of the air-conditioning system. The typical combinations of the key influencing factors were performed in Trnsy simulation. Then on the basis of the simulated results, the multiple regression models were developed respectively for the four climates of China—hot summer and warm winter, hot summer and cold winter, cold, and severely cold. According to the analysis of regression coefficients, the appropriate building envelope design schemes were discussed in different climates. At last, the regression model evaluations consisting of the simulation evaluations and the actual case evaluations were performed to verify the feasibility and accuracy of the regression models. The error rates are within±5% in the simulation evaluations and within±15% in the actual case evaluations. It is believed that the regression models developed in this paper can be used to estimate the energy consumption of office buildings in different climates when various building envelope designs are considered.

关键词: regression model     energy consumption     building envelope     office building     different climates    

Comparison of different energy saving lights using solar panel

Huzaifa MUBARAK,Saad Bin Abul KASHEM

《能源前沿(英文)》 2016年 第10卷 第4期   页码 466-472 doi: 10.1007/s11708-016-0417-7

摘要: The recent trend in light emitting diode or LED lighting applications and their claimed energy saving capabilities together with their overall attractiveness has us all convinced that they really are a greener alternative to the compact fluorescent lights or CFL. As convincing as it seems, the actual energy saving capabilities of LEDs are yet to be proven scientifically or at the least, on an empirical level when compared to CFLs. This paper tackles the issue with the use of a solar cell by evaluating the photovoltaic current and voltage generated by the solar cell subjected to each lighting system. Graphical representations are drawn and a conclusion is then reached based on the amount of power generation in the solar cells in order to determine the energy saving capabilities of each lighting system and its efficiency. From the result, it has been found that an LED is 3.7 times more power efficient than a CFL based light source of equal wattage.

关键词: CFL     LED     empirical     solar     lumens     energy saving     fluorescent    

Effect of harmonic distortion on electric energy meters of different metrological principles

Illia DIAHOVCHENKO, Vitalii VOLOKHIN, Victoria KUROCHKINA, Michal ŠPES, Michal KOSTEREC

《能源前沿(英文)》 2019年 第13卷 第2期   页码 377-385 doi: 10.1007/s11708-018-0571-1

摘要: This paper deals with the errors of electric energy metering devices as a result of distortions in the shape of the curves of voltage and current load. It is shown and proved that the errors in energy measurements depend on the design and the algorithms used in electricity meters. There are three main types of metering devises having different principles: inductive (electro-mechanical), electronic static, and digital electronic (microprocessor). Each of these types has its measuring features. Some devices take into account all the harmonic distortions and the constant component which occur in the network while others measure the power and energy values of the fundamental harmonic only. Such traits lead to the discrepancies in the readings of commercial electric energy meters of different types. Hence, the violations in the measurement system unity occur, and a significant error can be observed in the balance of transmitted/consumed electric energy.

关键词: current     distortion     electric energy meter     harmonics     power quality    

An optimized solar-air degree-day method to evaluate energy demand for poultry buildings in different

Yang WANG, Baoming LI

《农业科学与工程前沿(英文)》 2020年 第7卷 第4期   页码 478-489 doi: 10.15302/J-FASE-2019289

摘要:

The degree-day method is widely used to determine energy consumption but cannot be directly applied to poultry buildings without improvements in its accuracy. This study was designed to optimize the degree-day calculation and proposes a solar-air degree-day method, which can be used to calculate the cooling and heating degree-days and the annual cooling and heating loads under different climate conditions for poultry buildings. In this paper, the solar-air degree-day method was proposed, which considers the effects of solar radiation with different wall orientations and surface colors. Five Chinese cities, Harbin, Beijing, Chongqing, Kunming and Guangzhou, were selected to represent different climate zones to determine the solar-air degree-days. The heating and cooling energy requirements for different climates were compared by DeST (Designer’s Simulation Toolkit) simulation and the solar-air degree-day method. Approaches to decrease energy consumption were developed. The results showed that the maximum relative error was less than 10%, and the new method was not significantly different from the DeST simulation ( >0.05). The accuracy of calculating energy requirements was improved by the solar-air degree-day method in the different climate zones. Orientation and surface color effects on energy consumption need to be considered, and external walls of different orientations should have different surface colors.

关键词: base temperature     energy consumption     solar radiation     orientation     surface color    

Energy and exergy analysis of syngas production from different biomasses through air-steam gasification

S. Rupesh,C. Muraleedharan,P. Arun

《能源前沿(英文)》 2020年 第14卷 第3期   页码 607-619 doi: 10.1007/s11708-016-0439-1

摘要: Gasification is a thermo-chemical reaction which converts biomass into fuel gases in a reactor. The efficiency of conversion depends on the effective working of the gasifier. The first step in the conversion process is the selection of a suitable feedstock capable of generating more gaseous fuels. This paper analyses the performance of different biomasses during gasification through energy and exergy analysis. A quasi-equilibrium model is developed to simulate and compare the feasibility of different biomass materials as gasifier feedstock. Parametric studies are conducted to analyze the effect of temperature, steam to biomass ratio and equivalence ratio on energy and exergy efficiencies. Of the biomasses considered, sawdust has the highest energy and exergy efficiencies and lowest irreversibility. At a gasification temperature of 1000 K, the steam to biomass ratio of unity and the equivalence ratio of 0.25, the energy efficiency, exergy efficiency and irreversibility of sawdust are 35.62%, 36.98% and 10.62 MJ/kg, respectively. It is also inferred that the biomass with lower ash content and higher carbon content contributes to maximum energy and exergy efficiencies.

关键词: gasification     modeling     energy     exergy     syngas    

Unnormalized and normalized forms of gefura measures in directed and undirected networks

Raf GUNS,Ronald ROUSSEAU

《信息与电子工程前沿(英文)》 2015年 第16卷 第4期   页码 311-320 doi: 10.1631/FITEE.1400425

摘要: In some networks nodes belong to predefined groups (e.g., authors belong to institutions). Common network centrality measures do not take this structure into account. Gefura measures are designed as indicators of a node’s brokerage role between such groups. They are defined as variants of betweenness centrality and consider to what extent a node belongs to shortest paths between nodes from different groups. In this article we make the following new contributions to their study: (1) We systematically study unnormalized gefura measures and show that, next to the ‘structural’ normalization that has hitherto been applied, a ‘basic’ normalization procedure is possible. While the former normalizes at the level of groups, the latter normalizes at the level of nodes. (2) Treating undirected networks as equivalent to symmetric directed networks, we expand the definition of gefura measures to the directed case. (3) It is shown how Brandes’ algorithm for betweenness centrality can be adjusted to cover these cases.

关键词: Networks subdivided in groups     Partitions     Gefura measures     Q-measures     Brokerage role     Directed and undirected networks     Brandes’     algorithm    

Comparison of evapotranspiration and energy partitioning related to main biotic and abiotic controllersin vineyards using different irrigation methods

Lei GAO, Peng ZHAO, Shaozhong KANG, Sien LI, Ling TONG, Risheng DING, Hongna LU

《农业科学与工程前沿(英文)》 2020年 第7卷 第4期   页码 490-504 doi: 10.15302/J-FASE-2019310

摘要:

Knowledge of evapotranspiration (ET) and energy partitioning is useful for optimizing water management, especially in areas where water is scarce. A study was undertaken in a furrow-irrigated vineyard (2015) and a drip-irrigated vineyard (2017) in an arid region of north-west China to compare vineyard ET and energy partitioning and their responses to soil water content (SWC) and leaf area index (LAI). ET and soil evaporation (E) and transpiration (T) were determined using eddy covariance, microlysimeters, and sap flow. Seasonal average E/ET, T/ET, crop coefficient (Kc), evaporation coefficient (Ke), and basal crop coefficient (Kcb) were 0.50, 0.50, 0.67, 0.35, and 0.29, respectively, in the furrow-irrigated vineyard and 0.42, 0.58, 0.57, 0.29, and 0.43 in the drip-irrigated vineyard. The seasonal average partitioning of net radiation (Rn) into the latent heat flux (LE), sensible heat flux (H) and soil heat flux (G) (LE/Rn, H/Rn, and G/Rn), evaporative fraction (EF) and Bowen ratio (β) were 0.57, 0.26, 0.17, 0.69 and 0.63, respectively, in the furrow-irrigated vineyard and 0.46, 0.36, 0.17, 0.57 and 0.97 in the drip-irrigated vineyard. The LE/Rn, H/Rn, EF, and β were linearly correlated with LAI. The E, Kc, Ke, E/ET, LE/Rn, LEs/Rn (ratio of LE by soil E to Rn), H/Rn, EF and β were closely correlated with topsoil SWC (10 cm depth). Responses of ET and energy partitioning to the LAI and SWC differed under the two irrigation methods. Drip irrigation reduced seasonal average E/ET and increased average T/ET. From the perspective of energy partitioning, seasonal average H/Rn increased whereas LE/Rn, especially LEs/Rn, decreased. Compared with furrow irrigation, drip irrigation decreased the proportion of unproductive water consumption thereby contributing to enhanced water use efficiency and accumulation of dry matter.

关键词: crop coefficient     eddy covariance     microlysimeter     sap flow     soil evaporation     transpiration    

Characterization of phosphorus species and modeling for its organic forms in eutrophic shallow lake sediments

Hongguang CHENG,Xiao PU,Yiting CHEN,Fanghua HAO,Liming DONG

《环境科学与工程前沿(英文)》 2014年 第8卷 第6期   页码 905-921 doi: 10.1007/s11783-014-0650-4

摘要: Variations of phosphorus (P) and its species in surface sediment of Baiyangdian Lake, a eutrophic shallow lake located in North China, were investigated through combination of field survey and numerical calculation based on cluster analysis. P fractionation was performed by a sequential extraction scheme, categorized as loosely bound P (NH Cl-P), reductant soluble P (BD-P), metallic oxide bound P (NaOH-P), calcium bound P (HCl-P) and organic P (Org-P). P concentrations exhibited regional similarities and a total of four sub-areas were identified in which the same rank was HCl-P>Org-P>BD-P ≈ NaOH-P>NH Cl-P. NH Cl-P, BD-P and Org-P were found to contribute to P enrichment in overlying water column. Specifically, labile Org-P acted as a potential pool with a greater contribution in aerobic layer compared to anaerobic layer. A hysteresis (lag= 4 months) existed when labile Org-P concentration was negatively correlated with aerobic layer thickness. In view of magnitude of identified P contributors in sub-areas, higher potential of P release was present in Fuhe River and Tang River estuary areas. On the basis of calibration and verification, the mathematical model with parameter settings applied in this study was improved to serve as a tool for limnology management and eutrophic control.

关键词: phosphorus fractionation     variation characteristics     modeling     sediment     Baiyangdian Lake    

Analysis of catchment evapotranspiration at different scales using bottom-up and top-down approaches

Xiangyu XU, Dawen YANG,

《结构与土木工程前沿(英文)》 2010年 第4卷 第1期   页码 65-77 doi: 10.1007/s11709-010-0002-9

摘要: Physically-based hydrological models are used to predict catchment water balance through detailed simulation of hydrological processes at small temporal and spatial scales. However, annual catchment water balance can also be easily and simply predicted using lumped conceptual model. Comparison between physically-based hydrological models and lumped conceptual models can help us understand the dominant factors on catchment water balance at different scales. In this paper, a distributed physically-based hydrological model (i.e., bottom-up approach) and a simple water-energy balance model (i.e., top-down approach) are used to predict actual evapotranspiration in nine sub-catchments, and the whole basin of the Luan River in northern China. Both simulations give very close values of annual evapotranspiration and show the same complementary relationship between actual and potential evapotranspiration at annual time scale. From the analysis at different time scales through comparison of the top-down and the bottom-up methods, it is shown that the annual catchment evapotranspiration is controlled mainly by annual precipitation and potential evapotranspiration, and the variability of soil water and vegetation becomes more important at a smaller time scale in the study areas. It is also known that the relationship between potential and actual evapotranspiration shows a highly nonlinear relationship at the annual and catchment scale but can be simplified to a linear relationship at hourly temporal and hillslope scales, which is commonly used in the physically-based hydrological models.

关键词: catchment evapotranspiration     distributed hydrological model     water-energy balance model     top-down and bottom-up approaches    

Present situation and classification of piezoelectric pump

Fang YE, Shouyin WANG, Wei CHENG, Qixiao XIA, Jianhui ZHANG,

《机械工程前沿(英文)》 2009年 第4卷 第4期   页码 420-429 doi: 10.1007/s11465-009-0052-7

摘要: According to the present classification method for a piezoelectric pump, this paper reviews the development and present situation of piezoelectric pumps in the latest 30 years and finally puts forward a new classification. A volumetric piezoelectric pump, which belongs to traditional volumetric pumps, can be divided into a piezoelectric pump with or without valves. A new valveless piezoelectric pump nowadays becomes a hot issue in scientific research. It is constructed by using no-moving-part valves, which can induce positive flow resistance and negative flow resistance different, and in which the inlet and outlet are connected all the time. New forms of piezoelectric pumps, different from traditional ones, are only at the stage of conception and principle, and no practical application has been reported.

关键词: piezoelectric pump     development and present situation     new classification method     valveless piezoelectric pump     new forms of piezoelectric pump    

Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption

Junxiong LIN , Lan WANG ,

《环境科学与工程前沿(英文)》 2009年 第3卷 第3期   页码 320-324 doi: 10.1007/s11783-009-0030-7

摘要: The best-fit equations of linear and non-linear forms of the two widely used kinetic models, namely pseudo-first-order and pseudo-second-order equations, were compared in this study. The experimental kinetics of methylene blue adsorption on activated carbon was used for this research. Both the correlation coefficient () and the normalized standard deviation Δ(%) were employed as error analysis methods to determine the best-fitting equations. The results show that the non-linear forms of pseudo-first-order and pseudo-second-order models were more suitable than the linear forms for fitting the experimental data. The experimental kinetics may have been distorted by linearization of the linear kinetic equations, and thus, the non-linear forms of kinetic equations should be primarily used to obtain the adsorption parameters. In addition, the Δ(%) method for error analysis may be better to determine the best-fitting model in this case.

关键词: adsorption     pseudo-first order     pseudo-second order     kinetic model     linear method     non-linear method    

Effect of protein on PVDF ultrafiltration membrane fouling behavior under different pH conditions: interface

Xudong WANG,Miao ZHOU,Xiaorong MENG,Lei WANG,Danxi HUANG

《环境科学与工程前沿(英文)》 2016年 第10卷 第4期 doi: 10.1007/s11783-016-0855-9

摘要: pH values of the BSA solution significantly impact the process of membrane fouling. Dramatic flux decline is caused by membrane–BSA adhesion force at start of filtration. XDLVO theory shows the polar or Lewis acid–base interaction plays a major role in membrane fouling. To further determine the fouling behavior of bovine serum albumin (BSA) on different hydrophilic PVDF ultrafiltration (UF) membranes over a range of pH values, self-made atomic force microscopy (AFM) colloidal probes were used to detect the adhesion forces of membrane–BSA and BSA–BSA, respectively. Results showed that the membrane–BSA adhesion interaction was stronger than the BSA–BSA adhesion interaction, and the adhesion force between BSA–BSA-fouled PVDF/PVA membranes was similar to that between BSA–BSA-fouled PVDF/PVP membranes, which indicated that the fouling was mainly caused by the adhesion interaction between membrane and BSA. At the same pH condition, the PVDF/PVA membrane–BSA adhesion force was smaller than that of PVDF/PVP membrane–BSA, which illustrated that the more hydrophilic the membrane was, the better antifouling ability it had. The extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory predicts that the polar or Lewis acid–base (AB) interaction played a dominant role in the interfacial free energy of membrane–BSA and BSA–BSA that can be affected by pH. For the same membrane, the pH values of a BSA solution can have a significant impact on the process of membrane fouling by changing the AB component of free energy.

关键词: PVDF membrane     Membrane fouling     Adhesion force     Protein     Interfacial free energy    

标题 作者 时间 类型 操作

Micro/nanofluidics-enabled energy conversion and its implemented devices

Yang YANG, Jing LIU

期刊论文

Spatial distribution of phosphorus forms in sediments with different distances to the estuary of the

Shaoyong LU, Xiangcan JIN, Fengchang WU, Jing SI, Jianning GUO,

期刊论文

Comparison and analysis of energy consumption of energy-efficient office buildings in different climate

Ke ZHANG, Neng ZHU

期刊论文

Multiple regression models for energy consumption of office buildings in different climates in China

Siyu ZHOU, Neng ZHU

期刊论文

Comparison of different energy saving lights using solar panel

Huzaifa MUBARAK,Saad Bin Abul KASHEM

期刊论文

Effect of harmonic distortion on electric energy meters of different metrological principles

Illia DIAHOVCHENKO, Vitalii VOLOKHIN, Victoria KUROCHKINA, Michal ŠPES, Michal KOSTEREC

期刊论文

An optimized solar-air degree-day method to evaluate energy demand for poultry buildings in different

Yang WANG, Baoming LI

期刊论文

Energy and exergy analysis of syngas production from different biomasses through air-steam gasification

S. Rupesh,C. Muraleedharan,P. Arun

期刊论文

Unnormalized and normalized forms of gefura measures in directed and undirected networks

Raf GUNS,Ronald ROUSSEAU

期刊论文

Comparison of evapotranspiration and energy partitioning related to main biotic and abiotic controllersin vineyards using different irrigation methods

Lei GAO, Peng ZHAO, Shaozhong KANG, Sien LI, Ling TONG, Risheng DING, Hongna LU

期刊论文

Characterization of phosphorus species and modeling for its organic forms in eutrophic shallow lake sediments

Hongguang CHENG,Xiao PU,Yiting CHEN,Fanghua HAO,Liming DONG

期刊论文

Analysis of catchment evapotranspiration at different scales using bottom-up and top-down approaches

Xiangyu XU, Dawen YANG,

期刊论文

Present situation and classification of piezoelectric pump

Fang YE, Shouyin WANG, Wei CHENG, Qixiao XIA, Jianhui ZHANG,

期刊论文

Comparison between linear and non-linear forms of pseudo-first-order and pseudo-second-order adsorption

Junxiong LIN , Lan WANG ,

期刊论文

Effect of protein on PVDF ultrafiltration membrane fouling behavior under different pH conditions: interface

Xudong WANG,Miao ZHOU,Xiaorong MENG,Lei WANG,Danxi HUANG

期刊论文