| 1. |
- Zhang, Da, et al.
(författare)
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Direct assessment of solid–liquid interface noise in ion sensing using a differentialmethod
- 2016
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 108:15
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Tidskriftsartikel (refereegranskat)abstract
- This letter presents a microelectrode cell dedicated to direct assessment of the solid-liquid interface noise without recourse to a reference electrode. In the present design, two identical TiN electrodes of various sizes are used for differential measurements in KCl-based electrolytes. Measured noise of the TiN vertical bar electrolyte system is found to be of thermal nature. Scaling inversely with electrode area, the noise is concluded to mainly arise from the solid-liquid interface. This noise is comparable to or larger than that of the state-of-the-art MOSFETs. Therefore, its influence cannot be overlooked for the design of future ion sensors.
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| 2. |
- Zhang, Xingxing, et al.
(författare)
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Numerical study on thermal performance of a gravity assisted loop heat pipe
- 2017
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Konferensbidrag (refereegranskat)abstract
- This article carried out a parametric study of the thermal performance of a novel gravity assisted loop heat pipe (GALHP)with composite mesh-screen wick structure. A refined three-way structure with interior liquid-vapour separator wasdeveloped on top of the evaporator to enable a gravity-assisted operation, which not only simplified the correspondingwick structure but also eliminated the ‘dry-out’ potential in conventional GALHPs. A dedicated simulation model wasdeveloped on basis of the heat transfer and the flow characteristics derived from the governing equations of mass, energyand momentum. The essential impact parameters to the GALHP thermal performance were further discussed. It was foundthat the GALHP thermal performance, represented by the reciprocal of overall thermal resistance, varies directly withapplied heat load, evaporator diameter, and vapour-liquid separator diameter. The research results would be useful fordesign, optimisation and application of such GALHP in the gravity-assisted circumstance for thermal management.
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| 3. |
- Gao, D. -C, et al.
(författare)
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A GA-based NZEB-cluster planning and design optimization method for mitigating grid overvoltage risk
- 2022
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 243
-
Tidskriftsartikel (refereegranskat)abstract
- Net-zero energy buildings (NZEBs) are considered as a promising method to mitigating the energy problems. Due to the intermittent characteristics of renewable energy (e.g., solar energy), NZEBs need to frequently exchange energy with the grid, which imposes severe negative impacts on the grid especially the overvoltage risk. Both planning and design are essential for reducing NZEB connected grid overvoltage, but most existing studies isolated the efforts from planning to design, thereby failing to achieve the best cumulative result. More importantly, existing studies oversimplified overvoltage quantification by using aggregated power interactions to represent overvoltage risk, which cannot consider the complex voltage influences among grid nodes. Due to the isolated efforts and the quantification oversimplification, existing studies can hardly achieve overvoltage risk minimization. Therefore, this study proposes a novel GA (genetic algorithm)-based method in which the key planning and design parameters are optimized sequentially for mitigating the overvoltage risk. Meanwhile, distribution network model has been adopted to precisely quantify the grid overvoltage. The study results show that the proposed method is highly effective in reducing NZEB cluster connected grid overvoltage risk. The proposed method can be used in practice for improving NZEB cluster planning and system design as grid interaction is considered. © 2021 Elsevier Ltd
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| 4. |
- Han, Yuchen, et al.
(författare)
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Characteristics and Application Analysis of a Novel Full Fresh Air System Using Only Geothermal Energy for Space Cooling and Dehumidification
- 2024
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Ingår i: Buildings. - : MDPI. - 2075-5309. ; 14:5
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Tidskriftsartikel (refereegranskat)abstract
- To effectively reduce building energy consumption, a novel full fresh air system with a heat source tower (HST) and a borehole heat exchanger (BHE) was proposed for space cooling and dehumidification in this paper. The cooling system only adopts geothermal energy to produce dry and cold fresh air for space cooling and dehumidification through the BHE and HST, which has the advantage of non-condensate water compared to BHE systems integrated with a fan coil or chilled beam. Based on the established mathematical model of the cooling system, this paper analyzed the system characteristics, feasibility, operation strategy, energy performance, and cost-effectiveness of the proposed model in detail. The results show that the mathematical model has less than 10% error in estimating the system performance compared to the practical HST-BHE experimental set up. Under the specific boundary conditions, the cooling and dehumidification capacity of this system increases with the decrease in the air temperature, air moisture content, and inlet water temperature of the HST. The optimal cooling capacity and the system COP can be achieved when the air-water flow ratio is at 4:3. A case study was conducted in a residential building in Shenyang with an area of about 1800 m2. It was found that this system can fully meet the cooling and dehumidification demand in such a residential building. The operation strategy of the cooling system can be optimized by adjusting the air-water flow ratio from 4:3 to 3:2 during the early cooling season (7 June-1 July) and end cooling season (3 August-1 September). As a result, the average COP of the cooling system during the whole cooling season can be improved from 6.1 to 8.7. Compared with the air source heat pump (ASHP) and the ground source heat pump (GSHP) for space cooling, the proposed cooling system can achieve an energy saving rate of 123% and 26%, respectively. Considering that the BHE of the GSHP can be part of the proposed HST-BHE cooling system, the integration of the HST and GHSP for space cooling (and heating) is strongly recommended in actual applications.
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| 5. |
- He, Wei, et al.
(författare)
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Recent development and application of thermoelectric generator and cooler
- 2015
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 143, s. 1-25
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Tidskriftsartikel (refereegranskat)abstract
- Energy crisis and environment deterioration are two major problems for 21st century. Thermoelectric device is a promising solution for those two problems. This review begins with the basic concepts of the thermoelectric and discusses its recent material researches about the figure of merit. It also reports the recent applications of the thermoelectric generator, including the structure optimization which significantly affects the thermoelectric generator, the low temperature recovery, the heat resource and its application area. Then it reports the recent application of the thermoelectric cooler including the thermoelectric model and its application area. It ends with the discussion of the further research direction.
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| 6. |
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| 7. |
- Tseng, Chiao-Wei, et al.
(författare)
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Synergy of Ionic and Dipolar Effects by Molecular Design for pH Sensing beyond the Nernstian Limit
- 2020
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Ingår i: Advanced Science. - : Wiley. - 2198-3844. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of interfacial interactions between analytes and functionalized sensor surfaces, from where the signal originates, is key to the development and application of electronic sensors. The present work explores the tunability of pH sensitivity by the synergy of surface charge and molecular dipole moment induced by interfacial proton interactions. This synergy is demonstrated on a silicon‐nanoribbon field‐effect transistor (SiNR‐FET) by functionalizing the sensor surface with properly designed chromophore molecules. The chromophore molecules can interact with protons and lead to appreciable changes in interface dipole moment as well as in surface charge state. In addition, the dipole moment can be tuned not only by the substituent on the chromophore but also by the anion in the electrolyte interacting with the protonated chromophore. By designing surface molecules to enhance the surface dipole moment upon protonation, an above‐Nernstian pH sensitivity is achieved on the SiNR‐FET sensor. This finding may bring an innovative strategy for tailoring the sensitivity of the SiNR‐FET‐based pH sensor toward a wide range of applications.
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| 8. |
- Wei, Yixuan, et al.
(författare)
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Prediction of occupancy level and energy consumption in office building using blind system identification and neural networks
- 2019
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Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 240, s. 276-294
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Tidskriftsartikel (refereegranskat)abstract
- Occupancy behaviour plays an important role in energy consumption in buildings. Currently, the shallow understanding of occupancy has led to a considerable performance gap between predicted and measured energy use. This paper presents an approach to estimate the occupancy based on blind system identification (BSI), and a prediction model of electricity consumption by an air-conditioning system is developed and reported based on an artificial neural network with the BSI estimation of the number of occupants as an input. This starts from the identification of indoor CO2 dynamics derived from the mass-conservation law and venting levels. The unknown parameters, including the occupancy and model parameters, are estimated by using a frequentist maximum-likelihood algorithm and Bayesian estimation. The second phase is to establish the prediction model of the electricity consumption of the air-conditioning system by using a feed-forward neural network (FFNN) and extreme learning machine (ELM), as well as ensemble models. To analyse some aspects of the benchmark test for identifying the effect of structure parameters and input-selection alternatives, three studies are conducted on (1) the effect of predictor selection based on principal component analysis, (2) the effect of the estimated occupancy as the supplementary input, and (3) the effect of the neural network ensemble. The result shows that the occupancy number, as the input, is able to improve the accuracy in predicting energy consumption using a neural network model.
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| 9. |
- Xu, Xingxing, et al.
(författare)
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Considerations for the Cyclic Voltammetry of Gold in Sulfuric Acid Solutions
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A comprehensive understanding of the cyclic voltammetry (CV) for gold surfaces is essential for advanced applications. In the present study, a series of experiments were designed to investigate CV for gold under different experimental conditions when using a conventional configuration of a Ag/AgCl/sat. KCl reference electrode and a platinum wire counter electrode. The interferences introduced by the configuration were reflected in the three fingerprint regions of the voltammograms. It was found that the shape of the voltammograms was less reproducible at a lower sample volume when the cycle number was increased. This observation could be explained by different concentrations of Cl- leaking from the reference electrode and platinum dissolved from the counter electrode. The reproducibility of the gold oxidation and reduction (Ox/Re) region in the voltammograms was improved when gold dissolution and re-deposition caused by Cl- leakage was eliminated by using a bridge. In the hydrogen evolution and oxidation reactions (HER/HOR) region the catalytic performance of the gold electrode could be minimized by replacing the platinum counter electrode with a graphite rod. Alternatively, it could be enhanced by increasing the surface ratio of the co-deposited platinum to gold. In the electric double layer (EDL) region, peaks dependent on the concentrations of Cl- and SO42- were observed. To account for the occurrence of these peaks, a new mechanism based on the formation of neutral gold (I) complexes at very low Au+ concentrations, was proposed.
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| 10. |
- Xu, Xingxing, et al.
(författare)
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Revisiting the factors influencing gold electrodes prepared using cyclic voltammetry
- 2019
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 283, s. 146-153
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Tidskriftsartikel (refereegranskat)abstract
- Gold is widely used as the electrode material in different chemi- and biosensing applications while cyclic voltammetry (CV) in sulfuric acid solutions is a commonly employed method for gold surface preparation and characterization. However, as shown herein, chloride leakage from the Ag/AgCl/sat. KCl reference electrode and platinum dissolution from the platinum counter electrode can severely compromise the reproducibility and hence the reliability of the prepared gold electrodes. The aim of this work is to obtain a comprehensive understanding of the separate and interdependent effects of the aforementioned factors on the voltammetric behavior of microfabricated polycrystalline gold electrodes. It is shown that the leakage of chloride gives rise to etching of both the gold working and the platinum counter electrodes and that the chloride concentration has a strong influence on the ratio between the obtained gold and platinum concentrations in the electrolyte. The dissolved gold and platinum are then re-deposited on the gold electrode on the cathodic voltammetric scan, changing the structure and properties of the electrode. It is also demonstrated that the changes in the properties of the gold electrode are determined by the ratio between the co-deposited platinum and gold rather than the absolute amount of platinum deposited on the gold electrode. In addition, the chloride and sulfate adsorption behavior on the gold electrode is carefully investigated. It is proposed that redox peaks due to the formation ofthe corresponding Au(I) complexes can be seen in the double layer region of the voltammogram. The results show that the chloride leakage from the reference electrode needs to be carefully controlled and that platinum counter electrodes should be avoided when developing gold sensing electrodes. The present comprehensive understanding of the electrochemical performance of gold electrodes prepared using CV should be of significant importance in conjunction with both fundamental investigations and practical applications.
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| 11. |
- Zhang, Nan, et al.
(författare)
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Numerical investigations and performance comparisons of a novel cross-flow hollow fiber integrated liquid desiccant dehumidification system
- 2019
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 182, s. 1115-1131
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Tidskriftsartikel (refereegranskat)abstract
- The heat and mass transfer process of a novel cross-flow hollow fiber integrated liquid desiccant dehumidification system is analysed numerically. Compared with other porous media or packing towers in dehumidification applications, hollow fibre membranes have significant advantages including low weight, corrosion resistant and no liquid droplet carryover. A novel air-KCOOH cross-flow dehumidification system was designed and manufactured, with 5500 hollow fibres formed into a circular module. The variations of the dehumidification effectiveness and moisture removal rates were studied numerically and validated against experimental results under the incoming air mass flow rates of 0.08-0.26kg/s and relative humidity from 55% to 75%. The dehumidification performance comparisons for the proposed system using CaCl2, LiCl and KCOOH as the desiccants have been conducted as well. The results demonstrated that under the same m*(ratio between solution mass flow rate to the air mass flow rate), the proposed system using 62% KCOOH could achieve approximately the same latent effectiveness compared with 40% CaCl2 and 32% LiCl, with the at least 3.1% sensible effectiveness increased by. Therefore, it could be concluded that the proposed system using KCOOH as desiccant could be more applicable for dehumidification purpose compared with other systems using conventional liquid desiccants.
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| 12. |
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| 13. |
- Bai, Songang, et al.
(författare)
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Large third-order nonlinear refractive index coefficient based on gold nanoparticle aggregate films
- 2015
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 107:14
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Tidskriftsartikel (refereegranskat)abstract
- Au nanoparticles show large third-order nonlinear effect and ultra-fast response. Here a high nonlinear aggregate film based on self-assembled gold nanoparticles is reported and its third-order nonlinear refractive index coefficient is measured by Z-scan experiment. The third-order nonlinear refractive index coefficient of the Au nanoparticle aggregate film (gamma(1) = 9.2 x 10(-9) cm(2)/W) is found to be larger than that of an 8-nm-thick sputtered Au film (gamma(2)= 6.5 x 10(-9) cm(2)/W). This large nonlinear effect can be attributed to the strong field enhancement due to localized plasmon resonances between Au nanoparticles. The result shows that the self-assembled Au nanoparticle aggregate film could be a promising candidate as a third-order nonlinear optical material.
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| 14. |
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| 15. |
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| 16. |
- Chang, Li, et al.
(författare)
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Recent progress in research on PM2.5 in subways.
- 2021
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Ingår i: Environmental Science. - : Royal Society of Chemistry (RSC). - 2050-7887 .- 2050-7895. ; 23:5, s. 642-663
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Tidskriftsartikel (refereegranskat)abstract
- Nowadays, PM2.5 concentrations greatly influence indoor air quality in subways and threaten passenger and staff health because PM2.5 not only contains heavy metal elements, but can also carry toxic and harmful substances due to its small size and large specific surface area. Exploring the physicochemical and distribution characteristics of PM2.5 in subways is necessary to limit its concentration and remove it. At present, there are numerous studies on PM2.5 in subways around the world, yet, there is no comprehensive and well-organized review available on this topic. This paper reviews the nearly twenty years of research and over 130 published studies on PM2.5 in subway stations, including aspects such as concentration levels and their influencing factors, physicochemical properties, sources, impacts on health, and mitigation measures. Although many determinants of station PM2.5 concentration have been reported in current studies, e.g., the season, outdoor environment, and station depth, their relative influence is uncertain. The sources of subway PM2.5 include those from the exterior (e.g., road traffic and fuel oil) and the interior (e.g., steel wheels and rails and metallic brake pads), but the proportion of these sources is also unknown. Control strategies of PM mainly include adequate ventilation and filtration, but these measures are often inefficient in removing PM2.5. The impacts of PM2.5 from subways on human health are still poorly understood. Further research should focus on long-term data collection, influencing factors, the mechanism of health impacts, and PM2.5 standards or regulations.
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| 17. |
- Chen, X, et al.
(författare)
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Experimental investigation of a polymer hollow fibre integrated liquid desiccant dehumidification system with aqueous potassium formate solution
- 2018
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Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311 .- 1873-5606. ; 142
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Tidskriftsartikel (refereegranskat)abstract
- Hollow fibres have been studied as the substitute for metallic materials due to the advantages such as light weight, corrosion resistant and low cost in heat and mass transfer applications. A novel polymer hollow fibre liquid desiccant dehumidification system, in which a cross-flow hollow fibre module (fibre inside diameter=1.4mm) serves as the dehumidifier, is presented in this paper. This novel hollow fibre integrated liquid desiccant dehumidification system can be used in an air conditioning system to provide a comfortable indoor environment for hot and humid area. Compared with other conventional liquid desiccant dehumidifier, the polymer hollow fibre has a very small diameter which leads to significantly increased surface area. Moreover, the porous feature of the hollow fibre module can help to eliminate any liquid desiccant droplets carryover into the process air. As a less corrosive and more environmental friendly working fluid, aqueous potassium formate (KCOOH) solution has been selected. The dehumidification performance of the proposed system were analysed experimentally under the conditions of incoming air temperature in the range of 30°C to 45°C. The variations of dehumidification sensible and latent effectiveness, moisture removal rates were studied by varying the incoming air velocity from 0.65 m/s to 4.5m/s. With the various values of incoming air relative humidity in the range of 55% to 75% and the solution concentrations between 36% and 62%, the experimental obtained latent effectiveness are in the range of 0.25 to 0.43 and the sensible effectiveness are in the range of 0.31 to 0.52, which is in a satisfactory agreement with the empirical correlation of effectiveness-NTU in the literature.
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| 18. |
- Chen, X., et al.
(författare)
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Experimental investigations of polymer hollow fibre integrated evaporative cooling system with the fibre bundles in a spindle shape
- 2017
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Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788 .- 1872-6178. ; 154, s. 166-174
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Tidskriftsartikel (refereegranskat)abstract
- Due to the advantages of light weight, corrosion resistant and low cost, hollow fibres have been studied as the substitute for metallic materials. A novel hollow fibre integrated evaporative cooling system, in which the hollow fibre module constitutes as the humidifier and the evaporative cooler, is proposed. This novel hollow fibre integrated evaporative cooling system will provide a comfortable indoor environment for hot and dry area. Moreover, the water vapour can permeate through the hollow fibre effectively, and the liquid water droplets will be prevented from mixing with the processed air. In order to avoid the flow channelling or shielding of adjacent fibres, the fibres inside each bundle were made into a spindle shape to allow maximum contact between the air stream and the fibre. The cooling performances of the proposed novel polymer hollow fibre integrated evaporative cooling system were experimentally investigated under the incoming air temperature in the range of 26 °C to 32 °C and relative humidity of 25%–35%. The effects of air velocities on the cooling effectiveness, heat and mass transfer coefficients, specific water consumption and pressure drop across the polymer hollow fibre module were analysed. Two sets of experimentally derived non-dimensional heat and mass transfer correlations were summarized, which could be favourable for the future design of polymer hollow fibre integrated evaporative cooling system.
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| 19. |
- Clements-Croome, Derek, et al.
(författare)
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Research Roadmap for Intelligent and Responsive Buildings
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Intelligence has three parts cognitive, emotional and practical. A building needs to reflect this. So an intelligent building will responsive to people in terms of not only being functional but to the human senses besides serving a community in the location. It will be resource effective in terms of energy , water and waste with low pollution. It will be smart in terms of technology selected to enable the systems to respond effectively but also make them easier for people to use. Today there is a focus on health and wellbeing and so intelligent buildings must produce a healing environment. Buildings need to be functional and practical but also expressive. Equally important is the infrastructure that services buildings and the people moving between them.
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| 20. |
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| 21. |
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| 22. |
- Duan, Zhiyin, et al.
(författare)
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Indirect evaporative cooling : Past, present and future potentials
- 2012
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 16:9, s. 6823-6850
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Tidskriftsartikel (refereegranskat)abstract
- This paper reported a review based study into the Indirect Evaporative Cooling (IEC) technology, which was undertaken from a variety of aspects including background, history, current status, concept, standardisation, system configuration, operational mode, research and industrialisation, market prospect and barriers, as well as the future focuses on R&D and commercialisation. This review work indicated that the IEC technology has potential to be an alternative to conventional mechanical vapour compression refrigeration systems to take up the air conditioning duty for buildings. Owing to the continuous progress in technology innovation, particularly the M-cycle development and associated heat and mass transfer and material optimisation, the IEC systems have obtained significantly enhanced cooling performance over those the decade ago, with the wet-bulb effectiveness of greater than 90% and energy efficiency ratio (EER) up to 80. Structure of the IEC heat and mass exchanger varied from flat-plate-stack, tube, heat pipe and potentially wave-form. Materials used for making the exchanger elements (plate/tube) included fibre sheet with the single side water proofing, aluminium plate/tube with single side wicked setting (grooved, meshed, toughed etc), and ceramic plate/tube with single side water proofing. Counter-current water flow relevant to the primary air is considered the favourite choice; good distribution of the water stream across the wet surface of the exchanger plate (tube) and adequate (matching up the evaporation) control of the water flow rate are critical to achieving the expected system performance. It was noticed that the IEC devices were always in combined operation with other cooling measures and the commonly available IEC related operational modes are (1) IEC/DEC system; (2) IEC/DEC/mechanical vapour compression system; (3) IEC/desiccant system; (4) IEC/chilled water system; and (5) IEC/heat pipe system. The future potential operational modes may also cover the IEC-inclusive fan coil units, air handle units, cooling towers, solar driven desiccant cycle, and Rankine cycle based power generation system etc. Future works on the IEC technology may focus on (1) heat exchanger structure and material; (2) water flowing, distribution and treatment; (3) incorporation of the IEC components into conventional air conditioning products to enable combined operation between the IEC and other cooling devices; (4) economic, environment and social impacts; (5) standardisation and legislation; (6) public awareness and other dissemination measures; and (7) manufacturing and commercialisation. All above addressed efforts may help increase the market ratio of the IEC to around 20% in the next 20 years, which will lead to significant saving of fossil fuel consumption and cut of carbon emission related to buildings.
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| 23. |
- Feng, Xingxing, et al.
(författare)
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Human recognition with the optoelectronic reservoir-computing-based micro-Doppler radar signal processing
- 2022
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Ingår i: Applied Optics. - : Optica Publishing Group (formerly OSA). - 1559-128X .- 2155-3165. ; 61:19, s. 5782-5789
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Tidskriftsartikel (refereegranskat)abstract
- Current perception and monitoring systems, such as human recognition, are affected by several environmental factors, such as limited light intensity, weather changes, occlusion of targets, and public privacy. Human recognition using radar signals is a promising direction to overcome these defects; however, the low signal-to-noise ratio of radar signals still makes this task challenging. Therefore, it is necessary to use suitable tools that can efficiently deal with radar signals to identify targets. Reservoir computing (RC) is an efficient machine learning scheme that is easy to train and demonstrates excellent performance in processing complex time-series signals. The RC hardware implementation structure based on nonlinear nodes and delay feedback loops endows it with the potential for real-time fast signal processing. In this paper, we numerically study the performance of the optoelectronic RC composed of optical and electrical components in the task of human recognition with noisy micro-Doppler radar signals. A single-loop optoelectronic RC is employed to verify the application of RC in this field, and a parallel dual-loop optoelectronic RC scheme with a dual-polarization Mach–Zehnder modulator (DPol-MZM) is also used for performance comparison. The result is verified to be comparable with other machine learning tools, which demonstrates the ability of the optoelectronic RC in capturing gait information and dealing with noisy radar signals; it also indicates that optoelectronic RC is a powerful tool in the field of human target recognition based on micro-Doppler radar signals.
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| 24. |
- Feng, Xingxing, et al.
(författare)
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Numerical Study of Parallel Optoelectronic Reservoir Computing to Enhance Nonlinear Channel Equalization
- 2021
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Ingår i: Photonics. - : MDPI AG. - 2304-6732. ; 8:10
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Tidskriftsartikel (refereegranskat)abstract
- Nonlinear impairment is one of the critical limits to enhancing the performance of high-speed communication systems. Traditional digital signal processing (DSP)-based nonlinear channel equalization schemes are influenced by limited bandwidth, high power consumption, and high processing latency. Optoelectronic reservoir computing (RC) is considered a promising optical signal processing (OSP) technique with merits such as large bandwidth, high power efficiency, and low training complexity. In this paper, optoelectronic RC was employed to solve the nonlinear channel equalization problem. A parallel optoelectronic RC scheme with a dual-polarization Mach-Zehnder modulator (DPol-MZM) is proposed and demonstrated numerically. The nonlinear channel equalization performance was greatly enhanced compared with the traditional optoelectronic RC and the Volterra-based nonlinear DSP schemes. In addition, the system efficiency was improved with a single DPol-MZM.
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| 25. |
- Feng, Xingxing, et al.
(författare)
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The Parallel Optoelectronic Reservoir Computing Based Nonlinear Channel Equalization
- 2021
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Ingår i: 2021 Optoelectronics Global Conference, OGC 2021. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 230-234
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Konferensbidrag (refereegranskat)abstract
- The optoelectronic reservoir computing (RC) is considered as a promising optical signal processing technique for nonlinear channel equalization. In this paper, a parallel optoelectronic RC scheme with a dual-polarization Mach- Zehnder modulator (DPol-MZM) is proposed and demonstrated numerically. The nonlinear channel equalization performance is greatly enhanced compared with the traditional optoelectronic RC scheme and Volterra-based DSP scheme, since the nonlinear dynamics of RC are enriched from the dual-polarization methodology. Besides, the system efficiency is improved with a single DPol-MZM.
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| 26. |
- Freitas, Iuri, et al.
(författare)
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Green building rating systems in Swedish market : A comparative analysis between LEED, BREEAM SE, GreenBuilding and Miljöbyggnad
- 2018
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 153, s. 402-407
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Tidskriftsartikel (refereegranskat)abstract
- In Sweden, there are four most commonly used green building rating systems, which are LEED, BREEAM SE, GreenBuilding and Miljöbyggnad. In this study, each of them is analyzed under the aspects of certification process, implementation cost, educational needs and the variety of categories. SWOT method is further applied to extract the strengths, weaknesses, opportunities and threats of each of the rating system in a direct and indirect manner, making it clearer to choose among various options when considering the individual needs of each project in practice.
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| 27. |
- Fu, Jiapeng, et al.
(författare)
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One-step rapid pyrolysis activation method to prepare nanostructured activated coke powder
- 2020
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Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 262
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Tidskriftsartikel (refereegranskat)abstract
- A one-step rapid pyrolysis activation method is proposed to produce activated coke powder (ACP) via a drop tube reactor by using pulverized Datong coal (DTC) and pine wood (PW) as feedstock. Small feedstock particle size, high heating rate, and effective activation agent, i.e., the mixture of oxygen and steam were arranged for the fast formation and development of various pore structure of ACPs. Detail characteristics of the ACP were investigated by using the nitrogen adsorption measurement, scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR) analysis. Results showed that the ACP presented well-developed nanostructure with considerable pore volume, specific surface area and surface functional groups. The pore volume and specific surface area of PWC-O6S10 could reach 0.2373 cm3/g and 250.57 m2/g. Activation atmosphere had played an important role to develop the pore structure and morphology of the ACP. Under 6 vol% oxygen concentration, the optimum steam partial pressure for micropore development of DTC was about 15 vol%, while it mostly promoted the growth of mesopores for PWC. All ACP samples presented variety of C/O/N containing surface functional groups, including OH, CH, CC, CO, CO, COC, CN, CN, etc., which remained relatively stable as the activation agents concentration changed.
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| 28. |
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| 29. |
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| 30. |
- Gu, Yaxiu, et al.
(författare)
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Techno-economic analysis of a solar photovoltaic/thermal (PV/T) concentrator for building application in Sweden using Monte Carlo method
- 2018
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 165, s. 8-24
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Tidskriftsartikel (refereegranskat)abstract
- The solar energy share in Sweden will grow up significantly in next a few decades. Such transition offers not only great opportunity but also uncertainties for the emerging solar photovoltaic/thermal (PV/T) technologies. This paper therefore aims to conduct a techno-economic evaluation of a reference solar PV/T concentrator in Sweden for building application. An analytical model is developed based on the combinations of Monte Carlo simulation techniques and multi energy-balance/financial equations, which takes into account of the integrated uncertainties and risks of various variables. In the model, 11 essential input variables, i.e. average daily solar irradiance, electrical/thermal efficiency, prices of electricity/heating, operation & management (OM) cost, PV/T capital cost, debt to equity ratio, interest rate, discount rate, and inflation rate, are considered, while the economic evaluation metrics, such as levelized cost of energy (LCOE), net present value (NPV), and payback period (PP), are primarily assessed. According to the analytical results, the mean values of LCOE, NPV and PP of the reference PV/T connector are observed at 1.27 SEK/kW h (0.127 €/kW h), 18,812.55 SEK (1881.255 €) and 10 years during its 25 years lifespan, given the project size at 10.37 m2 and capital cost at 4482–5378 SEK/m2 (448.2–537.8 €/m2). The positive NPV indicates that the investment on the selected PV/T concentrator will be profitable as the projected earnings exceeds the anticipated costs, depending on the NPV decision rule. The sensitivity analysis and the parametric study illustrate that the economic performance of the reference PV/T concentrator in Sweden is mostly proportional to solar irradiance, debt to equity ratio and heating price, but disproportionate to capital cost and discount rate. Together with additional market analysis of PV/T technologies in Sweden, it is expected that this paper could clarify the economic situation of PV/T technologies in Sweden and provide a useful model for their further investment decisions, in order to achieve sustainable and low-carbon economics, with an expanded quantitative discussion of the real economic or policy scenarios that may lead to those outcomes.
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| 31. |
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| 32. |
- Han, Mengjie, 1985-, et al.
(författare)
-
A novel reinforcement learning method for improving occupant comfort via window opening and closing
- 2020
-
Ingår i: Sustainable cities and society. - : Elsevier BV. - 2210-6707. ; 61
-
Tidskriftsartikel (refereegranskat)abstract
- An occupant's window opening and closing behaviour can significantly influence the level of comfort in the indoor environment. Such behaviour is, however, complex to predict and control conventionally. This paper, therefore, proposes a novel reinforcement learning (RL) method for the advanced control of window opening and closing. The RL control aims at optimising the time point for window opening/closing through observing and learning from the environment. The theory of model-free RL control is developed with the objective of improving occupant comfort, which is applied to historical field measurement data taken from an office building in Beijing. Preliminary testing of RL control is conducted by evaluating the control method’s actions. The results show that the RL control strategy improves thermal and indoor air quality by more than 90 % when compared with the actual historically observed occupant data. This methodology establishes a prototype for optimally controlling window opening and closing behaviour. It can be further extended by including more environmental parameters and more objectives such as energy consumption. The model-free characteristic of RL avoids the disadvantage of implementing inaccurate or complex models for the environment, thereby enabling a great potential in the application of intelligent control for buildings.
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| 33. |
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| 34. |
- Han, Mengjie, et al.
(författare)
-
A review of reinforcement learning methodologies on control systems for building energy
- 2018
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The usage of energy directly leads to a great amount of consumption of the non-renewable fossil resources. Exploiting fossil resources energy can influence both climate and health via ineluctable emissions. Raising awareness, choosing alternative energy and developing energy efficient equipment contributes to reducing the demand for fossil resources energy, but the implementation of them usually takes a long time. Since building energy amounts to around one-third of global energy consumption, and systems in buildings, e.g. HVAC, can be intervened by individual building management, advanced and reliable control techniques for buildings are expected to have a substantial contribution to reducing global energy consumptions. Among those control techniques, the model-free, data-driven reinforcement learning method seems distinctive and applicable. The success of the reinforcement learning method in many artificial intelligence applications has brought us an explicit indication of implementing the method on building energy control. Fruitful algorithms complement each other and guarantee the quality of the optimisation. As a central brain of smart building automation systems, the control technique directly affects the performance of buildings. However, the examination of previous works based on reinforcement learning methodologies are not available and, moreover, how the algorithms can be developed is still vague. Therefore, this paper briefly analyses the empirical applications from the methodology point of view and proposes the future research direction.
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| 35. |
- Han, Mengjie, 1985-, et al.
(författare)
-
An Approach to Data Acquisition for Urban Building Energy Modeling Using a Gaussian Mixture Model and Expectation-Maximization Algorithm
- 2021
-
Ingår i: Buildings. - : MDPI. - 2075-5309. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years, a building’s energy performance is becoming uncertain because of factors such as climate change, the Covid-19 pandemic, stochastic occupant behavior and inefficient building control systems. Sufficient measurement data is essential to predict and manage a building’s performance levels. Assessing energy performance of buildings at an urban scale requires even larger data samples in order to perform an accurate analysis at an aggregated level. However, data are not only expensive, but it can also be a real challenge for communities to acquire large amounts of real energy data. This is despite the fact that inadequate knowledge of a full population will lead to biased learning and the failure to establish a data pipeline. Thus, this paper proposes a Gaussian mixture model (GMM) with an Expectation-Maximization (EM) algorithm that will produce synthetic building energy data. This method is tested on real datasets. The results show that the parameter estimates from the model are stable and close to the true values. The bivariate model gives better performance in classification accuracy. Synthetic data points generated by the models show a consistent representation of the real data. The approach developed here can be useful for building simulations and optimizations with spatio-temporal mapping.
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| 36. |
- Han, Mengjie, 1985-, et al.
(författare)
-
Generating hourly electricity demand data for large-scale single-family buildings by a decomposition-recombination method
- 2022
-
Ingår i: Energy and Built Environment. - : Elsevier BV. - 2666-1233.
-
Tidskriftsartikel (refereegranskat)abstract
- Household electricity demand has substantial impacts on local grid operation, energy storage and the energy performance of buildings. Hourly demand data at district or urban level helps stakeholders understand the demand patterns from a granular time scale and provides robust evidence in energy management. However, such type of data is often expensive and time-consuming to collect, process and integrate. Decisions built upon smart meter data have to deal with challenges of privacy and security in the whole process. Incomplete data due to confidentiality concerns or system failure can further increase the difficulty of modeling and optimization. In addition, methods using historical data to make predictions can largely vary depending on data quality, local building environment, and dynamic factors. Considering these challenges, this paper proposes a statistical method to generate hourly electricity demand data for large-scale single-family buildings by decomposing time series data and recombining them into synthetics. The proposed method used public data to capture seasonality and the distribution of residuals that fulfill statistical characteristics. A reference building was used to provide empirical parameter settings and validations for the studied buildings. An illustrative case in a city of Sweden using only annual total demand was presented for deploying the proposed method. The results showed that the proposed method can mimic reality well and represent a high level of similarity to the real data. The average monthly error for the best month reached 15.9% and the best one was below 10% among 11 tested months. Less than 0.6% improper synthetic values were found in the studied region.
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| 37. |
- Han, Mengjie, 1985-, et al.
(författare)
-
Perspectives of Machine Learning and Natural Language Processing on Characterizing Positive Energy Districts
- 2024
-
Ingår i: Buildings. - : MDPI. - 2075-5309. ; 14:2
-
Tidskriftsartikel (refereegranskat)abstract
- The concept of a Positive Energy District (PED) has become a vital component of the efforts to accelerate the transition to zero carbon emissions and climate-neutral living environments. Research is shifting its focus from energy-efficient single buildings to districts, where the aim is to achieve a positive energy balance across a given time period. Various innovation projects, programs, and activities have produced abundant insights into how to implement and operate PEDs. However, there is still no agreed way of determining what constitutes a PED for the purpose of identifying and evaluating its various elements. This paper thus sets out to create a process for characterizing PEDs. First, nineteen different elements of a PED were identified. Then, two AI techniques, machine learning (ML) and natural language processing (NLP), were introduced and examined to determine their potential for modeling, extracting, and mapping the elements of a PED. Lastly, state-of-the-art research papers were reviewed to identify any contribution they can make to the determination of the effectiveness of the ML and NLP models. The results suggest that both ML and NLP possess significant potential for modeling most of the identified elements in various areas, such as optimization, control, design, and stakeholder mapping. This potential is realized through the utilization of vast amounts of data, enabling these models to generate accurate and useful insights for PED planning and implementation. Several practical strategies have been identified to enhance the characterization of PEDs. These include a clear definition and quantification of the elements, the utilization of urban-scale energy modeling techniques, and the development of user-friendly interfaces capable of presenting model insights in an accessible manner. Thus, developing a holistic approach that integrates existing and novel techniques for PED characterization is essential to achieve sustainable and resilient urban environments.
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| 38. |
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| 39. |
- Han, Mengjie, 1985-, et al.
(författare)
-
Review of natural language processing techniques for characterizing positive energy districts
- 2023
-
Ingår i: journal of Physics; Conference series. - : Institute of Physics Publishing (IOPP).
-
Konferensbidrag (refereegranskat)abstract
- The concept of Positive Energy Districts (PEDs) has emerged as a crucial aspect of endeavours aimed at accelerating the transition to zero carbon emissions and climate-neutral living spaces. The focus of research has shifted from energy-efficient individual buildings to entire districts, where the objective is to achieve a positive energy balance over a specific timeframe. The consensus on the conceptualization of a PED has been evolving and a standardized checklist for identifying and evaluating its constituent elements needs to be addressed. This study aims to develop a methodology for characterizing PEDs by leveraging natural language processing (NLP) techniques to model, extract, and map these elements. Furthermore, a review of state-of-the-art research papers is conducted to ascertain their contribution to assessing the effectiveness of NLP models. The findings indicate that NLP holds significant potential in modelling the majority of the identified elements across various domains. To establish a systematic framework for AI modelling, it is crucial to adopt approaches that integrate established and innovative techniques for PED characterization. Such an approach would enable a comprehensive and effective implementation of NLP within the context of PEDs, facilitating the creation of sustainable and resilient urban environments. © 2023 Institute of Physics Publishing. All rights reserved.
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| 40. |
- Han, Mengjie, 1985-, et al.
(författare)
-
The reinforcement learning method for occupant behavior in building control : A review
- 2021
-
Ingår i: Energy and Built Environment. - : Elsevier BV. - 2666-1233. ; 2:2, s. 137-148
-
Tidskriftsartikel (refereegranskat)abstract
- Occupant behavior in buildings has been considered the major source of uncertainty for assessing energy consumption and building performance. Modeling frameworks are usually built to accomplish a certain task, but the stochasticity of the occupant makes it difficult to apply that experience to a similar but distinct environment. For complex and dynamic environments, the development of smart devices and computing power makes intelligent control methods for occupant behaviors more viable. It is expected that they will make a substantial contribution to reducing global energy consumption. Among these control techniques, the reinforcement learning (RL) method seems distinctive and applicable. The success of the reinforcement learning method in many artificial intelligence applications has given an explicit indication of how this method might be used to model and adjust occupant behavior in building control. Fruitful algorithms complement each other and guarantee the quality of the optimization. However, the examination of occupant behavior based on reinforcement learning methodologies is not well established. The way that occupant interacts with the RL agent is still unclear. This study briefly reviews the empirical applications using reinforcement learning, how they have contributed to shaping the modeling paradigms and how they might suggest a future research direction.
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| 41. |
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| 42. |
- He, Wei, et al.
(författare)
-
Operational performance of a novel heat pump assisted solar facade loop-heat-pipe water heating system
- 2015
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 146, s. 371-382
-
Tidskriftsartikel (refereegranskat)abstract
- This paper aims to present an investigation into the operational performance of a novel heat pump assisted solar façade loop-heat-pipe (LHP) water heating system using both theoretical and experimental methods. This involved (1) development of a computer numerical model; (2) simulation of the operational performance of the system by using the model; (3) test rig construction; and (4) dedicated experiment for verification of the model. It was found that the established model is able to predict the operational performance of the system at a reasonable accuracy. Analyses of the research results indicated that under the selected testing conditions, the average thermal efficiency of the LHP module was around 71%, much higher than that of the loop heat pipe without heat pump assistance. The thermal efficiency of the LHP module grew when the heat pump was turned-on and fell when the heat pump was turned-off. The water temperature remained a steadily growing trend throughout the heat pump turned-on period. Neglecting the heat loss of the water tank, the highest coefficient of the performance could reach up to 6.14 and its average value was around 4.93. In overall, the system is a new façade integrated, highly efficient and aesthetically appealing solar water heating configuration; wide deployment of the system will help reduce fossil fuel consumption in the building sector and carbon emission to the environment.
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| 43. |
- He, W., et al.
(författare)
-
Solar Heating, Cooling and Power Generation — Current Profiles and Future Potentials
- 2019
-
Ingår i: Advanced Energy Efficiency Technologies for Solar Heating, Cooling and Power Generation. - Cham : Springer. - 9783030172824 - 9783030172831 ; , s. 31-78
-
Bokkapitel (refereegranskat)abstract
- Due to the large amount of consumption of the fossil fuels, the ecological environment has suffered serious pollution and damage. Solar power technologies provide the best solution to the current energy and environment issues. In past decades, global solar thermal capacity increased rapidly, and now it has been used worldwide to provide heating, cooling and power generation. However, after years of development, solar energy utilization technology still faces problems such as low efficiency, high cost, difficulty in energy storage and unstable energy supply, which have been seriously restricting its applications. This chapter briefly summarizes the concept and classification of solar heating, cooling and power generation. Furthermore, some technology development and potential applications relating to solar heating, cooling and power generation are discussed.
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| 44. |
- He, Wei, et al.
(författare)
-
Theoretical investigation of the thermal performance of a novel solar loop-heat-pipe facade-based heat pump water heating system
- 2014
-
Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788 .- 1872-6178. ; 77, s. 180-191
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the paper was to present a dedicated theoretical investigation into the thermal performance of a novel solar loop-heat-pipe façade based heat pump water heating system. This involved thermo-fluid analyses, computer numerical model development, the model running up, modelling result analyses and conclusion. An energy balance network was established on each part and the whole range of the system to address the associated energy conversion and transfer processes. On basis of this, a computer numerical model was developed and run up to predict the thermal performance of such a system at different system configurations, layouts and operational conditions. It was suggested that the loop heat pipes could be filled with either water, R134a, R22 or R600a; of which R600a is the favourite working fluid owing to its relatively larger heat transfer capacity and positive pressure in operation. Variations in the system configuration, i.e., glazing covers, heat exchangers, would lead to identifiable differences in the thermal performance of the system, represented by the thermal efficiency and COP. Furthermore, impact of the external operational parameters, i.e., solar radiation and ambient air temperature, to the system's thermal performance was also investigated. The research was based on an innovative loop-heat-pipe façade and came up with useful results reflecting the thermal performance of the combined system between the façade and heat pump. This would help promote development and market penetration of such an innovative solar heating technology, and thus contribute to achieving the global targets in energy saving and carbon emission reduction.
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| 45. |
- Hedman, Åsa, et al.
(författare)
-
IEA EBC Annex83 Positive Energy Districts
- 2021
-
Ingår i: Buildings. - : MDPI AG. - 2075-5309. ; 11:3
-
Tidskriftsartikel (refereegranskat)abstract
- At a global level, the need for energy efficiency and an increased share of renewable energy sources is evident, as is the crucial role of cities due to the rapid urbanization rate. As a consequence of this, the research work related to Positive Energy Districts (PED) has accelerated in recent years. A common shared definition, as well as technological approaches or methodological issues related to PEDs are still unclear in this development and a global scientific discussion is needed. The International Energy Agency’s Energy in Buildings and Communities Programme (IEA EBC) Annex 83 is the main platform for this international scientific debate and research. This paper describes the challenges of PEDs and the issues that are open for discussions and how the Annex 83 is planned and organized to facilitate this and to actively steer the development of PEDs major leaps forward. The main topics of discussion in the PED context are the role and importance of definitions of PEDs, virtual and geographical boundaries in PEDs, the role of different stakeholders, evaluation approaches, and the learnings of realized PED projects.
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| 46. |
- Hu, J, et al.
(författare)
-
Electrical-thermal-mechanical properties of multifunctional OPV-ETFE foils for transparent membrane buildings
- 2018
-
Ingår i: Polymer testing. - : Elsevier BV. - 0142-9418 .- 1873-2348. ; 66, s. 394-402
-
Tidskriftsartikel (refereegranskat)abstract
- ETFE (ethylene tetrafluoroethylene) foils integrated organic photovoltaic cells (OPV) have attracted considerable attention in recent years due to the achievement of sustainability. As building materials, multifunctional OPV-ETFE foils could produce electricity, store thermal energy and possess structural capability. In this case, electrical, thermal and mechanical properties coexist and influence each other due to photovoltaic/thermal effects. Understanding the fundamental mechanism is significant to analyze and design corresponding structures. This paper concerns coupled properties of OPV-ETFE specimens with controlled experiments. One-parameter and two-parameter analysis of two typical specimens are performed to investigate essential properties. Experimental observations show that within normal working conditions, electrical properties are relatively independent but that thermal-mechanical properties are related to each other. Yield stress, yield strain and elastic modulus are calculated from stress-strain curves; these mechanical properties are comparable with those of original ETFE foils at the same temperature. It is concluded from temperature-stress curves that yield point has a critical effect on temperature-stress correlation and that mechanical properties of double OPV specimens are better than those of single OPV specimens. Generally, these mechanical properties could provide basic insights into evaluation of energetic performance and structural behavior of transparent membrane buildings.
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| 47. |
- Hu, Wei, et al.
(författare)
-
Axisymmetric and Asymmetric Naphthalene-Bisthienothiophene Based Nonfullerene Acceptors: On Constitutional Isomerization and Photovoltaic Performance
- 2020
-
Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 3:6, s. 5734-5744
-
Tidskriftsartikel (refereegranskat)abstract
- Two pairs of constitutional isomers of fused-octacyclic nonfullerene acceptors (NFAs) based on a naphthalene-bisthienothiophene core with or without fluorination at the ending groups have been developed. Compared with the axisymmetric NFAs N66-IC and N66-2FIC with two six-member-ring bridges, their asymmetric constitutional isomers N65-IC and N65-2FIC both with one six-member-ring bridge and one five-member-ring bridge exhibit remarkable red-shifted absorption, higher crystallinity, and slightly down-shifted LUMO energy levels. Organic solar cells based on PBDB-T-2F:N65-2FIC achieved a promising power conversion efficiency of 10.19%, which is three times higher than that of its counterpart PBDB-T-2F:N66-2FIC cell (3.46%). While being blended with PBDB-T as the donor material, the asymmetric acceptor analogue N65-IC based solar cell pronounces a PCE of 9.03%, being significantly improved from that of 5.45% for the PBDB-T:N66-IC based cell, which is in consistency with the results from those cells from their both fluorinated donor and acceptor counterparts. Design rules on either both fluorinated, both nonfluorinated, or cross-combined donor/acceptors for device fabrication has been explored. In addition, PBDB-T-2F:N65-2FIC possesses very promising device stability with 85% of its initial PCE after an exposure time of 1500 h under one sun illumination, which is meaningful for their future commercial devices.
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| 48. |
- Huang, Pei, 1992-, et al.
(författare)
-
A coordinated control to improve energy performance for a building cluster with energy storage, EVs, and energy sharing
- 2020
-
Ingår i: International Conference Organised by IBPSA-Nordic, 13th–14th October 2020, OsloMet. BuildSIM-Nordic 2020. Selected paper. - : SINTEF Academic Press. - 9788253616797 ; , s. 98-105
-
Konferensbidrag (refereegranskat)abstract
- Existing studies have developed some advanced controls for energy storage system charging/discharging in a building cluster (enabling PV power sharing among different buildings), which can effectively improve the aggregated performances. However, in the existing controls, the flexible demand shifting ability of electric vehicles (EVs) are rarely considered, leading to limited performance improvements at building cluster level. Thus, this study proposes a coordinated control of building cluster with both energy sharing and the EV charging considered, with the purpose of improving the cluster-level performance. The simulation results show that in a typical summer week in Sweden, the developed control can increase the cluster-level daily renewable selfconsumption by 40% and meanwhile reduce the electricity bills by as much as 20% compared with conventional controls for a summer week in Ludvika, Sweden
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| 49. |
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| 50. |
- Huang, Pei, et al.
(författare)
-
A hierarchical coordinated demand response control for buildings with improved performances at building group
- 2019
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 242, s. 684-694
-
Tidskriftsartikel (refereegranskat)abstract
- Demand response control is one of the common means used for building peak demand limiting. Most of the existing demand response controls focused on single building’s performance optimization, and thus may cause new undesirable peak demands at building group, imposing stress on the grid power balance and limiting the economic savings. A few latest studies have demonstrated the potential benefits of demand response coordination, but the proposed methods cannot be applied in large scales. The main reason is that, for demand response coordination of multiple buildings, associated computational load and coordination complexity, increasing exponentially with building number, are challenges to be solved. This study, therefore, proposes a hierarchical demand response control to optimize operations of a large scale of buildings for group-level peak demand reduction. The hierarchical control first considers the building group as a ‘virtual’ building and searches the optimal performance that can be achieved at building group using genetic algorithm. To realize such optimal performance, it then coordinates each single building’s operation using non-linear programming. For validations, the proposed method has been applied on a case building group, and the study results show that the hierarchical control can overcome the challenges of excessive computational load and complexity. Moreover, in comparison with conventional independent control, it can achieve better performances in aspects of peak demand reduction and economic savings. This study provides a coordinated control for application in large scales, which can improve the effectiveness and efficiency in relieving the grid stress, and reduce the end-users’ electricity bills.
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