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  • 651.
    Zhang, C.
    et al.
    Royal Institute of Technology, Sweden.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yang, J.
    Royal Institute of Technology, Sweden.
    Zhang, J.
    China Petroleum Daily, Jia NO.3, AnHuali 2, ChaoYang District, Beijing, China Petroleum Daily, China.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Royal Institute of Technology, Sweden.
    Can Solar Energy be an Alternative Choice of Milk Production in Dairy Farms?: -A Case study of Integrated PVWP System with Alfalfa and Milk Production in Dairy Farms in China2017Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, s. 3953-3959Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As China's dairy consumption grows, both the domestic milk production and the importation of dairy products are increasing to meet market demands. The objective of this study was to quantify electricity usage and cost of milk production with data analysis of dairy farms and evaluate the potential alternative energy supply-solar energy generated by PV water pumping system (PVWP). We collected data in milk production processes from 11 dairy farms in China. By selecting the optimal dairy farm, we simulate the scenario of solar power generation with PVWP system to provide power both for milk and alfalfa production. With estimations of electricity saving, economic cost saving and CO2 saving on every kg milk produced under PVWP system, we conclude that scenario PVWP with alfalfa and milk production can results in value add-ins, new sources of revenue, energy supply and emission reductions. 

  • 652.
    Zhang, C.
    et al.
    Royal Institute of Technology, Stockholm, Sweden.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    CDM's influence on technology transfers: A study of the implemented clean development mechanism projects in China2015Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 158, nr 15, s. 355-365Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Technology transfers through the Clean Development Mechanism (CDM) under the Kyoto Protocol is one of the most important catalysts in the cooperation between developed (Annex I) and developing (non-Annex I) countries for climate change mitigation. With the large-scale implementation of CDM projects in recent years, it is important to timely and comprehensively analyze the effectiveness of technology transfers in these implemented projects on the level of individual countries. In this context, China is of particular significance as it is the biggest host country of CDM projects in the world; 50% of total CDM projects implemented from 2007 to 2012 have issued Certified Emission Reductions (CERs) to 60% of all of the CDM projects. In this study, we evaluated the performance of technology transfers in an exclusive database of 754 CDM projects hosted by China between 2007 and 2012 with issued CERs since CERs were first issued in China. In addition, we developed a logistic regression approach using 11-variables that include a series of extended technology transfer-based indicators from the perspectives of project design, economic level, and technology capability that have not been studied in detail in the past. The results show that technology transfers are more likely to occur in large-sized projects with higher CER incomes, in projects with international participants, and in projects involving types such as HFC-23 reduction, fuel substitute, and N<inf>2</inf>O decomposition, in comparison to projects involving renewable energy. We observed that over 90% of the technology transfer projects only include importation of equipment or training to China. In our findings of the regression results, it shows that technology transfers occurred more often in regions with lower technology capabilities, less energy consumption, and a lower GDP growth rate. Supported by high local technology capability and the governmental strategy with independent innovation, the advantages of introducing technology from other countries are offset by local technology diffusion. In a market view, financial incentives hinder CDM host parties from introducing new equipment or trainings for the high marginal cost, unless the high marginal cost of technology transfer can be offset by a large CDM with a high CER income. Technology transfer is more income-driven than sustainability-driven at the present stage in China. In our analysis, the drive out effect between HFC-23 and renewable projects in CDM suggests China government to publish more effective incentives to attract more sustainable types of CDM projects with a higher level of technology innovation. The results are also discussed in the context of policy issues, which can be helpful for the decision makers when formulating future sustainable strategic plans and policy. 

  • 653. Zhang, Chi
    et al.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Liu, C.
    Zhang, Yang
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH, Sweden.
    Wang, K.
    Choice Preferences And Willingness‐To‐Pay For Crowd‐Funding With Integrated Photovoltaic Water Pumping System In Dairy Milk Production In China2018Konferensbidrag (Refereegranskat)
  • 654.
    Zhang, Chi
    et al.
    School of Chemical Science and Engineering, Royal Institute of Technology.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yang, Jan
    School of Chemical Science and Engineering, Royal Institute of Technology.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Economic performance of photovoltaic water pumping systems with business model innovation in China2017Ingår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 33, nr 1, s. 498-510Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Expansion by photovoltaic (PV) technologies in the renewable energy market requires exploring added value integrated with business model innovation. In recent years, a pilot trial of PV water pumping (PVWP) technologies for the conservation of grassland and farmland has been conducted in China. In this paper, we studied the added value of the PVWP technologies with an emphasis on the integration of the value proposition with the operation system and customer segmentation. Using the widely used existing PV business models (PV-roof) as a reference, we evaluated discounted cash flow (DCF) and net present value (NPV) under the scenarios of traditional PV roof, PVWP pilot, PVWP scale-up, and PVWP social network, where further added value via social network was included in the business model. The results show that the integrated PVWP system with social network products significantly improves the performance in areas such as the discounted payback period, internal rate of return (IRR), and return on investment (ROI). We conclude that scenario PVWP social network with business model innovation, can result in value add-ins, new sources of revenue, and market incentives. The paper also suggests that current policy incentives for PV industry are not efficient due to a limited source of revenue, and complex procedures of feed-in tariff verification.

  • 655.
    Zhang, Guoqiang
    et al.
    Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, China.
    Yan, Jinyue
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Jin, Hongguang
    Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing, China.
    Polygeneration system with CO2 capture integrated with black liquor gasification in pulp and paper mills to produce methanol and power2009Konferensbidrag (Refereegranskat)
    Abstract [en]

    Based on the KAMa reference pulp and paper mill, polygeneration systems integrating a black liquor gasifier with CO2 captured by means of oxygen-fuel combustion and Selexol pre-combustion are introduced and studied. Compared with the reference system the polygeneration system produces additional 73.5MW methanol while reducing electricity product of 11.2MW with the investment incremental of 8.6%. The energy penalty due to CO2 capture and compression is 0.46 MJ electricity per kg CO2 avoided for oxygen-fuel method at a cost of 25.9$ /tonne CO2. However, the energy penalty can reach 1.33 MJ Methanol per kg CO2 avoided in the Selexol pre-combustion CO2 capture process at a cost of 48.6$ /tonne CO2.

  • 656.
    Zhang, Jie
    et al.
    Univ Maryland, USA..
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yao, Tian
    Univ Space Res Assoc, Columbia, USA..
    Zhang, Yang
    KTH Royal Inst Technol, Stockholm, Sweden..
    Lundblad, Anders
    Malardalen Univ, Sch Business Soc & Engn, SE-72123 Vasteras, Sweden.;KTH Royal Inst Technol, Sch Chem Sci & Engn, SE-10044 Stockholm, Sweden..
    Melton, Forrest
    NASA ARC CREST, Calif State Univ Monterey Bay, USA..
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH Royal Inst Technol, Stockholm, Sweden..
    The water-food-energy nexus optimization approach to combat agricultural drought: a case study in the United States2018Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 227, s. 449-464Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The frequent recent drought events in the Great Plains of United States have led to significant crop yield reductions and crop price surges. Using an integrated water-food-energy nexus modelling and optimization approach, this study laid the basis for developing an effective agricultural drought management system by combining real-time drought monitoring with real-time irrigation management. The proposed water-food-energy simulation and optimization method is spatially explicit and was applied to one major corn region in Nebraska. The crop simulations, validated with yield statistics, showed that a drought year like 2012 can potentially reduce the corn yield by 50% as compared to a wet year like 2009. The simulation results show that irrigation can play a key role in halting crop losses due to drought and in sustaining high yields of up to 20 t/ha. Nevertheless, the water-food-energy relationship shows that significant investments on water and energy are required to limit the negative effects of drought. The multi-criteria optimization problem developed in this study shows that the optimal crop yield does not necessarily correspond to the maximum yield, resulting in potential water and energy savings. (C) 2017 Elsevier Ltd. All rights reserved.

  • 657.
    Zhang, Q.
    et al.
    Academy of China Energy Strategy, China University of Petroleum-Beijing, Changping, Beijing, China.
    Li, Y.
    Academy of China Energy Strategy, China University of Petroleum-Beijing, Changping, Beijing, China.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Wang, G.
    Academy of China Energy Strategy, China University of Petroleum-Beijing, Changping, Beijing, China.
    Chen, S.
    Academy of China Energy Strategy, China University of Petroleum-Beijing, Changping, Beijing, China.
    Study on the Impacts of the LNG Market Reform in China using a SVM based Rolling Horizon Stochastic Game Analysis2017Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, s. 3850-3855Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Natural gas is expected to play a much more important role in China in future decades and its market reform is crucial for its fast market penetration. At present, the main gas fields, pipeline and Liquefied Natural Gas (LNG) infrastructure are monopolized by the state owned big companies, and one of the important market reform policies is to open the LNG import rights to small private companies or traders. Therefore, in the present study, a Game Analysis Model is proposed to analyze and compare the impacts of different market structures on infrastructure deployment and social welfare. Moreover, a Support Vector Machine (SVM) based rolling horizon stochastic method has been adopted in the model to simulate the real LNG price fluctuations. The results indicate that, with the third part access (TPA) entrance into LNG market, the construction of LNG infrastructure will be promoted and more gas will be provided with lower prices, and thus the total social welfare will be improved greatly. 

  • 658.
    Zhang, Q.
    et al.
    China University of Petroleum-Beijing, Beijing, China .
    Mclellan, B. C.
    Kyoto University, Kyoto, Japan.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    An integrated scenario analysis for future zero-carbon energy system2015Ingår i: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114X, Vol. 39, nr 7, s. 993-1010Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An integrated scenario analysis methodology has been proposed for zero-carbon energy system in perspectives of social-economy, environment and technology. By using the methodology, service demands in all sectors were estimated based on social-economic data, and then the best technology and energy mixes were obtained to meet the service demands. The methodology was applied to Japan toward zero-carbon energy system out to the year of 2100, and three different scenarios of nuclear power development are considered in light of the Fukushima accident: (i) no further introduction of nuclear, (ii) fixed portion and (iii) no limit of nuclear. The results show that, zero-carbon energy scenario can be attained in the year 2100 when electricity will supply 75% of total energy consumption, and three power generation scenarios were proposed, 30% renewable and 70% gas-carbon capture and storage (CCS) in Scenario 1, respective one-third nuclear, renewable and gas-CCS in Scenario 2, and 60% nuclear power, 20% renewable and 10% gas-CCS in Scenario 3. Finally, Scenario 2 is rated as the most balanced scenario by putting emphasis on the availability of diversified power source, considering the inter-comparison of the three scenarios from the four aspects of cost, CO<inf>2</inf> emission, risk and diversity. 

  • 659.
    Zhang, Qi
    et al.
    China Univ Petr, Acad Chinese Energy Strategy, Beijing 102249, Peoples R China..
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Mclellan, Benjamin
    Kyoto Univ, Grad Sch Energy Sci, Kyoto 6068501, Japan..
    An Integrated Scenario Analysis for Future Zero-Carbon Energy System2014Ingår i: INTERNATIONAL CONFERENCE ON APPLIED ENERGY, ICAE2014 / [ed] Yan, J Lee, DJ Chou, SK Desideri, U Li, H, ELSEVIER SCIENCE BV , 2014, s. 2801-2804Konferensbidrag (Refereegranskat)
    Abstract [en]

    An integrated scenario analysis methodology has been proposed for zero-carbon energy system in perspectives of social-economy, environment and technology. In the methodology, firstly various service demands were estimated based on social-economic data, and best technology and energy mixes were obtained using the optimization model to meet the service demand. The methodology has been applied to Japan toward zero-carbon energy system out to 2100. The results show that, in the end user side, zero-carbon energy scenario was obtained based on 75% on electricity and three power generation scenarios were proposed, 30% renewable and 70% gas-CCS in scenario 1, respective one third nuclear, renewable and gas-CCS in scenario 2, and 60% nuclear power, 20% renewable and 10% gas-CCS in scenario 3. Finally, the scenario 2 with balanced diversity in nuclear, renewable and gas-CCS was recommended based on comprehensive inter-comparisons. The feasibility of the proposed methodology has been demonstrated. (C) 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

  • 660.
    Zhang, Qi
    et al.
    China University of Petroleum.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Zhu, Lijing
    China University of Petroleum.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lu, Huihui
    China University of Petroleum.
    Wallin, Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Sun, Qie
    Shandong University.
    Factors influencing the economics of public charging infrastructures for EV: A review2018Ingår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 97, s. 500-509Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Growing concerns about energy conservation and the environmental impacts of greenhouse gas emissions over the world have promoted the development of the electric vehicles (EVs) market. However, one of the biggest barriers in the development of the EV market is the lack of the public charging infrastructure. This paper reviews the factors that can directly and indirectly influence the economics of the public charging infrastructure. The knowledge gaps, barriers and opportunities in the development of the charging infrastructure have been identified and analyzed. In order to promote the development of the public charging infrastructure, more research efforts should be paid on the impacts of psychological factors of customers and the technical development of charging infrastructures and EV batteries. The government support has been proved to play an important role, so that how the government policy can be tailored for the development of the charging infrastructure market should receive more attentions. In addition, the charging price as an endogenous factor should be considered more carefully in modelling the charging infrastructure market. New business models are also urgently needed to accelerate the future development of the public charging infrastructure.

  • 661.
    Zhang, Qi
    et al.
    China University of Petroleum, China.
    Li, Zhang
    China University of Petroleum, China.
    Wang, Ge
    China University of Petroleum, China.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Study on the impacts of natural gas supply cost on gas flow and infrastructure deployment in China2016Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 162, s. 1385-1398Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The impacts of gas supply costs on interregional gas flow and gas infrastructure deployment in China are analyzed out to 2035 by using an optimization model in the present study. There two options for gas supply includes successive two-step procedures of imports or domestic productions and transportation by using infrastructures within China. Four possible supply cost scenarios are proposed considering the uncertainties of import price, domestic unconventional gas production cost and geopolitical turbulence in import source countries. The analysis results show that (1). Domestic unconventional gas production cost (wellhead price) and gas import cost (import gas price represented by CIF) are two key points to gas flow and infrastructure deployment in China; (2). The development of unconventional gas is conductive to supply cost reduction and maintenance of infrastructure deployment stability, especially to Southwest and North China regions; (3). When gas import price increases, LNG import will decrease more than pipeline import, and imported LNG will be partly replaced by pipeline import rather than domestic gas in coastal regions; (4). The disruption of gassupply from Myanmar will lead to great changes of gas flow and infrastructure deployment in Southwest China regions; (5). The infrastructures are deployed according to the optimization gas flow in different scenarios.

  • 662.
    Zhang, X.
    et al.
    ABB AB, Corporate Research, Västerås, Sweden.
    Lindberg, T.
    Karlstad University, Sweden.
    Xiong, Ning
    Mälardalens högskola, Akademin för innovation, design och teknik, Inbyggda system.
    Vyatkin, V.
    Luleå University of Technology, Sweden.
    Mousavi, A.
    Luleå University of Technology, Sweden.
    Cooling Energy Consumption Investigation of Data Center IT Room with Vertical Placed Server2017Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, s. 2047-2052Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As energy consumption by cooling data center IT equipment can be over 40% of total energy consumption, efficient cooling for large data centers is essential for reducing operation costs. Modern data centers are complex systems involving IT facilities, power system, cooling and ventilation systems. In our previous work, literature study was made to investigate available data center energy consumption models; and energy consumption models for data center IT room with distributed air flow control were developed. In this paper, the models are further extended and developed to cover the combined distributed air flow control and vertical placed servers in raised floor ventilation system. Simulation of the three types of ventilation systems with Even load, Idle server and Uneven load scenarios showed that significant cooling energy consumed by a traditional ventilation system can be saved by applying the proposed new concept and method. 

  • 663.
    Zhang, X.
    et al.
    ABB AB, Corporate Research, Vasteras, Sweden.
    Yan, J.
    Vattenfall AB, Stockholm, Sweden.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Chekani, S.
    Royal Institute of Technology, Stockholm, Sweden .
    Liu, L.
    Royal Institute of Technology, Stockholm, Sweden .
    Energy saving for biogas production and upgrading - Thermal integration2014Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 61, s. 121-125Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal integration of anaerobic digestion (AD) biogas production with amine based biogas upgrading has been studied for improving the overall thermal efficiencies of the two systems. The thermal characteristics have been investigated for typical AD raw biogas generation and MEA absorption biogas upgrading. The investigation provides a basic understanding of energy saving for both industrial scale biogas production and upgrading processes. The thermal integration is carried out based on the thermal characteristics of the two systems by well-defined case studies, which take the following factors into account such as important thermal conditions of sub-systems, material and energy balances, the efficiencies of heat exchange and heat transfer, necessary integration optimization and ambient conditions. The results show that the thermal integration is achievable with very positive effects for overall energy efficiency and water usage.

  • 664.
    Zhang, Xiaojing
    et al.
    ABB AB, Corp Res, Västerås, Sweden.
    Yan, Jinying
    Vattenfall AB, Stockholm, Sweden.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Chekani, Shabnam
    Royal Inst Technol,Stockholm, Sweden.
    Liu, Loncheng
    Royal Inst Technol,Stockholm, Sweden.
    Investigation of thermal integration between biogas production and upgrading2015Ingår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 102, s. 131-139Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Thermal integration of anaerobic digestion (AD) biogas production with amine-based chemical absorption biogas upgrading has been studied to improve the overall efficiency of the intergraded system. The thermal characteristics have been investigated for industrial AD raw biogas production and amine-based chemical absorption biogas upgrading. The investigation provides a basic understanding for the possibilities of energy saving through thermal integration. The thermal integration is carried out through well-defined cases based on the thermal characteristics of the biogas production and the biogas upgrading. The following factors are taken into account in the case study: thermal conditions of sub-systems, material and energy balances, cost issues and main benefits. The potential of heat recovery has been evaluated to utilise the waste heat from amine-based upgrading process for the use in the AD biogas production. The results show that the thermal integration has positive effects on improving the overall energy efficiency of the integrated biogas plant. Cost analysis shows that the thermal integration is economically feasible. 

  • 665.
    Zhang, X.X.
    et al.
    Beijing Forestry University, China.
    Liu, J.G.
    South University of Science & Technology of China (SUSTC), China.
    Tang, Y.
    South University of Science & Technology of China, China.
    Zhao, X.
    Hohai University, China.
    Yang, H.
    University of Basel, Suisse.
    Gerbens-Leenes, P.W.
    University of Groningen, Netherlands.
    Van Vliet, M.T.H
    Wageningen University & Research, Netherlands.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    China's coal-fired power plants impose pressure on water resources2017Ingår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 161, s. 1171-1179Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Coal is the dominant fuel for electricity generation around the world. This type of electricity generation uses large amounts of water, increasing pressure on water resources. This calls for an in-depth investigation in the water-energy nexus of coal-fired electricity generation. In China, coal-fired power plants play an important role in the energy supply. Here we assessed water consumption of coal-fired power plants (CPPs) in China using four cooling technologies: closed-cycle cooling, once-through cooling, air cooling, and seawater cooling. The results show that water consumption of CPPs was 3.5 km(3), accounting for 11% of total industrial water consumption in China. Eighty-four percent of this water consumption was from plants with closed-cycle cooling. China's average water intensity of CPPs was 1.15 l/kWh, while the intensity for closed-cycle cooling was 3-10 times higher than that for other cooling technologies. About 75% of water consumption of CPPs was from regions with absolute or chronic water scarcity. The results imply that the development of CPPs needs to explicitly consider their impacts on regional water resources. 

  • 666.
    Zhang, Y.
    et al.
    KTH Royal Institute of Technology, Sweden.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lundblad, A.
    KTH Royal Institute of Technology, Sweden.
    Wang, L.
    Chongqing University, Chongqing, China.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH Royal Institute of Technology, Swed.
    The Influence of Photovoltaic Models and Battery Models in System Simulation and Optimization2017Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 105, s. 1184-1191Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Selecting accurate and robust models is important for simulation and optimization of a clean energy system. This paper compares two photovoltaic (PV) models and two battery models in an open-source code, Opti-CE. The PV models are single diode model and its simplified model. The battery models are Improved Shepherd model and energy balance model. The models are compared from a perspective of overall system simulation and optimization in particular on both accuracy and computational time. The results indicate that simplified PV model causes 0.86% normalized root mean square error (nRMSE) compared with the single diode model, while decreases the simulation time from more than 800s to less than 0.01s. The energy balance battery model reduces simulation time from more than 5s to less than 0.03s. The energy balance model tends to underestimate the battery State of Charge (SOC) compared with the Improved Shepherd model. However, the error is not accumulative during the simulation. Compared to the Pareto front with single diode model and Improved Shepherd model, the simplified PV model increases the Pareto front values and result in both higher Self Sufficiency Ratio (SSR) and Net Present Value (NPV), while the energy balance battery model decreases the part of Pareto front, where individuals have low NPV. 

  • 667.
    Zhang, Y.
    et al.
    KTH-Royal Institute of Technology, Stockholm, Sweden.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH-Royal Institute of Technology, Stockholm, Sweden.
    Yang, Ying
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Stridh, Bengt
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lundblad, A.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. RISE Research Institutes of Sweden, Borås, Sweden.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH-Royal Institute of Technology, Stockholm, Sweden.
    Energy flexibility from the consumer: Integrating local electricity and heat supplies in a building2018Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 223, s. 430-442Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The increasing penetration level of renewable energy requires more flexibility measures to be implemented in future energy systems. Integrating an energy consumer’s local energy supplies connects multiple energy networks (i.e., the electrical grid, the district heating network, and gas network) in a decentralized way. Such integration enhances the flexibility of energy systems. In this work, a Swedish office building is investigated as a case study. Different components, including heat pump, electrical heater, battery and hot water storage tank are integrated into the electricity and heat supply system of the building. Special focus is placed on the flexibility that the studied building can provide to the electrical grid (i.e., the building modulates the electricity consumption in response to the grid operator’s requirements). The flexibility is described by two metrics including the flexibility hours and the flexibility energy. Optimization of the component capacities and the operation profiles is carried out by using Mixed Integer Linear Programming (MILP). The results show that the system fully relies on electricity for the heat demand when not considering the flexibility requirements of the electrical grid. This suggests that district heating is economically unfavorable compared with using electricity for the heat demand in the studied case. However, when flexibility requirements are added, the system turns to the district heating network for part of the heat demand. The system provides great flexibility to the electrical grid through such integration. The flexibility hours can be over 5200 h in a year, and the flexibility energy reaches more than 15.7 MWh (36% of the yearly electricity consumption). The yearly operation cost of the system slightly increases from 62,273 to 65,178 SEK when the flexibility hours increase from 304 to 5209 h. The results revealed that flexibility can be provided from the district heating network to the electrical grid via the building.

  • 668.
    Zhang, Y.
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Lundblad, A.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH Royal Institute of Technology, Stockholm, Sweden.
    Comparative Study of Battery Storage and Hydrogen Storage to Increase Photovoltaic Self-sufficiency in a Residential Building of Sweden2016Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 103, s. 268-273Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Photovoltaic (PV) is promising to supply power for residential buildings. Battery is the most widely employed storage method to mitigate the intermittence of PV and to overcome the mismatch between production and load. Hydrogen storage is another promising method that it is suitable for long-term storage. This study focuses on the comparison of self-sufficiency ratio and cost performance between battery storage and hydrogen storage for a residential building in Sweden. The results show that battery storage is superior to the hydrogen storage in the studied case. Sensitivity study of the component cost within the hydrogen storage system is also carried out. Electrolyzer cost is the most sensitive factor for improving system performance. A hybrid battery and hydrogen storage system, which can harness the advantages of both battery and hydrogen storages, is proposed in the last place.

  • 669.
    Zhang, Y.
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Lundblad, Anders
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH Royal Institute of Technology, Stockholm, Sweden.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Benavente, F.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH Royal Institute of Technology, Stockholm, Sweden.
    Battery sizing and rule-based operation of grid-connected photovoltaic-battery system: A case study in Sweden2017Ingår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 133, s. 249-263Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The optimal components design for grid-connected photovoltaic-battery systems should be determined with consideration of system operation. This study proposes a method to simultaneously optimize the battery capacity and rule-based operation strategy. The investigated photovoltaic-battery system is modeled using single diode photovoltaic model and Improved Shepherd battery model. Three rule-based operation strategies—including the conventional operation strategy, the dynamic price load shifting strategy, and the hybrid operation strategy—are designed and evaluated. The rule-based operation strategies introduce different operation parameters to run the system operation. multi-objective Genetic Algorithm is employed to optimize the decisional variables, including battery capacity and operation parameters, towards maximizing the system's Self Sufficiency Ratio and Net Present Value. The results indicate that employing battery with the conventional operation strategy is not profitable, although it increases Self Sufficiency Ratio. The dynamic price load shifting strategy has similar performance with the conventional operation strategy because the electricity price variation is not large enough. The proposed hybrid operation strategy outperforms other investigated strategies. When the battery capacity is lower than 72 kW h, Self Sufficiency Ratio and Net Present Value increase simultaneously with the battery capacity.

  • 670.
    Zhang, Y.
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Lundblad, Anders
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH Royal Institute of Technology, Stockholm, Sweden.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH Royal Institute of Technology, Stockholm, Sweden.
    Employing battery storage to increase photovoltaic self-sufficiency in a residential building of Sweden2016Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 88, s. 455-461Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Photovoltaic (PV) or hybrid PV-battery systems are promising to supply power for residential buildings. In this study, the load profile of a multi apartment building in Gothenburg and the PV production profile under local weather conditions are compared and analyzed. Three different types of batteries, including lead acid, NaNiCl (Sodium-Nickel-Chloride) and Lithium ion, are studied in combination with the PV systems. It is found that Lithium ion battery system is superior in achieving higher Self-Sufficiency Ratio (SSR) with the same Life Cycle Cost (LCC). Achieving high SSR with the hybrid PV-battery system is unrealistic because of the seasonal mismatch between the load and electricity production profile. The capacity match between the PV and battery to maximize SSR was investigated, showing different trends under system LCC range of 0.1-40 Million SEK (1SEK≈0.12USD). The system LCC should be lower than 10.6 Million SEK (at the SSR of 36%) in order to keep the payback time positive. 

  • 671.
    Zhang, Yang
    et al.
    KTH Royal Inst Technol, Sweden.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Anders, Lundblad
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH Royal Inst Technol, Sweden.
    Comparative study of hydrogen storage and battery storage in grid connected photovoltaic system: Storage sizing and rule-based operation2017Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 201, s. 397-411Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The paper studies grid-connected photovoltaic (PV)-hydrogen/battery systems. The storage component capacities and the rule-based operation strategy parameters are simultaneously optimized by the Genetic Algorithm. Three operation strategies for the hydrogen storage, namely conventional operation strategy, peak shaving strategy and hybrid operation strategy, are compared under two scenarios based on the pessimistic and optimistic costs. The results indicate that the hybrid operation strategy, which combines the conventional operation strategy and the peak shaving strategy, is advantageous in achieving higher Net Present Value (NPV) and Self Sufficiency Ratio (SSR). Hydrogen storage is further compared with battery storage. Under the pessimistic cost scenario, hydrogen storage results in poorer performance in both SSR and NPV. While under the optimistic cost scenario, hydrogen storage achieves higher NPV. Moreover, when taking into account the grid power fluctuation, hydrogen storage achieves better performance in all three optimization objectives, which are NPV, SSR and GI (Grid Indicator). 

  • 672. Zhang, Yang
    et al.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Anders, Lundblad
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Zhang, Chi
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. KTH, Sweden.
    Building Energy System: From System Planning To Operation2018Konferensbidrag (Refereegranskat)
  • 673.
    Zhang, Yang
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yang, Ying
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lundblad, Anders
    Division Safety and Transport/Electronics, RISE Research Institutes of Sweden, SE-50462 Borås, Sweden.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Energy Flexibility through the Integrated Energy Supply System in Buildings: A Case Study in Sweden2018Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 145, s. 564-569Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The increasing penetration level of renewable energies requires more flexibility measures at the consumption side. Flexible energy prices have been placed by energy providers to promote flexibility measures from energy users. However, because of the current energy supply system in buildings, these flexible energy prices haven’t been fully taken advantage of. This study focuses on the integrated energy supply system in buildings. A Swedish office building is used as the case study. The integrated energy supply system is built by installing new components, including battery, heat pump and electrical heater, and hot water tank. Mixed Integer Linear Programming (MILP) problems are solved to determine the optimal component capacities and operation profiles. The results indicate that all the studied system configurations achieve lower net present cost (NPC) than the current system. It suggests that the integrated energy supply system can take advantage of the flexible energy prices and lower the overall energy cost in the building. Among the studied configurations, the combination of air source heat pump (ASHP) and electrical heater (EH) has the lowest investment cost. This combination also has the lowest NPC except in the scenario with low borehole cost.

  • 674.
    Zhanga, C.
    et al.
    Royal Institute of Technology, Stockholm, Sweden.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Business model innovation on the photovoltaic water pumping systems for grassland and farmland conservation in China2014Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 61, s. 1483-1486Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Penetration of the renewable market of Photovoltaic PV technologies calls for the extension of the additional values generated from the technology including climate and social co-benefits as radical innovations in a new business model. Compared with existing PV business models, this paper extends the value proposition into operation system and customer segmentation, investigated by a pilot demonstration of PV water pumping (PVWP) systems for the conservation of grassland and farmland in China. The paper suggests that the integrated PVWP systems can combine the implementation of technology with environmental co-benefits, agricultural products by developing an interactive interface to link a social network. This can further disseminate benefits to stimulate the active participations of investments from individuals and corporations. Discounted cash flow (DCF) model and net present value (NPV) evaluations have been conducted on the traditional PV roof, PVWP pilot and PVWP scale up scenarios. The results show that the scenario of integrated PVWP system with social network products can significantly improve the payback period (PP) and increase internal rate of return (IRR). Based on the PVWP pilots and relevant industrial environments, the results in this paper provide how the innovative PV business model innovation can improve the present practices and policies on PV technologies implementation.

  • 675.
    Zhao, R.
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Liu, L.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Zhao, L.
    Ministry of Education of China, Tianjin, China.
    Deng, S.
    Ministry of Education of China, Tianjin, China.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Thermodynamic analysis on carbon dioxide capture by Electric Swing Adsorption (ESA) technology2018Ingår i: Journal of CO2 Utilization, ISSN 2212-9820, E-ISSN 2212-9839, Vol. 26, s. 388-396Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study explores the impacts of materials, such as adsorbents and electrodes, on the energy efficiency of a 4-step ESA cycle for CO2 capture. Three types of adsorbents including activated carbon honeycomb monolith (ACHM) and two hybrid adsorbents are compared, and two kinds of electrodes such as aluminum and brass are combined for comparative analysis. Process description of ESA cycle, including feed, electrification, electrification with purge and cooling, is presented via the adsorption isotherm diagram. By the theory of thermodynamic carbon pump, sensitivity analysis of cycle parameters is evaluated in terms of the second-law efficiency (Eff2nd) and the electrical heating efficiency (Effele). The results show that Eff2nd of the employed adsorbents is in the range of 1.17%-6.15%, and Effele of the selected electrodes is between 27.46% and 60.91%. Among the three adsorbents, Eff2nd of ACHM is the lowest one compared to the others. Similarly, Effele of the combination with brass is superior to that of the groups with aluminum. However, the actual efficiency of ESA cycle is the production of both Eff2nd and Effele, which is approximately 1.03%-3.66%. Typical measures are proposed to reduce the heat loss of the adsorbents and electrodes as well for future work. 

  • 676.
    Zhao, R.
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Liu, L.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Zhao, L.
    Ministry of Education of China, Tianjin, China.
    Deng, S.
    Ministry of Education of China, Tianjin, China.
    Li, S.
    Ministry of Education of China, Tianjin, China.
    Zhang, Y.
    Ministry of Education of China, Tianjin, China.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Thermodynamic exploration of temperature vacuum swing adsorption for direct air capture of carbon dioxide in buildings2019Ingår i: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 183, s. 418-426Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Abrupt climate change such as the loss of Arctic sea-ice area urgently needs negative emissions technologies. The potential application of direct air capture of carbon dioxide from indoor air and outdoor air in closed buildings or crowded places has been discussed in this paper. From the aspects of carbon reduction and indoor comfort, the ventilation system integrating a capture device is of great value in practical use. For ultra-dilute carbon dioxide sources, many traditional separation processes have no cost advantages, but adsorption technologies such as temperature vacuum swing adsorption is one of suitable methods. Thermodynamic exploration has been investigated regarding minimum separation work and second-law efficiency at various concentrations in the air. The influence of concentration, adsorption temperature, desorption temperature and desorption pressure on the energy efficiency has also been evaluated. Results show that the minimum separation work for the level of 400 ppm is approximately 20 kJ/mol. The optimal second-law efficiencies are 44.57%, 37.55% and 31.60%, respectively for 3000 ppm, 2000 ppm and 1000 ppm. It means that a high energy-efficiency capture device in buildings merits attention in the exploration of the possibility of approaching negative carbon buildings. 

  • 677.
    Zhao, R.
    et al.
    Ministry of Education of China, Tianjin, China.
    Zhao, L.
    Ministry of Education of China, Tianjin, China.
    Wang, S.
    Tianjin University, Tianjin, China.
    Deng, S.
    Ministry of Education of China, Tianjin, China.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yu, Z.
    University of Stavanger, Stavanger, Norway.
    Solar-assisted pressure-temperature swing adsorption for CO2 capture: Effect of adsorbent materials2018Ingår i: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 185, s. 494-504Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Because of the ability to utilize the low-grade solar thermal energy for regeneration, a CO2 capture system characterized by solar-assisted pressure temperature swing adsorption (SOL-PTSA) is studied on the effects of adsorbent materials. A detailed cycle description is firstly presented within the diagram of adsorption isotherm for the energy-efficiency analysis. Typical adsorbent materials, including zeolites and chemical adsorbent, are assessed in terms of sensible heat and latent heat, etc. Then, the energy consumption and the second-law efficiency, which can be considered as lumped indicators from such material parameters, are chosen as performance indicators as well. The influence of separation temperature, desorption temperature, CO2 concentration and CO2 adsorption pressure on system performance are finally obtained. For the chosen three adsorbent materials, the energy consumption of SOL-PTSA system is at the range of 25.96–87.76 kJ/mol, and the corresponding second-law efficiencies are at the range of 9.18–26.89%. The effect of adsorbent materials on the energy-efficiency of SOL-PTSA system mainly depends on specific heat, CO2 working capacity and cycle design. In addition, the integration options of solar energy into PTSA technology are also discussed from the standpoint of the utilization of solar grade heat due to two energy loads required for PTSA's operation.

  • 678.
    Zhu, C.
    et al.
    Building Energy Research Center, Department of Building Science, Tsinghua University, Beijing, China; Oak Ridge National Laboratory, Building Equipment Research, Energy & Transportation Science Division, Oak Ridge, United States.
    Gluesenkamp, K. R.
    Oak Ridge National Laboratory, Building Equipment Research, Energy & Transportation Science Division, Oak Ridge, United States.
    Yang, Z.
    Lyle School of Civil Engineering, Purdue University, West Lafayette, United States.
    Blackman, Corey
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. SaltX Technology AB, Stockholm, Sweden; Dalarna University, Borlänge, Sweden.
    Unified thermodynamic model to calculate COP of diverse sorption heat pump cycles: Adsorption, absorption, resorption, and multistep crystalline reactions2019Ingår i: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 99, s. 382-392Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A straightforward thermodynamic model is developed in this work to analyze the efficiency limit of diverse sorption systems. A method is presented to quantify the dead thermal mass of heat exchangers. Solid and liquid sorbents based on chemisorption or physical adsorption are accommodated. Four possible single-effect configurations are considered: basic absorption or adsorption (separate desorber, absorber, condenser, and evaporator); separate condenser/evaporator (two identical sorbent-containing reactors with a condenser and a separate direct expansion evaporator); combined condenser/evaporator (one salt-containing reactor with a combined condenser/evaporator module); and resorption (two sorbent-containing reactors, each with a different sorbent). The analytical model was verified against an empirical heat and mass transfer model derived from component experimental results. It was then used to evaluate and determine the optimal design for an ammoniate salt-based solid/gas sorption heat pump for a space heating application. The effects on system performance were evaluated with respect to different working pairs, dead thermal mass factors, and system operating temperatures. The effect of reactor dead mass as well as heat recovery on system performance was also studied for each configuration. Based on the analysis in this work, an ammonia resorption cycle using LiCl/NaBr as the working pair was found to be the most suitable single-effect cycle for space heating applications. The maximum cycle heating coefficient of performance for the design conditions was 1.50 with 50% heat recovery and 1.34 without heat recovery. 

  • 679.
    Zhu, K.
    et al.
    Tianjin University of Commerce, China.
    Cui, Z.
    Tianjin University of Commerce, China.
    Wang, Y.
    Tianjin University of Commerce, China.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Tianjin University of Commerce, China.
    Zhang, X.
    ABB Corporate Research, Sweden.
    Franke, C.
    Estimating the maximum energy-saving potential based on IT load and IT load shifting2017Ingår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 138, s. 902-909Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cooling system consumes more than 35% of total electricity in most data centers. The provided cooling normally exceeds the actual demand of IT equipment in order to assure the safe operation, resulting in a low energy efficiency. In this paper, a novel method based on demand response was proposed to precisely control the cooling supply, and the energy saving potential was assessed systematically. Compared to the reference case, in which the cooling demand is determined by assuming all of servers are in the running status, when the cooling demand was determined based on the measured dynamic IT load at room level, row level, rack level and server level, it can be reduced by 7.9%, 14.2%, 15.6% and 17.9% respectively for the random selected 48 h. In addition, IT load shifting also has a big potential to save energy, as it can make the cooling system working at a higher energy efficiency, which varies with loads. Two cases were studied: even distribution of IT load and optimized IT load shifting. Compared to the best case that determines the cooling demand according to the IT load at server level, they can further reduce the electricity consumption of cooling systems by 0.9%, and 1.2%. 

  • 680.
    Zhu, K.
    et al.
    Tianjin University of Commerce, Tianjin, China.
    Li, X.
    Tianjin University of Commerce, Tianjin, China.
    Wang, Y.
    Tianjin University of Commerce, Tianjin, China.
    Chen, X.
    Tianjin University of Commerce, Tianjin, China.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Dynamic performance of loop heat pipes for cooling of electronics2017Ingår i: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 142, s. 4163-4168Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With the performance improvement of electronics, the recent trends in electronic industry pose a big challenge on heat dissipation. Conventional methods, i.e. air cooling, may not be able to handle the fast increasing heat flux. Using heat pipes, which have numerous advantages such as high heat transfer coefficient, non-movable components, longer transport distance, and compact structures, emerges to be one competitive option for electronics cooling. Based on the node analysis method and the conservation of energy and mass, this work develops a mathematic model to simulate the operation of heat pipes. After it is validated against experimental data, it is further applied to evaluate the dynamic performance of using a heat pipe for electronics cooling. Results show that the operation temperature of evaporator ranges from 47.5°C to73.1°C, which implies that the heat pipe can effectively cool down the CPU at different running status. The charging ratio of working fluid is identified as a key parameter and exists an optimal value. When keeping the charging ratio constant, a larger evaporator area can achieve a lower operating temperature. 

  • 681.
    Zhu, K.
    et al.
    Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin, China.
    Li, Xueqiang
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. School of Environmental Science and Engineering, Tianjin University, Tianjin, China.
    Campana, Pietro Elia
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Yan, Jinyue
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. School of Chemical Science & Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Techno-economic feasibility of integrating energy storage systems in refrigerated warehouses2018Ingår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 216, s. 348-357Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work evaluates the techno-economic feasibility of integrating the cold energy storage system and the electrical energy storage system in a refrigerated warehouse for shifting the power consumption. A dynamic model has been developed in TRNSYS®. Based on the dynamic simulation, the performance and benefit of those two types of energy storage systems were compared. Results showed that, the integration of a cold energy storage can reduce the electricity consumption and operational cost by 4.3% and 20.5%, respectively. Even though integrating a battery system will increase the electricity consumption by 3.9%, it can reduce the operational cost by 18.7%. The capacity of the energy storage systems, the battery price and the peak electricity price had been identified as key parameters affecting the performance and benefit. To achieve a payback period less than 3 year, for the integration of a cold energy storage system, the peak electricity price should be increased by 25% from the current level, while for the integration of a battery system, the battery price should drop to 0.7 kRMB/kWh.

  • 682.
    Zhu, K.
    et al.
    Key Laboratory of Refrigeration Technology of Tianjin, Tianjin University of Commerce, Tianjin, China.
    Li, Xueqiang
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Key Laboratory of Refrigeration Technology of Tianjin, Tianjin University of Commerce, Tianjin, China.
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Key Laboratory of Refrigeration Technology of Tianjin, Tianjin University of Commerce, Tianjin, China.
    Chen, X.
    Key Laboratory of Refrigeration Technology of Tianjin, Tianjin University of Commerce, Tianjin, China.
    Wang, Y.
    Key Laboratory of Refrigeration Technology of Tianjin, Tianjin University of Commerce, Tianjin, China.
    Experimental and theoretical study of a novel loop heat pipe2018Ingår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 130, s. 354-362Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to reduce the heat leakage from the evaporator and achieve a longer transport distance, a new type of loop heat pipe (LHP) has been proposed based on a hypothesis that the circulation of working fluids is driven by not only the capillary head, but also the pressure head due to evaporation. In the evaporator, the wick is separated from the heating surface by a chamber, which can effectively use the pressure head generated by evaporation. In this work, a prototype of such a LHP was studied experimentally and theoretically. In order to understand the mechanism of operation, a new mathematical model was established. Comparing the simulated results with the experimental data about the operation temperature, a good agreement was observed that the average absolute deviation and the maximum absolute deviation were in ranges of 0.67–1.21 °C and −1.3 to 6 °C, respectively. With the validated model, the two driving forces were investigated. Results showed that the ratio of the pressure head of evaporation to the capillary head was in a range of 59–54% corresponding to heating powers from 30 W to 110 W. It confirms that the pressure head due to evaporation plays an important role in the circulation of working fluids.

  • 683.
    Zhu, Kai
    et al.
    Tianjin University of Commerce, Tianjin, China .
    Chen, Xiaoqing
    Tianjin University of Commerce, Tianjin, China .
    Dai, Baomin
    Tianjin University of Commerce, Tianjin, China .
    Zheng, Mingzhu
    Tianjin University of Commerce, Tianjin, China .
    Wang, Yabo
    Tianjin University of Commerce, Tianjin, China .
    Li, Hailong
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. Tianjin University of Commerce, Tianjin, China .
    Operation characteristics of a new-type loop heat pipe (LHP) with wick separated from heating surface in the evaporator2017Ingår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 123, s. 1034-1041Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The loop heat pipe (LHP) has been widely used for cooling devices with high heat flux. In addition to the capillary pumping force, the pressure head due to evaporation has been assumed to play an important role in the circulation of working fluid. Based on such a hypothesis, a new LHP is designed, in which the wick is separated from the heating surface in the evaporator. Experiments show that such a LHP can start up successfully and reach steady operation, which indirectly verified the hypothesis. The influences of heating power, height of steam chamber, pore radius and porosity of wick are comprehensively investigated. The results show that the start-up time of the new-designed LHP is shorter and the temperature fluctuation is smaller at higher heating power. The steam chamber height has clear impacts on the start-up time and the thermal resistance. The start-up time with the steam chamber height of 2 mm is shorter than that of 3 mm, but the thermal resistance is relatively higher. Moreover, a larger pore radius and a higher porosity of the wick can lead to a shorter start-up time and a smaller thermal resistance of the new LHP.

  • 684.
    Zimmerman, Nathan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindberg, Carl-Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB Force Measurement, Västerås, Sweden.
    Achieving lower district heating network temperatures using feed-forward MPC2019Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, nr 15, artikel-id 2465Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The focus of this work is to present the feasibility of lowering the supply and return temperatures of district heating networks in order to achieve energy savings through the implementation of feed-forward model predictive control. The current level of district heating technology dictates a need for higher supply temperatures, which is not the case when considering the future outlook. In part, this can be attributed to the fact that current networks are being controlled by operator experience and outdoor temperatures. The prospects of reducing network temperatures can be evaluated by developing a dynamic model of the process which can then be used for control purposes. Two scenarios are presented in this work, to not only evaluate a controller's performance in supplying lower network temperatures, but to also assess the boundaries of the return temperature. In Scenario 1, the historical load is used as a feed-forward signal to the controller, and in Scenario 2, a load prediction model is used as the feed-forward signal. The findings for both scenarios suggest that the new control approach can lead to a load reduction of 12.5% and 13.7% respectively for the heat being supplied to the network. With the inclusion of predictions with increased accuracy on end-user demand and feed-back, the return temperature values can be better sustained, and can lead to a decrease in supply temperatures and an increase in energy savings on the production side.

  • 685.
    Zimmerman, Nathan
    et al.
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Kyprianidis, Konstantinos
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi.
    Lindberg, Carl-Fredrik
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, Framtidens energi. ABB Force Measurement, Västerås, Sweden.
    Waste fuel combustion: Dynamic modeling and control2018Ingår i: Processes, ISSN 2227-9717, Vol. 6, nr 11, artikel-id 222Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The focus of this study is to present the adherent transients that accompany the combustion of waste derived fuels. This is accomplished, in large, by developing a dynamic model of the process, which can then be used for control purposes. Traditional control measures typically applied in the heat and power industry, i.e., PI (proportional-integral) controllers, might not be robust enough to handle the the accompanied transients associated with new fuels. Therefore, model predictive control is introduced as a means to achieve better combustion stability under transient conditions. The transient behavior of refuse derived fuel is addressed by developing a dynamic modeling library. Within the library, there are two models. The first is for assessing the performance of the heat exchangers to provide operational assistance for maintenance scheduling. The second model is of a circulating fluidized bed block, which includes combustion and steam (thermal) networks. The library has been validated using data from a 160 MW industrial installation located in Västerås, Sweden. The model can predict, with satisfactory accuracy, the boiler bed and riser temperatures, live steam temperature, and boiler load. This has been achieved by using process sensors for the feed-in streams. Based on this model three different control schemes are presented: a PI control scheme, model predictive control with feedforward, and model predictive control without feedforward. The model predictive control with feedforward has proven to give the best performance as it can maintain stable temperature profiles throughout the process when a measured disturbance is initiated. Furthermore, the implemented control incorporates the introduction of a soft-sensor for measuring the minimum fluidization velocity to maintain a consistent level of fluidization in the boiler for deterring bed material agglomeration.

  • 686.
    Öberg, Filip
    Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling.
    Modellering av Panna 5 Mälarenergi AB: utveckling av en beräkningsmodell med simuleringsverktyget IPSEpro2009Självständigt arbete på avancerad nivå (magisterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Heat and power stations are often in need of optimizations. A simulation model is a tool for findingways to optimize the plant. The scope of this diploma work is to develop a simulation model ofBoiler 5 at Mälarenergi AB. Boiler 5 is a circulated fluidized bed boiler that was taken into service inyear 2001. Among the included parts in the boiler are cyclone, convection part andINTREX-chambers. The software that was used for the simulation was SimTech’s IPSEpro. IPSEprois a heat and mass balance software for steady state calculations. The program comes with a set ofmodules in a library called APP_lib which contains modules such as preaheaters, pump, boiler andturbine stages. The user can however design own modules in the Model Development Kit, since thelibrary code is open source. The development of the simulation model started with an updating of anold model from year 2003. Values provided from Foster Wheeler where then used to make the modelcalculate in a right way. Thereafter some calculations of the super heaters’ heat transfer coefficientswere made. The coefficients were then translated into IPSEpro’s own programming language ModelDescription Language, and were put into the model’s modules. The results were compared with realvalues from the plant’s system. It showed that the calculated values needed more investigations to bemore accurate. The conclusion was that the final model needs more equations to describe the plant in amore realistic way.

  • 687.
    Ševčík, Martin
    Mälardalens högskola, Akademin för ekonomi, samhälle och teknik.
    NEAR-INFRARED SPECTROSCOPY FOR REFUSE DERIVED FUEL: Classification of waste material components using hyperspectral imaging and feasibility study of inorganic chlorine content quantification2019Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This degree project focused on examining new possible application of near-infrared (NIR) spectroscopy for quantitative and qualitative characterization of refuse derived fuel (RDF). Particularly, two possible applications were examined as part of the project. Firstly, use of NIR hyperspectral imaging for classification of common materials present in RDF. The classification was studied on artificial mixtures of materials commonly present in municipal solid waste and RDF. Data from hyperspectral camera was used as an input for machine learning models to train them, validate them, and test them. Three classification machine learning models were used in the project; partial least-square discriminant analysis (PLS-DA), support vector machine (SVM), and radial basis neural network (RBNN). Best results for classifying the materials into 11 distinct classes were reached for SVM (accuracy 94%), even though its high computational cost makes it not very suitable for real-time deployment. Second best result was reached for RBNN (91%) and the lowest accuracy was recorded for PLS-DA model (88%). On the other hand, the PLS-DA model was the fastest, being 10 times faster than the RBNN and 100 times faster than the SVM. NIR spectroscopy was concluded as a suitable method for identification of most common materials in RDF mix, except for incombustible materials like glass, metals, or ceramics. The second part of the project uncovered a potential in using NIR spectroscopy for identification of inorganic chlorine content in RDF. Experiments were performed on samples of textile impregnated with a water solution of kitchen salt representing NaCl as inorganic chlorine source. Results showed that contents of 0.2-1 wt.% of salt can be identified in absorbance spectra of the samples. Limitation appeared to be water content of the examined samples, as with too large amount of water in the sample, the influence of salt on NIR absorbance spectrum of water was too small to be recognized.

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