mdh.sePublications
Change search
Refine search result
1 - 9 of 9
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Li, Hailong
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Wilhelmsen, Øivind
    SINTEF Energy Research.
    Lv, Yuexia
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Wang, Weilong
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Viscosities, thermal conductivities and diffusion coefficients of CO2 mixtures:Review of experimental data and theoretical models2011In: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 5, no 5, p. 1119-1139Article in journal (Refereed)
    Abstract [en]

    Accurate experimental data on the thermo-physical properties of CO2-mixtures are pre-requisites fordevelopment of more accurate models and hence, more precise design of CO2 capture and storage (CCS)processes. A literature survey was conducted on both the available experimental data and the theoreticalmodels associated with the transport properties of CO2-mixtures within the operation windows ofCCS. Gaps were identified between the available knowledge and requirements of the system design andoperation. For the experimental gas-phase measurements, there are no available data about any transportproperties of CO2/H2S, CO2/COS and CO2/NH3; and except for CO2/H2O(/NaCl) and CO2/amine/H2Omixtures, there are no available measurements regarding the transport properties of any liquid-phasemixtures. In the prediction of gas-phase viscosities using Chapman–Enskog theory, deviations are typically<2% at atmospheric pressure and moderate temperatures. The deviations increase with increasingtemperatures and pressures. Using both the Rigorous Kinetic Theory (RKT) and empirical models in theprediction of gas-phase thermal conductivities, typical deviations are 2.2–9%. Comparison of popularempirical models for estimation of gas-phase diffusion coefficients with newer experimental data forCO2/H2O shows deviations of up to 20%. For many mixtures relevant for CCS, the diffusion coefficientmodels based on the RKT show predictions within the experimental uncertainty. Typical reported deviationsof the CO2/H2O system using empirical models are below 3% for the viscosity and the thermalconductivity and between 5 and 20% for the diffusion coefficients. The research community knows littleabout the effect of other impurities in liquid CO2 than water, and this is an important area to focus infuture work.

  • 2.
    Wang, Weilong
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Mobilized Thermal Energy Storage for Heat Recovery for Distributed Heating2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Conventional energy sources—oil and electricity—dominate the heat supply market. Due to their rising costs and their negative environmental effects on global climate change, it is necessary to develop an alternative heat supply system featuring low cost, high energy efficiency and environment friendliness. At present, it is often challenging to supply heat to detached buildings due to low energy efficiency and high distribution cost. Meanwhile, significant amounts of industrial waste and excess heat are released into the environment without recycling due to the difficulty of matching time and space differences between suppliers and end users. Phase change materials (PCMs), with the advantages of being storable and transportable, offer a solution for delivering that excess heat from industrial plants to detached buildings in sparse, rural areas.

     

    The objective of this thesis is to study PCMs and latent thermal energy storage (LTES) technology, and to develop a mobilized thermal energy storage (M-TES) system that can use industrial waste or excess heat for heat recovery and distribution to areas in need.

     

    Organic PCMs were chosen for study because they are non-toxic and non-corrosive, and they exhibit no phase separation and little sub-cooling when compared to inorganic PCMs. Two major issues including leakage of liquid PCMs and low thermal conductivity. Polyethylene glycol (PEG) was chosen to help analyze the thermal behavior of organic PCMs and PEG-based form-stable composites. To overcome the issue of low thermal conductivity, modified aluminum nitride (AlN) powder was added to the composites. Increased thermal conductivity traded off decreased latent heat. The PEG/EG composite, prepared by mixing the melted PEG into an expanded graphite (EG) matrix showed good thermal performance due to its large enthalpy and high thermal conductivity.

     

    To make a systematic study of the M-TES system, a compact lab-scale system was designed and built. Characteristics of PCM were studied, and the performance of the direct-contact TES container was investigated. A case study using an M-TES system to deliver heat from a combined heat and power (CHP) plant to a small village was conducted. A technical and economic feasibility study was conducted for an integrated heat supply system using the M-TES system. In addition, the options for charging a TES container at a CHP plant were analyzed and compared from the viewpoints of power output, heat output and incomes.

  • 3.
    Wang, Weilong
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Preparation and performance of energy storage materials and application for recovery of industrial waste heat2009Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Due to the rapid increase of energy consumption and the environmental concerns on climate change caused by the fossil fuel combustion, it becomes a big issue on how to use alternative renewable energy resources to replace fossil fuel and to improve energy utilization efficiency. In Sweden, there are plenty of detached buildings without connection with district heating (DH) network, which use oil to supply the hot water for space heating and tap water. One way is to extend the district heating network for supply the heat for the detached houses. However, this will need increased costs for the district heat pipeline which might not be economically variable for the area with less density of population. Another alternative is to apply so called mobilized thermal energy storage (M-TES) to transport heat from, e.g. industrial waste heat, to the end-users of the detached houses. This will enable to keep the detached houses in the same state as a distributed heat system while replacing the fossil fuels for heating demand.

     

    The mechanism of energy storage and release is on the basis of transition of phase change materials (PCMs), which can solve the problem in time and spatial mismatch between the energy supply and consumption. Polyethylene glycol (PEG) as a type of organic PCMs is studied in this licentiate thesis due to its large heat capacity and multi-melting temperatures. As a representative of organic PCMs, PEG also has some disadvantages, like encapsulation needed for preventing leakage and low thermal conductivity. To resolve those, a type of so-called form-stable energy storage materials is prepared by blending PEG with silica gel. Modified aluminium nitride (AlN) powder is then added to enhance the thermal conductivity of materials. Meanwhile, another form-stable energy storage material is prepared by mixing the melted PEG into expanded graphite (EG). The results show that two types of composite materials can keep the form stable during the transition, and AlN powder can enhance the thermal conductivities of energy storage materials.

     

    Based on the knowledge of energy storage technology, M-TES system is designed and combined with the existing heat system in Eskilstuna. The feasibility study of M-TES is carried out through the data collected from CHP plant and end-user in this licentiate thesis. The results show that there are economic and environmental benefits by using M-TES system to supply heat for detached houses.

  • 4.
    Wang, Weilong
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Hu, Yukun
    Royal Institute of Technology, Stockholm, Sweden.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Nyström, Jenny
    Eskilstuna Energi och Miljo AB, Eskilstuna, Sweden.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Combined heat and power plant integrated with mobilized thermal energy storage (M-TES) system2010In: Frontiers of Energy and Power Engineering in China, ISSN 1673-7393, Vol. 4, no 4, p. 469-474Article in journal (Refereed)
    Abstract [en]

    Energy consumption for space heating and hot tap water in residential and service sectors accounts for one third of total energy utilization in Sweden. District heating (DH) has been used for heat supply to areas with high energy demand. However, there are still a lot of detached houses and sparse areas with no connection to a DH network where electrical heating or oil/pellet boilers are used to meet heat demand. Sometimes, extending the existing DH network to those spare areas is not economically feasible because of the small heat demands and the large investment. Mobilized thermal energy storage (M-TES) system is an alternative way to supply heat for detached buildings or sparse areas by using industrial heat. In this paper, integration of a combined heat and power (CHP) plant and an M-TES system is analyzed. The impacts of four options of the integrated system are discussed including the power and heat output in the CHP plant, as well as the performance of M-TES system.

  • 5.
    Wang, Weilong
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Enhanced thermal conductivity and thermal performance of form-stable composite phase change materials by using β-Aluminum nitride2009In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 86, no 7-8, p. 1196-1200Article in journal (Refereed)
    Abstract [en]

    β-Aluminum nitride powder is a promising additive due to its great conductivity value, which can enhance the thermal conductivity of organic phase change materials. In this paper, a high conductivity form-stable phase change material was prepared by blending polyethylene glycol, silica gel, and β-Aluminum nitride powder. The conductivity value of the composite PCMs was determined using the Hotdisk thermal analyzer, which is based on the transient plane source technique. Experiment of heat storage and release performance was carried out to investigate heat efficiencies of TES system. The results showed that thermal conductivity of composite PCMs increased with an increase in β-Aluminum nitride content, but the value of latent heat decreased correspondingly. There was no change on the melting temperature while different ratios of composites. The value of thermal conductivity changed from 0.3847 W m−1 K−1 to 0.7661 W m−1 K−1 with the increase of mass ratio of β-Aluminum nitride from 5% to 30%. The heat storage and release rate of the composite PCMs was higher than that of pure polyethylene glycol.

  • 6.
    Wang, Weilong
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Yan, jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Preparation and thermal properties of polyethylene glycol/expanded graphite blends for energy storage2009In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 86, no 9, p. 1479-1483Article in journal (Refereed)
    Abstract [en]

    Expanded graphite is a promising heat transfer promoter due to its high conductivity, which improves the thermal conductivity of organic phase change materials. Moreover, it can also serve as supporting materials to keep the shape of the blends stable during the phase transition. After various investigation, the results showed that the maximum weight percentage of polyethylene glycol was as high as 90% in this paper without any leakage during the melting period, with the latent heat of 161.2 J g−1 and the melting point of 61.46 °C. It was found that the value of the latent heat was related to the polyethylene glycol portion, increased with the increase in polyethylene glycol content. Moreover, the measured enthalpy of the composite phase change materials was proportional to the mass ratio of the polyethylene glycol component. The melting temperatures were almost the same with different ratios of composites. The conductivity of blends was improved significantly with the high value of 1.324 W m−1 K−1 compared to the pure polyethylene glycol conductivity of 0.2985 W m−1 K−1.

  • 7.
    Wang, Weilong
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Dahlquist, Erik
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Thermal performance of the mobilized thermal energy storage system2011Conference paper (Refereed)
    Abstract [en]

    A direct-contact mobilized thermal energy storage (M-TES) system with high heat density and heat transfer rate has been exploited to transport industrial heat for distributed users. In this paper, a lab-scale experimental setup has been built consisting of a direct-contact thermal energy storage (TES) container, oil/water tank, electrical boiler, oil/water pump and plate heat exchanger. Erythritol was chosen to work as an organic phase change material (PCM) due to its large heat density, suitable melting point (118oC) for industrial heat recovery, and non toxic and corrosive. Heat transfer oil (HTO) served as a heat transfer medium to carry and transfer heat. The theoretical heat capacity of the TES container is 13.1 kWh with 74 kg of Erythritol and 42 kg of HTO. In the charging process, electrical boiler heated HTO first, and then HTO was pumped into the bottom of the TES container to melt Erythritol directly. In the discharging process, heat was transferred to the cooling water through a plate heat exchanger. Results show that, the sub-cooling problem of Erythritol, which was found in the static experiments, was totally solved by dynamic heat exchange between Erythritol and HTO. During the whole process, the two liquid phases (oil and melted Erythritol) were separated clearly due to the big difference of their densities, and meanwhile a foam layer was also observed between the two sectors. In the charging process, the higher the flow rate of HTO, the less the charging time was needed, which resulted in the lower charging heat consumption. In the discharging process, the maximum heat of 10.6 kWh was released with the HTO flow rate of 12.5 l/min, which accounted for 80.9 % of the theoretical heat capacity of the TES container.

  • 8.
    Wang, Weilong
    et al.
    Mälardalen University, School of Sustainable Development of Society and Technology.
    Yan, Jinyue
    Mälardalen University, School of Sustainable Development of Society and Technology. Royal Institute of Technology, Stockholm, Sweden.
    Nyström, Jenny
    Eskilstuna Energi och Miljö AB.
    A new mobilized energy storage system for industrial waste heat recovery for distributed heat supply2009Conference paper (Refereed)
    Abstract [en]

    This paper introduces a new mobilized thermal energy storage (M-TES) for the recovery ofindustrial waste heat for distributed heat supply to the distributed users which have not beenconnected to the district heating network. In the M-TES system, phase-change materials (PCM)are used as the energy storage and carrier to transport the waste heat from the industrial site to theend users by a lorry. A technical feasibility and economic viability of M-TES has been conductedwith the comparison of the district heating system as a reference. Thermal performance and costimpacts by different PCM materials have been analyzed compared, aiming at determining theoptimum operation conditions. A case study is investigated by utilizing the waste heat from acombine heat and power (CHP) plant for the distributed users which are located at over 30kilometers away from the plant. The results show that the M-TES may offer a competitivesolution compared to building or extending the existing district heating network.

  • 9.
    Wang, Weilong
    et al.
    School of Chemical and Energy Engineering, Guangzhou, China.
    Yang, Xiaoxi
    School of Chemical and Energy Engineering, Guangzhou, China.
    Fang, Y.
    School of Chemical and Energy Engineering, Guangzhou, China.
    Ding, J.
    School of Chemical and Energy Engineering, Guangzhou, China.
    Preparation and performance of form-stable polyethylene glycol/silicon dioxide composites as solid–liquid phase change materials2009In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 86, no 2, p. 170-174Article in journal (Refereed)
    Abstract [en]

    This work mainly involved the preparation and characterization of form-stable polyethylene glycol (PEG)/silicon dioxide (SiO2) composite as a novel solid–liquid phase change material (PCM). In this study, the polyethylene glycol/silicon dioxide composites as form-stable, solid–liquid phase change material (PCM) was prepared. In this new material, the polyethylene glycol acts as the latent heat storage material and silicon dioxide serves as the supporting material, which provides structural strength and prevents the leakage of the melted polyethylene glycol. Results indicated that the composite remained solid when the weight percentage of silicon dioxide was higher than 15%. Moreover, the polyethylene glycol was observed to disperse into the network of the solid silicon dioxide by investigation of the structure of the composite PCMs using a scanning electronic microscope (SEM). The properties of the porous materials and phase change materials were characterized using Fourier transformation infrared spectroscope (FTIR). The transition process was observed using polarizing optical microscope (POM) and dynamic thermo mechanic analysis (DMA). The melting temperatures and latent heats of the form-stable PEG/SiO2 composite PCMs were determined using differential scanning calorimeter (DSC).

1 - 9 of 9
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf