du.sePublications
Change search
Refine search result
24252627 1301 - 1342 of 1342
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • 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.
  • 1301.
    Zhang, Xingxing
    et al.
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Xiao, M.
    He, W.
    Qiu, Z.
    Zhao, Xiaoyun
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Heat Pump Technologies and Their Applications in Solar Systems2019In: Advanced Energy Efficiency Technologies for Solar Heating, Cooling and Power Generation / [ed] Xudong Zhao, Xiaoli Ma, Springer, 2019, p. 311-339Chapter in book (Refereed)
    Abstract [en]

    As the well known that global energy demand is on a trend of continuous growth, reducing energy demand and making good use of renewable energy are thought to be the major routes toward low carbon and sustainable future, in particular for the building sector. Compared to traditional gas-fired heating systems, heat pumps have been proved to be an energy-efficient heating technology which can save fossil fuel energy and consequently reduce CO2 emission. However, the most outstanding challenges for the application of heat pumps lie in their high demand for electrical power, and the insufficient heat transfer between the heat source and the refrigerant. To overcome these difficulties, a solar-assisted heat pump has been proposed to tackle these challenges. A solar-assisted heat pump combines a heat pump with a solar collector, enabling the use of solar energy to provide space heating and hot water for buildings. This chapter introduces heat pump technologies and their applications in solar systems. Two types of solar-assisted heat pump, direct and indirect expansion, are illustrated in details. This work has provided the fundamental research and experience for developing a solar heat pump system and contributing to a significant fossil fuel saving and carbon reduction in the global extent.

  • 1302. Zhang, Xingxing
    et al.
    Xu, Peng
    Shen, Jingchun
    Tang, Llewellyn
    Hu, Di
    Xiao, Manxuan
    Wu, Yupeng
    Parametric study of a novel gravity assisted loop heat pipe (GALHP) with composite mesh-screen wick structure2016Conference paper (Refereed)
  • 1303. Zhang, Xingxing
    et al.
    Xu, Ying
    Xu, Jihuan
    A novel modular solar thermal facade2014Patent (Other (popular science, discussion, etc.))
  • 1304. Zhang, Xingxing
    et al.
    Xu, Ying
    Xu, Jihuan
    A novel solar photovoltaic/thermal cogeneration system using the corrugated flat-plate thin-metal sheets2014Patent (Other (popular science, discussion, etc.))
  • 1305. Zhang, Xingxing
    et al.
    Xu, Ying
    Xu, Jihuan
    A novel solar photovoltaic/thermal cogeneration system using the corrugated flat-plate thin-metal sheets2015Patent (Other (popular science, discussion, etc.))
  • 1306. Zhang, Xingxing
    et al.
    Xu, Ying
    Xu, Jihuan
    A novel solar thermal absorber for integration of photovoltaic panels2014Patent (Other (popular science, discussion, etc.))
  • 1307. Zhang, Xingxing
    et al.
    Xu, Ying
    Xu, Jihuan
    A novel thin-conductive solar thermal absorber and flat-plate solar collector2014Patent (Other (popular science, discussion, etc.))
  • 1308.
    Zhang, Xingxing
    et al.
    De Montfort University.
    Zhao, X.
    Xu, J.
    Yu, X.
    Study of the heat transport capacity of a novel gravitational loop heat pipe2013In: International Journal of Low-Carbon Technologies, ISSN 1748-1317, E-ISSN 1748-1325, Vol. 8, no 3, p. 210-223Article in journal (Refereed)
    Abstract [en]

    This article presented a theoretical analysis of the heat transfer limits associated with a gravitational loop heat pipe (LHP), which involves the utilization of an innovative liquid feeding/distributing and vapour/liquid-separating structure. The mathematical equations governing the heat transport capacity were applied to simulate several commonly known heat transfer limits of the pipe, namely, viscous, sonic, entrainment, capillary, boiling and liquid filling mass limits. This will allow the determination of the actual figure of the limitation and analyses of the factors effecting the limits, including the loop operational temperature, wick type, evaporator diameter/length, evaporator inclination angle, vapour column diameter in the three-way fitting, liquid filling mass and evaporator-to-condenser height difference. During the study, the heat-transfer limits associated with the three-way fitting for liquid feeding/distribution and vapour/liquid separation were given particular attention. The results derived from the analytical model indicated that the compound screen mesh wick can achieve better thermal performance over the sintered powder and open rectangular groove wicks. It was also found that the heat transport capacity of such LHP operation is positively proportional to the operational temperature, evaporator diameter, evaporator inclination angle, vapour column diameter within the three-way fitting, liquid filling mass and evaporator-to-condenser height difference, and in a reciprocal order to the evaporator length. With the specified loop configuration and operational conditions, the LHP can achieve a high heat transport capacity of around 900 W. Overall, the work presented in this article provided an approach to determine the heat transfer limitations for such a specific LHP operation that will be of practical use for the associated system design and performance evaluation. 

  • 1309. Zhang, Xingxing
    et al.
    Zhao, Xudong
    Characterization of a Hybrid Photovoltaic/ Heat-Pump Water Heating System2012In: Proceeding 5th International Forum on Energy Saving and Environmental Protection Technologies for Air-Conditioning and Refrigeration, Beijing, China, 13th -14th June, 2012, 2012Conference paper (Refereed)
  • 1310. Zhang, Xingxing
    et al.
    Zhao, Xudong
    Shen, Jingchun
    Case study of a pilot-scale solar Photovoltaic/thermal (PV/T) system and its opportunities for future development2013In: Proceeding Portugal Sustainable Building 2013 (SB13) conference, Lisbon, Portugal, 30th Oct - 1st November, 2013, 2013Conference paper (Refereed)
  • 1311. Zhang, Xingxing
    et al.
    Zhao, Xudong
    Shen, Jingchun
    Feasibility Study of a Solar Photovoltaic/Loop-Heat-Pipe Heat Pump Water Heating System2013In: Proceeding 13th International Conference on Sustainable Energy Technologies, Hong Kong, 28th -30th August 2013, 2013Conference paper (Refereed)
  • 1312.
    Zhang, Xingxing
    et al.
    University of Hull.
    Zhao, Xudong
    Shen, Jingchun
    Hu, Xi
    Liu, Xuezhi
    Xu, Jihuan
    Design, fabrication and experimental study of a solar photovoltaic/loop-heat-pipe based heat pump system2013In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 97, p. 551-568Article in journal (Refereed)
    Abstract [en]

    In this paper, a novel solar photovoltaic/loop-heat-pipe (PV/LHP) module-based heat pump system was designed and fabricated for both electricity and hot water generation. A coated aluminium-alloy (Al-alloy) sheet was applied as the baseboard of PV cells for enhanced heat dissipation to the surroundings, which was characterised by a series of laboratory-controlled conditions over the conventional Tedlar–Polyester–Tedlar (TPT) baseboard. The whole prototype system was subsequently evaluated in outdoor weather conditions throughout a consecutive period for about one week. Impact of several external parameters to the PV panel with different baseboards was discussed and the results showed that weaker incident radiation, lower air temperature, higher wind speed, and ground mounting solution, were propitious to the PV electrical performance. Given the specific indoor testing conditions, temperature of the Al-alloy based PV cells was observed at about 62.4 °C, which was 5.2 °C lower than that of the TPT based PV cells, and its corresponding PV efficiency was about 9.18%, nearly 0.26% higher than the TPT based type. During the outdoor testing, the mean daily electrical, thermal and overall energetic and exergetic efficiencies of the PV/LHP module were measured at 9.13%, 39.25%, 48.37% and 15.02% respectively. The basic-thermal system performance coefficient (COPth) was found at 5.51 and the advanced system performance coefficient (COPPV/T) was nearly 8.71. A simple comparison was also conducted between the PV/LHP based heat-pump system and those conventional solar/air energy systems, which indicated that this advanced system harvests larger amount of solar energy and therefore enables enhanced solar efficiency and system performance. Basic analysis into the economic and environmental benefits of this prototype system further demonstrated such technology will be competitive in the future energy supply industry with a payback period of 16 (9) years and a life-cycle carbon reduction of 12.06 (2.94) tons in Shanghai (London).

  • 1313.
    Zhang, Xingxing
    et al.
    University of Hull.
    Zhao, Xudong
    Shen, Jingchun
    Xu, Jihuan
    Yu, Xiaotong
    Dynamic performance of a novel solar photovoltaic/loop-heat-pipe heat pump system2014In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 114, p. 335-352Article in journal (Refereed)
    Abstract [en]

    Objective of the paper is to present an investigation into the dynamic performance of a novel solar photovoltaic/loop-heat-pipe (PV/LHP) heat pump system for potential use in space heating or hot water generation. The methods used include theoretical computer simulation, experimental verification, analysis and comparison. The fundamental equations governing the transient processes of solar transmission, heat transfer, fluid flow and photovoltaic (PV) power generation were appropriately integrated to address the energy balances occurring in different parts of the system, e.g., glazing cover, PV cells, fin sheet, loop heat pipe, heat pump cycle and water tank. A dedicated computer model was developed to resolve the above grouping equations and consequently predict the system’s dynamic performance. An experimental rig was constructed and operated under the real weather conditions for over one week in Shanghai to evaluate the system living performance, which was undertaken by measurement of various operational parameters, e.g., solar radiation, photovoltaic power generation, temperatures and heat pump compressor consumption. On the basis of the first- (energetic) and second- (exergetic) thermodynamic laws, an overall evaluation approach was proposed and applied to conduct both quantitative and qualitative analysis of the PV/LHP module’s efficiency, which involved use of the basic thermal performance coefficient (COPth) and the advanced performance coefficient (COPPV/T) of such a system. Moreover, a simple comparison between the PV/LHP heat-pump system and conventional solar/air energy systems was conducted. The research results indicated that under the testing outdoor conditions, the mean daily electrical, thermal and overall energetic and exergetic efficiencies of the PV/LHP module were 9.13%, 39.25%, 48.37% and 15.02% respectively, and the average values of COPth and COPPV/T were 5.51 and 8.71. The PV/LHP module was found to achieve 3–5% higher solar exergetic efficiency than standard PV systems and about 7% higher overall solar energetic efficiency than the independent solar collector. Compared to the conventional solar/air heat pump systems, the PV/LHP heat pump system could achieve a COP figure that is around 1.5–4 times that for the conventional systems. It is concluded that the computer model is able to achieve a reasonable accuracy in predicting the system’s dynamic performance. The PV/LHP heat pump system is able to harvest significant amount of solar heat and electricity, thus enabling achieving enhanced solar thermal and electrical efficiencies. All these indicate a positive implication that the proposed system has potential to be developed into a high performance PV/T technology that can contribute to significant fossil fuel energy saving and carbon emission.

  • 1314.
    Zhang, Xingxing
    et al.
    De Montfort University.
    Zhao, Xudong
    Smith, Stefan
    Xu, Jihuan
    Yu, Xiaotong
    Review of R&D progress and practical application of the solar photovoltaic/thermal (PV/T) technologies2012In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 16, no 1, p. 599-617Article in journal (Refereed)
    Abstract [en]

    In this paper, the global market potential of solar thermal, photovoltaic (PV) and combined photovoltaic/thermal (PV/T) technologies in current time and near future was discussed. The concept of the PV/T and the theory behind the PV/T operation were briefly introduced, and standards for evaluating technical, economic and environmental performance of the PV/T systems were addressed. A comprehensive literature review into R&D works and practical application of the PV/T technology was illustrated and the review results were critically analysed in terms of PV/T type and research methodology used. The major features, current status, research focuses and existing difficulties/barriers related to the various types of PV/T were identified. The research methods, including theoretical analyses and computer simulation, experimental and combined experimental/theoretical investigation, demonstration and feasibility study, as well as economic and environmental analyses, applied into the PV/T technology were individually discussed, and the achievement and problems remaining in each research method category were described. Finally, opportunities for further work to carry on PV/T study were identified. The review research indicated that air/water-based PV/T systems are the commonly used technologies but their thermal removal effectiveness is lower. Refrigerant/heat-pipe-based PV/Ts, although still in research/laboratory stage, could achieve much higher solar conversion efficiencies over the air/water-based systems. However, these systems were found a few technical challenges in practice which require further resolutions. The review research suggested that further works could be undertaken to (1) develop new feasible, economic and energy efficient PV/T systems; (2) optimise the structural/geometrical configurations of the existing PV/T systems; (3) study long term dynamic performance of the PV/T systems; (4) demonstrate the PV/T systems in real buildings and conduct the feasibility study; and (5) carry on advanced economic and environmental analyses. This review research helps finding the questions remaining in PV/T technology, identify new research topics/directions to further improve the performance of the PV/T, remove the barriers in PV/T practical application, establish the standards/regulations related to PV/T design and installation, and promote its market penetration throughout the world.

  • 1315. Zhang, Xingxing
    et al.
    Zhao, Xudong
    Tan, Junyi
    Ma, Shige
    Development of low-temperature air-source heat pump technology in Europe2015In: Heating, Ventilating and Air Conditioning, ISSN 1002-8501, Vol. 7, p. 48-52Article in journal (Refereed)
  • 1316. Zhang, Xingxing
    et al.
    Zhao, Xudong
    Xu, Jihuan
    Investigation of a Novel Solar Driven Water Heating System with Enhanced Energy Yield for Buildings2012In: Proceeding International Conference for Enhanced Building Operations (ICEBO) 2012, Manchester, UK, 23rd - 26th October 2012, 2012Conference paper (Refereed)
  • 1317. Zhang, Xingxing
    et al.
    Zhao, Xudong
    Xu, Jihuan
    Yu, Xiaotong
    A novel gravitational loop heat pipe using for micro solar photovoltaic/thermal cogeneration system2013Patent (Other (popular science, discussion, etc.))
  • 1318.
    Zhang, Xingxing
    et al.
    De Montfort University.
    Zhao, Xudong
    Xu, Jihuan
    Yu, Xiaotong
    Characterization of a solar photovoltaic/loop-heat-pipe heat pump water heating system2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 102, p. 1229-1245Article in journal (Refereed)
    Abstract [en]

    This paper introduced the concept, potential application and benefits relating to a novel solar photovoltaic/loop-heat-pipe (PV/LHP) heat pump system for hot water generation. On this basis, the paper reported the process and results of characterizing the performance of such a system, which was undertaken through dedicated thermo-fluid and energy balance analyses, computer model development and operation, and experimental verification and modification. The fundamental heat transfer, fluid flow and photovoltaic governing equations were applied to characterize the energy conversion and transfer processes occurring in each part and whole system layout; while the energy balance approach was utilized to enable inter-connection and resolution of the grouped equations. As a result, a dedicated computer model was developed and used to calculate the operational parameters, optimise the geometrical configurations and sizes, and recommend the appropriate operational condition relating to the system. Further, an experimental rig was constructed and utilized to acquire the relevant measurement data that thus enabled the parallel comparison between the simulation and experiment. It is concluded that the testing and modelling results are in good agreement, indicating that the model has the reasonable accuracy in predicting the system’s performance. Under the given experimental conditions, the electrical, thermal and overall efficiency of the PV/LHP module were around 10%, 40% and 50% respectively; whilst the system’s overall performance coefficient (COPPV/T) was 8.7. Impact of the operational parameters (i.e. solar radiation, air temperature, air velocity, heat-pump’s evaporation temperature, glazing covers, and number of the absorbing heat pipes) to the performance of the system (in terms of efficiencies of the PV/LHP module and the system’s overall performance coefficient COPPV/T) was investigated individually. The results indicated that lower solar radiation, lower air temperature, higher air velocity and smaller cover number led to enhanced electrical efficiency but reduced thermal efficiency of the module; whereas lower heat-pump’s evaporation temperature and larger number of heat absorbing pipes gave rise to both thermal and electrical efficiencies of the module. The research results would assist in developing a high efficient solar (space or hot water) heating system and thus contribute to realisation of the energy saving and associated carbon emission targets set for buildings globally.

  • 1319.
    Zhao, Xiaoyun
    et al.
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Carling, Kenneth
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    Håkansson, Johan
    Dalarna University, School of Technology and Business Studies, Microdata Analysis.
    An evaluation of the reliability of GPS-based transportation data2017In: Proceedings of IAC in Vienna 2017, 2017, p. 323-334, article id IAC201711035Conference paper (Refereed)
    Abstract [en]

    GPS-based data are becoming a cornerstone for real-time transportation applications. Tracking data of vehicles from GPS receivers are however susceptible to measurement errors. The assessment of the reliability of data from GPS receiver is a neglected issue, especially in a real road network setting and in the phase after data transfer but before information identification. An evaluation method is outlined and carried out by conducting a randomized experiment. We assess the reliability of GPS-based transportation data on geographical position, speed, and elevation from three varied receivers GlobalSat BT-338X, Magellan SporTrak Pro and smart phone for three transportation modes: bicycle, car, and bus. The positional error ranging from 0158 meters, and 74% to 100% with an error within 5 meters depending on the transportation mode and route, there is also a non-negligible risk for aberrant positioning. Speed is slightly underestimated or overestimated with errors around 5km/h except for SporTrak Pro which had an error of -10 km/h. Elevation measurements are unreliable with errors bigger than 100 meters.

  • 1320. Zhao, Xudong
    et al.
    Zhang, Xingxing
    Solar Photovoltaic/Thermal Technologies and their Application in Building Retrofitting2013In: Nearly Zero Energy Building Refurbishment: A Multidisciplinary Approach / [ed] Pacheco et al, Springer, 2013, p. 615-658Chapter in book (Refereed)
  • 1321. Zhao, Xudong
    et al.
    Zhang, Xingxing
    De Montfort University.
    Riffat, Saffa B.
    Su, Yaxin
    Theoretical study of the performance of a novel PV/e roof module for heat pump operation2011In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 52, no 1, p. 603-614Article in journal (Refereed)
    Abstract [en]

    In this paper, a novel PV/e roof module was designed to act as the roof element, electricity generator and the evaporator of a heat pump system. The modules, in conjunction with a heat pump, are able to provide heat and power supply to buildings with an enhanced efficiency. Energy profiles of the PV/e modules and modules-based heat pump system were analysed and temperature distribution across the module layers was studied. It was found that the PV/e roof modules-based heat pump system can achieve significant improvement in thermal and electrical efficiencies. Variation of the system efficiencies (thermal, electrical and total) with a number of factors, i.e., top cover, PV cells, evaporation and condensation temperature of the heat pump was investigated, which led to suggestion of the optimised system configuration and operating conditions. The study indicated that the combined system should operate at 10 °C of evaporation and 60 °C of condensation temperature. Borosilicate as a top cover has better thermal performance than polycarbonate and glass; whilst the mono-crystalline photovoltaic cells are of higher electrical efficiency over the poly-crystalline and thin-films. Under a typical Nottingham (UK) operating condition, the modules would achieve 55% of thermal efficiency and 19% of electrical efficiency, while the module-based heat pump system would have an overall efficiency of above 70%. It was also addressed that the integration of the PV cells and evaporation coil into a prefabricated roof would lead to large saving in both capital and running costs over separate arrangements of PV, heat pump and roof structure.

  • 1322.
    Zhou, Nian
    Dalarna University, School of Technology and Business Studies, Materials Technology. KTH.
    Influence of grinding operations on surface integrity and chloride induced stress corrosion cracking of stainless steels2016Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Stainless steels were developed in the early 20th century and are used where both the mechanical properties of steels and corrosion resistance are required. There is continuous research to allow stainless steel components to be produced in a more economical way and be used in more harsh environments. A necessary component in this effort is to correlate the service performance with the production processes.

    The central theme of this thesis is the mechanical grinding process.  This is commonly used for producing stainless steel components, and results in varied surface properties that will strongly affect their service life. The influence of grinding parameters including abrasive grit size, machine power and grinding lubricant were studied for 304L austenitic stainless steel (Paper II) and 2304 duplex stainless steel (Paper I). Surface integrity was proved to vary significantly with different grinding parameters. Abrasive grit size was found to have the largest influence. Surface defects (deep grooves, smearing, adhesive/cold welding chips and indentations), a highly deformed surface layer up to a few microns in thickness and the generation of high level tensile residual stresses in the surface layer along the grinding direction were observed as the main types of damage when grinding stainless steels. A large degree of residual stress anisotropy is interpreted as being due to mechanical effects dominating over thermal effects.

    The effect of grinding on stress corrosion cracking behaviour of 304L austenitic stainless steel in a chloride environment was also investigated (Paper III). Depending on the surface conditions, the actual loading by four-point bend was found to deviate from the calculated value using the formula according to ASTM G39 by different amounts. Grinding-induced surface tensile residual stress was suggested as the main factor to cause micro-cracks initiation on the ground surfaces. Grinding along the loading direction was proved to increase the susceptibility to chloride-induced SCC, while grinding perpendicular to the loading direction improved SCC resistance.

    The knowledge obtained from this work can provide a reference for choosing appropriate grinding parameters when fabricating stainless steel components; and can also be used to help understanding the failure mechanism of ground stainless steel components during service.

  • 1323.
    Zhou, Nian
    Dalarna University, School of Technology and Business Studies, Materials Technology. KTH, Yt- och korrosionsvetenskap.
    Surface integrity and corrosion behavior of stainless steels after grinding operations2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Stainless steels are widely used in applications where both the mechanical properties of steels and high corrosion resistance are required. There is continuous research to enable stainless steel components to be produced in a more economical way and be used in more harsh environments. A way to achieve this is to correlate the service performance with the production processes.

    The central theme of this thesis is surface integrity and corrosion, especially the stress corrosion cracking behavior, after grinding processes. Controlled grinding parameters, including abrasive grit size, machine power and grinding lubricant, were used and the resulting surface properties studied for austenitic 304L and duplex 2304 stainless steels. The abrasive grit size effect was found to have a larger influence. Surface defects, a highly deformed surface layer and the generation of a high level surface tensile residual stresses along the grinding direction were observed as the main types of damage. 

    The effect of grinding on stress corrosion cracking behavior of austenitic 304L, ferritic 4509 and duplex 2304 stainless steels in chloride-containing environments was also investigated.  The abrasive grit size effect on corrosion behavior for the three grades was compared. Grinding-induced surface tensile residual stress was suggested as the main factor to cause micro-cracks on the ground surface for 304L and 2304; for 4509, grinding-induced grain fragmentation was considered as the main factor for the initiation of extensive micro-pits. For duplex 2304, the microstructure and micro-notches in the as-ground surface also had significant influence. Depending on the surface conditions, the actual loading by four-point bending was found to deviate from the calculated value using the formula according to ASTM G39 by different amounts. The knowledge obtained from this work can provide guidance for choosing appropriate stainless steel grades and grinding parameters; and can also be used to help understanding the failure mechanism of ground stainless steel components during service.

  • 1324.
    Zhou, Nian
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology. KTH.
    Lin Peng, Ru
    Linköping University.
    Pettersson, Rachel
    Jernkontoret, KTH.
    Surface characterization of austenitic stainless steel 304L after different grinding operations2017In: International Journal of Mechanical and Materials Engineering, ISSN 2198-2791, Vol. 12, no 6Article in journal (Refereed)
    Abstract [en]

    Background: The austenitic stainless steel 304L is widely used as a structural material for which the finished surface has significant effect on the service performance. A study of the grinding process with regard to the quality of the ground surfaces is therefore interesting from the point of view of both industrial application and scientific research.

    Method: This work investigates the influence of grinding parameters including abrasive grit size, machine power, and grinding lubrication on the surface integrity of the austenitic stainless steel 304L. The induced normal grinding force, grinding surface temperature, metal removal rate, and surface property changes have been investigated and compared.

    Results and Conclusion: Using grinding, lubrication significantly enhanced the metal removal rate. Surface defects (deep grooves, smearing, adhesive chips, and indentations), a highly deformed thin surface layer up to a few microns in thickness, and high surface tensile residual stresses parallel to the grinding direction have been observed as the main damage induced by the grinding operations. Surface finish and deformation were found to be improved by using smaller abrasive grits or by using lubrication during grinding. Increasing the machine power increased surface deformation while reducing surface defects. The results obtained can provide a reference for choosing appropriate grinding parameters when machining 304L; and can also help to understand the failure mechanism of ground austenitic stainless steel components during service.

  • 1325.
    Zhou, Nian
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology. KTH.
    Lin Peng, Ru
    Linköping University.
    Pettersson, Rachel
    Jernkontoret, KTH.
    Schönning, Mikael
    Avesta Research Center - Outokumpu Stainless AB.
    Residual stress in stainless steels after surface grinding and its effect on chloride induced SCC2016In: Materials Research Proceedings: Residual Stresses 2016: ICRS-10, 2016, p. 289-294Conference paper (Refereed)
    Abstract [en]

    The induced residual stresses in stainless steels as a consequence of surface grinding as well as their influence on the chloride induced stress corrosion cracking (SCC) susceptibility have been investigated. Three types of materials were studied: 304L austenitic stainless steel, 4509 ferritic stainless steel and 2304 duplex stainless steel. Surface grinding using 60# and 180# grit size abrasives was performed for each material. Residual stress depth profiles were measured using X-ray diffraction. The susceptibility to stress corrosion cracking was evaluated in boiling MgCl2 according to ASTM G36. Specimens were exposed without applying any external loading to evaluate the risk for SCC caused solely by residual stresses. Induced residual stresses and corrosion behavior were compared between the austenitic, ferritic and duplex stainless steels to elucidate the role of the duplex structure. For all materials, the grinding operation generated tensile residual stresses in the surface along the grinding direction but compressive residual stresses perpendicular to the grinding direction. In the subsurface region, compressive stresses in both directions were present. Micro-cracks initiated due to high grinding-induced tensile residual stresses in the surface layer were observed in austenitic 304L and duplex 2304, but not in the ferritic 4509. The surface residual stresses decreased significantly after exposure for all specimens.

  • 1326.
    Zhou, Nian
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology. KTH.
    Lin Peng, Ru
    Linköping University.
    Schönning, Mikael
    Avesta Research Center–Outokumpu Stainlelss AB.
    Pettersson, Rachel
    Jernkontoret, KTH.
    SCC of 2304 duplex stainless steel - microstructure, residual stress and surface grinding effects2017In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 10, no 3, article id 221Article in journal (Refereed)
    Abstract [en]

    The influence of surface grinding and microstructure on chloride induced stress corrosion cracking (SCC) behavior of 2304 duplex stainless steel has been investigated. Grinding operations were performed both parallel and perpendicular to the rolling direction of the material. SCC tests were conducted in boiling magnesium chloride according to ASTM G36; specimens were exposed both without external loading and with varied levels of four-point bend loading. Residual stresses were measured on selected specimens before and after exposure using the X-ray diffraction technique. In addition, in-situ surface stress measurements subjected to four-point bend loading were performed to evaluate the deviation between the actual applied loading and the calculated values according to ASTM G39. Micro-cracks, initiated by grinding induced surface tensile residual stresses, were observed for all the ground specimens but not on the as-delivered surfaces. Loading transverse to the rolling direction of the material increased the susceptibility to chloride induced SCC. Grinding induced tensile residual stresses and micro-notches in the as-ground surface topography were also detrimental.

  • 1327.
    Zhou, Nian
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Peng, R. L.
    Pettersson, R.
    Surface integrity of 2304 duplex stainless steel after different grinding operations2016In: Journal of Materials Processing Technology, ISSN 0924-0136, E-ISSN 1873-4774, Vol. 229, p. 294-304Article in journal (Refereed)
    Abstract [en]

    Surface integrity has significant effect on service performance of a component. In this study, the evolution of the surface and sub-surface changes induced by grinding duplex stainless steel (DSS) 2304 was studied with regard to the residual stress, the microstructure, surface roughness and surface defects. The results provide insights into the effect of abrasive grit size, grinding force and lubrication on the surface integrity. The abrasive grit size was found to have the largest influence. Surface defects, a highly deformed surface layer and the generation of tensile residual stresses along the grinding direction have been found to be the main types of damage induced by the grinding operation. Residual stresses induced by mechanical effects dominate over thermal effects in this study. The results obtained can be used to understand the contribution of surface condition and residual stress on failure of duplex stainless steels in service by fatigue or stress corrosion cracking.

  • 1328.
    Zhou, Nian
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology. KTH.
    Pettersson, R.
    Schönning, M.
    Peng, R. L.
    Influence of surface grinding on corrosion behavior of ferritic stainless steels in boiling magnesium chloride solution2018In: Materials and corrosion - Werkstoffe und Korrosion, ISSN 0947-5117, E-ISSN 1521-4176, Vol. 69, no 11, p. 1560-1571Article in journal (Refereed)
    Abstract [en]

    The influence of grinding operations on surface properties and corrosion behavior of a ferritic stainless steel (FSS), EN 1.4509, has been investigated and limited comparisons also made to the grade EN 1.4622. Surface grinding was performed along the rolling direction of the material. Corrosion tests were conducted in boiling magnesium chloride solution according to ASTM G36; specimens were exposed both without external loading and under four‐point bend loading. The surface topography and cross‐section microstructure before and after exposure were investigated, and residual stresses were measured on selected specimens before and after corrosion tests using X‐ray diffraction. In addition, in situ surface stress measurements were performed to evaluate the actual surface stresses of specimens subject to four‐point bend loading according to ASTM G39. Micro‐pits showing branched morphology initiated from the highly deformed ground surface layer which contained fragmented grains, were observed for all the ground specimens but not those in the as‐delivered condition. Grain boundaries under the surface layer appeared to hinder the corrosion process. No macro‐cracking was found on any specimen after exposure even at high calculated applied loads.

  • 1329.
    Zhou, Nian
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology. KTH.
    Pettersson, Rachel
    KTH; Jernkontoret.
    Peng, Ru Lin
    Linköping universitet.
    Schonning, Mikael
    Outokumpu Stainless AB, Avesta.
    Effect of surface grinding on chloride induced SCC of 304L2016In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 658, p. 50-59Article in journal (Refereed)
    Abstract [en]

    The effect of surface grinding on the stress corrosion cracking (SCC) behavior of 304L austenitic stainless steel in boiling magnesium chloride has been investigated. SCC tests were conducted both without external loading and with varied levels of four-point bend loading for as-delivered material and for specimens which had been ground parallel or perpendicular to the loading direction. Residual stresses due to the grinding operation were measured using the X-ray diffraction technique. In addition, surface stress measurements under applied load were performed before exposure to evaluate the deviation between actual applied loading and calculated values according to ASTM G39. Micro-cracks initiated by a high level of tensile residual stress in the surface layer were observed for all the ground specimens but not those in the as-delivered condition. Grinding along the loading direction increased the susceptibility to chloride induced SCC; while grinding perpendicular to the loading direction improved SCC resistance. Surface tensile residual stresses were largely relieved after the initiation of cracks. (C) 2016 Elsevier B.V. All rights reserved.

  • 1330. Zhu, Chaoyi
    et al.
    Gluesenkamp, Kyle R
    Yang, Zhiyao
    Blackman, Corey
    Dalarna University, School of Technology and Business Studies, Energy Technology. SaltX Technology; Mälardalens högskola.
    Unified thermodynamic model to calculate COP of diverse sorption heat pump cycles: Adsorption, absorption, resorption, and multistep crystalline reactions2019In: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 99, p. 382-392Article in journal (Refereed)
    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.

    The full text will be freely available from 2020-06-30 23:36
  • 1331.
    Åberg, Anna Cristina
    et al.
    The Swedish School of Sport and Health Sciences, Box 5626, SE-114 86 Stockholm, Sweden ; Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Uppsala Science Park, SE-751 85 Uppsala, Sweden.
    Elmgren Frykberg, Gunilla
    Uppsala universitet, Rehabiliteringsmedicin.
    Halvorsen, Kjartan
    Uppsala universitet, Reglerteknik; Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Medio-lateral stability of sit-to-walk performance in older individuals with and without fear of falling2010In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 31, no 4, p. 438-443Article in journal (Refereed)
  • 1332.
    Åberg, Anna Cristina
    et al.
    The Swedish School of Sport and Health Sciences, Stockholm, Sweden ; Department of Public Health and Caring Sciences/Geriatrics, Uppsala, Sweden.
    Thorstensson, Alf
    The Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Tarassova, Olga
    The Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Halvorsen, Kjartan
    Uppsala universitet, Avdelningen för systemteknik ; School of Technology and Health, KTH-Royal Institute of Technology, Stockholm, Sweden.
    Calculations of mechanisms for balance control during narrow and single-leg standing in fit older adults: a reliability study2011In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 34, no 3, p. 352-357Article in journal (Refereed)
  • 1333.
    Åkerman, Hampus
    et al.
    Dalarna University, School of Technology and Business Studies, Construction.
    Larsson, Eric
    Dalarna University, School of Technology and Business Studies, Construction.
    Lipton - Det smarta trähuset: Energieffektivisering av Dalahus lägenhetskomplex i trä2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Earth's climate is affecting all countries and Sweden is no exception. With agrowing global environmental problem everyone needs to contribute to change.The project's contribution to the environment is to show how energyconsumption of a multi-family apartment block can be reduced. By calculatingUm for the house Lipton's current building envelope and identify the parts whereimprovements could be made, and compile the elements of design which aremost promising for improving the building envelope. Technical measures witch isnot directly related to the building envelope, such as demand controlledventilation, electrically efficient fans and other energy-smart solutions will beutilized to reduce Lipton specific energy consumption.Buildings lose heat through the building envelope but by harnessing the sun'senergy, think carefully about the building's placement, increase insulationthickness and use smart ventilation solutions, the project aims to reduce thehouse Liptons specific energy consumption to at least half of Boverkets energydemands in 2014 for new buildings in climate zone 2 which is set to110 kWh/m2 year.To calculate the specific energy consumption in use phase, a simple calculationprogram, TMF-Energy 2.3, will be used. In the project, the heating system,water/sewer and use of household energy is not to be included.The original design of the house Lipton has a specific energy consumption of56.9 kWh/m2 year which is relatively low and almost half of Boverkets energyrequirementsThe energy consumption of Lipton will be decreased by:• Improving Um for Lipton's building envelope.• Using a double-shell technology.Högskolan Dalarna• Plan where the house is located for favorable outer conditions• Using demand-controlled ventilation with energy efficient fans

  • 1334.
    Åkerström, Johan
    et al.
    Dalarna University, School of Technology and Business Studies, Construction.
    Blomqvist, Andreas
    Dalarna University, School of Technology and Business Studies, Construction.
    Tillbyggnad av miljonprogramsvilla: Olika tillbyggnader anpassade för miljonprogramsvillor2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Many villas built under the "miljonprogram" is in need of extension due to being too narrow in addition of being worn out. For this reason, many families chose to move out of these villas in favor of buying a bigger and more modern house. This means that the "miljonprogram" villas are in need of refurbishment to not lose too much value and popularity. Refurbishment of these villas can be done in many ways. One being a extension of the house, changing the truss or just a flat overall refurbishment. The method varies depending on the build of the house, as most if not all houses are constucted in different ways. A purpose of this report is to present a variety of how these villas can be rebuilt in favor of higher standards and a bigger living area. Various proposals will be presented where each development is made in different ways. Another purpose of the report is to compile the material costs for the various additions.

    This is done in order to gain an economic perception of the various additions and which add-on option is most economically sustainable

    The test object used in the report is stationed in Falun. The building is a typical miljonprograms villa with a pitched roof. The façade material for the villa consists of non-bearing façade pointers. The various additions to the project are based on the test object's original drawings. The new blueprints for the villa is drawn in the architectureprogram Revit.

    In the results section, various supplementary proposals are presented and finally an economic comparison is made.

    This is made to get an economic view of the various additions proposed in this report. Where the prices are compared in SEK per square meter.

    The discussion section discusses, among other things, the various additions suggested earlier.

    How the surfaces of the test object are trying to be preserved and the though process behind the new additions.

    Finally, economic aspects are discussed in the results part of the report. Four different conclusions are included in the report.

    One conclusion is that a mansard chair creates many new surfaces upstairs, and that it is also economically advantageous from a material cost perspective.

  • 1335.
    Ålander, Atte
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Electricity Supply Solutions for an Educational Center in Tanzania2013Independent thesis Advanced level (degree of Master (One Year)), 12 credits / 18 HE creditsStudent thesis
    Abstract [en]

    The aim of this study was to investigate electricity supply solutions for an educationalcenter that is being built in Chonyonyo Tanzania. Off-grid power generation solutions andfurther optimization possibilities were studied for the case.The study was done for Engineers Without Borders in Sweden. Who are working withMavuno Project on the educational center. The school is set to start operating in year 2015with 40 girl students in the beginning. The educational center will help to improve genderequality by offering high quality education in a safe environment for girls in rural area.It is important for the system to be economically and environmentally sustainable. Thearea has great potential for photovoltaic power generation. Thus PV was considered as theprimary power generation and a diesel generator as a reliable backup. The system sizeoptimization was done with HOMER. For the simulations HOMER required componentdata, weather data and load data. Common components were chose with standardproperties, the loads were based on load estimations from year 2011 and the weather datawas acquired from NASA database. The system size optimization result for this base casewas a system with 26 kW PW; 5.5 kW diesel generator, 15 kW converter and 112 T-105batteries. The initial cost of the system was 55 875 €, the total net present cost 92 121 €and the levelized cost of electricity 0.264 €/kWh.In addition three optimization possibilities were studied. First it was studied how thesystem should be designed and how it would affect the system size to have night loads(security lights) use DC and could the system then be extended in blocks. As a result it wasfound out that the system size could be decreased as the inverter losses would be avoided.Also the system extension in blocks was found to be possible. The second study was aboutinverter stacking where multiple inverters can work as one unit. This type of connectionallows only the required number of inverters to run while shutting down the excess ones.This would allow the converter-unit to run with higher efficiency and lower powerconsumption could be achieved. In future with higher loads the system could be easilyextendable by connecting more inverters either in parallel or series depending on what isneeded. Multiple inverters would also offer higher reliability than using one centralizedinverter. The third study examined how the choice of location for a centralized powergeneration affects the cable sizing for the system. As a result it was found that centralizedpower generation should be located close to high loads in order to avoid long runs of thickcables. Future loads should also be considered when choosing the location. For theeducational center the potential locations for centralized power generation were found outto be close to the school buildings and close to the dormitories.

  • 1336.
    Ångström, Carl-Johan
    et al.
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Karlsson, Johan
    Dalarna University, School of Technology and Business Studies, Materials Technology.
    Studie av fasomvandlingar vid värmebehandling av bi-metallblad i kontinuerlig process2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Håkansson Sågblad manufactures saw blades for metal cutting. The saw blades are of the bimetal type, which means they are build with one part of hot worked steel and one part of high speed steel. Håkansson have invested in a new production line for a quicker tempering, the line is still under optimization.

    The aim of this work is to determine phase transformations in the high speed steel in the tooth tip during heat treatment. There should also be a suggestion for adjusting temperatures and speed during tempering of the saw blades. To meet the aim some samples from both the old and the new producing line were made and studied, focusing on the high speed steel in the tooth tip. The samples was studied in microscope and the hardness tested. The samples showed a structure of martensite, rest austenite and carbides, in different fractions for different samples. Hardness varies from 920 to 970 HV, which was in the expected range. Samples from the new line showed a higher fraction of rest austenite than other samples. Rest austenite will increase the hardness in further tempering.

    Therefore temperature in tempering furnaces should be higher or the temperature in the preheating assembly should be higher. To avoid a high fraction of rest austenite in finished saw blades.

  • 1337.
    Åsberg, Jimmy
    Dalarna University, School of Technology and Business Studies, Mechanical Engineering.
    Analys av SCA Ortvikens massafabrik gällande totala utrustningseffektiviteten2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report is about the pulp´s implements, a system for measuring their overall equipment efficiency at the plants. This is called OEE-measurement system where the input parameters are availability, plant utilization and quality. Today Ortviken got a problem whit that there is no good way to measure the pulp´s availability and plant utilization of the equipment included in the facility. When it comes to their quality measurement, it is the one they've come along and is considered a good and working method to keep track of the quality. In this report I will bring forward a proposal on how the pulp mill can break down their measurements on individual devices. This proposal will provide a basis for the pulp mill, better able to more quickly find faults that exist out there in the plant and where they can find measures that improve the lot of the plant's total equipment efficiency

  • 1338.
    Åsén, Rickard
    Dalarna University, School of Languages and Media Studies, Sound and Music Production.
    Game Audio in Audio Games: Towards a Theory on the Roles and Functions of Sound in Audio Games2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    For the past few decades, researchers have increased our understanding of how sound functions within various audio–visual media formats. With a different focus in mind, this study aims to identify the roles and functions of sound in relation to the game form Audio Games, in order to explore the potential of sound when acting as an autonomous narrative form. Because this is still a relatively unexplored research field, the main purpose of this study is to help establish a theoretical ground and stimulate further research within the field of audio games. By adopting an interdisciplinary approach to the topic, this research relies on theoretical studies, examinations of audio games and contact with the audio game community. In order to reveal the roles of sound, the gathered data is analyzed according to both a contextual and a functional perspective.

    The research shows that a distinction between the terms ‘function’ and ‘role’ is important when analyzing sound in digital games. The analysis therefore results in the identification of two analytical levels that help define the functions and roles of an entity within a social context, named the Functional and the Interfunctional levels. In addition to successfully identifying three main roles of sound within audio games—each describing the relationship between sound and the entities game system, player and virtual environment—many other issues are also addressed. Consequently, and in accordance with its purpose, this study provides a broad foundation for further research of sound in both audio games and video games.

  • 1339.
    Öhrèn, Rasmus
    Dalarna University, School of Technology and Business Studies, Construction.
    Tekniskt samråd: Studie av likvärdighet i utförandet2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A new planning- and building act was applied the 2nd may 2011. The intention was to simplify the planning- and building process as the control of constructing where tightened. In the new act there has been introduced a deadline for the building permits of ten weeks. To be allowed to begin the constructing you will need a starting clearance. The clearance is preceded by a technical consultation.

    The purpose of this study was to survey if the technical consultation is performed equivalent between different municipalities in the county of Dalarna. Other purposes was:

     To create a basis for improvement regarding the technical consultation.

     Examine how to facilitate or improve the consultation.

     Illustrate why the technical consultation is so important in the building process.

     Clarify the differences in the new and the old act regarding the consultation.

    To understand what a technical consultation is and how it should be performed the work began with a literature study. A literature study was also performed to pick a method for the work. These studies resulted in a method based on the semi-structured interview form. A number of interviews were conducted in five building committees in Dalarnas County. To study the technical consultation in practice a visit during a consultation were conducted at Mora – Orsa and Falun municipalities.

    This thesis was delimited to examining how technical consultation is performed and works in various building committees in Dalarnas county. The work was delimited to only process opinions from building inspectors and a control manager.

    The results have been compiled and are reported in the results chapter. All respondents in this thesis have the opinion that complete documentation is essential to carry out a technical consultation. The developer should be well-informed and familiar with the project and an experienced developer could simplify the building process. A technical consultation is of great importance to ensure that the society’s conditions upholds. It is particularly important to hold a consultation when the developer is inexperienced.

  • 1340.
    Östling, Lina
    Dalarna University, School of Technology and Business Studies, Graphic Arts Technology.
    Grafisk profilering i tatueringsbranschen2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    En väl utformad grafisk profil kan hjälpa ett företag att skapa medvetenhet och kundlojalitet. Den grafiska profilen består bland annat av logotyp, färger, typsnitt och profil- och korrespondensmaterial som allt måste vara enhetligt utformat och anpassat efter företagets kultur, målgrupp och vision. Projektet syftar till att undersöka och beskriva hur tatuerares grafiska profil bör vara utformad för att bäst fylla sitt syfte. En enkätundersökning gjordes med målet att skapa förståelse för tatueringskundernas syn på den grafiska profilen och kompletterades med en intervju med en förtroendeingivande tatuerare som i sina åsikter fick representera tatueringsbranschen. Litteratur i ämnet grafisk profilering och grafisk design kompletterade undersökningen ytterligare. Resultaten från enkätundersökningen stämde inte helt överens med litteraturen vilket gör det svårt att ge ett exakt svar på projektets frågeställningar

  • 1341.
    Šumić, Mersiha
    Dalarna University, School of Technology and Business Studies, Energy and Environmental Technology.
    Thermal Performance of a Solarus CPC-Thermal Collector2014Independent thesis Advanced level (degree of Master (One Year)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    The  aim  of  this  master  thesis  is  an  investigation  of  the  thermal  performance  of  a  thermal compound parabolic concentrating (CPC) collector from Solarus. The collector consists of two troughs with absorbers which are coated with different types of paint with  unknown  properties.  The  lower  and  upper  trough  of  the  collector  have  been  tested individually.

    In  order  to  accomplish  the  performance  of  the  two  collectors,  a  thorough  literature  study  in  the  fields  of  CPC  technology,  various  test  methods,  test  standards  for  solar thermal  collectors  as  well  as  the  latest  articles  relating  on  the  subject  were  carried  out. In addition, the set‐up of the thermal test rig was part of the thesis as well. The thermal  performance  was  tested  according  to  the  steady  state  test  method  as  described in the European standard 12975‐2. Furthermore, the thermal performance of  a  conventional  flat  plate  collector  was  carried  out  for  verification  of  the  test  method.

    The  CPC‐Thermal  collector  from  Solarus  was  tested  in  2013  and  the  results  showed  four  times  higher  values  of  the  heat  loss  coefficient  UL (8.4  W/m²K)  than  what  has been reported for a commercial collector from Solarus. This value was assumed to be too large and it was assumed that the large value was a result of the test method used that time. Therefore, another aim was the comparison of the results achieved in this work with the results from the tests performed in 2013.

    The results of the thermal performance showed that the optical efficiency of the lower trough of the CPC‐T collector is 77±5% and the corresponding heat loss coefficient UL 4.84±0.20  W/m²K.  The  upper  trough  achieved  an  optical  efficiency  of  75±6  %  and  a  heat loss coefficient UL of 6.45±0.27 W/m²K. The results of the heat loss coefficients  are  valid  for  temperature  intervals  between  20°C  and  80°C.  The  different  absorber paintings have a significant impact on the results, the lower trough performs overall better.  The  results  achieved  in  this  thesis  show  lower  heat  loss  coefficients UL and higher optical efficiencies compared to the results from 2013. 

  • 1342.
    Bales, Chris (Editor)
    Dalarna University, School of Technology and Business Studies, Energy Technology.
    Engineering tools2010Report (Other academic)
    Abstract [en]

    The aim of this report is to give an overview of the results of Work Package 5 “Engineering Tools”. In this workpackage numerical tools have been developed for all relevant CHCP systems in the PolySMART demonstration projects (WP3). First, existing simulation platforms have been described and specific characteristics have been identified. Several different simulation platforms are in principle appropriate for the needs in the PolySMART project. The result is an evaluation of available simulation and engineering tools for CHCP simulation, and an agreement upon a common simulation environment within the PolySMART project. Next, numerical models for components in the demonstration projects have been developed. These models are available to the PolySMART consortium. Of all modeled components an overall and detailed working principle is formulated, including a parameter list and (in some cases) a control strategy. Finally, for four CHCP systems in the PolySMART project, a system simulation model has been developed. For each system simulation a separate deliverable is available (D5.5b to D5.5e) These deliverables replace deliverable 5.4 ‘system models’. The numerical models for components and systems developed in the Polysmart project form a valuable basis for the component development and optimisation and for the system optimisation, both within and outside the project. Developers and researchers interested in more information about specific models can refer to the institutes and contact persons involved in the model development. 

24252627 1301 - 1342 of 1342
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • 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