Papers by Keyword: High Temperature Application

Abstract: The increasing market share of highly volatile electricity generated from renewable sources like wind or solar energy, leads to enormous challenges in the energy sector. Since large-scale storage systems are neither currently nor in the near future available, the gap between electricity from renewable sources and current electricity demand has to be closed with flexibly operated conventional power plants. In order to be a viable, cost-effective option in tomorrow’s energy market future power plants must be highly efficient while having low CO₂ emissions. Furthermore, they have to be highly reactive to counter instabilities in the electrical grid due to fluctuations in renewable sources. Current materials used in power plants are only within limits suited to experience extreme changes in operational loads. However, extreme changes of operational loads will become increasingly severe with a growing share of renewables. Our project team has developed a new concept for CMC-jacketed pipes to alleviate these issues. Recently, this concept was further developed and tested in laboratory as well as a large-scale application test at Grosskraftwerk Mannheim (GKM). All tests are still ongoing. Additionally, to the use in modern highly efficient power plants such CMC-jacketed piping is also suitable for other high-temperature applications, like e.g. solar power plants or industrial chemical applications.

Abstract: Within the scope of the project ENERTHERM: Energy efficiency of thermal processes which is funded by the Bavarian Ministry of Economy (BMWi) components and systems for high-temperature are being developed. Monolithic oxide ceramics (mullite, Al₂O₃) and oxide-fiber reinforced ceramics (O-CMC) show a high potential for high temperature (HT) applications. Additionally, the demand for complex HT-components such as HT-fanwheels for kilns, supporting HT-lightweight structures or hot gas liners increases. In according to the required component design, joining techniques are needed in order to realize such complex geometries. The generated joints were made by using commercial glass solder from the type Al₂O₃-SiO₂-MgO. For realizing the joining process sintering-joining in HT-kilns was used because of the homogeneous temperature distribution. A CO₂ laser (wavelength of 10.6 microns and a power of 1.5 kW) was used for rapid joining process. The mechanical properties were determined in according to DIN EN 843-1 and DIN EN 658-3 (4-point bending strength) and evaluated according to Weibull distribution.

Abstract: This research has investigated the advantages of Sn-0.7Cu composite solder compared to conventional Sn-0.7Cu solder. The method used for fabricating the composite solder is a powder metallurgy (PM) technique. SiC and Al particles were added to Sn-0.7Cu powder during the mixing process. The Sn-0.7Cu solder composite that reinforced with 0.25 wt% of SiC and 0.5 wt% of Al, were successfully synthesized via PM technique. The result showed that the addition of SiC and Al were improving the mechanical properties and thermal stability of the solder as well as reduces the material cost.

Abstract: Na0.5Bi4.5Ti4O15-based materials with A-site vacancy were synthesized using conventional solid state processing. The (Li,Ce) modification of Na0.5Bi4.5Ti4O15-based materials resulted in the obvious improvement of the piezoelectric activity and dielectric permittivity. The dielectric and piezoelectric properties of Na0.5Bi4.5Ti4O15-based ceramics exhibiting a very stable temperature behavior, together with its high TC ~641oC, excellent piezoelectric coefficient ~28pC/N and very low temperature coefficient of resonant frequency, making the (Li,Ce) modified Na0.5Bi4.5Ti4O15-based ceramics a promising candidate for high temperature applications.

Abstract: Rapid penetration of diesel engines is expected in North America because of their better fuel efficiency and lower greenhouse gas (GHG) emissions. Diesel engine components, particularly cylinder heads, are made of cast irons and replacing them with aluminium alloys could result in a significant weight reduction and consequently better fuel efficiency. Aluminum alloys for diesel engine applications need to withstand higher operating temperatures and pressures as compared to conventional 3xxx based alloys that lose strength above 150oC. This paper presents selected results pertaining to alloy development with improved high temperature performance based on the modified 356 composition. Such alloys with engineered chemical composition and properly designed heat treatment could have improved properties at temperatures up to 250oC. The advanced thermal analysis techniques including dilatometer analysis were used to determine the effect of alloying additions on thermal characteristics including aging kinetics and its impact on casting service performance. Selected structure analysis results including XRD and TEM/EDX as well as elevated temperature tensile testing are presented.