Publications Search Results

Now showing 1 - 9 of 9
  • Publication
    High-temperature solar organic rankine cycle - annual simulation of various system designs
    ( 2015) ;
    Strauch, Sabine
    ;
    ; ;
    Grob, Johannes
    ;
    This paper deals with the simulation of high-temperature solar organic Rankine cycles. In contrast to previous simulations the diurnal variations and the effect of charging and discharging the thermal energy storage are taken into account. Furthermore, the presented simulations cover one full year. The simulations use discrete time steps with a constant operation over a period of one hour. Considering a full year, 8 760 connected simulations have been carried out to describe the full and part load operation of one plant. Annual simulations allow a detailed evaluation of a solar organic Rankine cycle. The work describes the effect of varying solar field area and thermal energy storage capacity with different design points. High values of irradiance result in small solar fields. These fields often cannot provide enough thermal energy to produce the nominal electrical power at time steps with low irradiance. Design points using a low value for irradiance allow full load operations during the winter season. On the other hand, they generate a large percentage of waste heat during summer, which cannot be used due to limited storage and power capacity. The presented annual simulations show that different design points for a solar organic Rankine cycle cause various results for the plant performance over a full year. A design point in December leads to a large solar field and a thermal energy storage with a high capacity. The annual simulations show the continuous operation over a full year and are used to evaluate the plant designs.
  • Publication
    Biomethan aus Biogut - eine Hemmnisanalyse
    ( 2015)
    Strauch, Sabine
    ;
    ;
    Raussen, Tobias
    ;
    Koj, Ulla
    ;
    Hildebrand, Jan
    ;
    Schweizer-Ries, Petra
  • Publication
    Optimization of ammonia pretreatment of wheat straw for biogas production
    ( 2015)
    Li, Yanjun
    ;
    Merrettig-Bruns, Ute
    ;
    Strauch, Sabine
    ;
    ;
    Chen, Hongzhang
    BACKGROUND Agricultural residues such as straw are abundant and low-cost feedstocks for biogas production. However, these lignocelluloses evolved naturally to be recalcitrant to microbial and enzymatic degradation. Ammonia pretreatment has been seen as a potential treatment method to enhance the hydrolysis of biomass, as it selectively removes the lignin and preserves most of the fermentability. This study investigated ammonia pretreatment of wheat straw for biogas production. Biogas yields were determined by standardized batch digestion tests. Additionally, lignin removal, hemicellulose retention and cellulose retention were determined. RESULTS The highest biogas yield of ammonia pretreated straw reached 625 mLNg-1VS, compared with 400 mL from untreated straw. The optimal pretreatment condition was 51.0 °C, 14.8% ammonia concentration and 27.0 h residence time. Corresponding lignin removal, hemicellulose retention, cellulose retention and cumulative biogas yield values were 25.2%, 60.6%, 96.6% and 573 mLNg−1VS, respectively. In addition, different response modes of lignin removal and biogas yield related to the same pretreatment condition were revealed. CONCLUSION Ammonia pretreatment significantly improved cumulative biogas yield, biogas production rate and volatile solid (VS) reduction of wheat straw. Lignin removal was positively related to biogas yield.
  • Publication
  • Publication
  • Publication
    Biogas. Biologische Entschwefelung ohne Lufteintrag
    ( 2012) ;
    Strauch, Sabine
    Biogas muss vor der motorischen Nutzung oder vor der Einspeisung in das Erdgasnetz entschwefelt werden. Mit Hilfe des von Fraunhofer Umsicht entwickelten biologischen Grobentschwefelungsverfahrens BioSX wird Biogas ohne Zugabe von Luft in den Biogasstrom und ohne Erzeugung stark saurer Reaktionsprodukte auf Konzentrationen unter 50 ppmv H2S gereinigt.