Inhaltszusammenfassung

Better realization of isothermal changes of state can be seen as a decisive general prerequisite for the improvement of reachable overall efficiencies of compressors, power plants or Stirling engines. The injection of water during a compression or expansion stroke is a promising method for approximating isothermal change of state, as there is a big potential of high heat transfer rates in comparison to traditional cooling and heating methods through walls. Water injection into atmospheres of ...Better realization of isothermal changes of state can be seen as a decisive general prerequisite for the improvement of reachable overall efficiencies of compressors, power plants or Stirling engines. The injection of water during a compression or expansion stroke is a promising method for approximating isothermal change of state, as there is a big potential of high heat transfer rates in comparison to traditional cooling and heating methods through walls. Water injection into atmospheres of nitrogen and helium up to 18 bar is investigated in an experimental setup varying initial temperature difference between injected water and gas temperatures and by varying the injection pressure, injection time or the gas type. It is shown that thermal resistance remains relatively independent of the temperature difference but strongly depends on the injection pressure difference. Transferred heat and heat flow rise with the pressure of the gas atmospheres. Numerical simulations are conducted along an expansion stroke and lead to the result that the delivered work can reach 94.2% of the isothermal course. By water injection with preheated water with a low initial temperature difference of 55 K, the expansion can deliver the same amount or even higher amount of work as the isothermal case.» weiterlesen» einklappen

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Klassifikation

DFG Fachgebiet:
Strömungsmechanik, Technische Thermodynamik und Thermische Energietechnik

DDC Sachgruppe:
Ingenieurwissenschaften