A Small Angle Scattering Sensor System for the Characterization of Combustion Generated Particulate

One of the critical issues for the US space program is fire safety of the space station and future launch vehicles. A detailed understanding of the scattering signatures of particulate is essential for the development of a false alarm free fire detection system. This paper describes advanced optical instrumentation developed and applied for fire detection. The system is being designed to determine four important physical properties of disperse fractal aggregates and particulates including size distribution, number density, refractive indices, and fractal dimension. Combustion generated particulate are the primary detection target; however, in order to discriminate from other particulate, non-combustion generated particles should also be characterized. The angular scattering signature is measured and analyzed using two photon optical laser scattering. The Rayleigh-Debye-Gans (R-D-G) scattering theory for disperse fractal aggregates is utilized. The system consists of a pulsed laser module, detection module and data acquisition system and software to analyze the signals. The theory and applications are described

Comparison of basic gas cycles under the restriction of constant heat addition

Theoretical thermal efficiencies and theoretical effectivenesses of six kinds of basic gas cycles, including the Carnot, Otto, Diesel, Takemura, Atkinson and Joule cycles, were compared with one another under the restriction of constant heat-addition. Relations between the available work content of heat added and the exergy change in several thermodynamic processes were also examined. It is concluded that the Atkinson cycle has the highest thermal efficiency and the second best effectiveness among the gas cycles examined. The exergy changes in an isochoric heating-process in closed systems and in an isobaric heating-process in open systems agree with the available work contents of heat added in these processes. Thus, the exergy increment in a heating process should not be generally adopted as the denominator for the theoretical effectiveness.Theoretical thermal efficiency Theoretical effectiveness Gas cycles Constant heat addition Available energy Exergy change

CO2 adsorption equilibria of the honeycomb zeolite beds

The CO2 adsorption equilibria of the honeycomb zeolite beds consisting of MS-13X or MS-4A were determined from breakthrough curves for various CO2-N2 mixtures, and the fitness of the Dubinin-Astakhov equation (Dubinin MM, Astakhov VA. Description of adsorption equilibria of vapors on zeolite over wide ranges of temperature and pressure. In: Flanigen M, Sand LB, editors. Molecular sieves zeolite II. Washington: American Chemical Society, 1971) to the obtained data was examined. The Langmuir approximation to the Dubinin-Astakhov equation was also proposed and its validity was discussed. It is found that the CO2 adsorption equilibria of the examined honeycomb zeolite beds well correlate with the Dubinin-Astakhov equation and that the evaluated Langmuir parameters can be represented by an exponential function of the temperature.

Effect of desorption temperature on CO2 adsorption equilibria of the honeycomb zeolite beds

The behaviours of MS-13X and MS-4A were examined. The fitness of the Dubinin-Astakhov equation to the adsorption equilibria of the fully-desorbed honeycomb beds was examined. The validity of the Langmuir approximation to the obtained adsorption equilibria for relatively low CO2 partial pressures was also discussed. The CO2 adsorption equilibria of the honeycomb zeolite beds are not affected by it's desorption temperature, as long as the examined honeycomb beds are desorbed at a temperature greater than 250 °C, and are well correlated with the Dubinin-Astakhov equation, irrespective of adsorption temperature. The Langmuir approximation works well for CO2 partial pressures less than about 0.2 bar, but the accuracy of the approximation deteriorates as the adsorption temperature increases.

Thermal characteristics of a solar tank with aerogel surface insulation

The transient thermal characteristics of a solar tank (a shallow solar-pond water heater) with a silica aerogel surface insulation have been examined both experimentally and theoretically. It is found that the temperature drop of the water within the solar tank after sunset can be appreciably suppressed by introducing the aerogel surface insulation system and that the proposed theoretical model can predict sunny-day hourly variations in the hot-water temperature within the solar tank with acceptable accuracy.