PHOTOFLASH AND LASER IGNITION OF HIGH-NITROGEN MATERIALS

Gas-producing energetic materials that can be readily ignited with a photoflash are typically opaque sensitive primary explosives. This study explores the photoactivity of select high-nitrogen (HiN) compounds that are much less sensitive than primary explosives. These HiN materials produce large amounts of gas upon decomposition. This makes them suitable for use in actuators, igniters, or micro-thrusters. Detailed Ignition studies were conducted using similar shaped pulses at two different wavelength ranges; specifically using a xenon photoflash and a single wavelength CO2 laser. Several select HiN materials were tested for flash ignitability, and those that were found to be flash ignitable were further ignited with CO2 laser heating. By comparing ignition behavior at various laser and flash intensities, some ignition mechanisms are suggested. Thermal heating, regardless of source, appears to be the dominant mechanism responsible for ignition and photochemical effects appear to be negligible in the ignition of the materials considered in this study. Higher laser and photoflash irradiance is shown to require less energy, and is therefore more efficient. The opacity of the material is an important consideration in ignitability, but not a sufficient criteria. Opaque materials that successfully propagate well in small capillary tubes are seen to be more likely to successfully flash ignite. It is suggested that this is due to the higher burning rate of these materials and also in part to the exothermic reaction occurring at or near the burning surface, rather than further from the burning surface. Both of these characteristics better allow reaction to proceed without quenching and will lead both to more successful microchannel combustion and flash/laser ignition

Cooking rice with minimum energy

Detailed experimental studies on procedures of reducing “On-stove time” and cooking with minimum Energy (Heat) using new energy efficient cooking techniques have been carried out. The total minimum amount of heat, Qm (after subtracting radiation losses), to be delivered to the pot, the sensible heat required for cooking, hs, and on-stove time t1 required to cook 1 kg of dry rice, using a new technique (Technique I) of cooking with a stove of effective power, Peff, 626610W are found as 56066 kJ, 46565 kJ, and 911610 s, respectively; while conventional method with pressure cooker (Technique II) required Qm¼824610 kJ heat and 1357 6 16 s on-stove time. The corresponding energy and time without a pressure cooker (Technique III) were 1.5 MJ and 2640 s, respectively. When compared with other published works, our method gives the lowest energy to cook 1 kg of dry rice. The efficiencies of the cooking method for different techniques are evaluated. The Clean Development Mechanism potentials of the new cooking method are also evaluated. The results obtained are expected to help develop new cooking apparatus to cook with the lowest amount of energy and thus conserve food nutrient energy and protect environment by minimizing CO2 and other toxic emissions associated with all kinds of stoves/ovens. Discussion is made how to apply Technique I in solar cooker to reduce the cooking tim

Energy-efficient cooking methods

Energy-efficient new cooking techniques have been developed in this research. Using a stove with 649±20 Wof power, the minimum heat, specific heat of transformation, and on-stove time required to completely cook 1 kg of dry beans (with water and other ingredients) and 1 kg of raw potato are found to be: 710 (±24)kJ, 613 (±20)kJ, and 1,144±10 s, respectively, for beans and 287±12 kJ, 200±9 kJ, and 466±10 s for Irish potato. Extensive researches show that these figures are, to date, the lowest amount of heat ever used to cook beans and potato and less than half the energy used in conventional cooking with a pressure cooker. The efficiency of the stove was estimated to be 52.5±2 %. Discussion is made to further improve the efficiency in cooking with normal stove and solar cooker and to save food nutrients further.Our method of cooking when applied globally is expected to contribute to the clean development management (CDM) potential. The approximate values of the minimum and maximum CDM potentials are estimated to be 7.5×1011 and 2.2×1013kg of carbon credit annually. The precise estimation CDM potential of our cooking method will be reported later