The Japan-German joint research program “PHOENIX-2” on the cool flame dynamics using TEXUS sounding rocket is planned and in progress. The reference data of spontaneous ignition of fuel droplet arrays and pairs in hot air and those of succeeding cool flame combustion are to be obtained through the microgravity experiments. The present review introduces the known mechanism of cool flame and the importance of the flame in various practical combustion applications. The recent research revealed the significant scientific needs for reliable modelling of cool flame chemistry, especially for the case of non-uniform field where heat and species dissipate. The droplet combustion system is suited for controlling the dissipative field, and the experimental data are promised to be the reference for the chemical modelling. The scope of the experiments is explained in view of this needs.

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Cool flame dynamics is simulated considering gas-liquid equilibrium with the ambient temperature of 550 K and 600 K, and pressure of 1.0 atm. The ignition delay time of the droplet pair are longer than that of the single one, and the ignition of the droplet pair occurred from the outside of the droplet for 550 K. Meanwhile, significant difference in each ignition delay time was not found, and the ignition of the droplet pair occurred almost spatially uniform for 600 K while the temperature rising of the inter-droplet region slightly led that of the outer region. It is thought that species and heat transfer are not dominant for 600 K due to a higher reaction rate. As the noteworthy behavior, the multi-stage cool flame ignition was found for 600 K. It is thought that the long ignition delay time cause supplying the enough fuel, which contributes to keep cool flame burning for 550 K. In contrast, cool flame cannot be supported due to insufficient fuel, and it should become weak after ignition for 600 K. The subsequent accumulation of the chain agent should reactivate the next ignition.

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As fundamental research on spray combustion, spontaneous ignition phenomenon is important and research has been conducted by various approaches. The Japan-German joint research program “PHOENIX-2” aims to clarify ignition process accompanying the cool flame around ignition limit by utilizing a TEXUS sounding rocket and it is very important study conjunction with the vaporization and flame spread. The design of the experimental equipment has been carried out by confirming the functions of each part by conducting element prototypes and parabolic flight experiments. At present, the detailed design review has been completed and the production phase is underway.

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Microgravity utilization in space is a powerful technique for high-quality protein crystallization. Drug design requires information regarding three-dimensional atomic coordinates from a precious protein structure at atomic resolution. Crystals obtained in space have greater availability for the analysis of drug/protein interactions compared to crystals on the ground. In this study, we assessed the reliabilities of crystal characterization based on the mosaicities of the space and ground crystals and determined a complex whole structure of the 20S proteasome with an anticancer drug.

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