Supercritical operation is considered a main technique to achieve higher cycle efficiency in various thermodynamic systems. The present paper is a review of experimental investigations on supercritical operation considering both heat-to-upgraded heat and heat-to-power systems. Experimental works are reported and subsequently analyzed. Main findings can be summarized as: steam Rankine cycles does not show much studies in the literature, transcritical organic Rankine cycles are intensely investigated and few plants are already online, carbon dioxide is considered as a promising fluid for closed Brayton and Rankine cycles but its unique properties call for a new thinking in designing cycle components. Transcritical heat pumps are extensively used in domestic and industrial applications, but supercritical heat pumps with a working fluid other than CO2 are scarce. To increase the adoption rate of supercritical thermodynamic systems further research is needed on the heat transfer behavior and the optimal design of compressors and expanders with special attention to the mechanical integrity.
This paper presents the results of systematic studies carried out on the role of fine RDX in determining the burning rate and ballistics of LOVA gun propellants. Propellant formulations containing fine RDX particles with a size of 4.5, 6, 13 and 32 µm as energetic ingredient, cellulose acetate as inert binder, triacetin as inert plasticizer, nitrocellulose of lower percentage nitrogen content as energetic binder and carbamite as stabilizer were made. The evaluation of the propellant batches has been carried out by static firing using closed vessel technique. It indicates the linear relation between the burning rate of the propellant and the fine RDX particle size used in this formulation. The results of the present studies revealed that fine RDX of 4.5 to 6 µm size may be the most suitable for LOVA gun propellant to meet the desired burning rate for satisfactory ballistics.
Currently triple base propellants are used for tank gun ammunition. Nitroguanidine (NQ) propellant is the most promising among them due to various advantages like low flame temperature, flashlessness, low barrel erosion, long shelf life, etc. Therefore, it will continue to be used in the field of gun propulsion systems for several years to come. However, there is scope for enhancing the performance of triple base propellant with respect to energy level and mechanical properties.Nitrocellulose (NC) is the energetic binder cum fuel used in the triple base composition propellant and constitutes a sizeable percentage of the compound. Hence, one of the promising triple base compositions was selected, and a systematic study was carried out by using different types of NC (having varying percentages of nitrogen content) to study the variation in mechanical properties, energy content, linear burning rate coefficient, and pressure exponent. The results are discussed in this paper.
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