Roman Domański

Experimental study of solid–liquid phase change in a spiral thermal energy storage unit

Abstract A new idea on the use of a vertical spiral heat exchanger in a latent heat thermal energy storage system is analyzed experimentally. In this context, two important subjects are addressed. The first one is the temporal behavior of a phase change medium undergoing a non-isothermal solid–liquid phase change transition during its two-side heating or cooling by a working fluid flowing in a spiral channel. The second one is the analysis of temporal thermal characteristics of the paraffin wax–air thermal energy storage unit of the Archimedes spiral geometry during its charging and discharging. The results are presented in terms of temperature changes of both media. Moreover, thermal analysis of the storage energy unit is carried out where temporal energy stored, overall charging ratio, total time of charging or discharging processes and time changes of melted and solid phases of the storage medium are estimated.

Exergy analysis for the evaluation of a thermal storage system employing PCMS with different melting temperatures

This article presents evaluation of the performance of phase-change, thermal-energy storage units from the second-law viewpoint. The analysis is performed for a complete charging-discharging cycle of a system consisting of two storage units in series. Both units are melted and solidified by the same hot and cold working fluids. The upstream unit has the higher of the two melting temperatures. The storage capacity of each unit is sized such that both units must change phase over the same period of time. A computer program is developed to find the dependence of the best second-law efficiency on different operational and design parameters.

Thermoeconomic analysis of sensible heat, thermal energy storage systems

Abstract The paper considers the advantages of employing a thermoeconomic analysis for describing the complete charging–discharging cycle of sensible heat, thermal energy storage systems. The main task is to find the performance of the storage systems at the minimum total cost of owning, maintaining, and operating such systems. The effect of different monetary values on optimum number of heat transfer units, charging time, and second-law efficiency are presented in graphical form. Comparison with results that are based on exergy analysis alone shows the advantages of adopting such an approach for designing and operating thermal energy storage units.

Solid-fuel Rocket Engines: Layered Composite Materials Manufacturing and Thermal Diffusivity Measurements

Abstract This communication presents thermal diffusivity measurements of fourteen layered insulating composite materials. Composite materials that were taken under investigation contained matrixes based on epoxy and phenol-formaldehyde resins and reinforcements, such as glass, basalt fiber and wrapping or ceramic paper. They were all prepared by the Rocket Section of the Students Space Association (RS-SSA). Manufacturing process of samples is described. Additional objective of this research was to obtain the quality of such prepared materials and if they are reliable enough to be used in solid-fuel rocket motors. Use of composite materials to build combustion chamber walls of solid fuel rocket engines, rather than metal, leads to weight reduction and increases amount of fuel that rocket can carry. That improves performances and gives new possibilities for rocket applications. To apply new high performance solid fuels, development of new composite materials was required. Analysis of thermal properties gives the answer, which material should be used for new solid-fuel rockets designed by RS-SSA.