Low-temperature plasma technology as part of a closed-loop resource management system

The results of this testing indicate that the agitated low-temperature plasma reactor system successfully converted carbon, hydrogen, and nitrogen into gaseous products at residence times that were about ten times shorter than those achieved by stationary processing. The inorganic matrix present was virtually unchanged by the processing technique. It was concluded that this processing technique is feasible for use as part of a close-looped processing resource management system

Removal of Particles from a Powdery Fouled Surface due to Impaction

Particulate fouling is defined as the unwanted deposition of particles on heat exchange surfaces. The fouling layer reduces the heat transfer rate and leads to inefficient operation. The net fouling rate is the result of the difference between the deposition rate and the removal rate of particles. One of the mechanisms that contribute to the removal of particles from powdery fouled surfaces is the collision of an incident particle with the fouled surface. In the present study, removal of particles from powdery fouled surfaces due to an incident particle impact is studied numerically and experimentally. A numerical model is developed to study the interaction of an incident particle with a bed of particles. The numerical model is based on the molecular dynamic theory of granular matter. The numerical model is tested for an incident copper particle hitting a bed of particles at different impact speeds. The numerical results are verified experimentally. An experimental setup has been built to study the removal of particles from powdery fouling layers due to an incident particle impact. It is shown that depending on the impact speed, zero, one, two or three particles are ejected from the powdery layer. By comparing the numerical results with the experimental measurements it is shown that the numerical results fit in the measured range of impact mentioned above. The numerical model will be used further to characterize the removal of particles from powdery fouling layers as function of particle size, material, incident particle impact speed and the bed of particles porosity

PARTICULATE FOULING GROWTH RATE AS INFLUENCED BY THE CHANGE IN THE FOULING LAYER STRUCTURE

Particulate fouling in biomass gasifiers is a majorproblem, which may lead to inefficient operation. As the fouling layer grows, its thermal resistance increases resulting in an increase in the surface temperature of the fouling layer. The increase in the fouling layer surface temperature can lead to sintering of the layer, which changes the layer structure from a fragile powder to a robust coherent structure. The influence of the change in the fouling layer structure on the growth rate of particulate fouling is studied experimentally. Impaction experiments were carried out to determine the velocities at which an incident particle sticks, bounces off or removes particles outof the fouling layer as a function of fouling layer structure. The sticking velocity of a particle hitting a clean tube is determined theoretically. The sticking velocity of a bronze particle hitting a bronze plate is 0.006 m/s, for a powdery layer is 0.3 m/s and for a sintered layer is 0.04 m/s. The change in the heat exchanger surface from solid to powdery increases the sticking velocity, which consequently speeds up the fouling process. The further change in the heat exchanger surface from powdery to sintered decreases the sticking velocity, which reduces back the fouling process. The change in the fouling layer structures affects the sticking velocity as well as the removal velocity of incident particles, which consequently affect the fouling process

Energy density and storage capacity cost comparison of conceptual solid and liquid sorption seasonal heat storage systems for low-temperature space heating

Sorption heat storage can potentially store thermal energy for long time periods with a higher energy density compared to conventional storage technologies. A performance comparison in terms of energy density and storage capacity costs of different sorption system concepts used for seasonal heat storage is carried out. The reference scenario for the analysis consisted of satisfying the yearly heating demand of a passive house. Three salt hydrates (MgCl2, Na2S, and SrBr2), one adsorbent (zeolite 13X) and one ideal composite based on CaCl2, are used as active materials in solid sorption systems. One liquid sorption system based on NaOH is also considered in this analysis. The focus is on open solid sorption systems, which are compared with closed sorption systems and with the liquid sorption system. The main results show that, for the assumed reactor layouts, the closed solid sorption systems are generally more expensive compared to open systems. The use of the ideal composite represented a good compromise between energy density and storage capacity costs, assuming a sufficient hydrothermal stability. The ideal liquid system resulted more affordable in terms of reactor and active material costs but less compact compared to the systems based on the pure adsorbent and certain salt hydrates. Among the main conclusions, this analysis shows that the costs for the investigated ideal systems based on sorption reactions, even considering only the active material and the reactor material costs, are relatively high compared to the acceptable storage capacity costs defined for different users. However, acceptable storage capacity costs reflect the present market condition, and they can sensibly increase or decrease in a relatively short period due to for e.g. the variation of fossil fuels prices. Therefore, in the upcoming future, systems like the ones investigated in this work can become more competitive in the energy sector.This project receives the support of the European Union, the European Regional Development Fund ERDF, Flanders Innovation & Entrepreneurship and the Province of Limburg. TU/e has received funding from European Union’s Horizon 2020 research and innovation programme under grant agreement Nº 657466 (INPATH-TES). The results of this study can contribute to the development of educational material within INPATH-TES

Sorption heat storage for long-term low-temperature applications: A review on the advancements at material and prototype scale

Sorption heat storage has the potential to store large amounts of thermal energy from renewables and other distributed energy sources. This article provides an overview on the recent advancements on long-term sorption heat storage at material- and prototype- scales. The focus is on applications requiring heat within a temperature range of 30–150 °C such as space heating, domestic hot water production, and some industrial processes. At material level, emphasis is put on solid/gas reactions with water as sorbate. In particular, salt hydrates, adsorbents, and recent advancements on composite materials are reviewed. Most of the investigated salt hydrates comply with requirements such as safety and availability at low cost. However, hydrothermal stability issues such as deliquescence and decomposition at certain operating conditions make their utilization in a pure form challenging. Adsorbents are more hydrothermally stable but have lower energy densities and higher prices. Composite materials are investigated to reduce hydrothermal instabilities while achieving acceptable energy densities and material costs. At prototype-scale, the article provides an updated review on system prototypes based on the reviewed materials. Both open and closed system layouts are addressed, together with the main design issues such as heat and mass transfer in the reactors and materials corrosion resistance. Especially for open systems, the focus is on pure adsorbents rather than salt hydrates as active materials due to their better stability. However, high material costs and desorption temperatures, coupled with lower energy densities at typical system operating conditions, decrease their commercial attractiveness. Among the main conclusions, the implementation within the scientific community of common key performance indicators is suggested together with the inclusion of economic aspects already at material-scale investigations.This project receives the support of the European Union, the European Regional Development Fund ERDF, Flanders Innovation & Entrepreneurship and the Province of Limburg. TU/e has received funding from European Union’s Horizon 2020 research and innovation programme under grant agreement No 657466 (INPATH-TES). The results of this study can contribute to the development of educational material within INPATH-TES