Thermal and bifurcation characteristics of heat-recirculating conversion of gaseous fuels

The paper investigates the possibility of utilization of heat-recirculating systems for fuel conversions having low net thermal effect. The experimental part is conducted with an electrically heated heat exchanger. It is shown that heat-recirculating systems can operate under superadiabatic conditions. Their thermal characteristics are provided by means of the dependencies of heat recirculation ratio on process parameters. Further, the heat-recirculating catalytic combustion system is characterised via combustion bifurcation diagrams. The similarities and differences of both those heat-recirculating systems are qualitatively compared and explained. Bifurcation characteristics proves to be useful tools in concise description of practical complex heat-recirculating fuel conversion systems in energy generation

Effect of pressure on conversion of gaseous fuels in structured catalytic reactors

Zbadano wpływ wysokiego ciśnienia na konwersję i gradienty stężeniowe w procesie spalania i oksyformowania węglowodorów w strukturalnym reaktorze katalitycznym. Zdefiniowano, scharakteryzowano i wykorzystano w przykładzie wyrażenia S przydatne w analizie oporów dyfuzyjnych występujących w reaktorach strukturalnych wysokociśnieniowych. Zaproponowano metodykę nastawiania ciśnienia w reaktorach strukturalnych.The paper investigated the effect of high pressure on conversion and concentration gradients in combustion and oxyforming of hydrocarbons in structured catalytic reactors. The terms S were defined, characterized and used for the analysis of transport resistances exhibited in high-pressure structured reactors. The method for pressure elevation in structured reactors was proposed

A heat recirculator for superdiabatic combustion of low-calorific industrial gases

Zaproponowano rckuperacyjny recyrkulator ciepła. Przedstawiono zależności stopnia recyrkulacji ciepła R od mocy elementu grzejnego i masowego strumienia przepływającego gazu (m). W zastosowanej geometrii aparatu uzyskano RA na poziomie 11, co potwierdza przydatność rccyrkulatora w praktyce przemysłowej do superadiabatycznego spalania gazów niskokalorycznych. Wskazano, że straty cieplne ulegają zmniejszeniu przy większych wartościach m. Stwierdzono, że nachylenie funkcji R(m) zmniejsza się dla wyższych m.The paper proposed the heat recirculator. The dependencies of the heat re-circulation ratio R on the power of heater and on the mass flow rate of gas (m) were provided. In the current geometry R as high as 11 was attained, which confirmed suitability of the heat recirculator in industrial practice for superadiabatic combustion of low-calorific gases. It was indicated that heat losses were reduced for higher values of m. It was found that the slope of R(m) decreased for higher values of m

Recent key technical barriers in solid oxide fuel cell technology

High-temperature solid oxide fuel cells (SOFCs) are considered as suitable components of future large-scale clean and efficient power generation systems. However, at its current stage of development some technical barriers exists which limit SOFC’s potential for rapid large-scale deployment. The present article aims at providing solutions to key technical barriers in SOFC technology. The focus is on the solutions addressing thermal resistance, fuel reforming, energy conversion efficiency, materials, design, and fuel utilisation issues

Perspectives for low-carbon electricity production until 2030: lessons learned from the comparison of local contexts in Poland and Portugal

This paper compares perspectives for low-carbon electricity production in two EU member states - Poland and Portugal until 2030. Electricity production capacities, carbon emissions of electricity production, and production cost of electricity (COE) of Poland and Portugal are analyzed. The dilemmas of investments into low-carbon electricity production technologies relying on: (i) renewable energy sources (RES), (ii) nuclear fuel, and (iii) fossil fuels integrated with carbon capture and sequestration (CCS) are discussed. Roadmap 2050 recommends about 40% decarbonization of electricity generation by 2030 and 100% by 2050. Based on electricity productionmix forecast for 2030, carbon emissions of electricity are estimated at 163 GgC TWh(e)(-1) in Poland and at 93.2 GgC TWh(e)(-1) in Portugal. Therefore, both compared countries must implement energy policies aimed at carbon emissions reduction through expanded utilization of RES (Poland - bioenergy, wind; Portugal - hydro, wind, solar), advanced CCS options (using local synergy opportunities), and optionally nuclear power (Poland).POKL.08.01.04-02-003/08info:eu-repo/semantics/publishedVersio

Environment-Controlled Postsynthetic Modifications of Iron Formate Frameworks

New hybrid iron-formate perovskites have been obtained in high-pressure reactions. Apart from the pressure range, also the liquid environment of the sample regulates the course of transformations. Formate α-DmaFe2+Fe3+For6, when compressed in oil and in isopropanol at 1.40 GPa, transforms to a new phase γ, different than that phase β obtained at low-temperature. In glycerol phase α can be compressed to 1.40 GPa, but then reacts to DmaFe2+For3, with all Fe(III) cations reduced, surrounded by amorphous iron formate devoid of Dma cations. Another mixed-valence framework Dma3[Fe2+3Fe3+For6]2·CO2, can be produced from phase α incubated in methanol and ethanol at 1.15 GPa. These pressure-induced environment-sensitive modifications have been rationalised by the volume effects involving the oxidation states of Fe(II) and Fe(III), their high- and low-spin states as well as the properties of pressure transmitting media. The topochemical redox reactions controlled by pressure and the liquid environment offer new highly efficient, safe and environment-friendly reactions leading to new advanced materials and their post-synthesise modifications.</b