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Digital model for analysis of two-dimensional direct current corona field and induced electrohydrodynamic air flow field in wire-to-plane electrode system is discussed. Finite-difference method in polar coordinate system is used for corona field computation. Results of computation of corona field are checked by comparison of digital and experimental data of current-voltage characteristics. Maximum difference of these values of linear current density is 150 µA/m corresponding to the voltage value of 7 kV. The digital model of EHD air flow field consists of finite-difference approximation of the Navier-Stokes equation and the continuity equation in Cartesian coordinates. Check of digital velocity values by comparison of these values with the experimental ones is only qualitative because of the distortion of corona field and air flow field by the probe of hot-wire anemometer. Ill. 6, bibl. 6 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.275

The paper analyses low grade heat recovery problem for modern woodfuel cogeneration plant. The woodfuel flue gas, behind the condensing economizer, still contains a considerable amount of heat, main part of which is the latent one. To recover this low grade heat, the heat pump technology can be used, which is related with additional consumption of energy (electric, mechanical or heat). Another technique that could be applied is a heat regeneration when flue gas heat, mostly latent, is transmitted to air blown towards burning chamber. Therefore, the analysed heat recovery system operates mainly like mass regenerator which contains only blowers that use some electric energy. The regenerator consists of two cyclically operating columns with packing material. Energetic analysis demonstrates that 13% of additional heat can be produced utilizing this low grade heat. The economic valuation shows that investment in a heat recovery system is quite effective; the payback time is about four years.

The paper is based on the study of Lithuania facing the need for huge investments in both the replacement of the Ignalina nuclear power station and the replacement of district heating production units in many of the existing systems. Lithuania has a big technical potential for implementing small‐scale combined heat and power production (CHP) systems. Meanwhile, such implementation needs public regulation to become feasible not only from a socio‐economic, but also from a business economic point of view. The study focuses upon the analysis of methods for the incorporation of technical, economical and environmental considerations into large‐scale investment decision‐making in the energy sector. The research study could be a guideline for determination of national potential for high efficiency CHP not only from the technical, but both the economical and the environmental point of view. Based upon the results of the study investigation and analysis, areas for improvement in current energy sector investment decision-making processes are highlighted, and areas for further research are recommended.

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