Poland, as for Europe, is a country with an average forest cover of approximately 30%. In these forests, more than 37M m3 of wood, mostly coniferous (over 80%), is harvested per year. In 2012, 4.2M m3 of sawn timber was produced (sawn timber without factory lumber). At the same time, in Poland there are over 8000 sawmills, whereas only about 700 of them saw over 90% of the harvested timber. So much fragmentation is a major cause of low sawmills innovation, particularly of those small ones. However, in recent years, a trend of development in this sector is noticeable, and it is through rationalisation of material and energy economy. One of the methods to increase the technical and economic effectiveness of enterprises involved in woodworking is to build in the combined heat and power system (CHP) plant with the ORC system into the existing infrastructure, which will be matched to the needs of the company. This article presents an analysis of the profitability of the investment based on the example of a medium-sized company sawing approximately 50,000 m3 of timber per year, and the economic analysis was performed for prices and costs valid in Poland. The analysis made for the 1650 kW(el) organic Rankine cycle (ORC) system, has resulted in a profitability index PI = 1.3, on the assumptions that the ORC system operates for 6000 h y(-1), will be purchased at the price of 4500 € kW(el)(-1) and at the price of electricity sales of 130 € MWh(-1).
The influence of vapor superheating on the level of heat regeneration in a subcritical ORC coupled with gas power plantThe authors presented problems related to utilization of exhaust gases of the gas turbine unit for production of electricity in an Organic Rankine Cycle (ORC) power plant. The study shows that the thermal coupling of ORC cycle with a gas turbine unit improves the efficiency of the system. The undertaken analysis concerned four the so called "dry" organic fluids: benzene, cyclohexane, decane and toluene. The paper also presents the way how to improve thermal efficiency of Clausius-Rankine cycle in ORC power plant. This method depends on applying heat regeneration in ORC cycle, which involves pre-heating the organic fluid via vapour leaving the ORC turbine. As calculations showed this solution allows to considerably raise the thermal efficiency of Clausius-Rankine cycle.
Skull base tumors form a highly heterogeneous group. As there are several structures in this anatomical site, a large number of different primary malignancies might develop, as well as a variety of secondary (metastatic) tumors. In this article, the most common malignancies are presented, along with a short histopathologic description. For some entities, an immunohistochemical profile is also given that should be helpful in proper diagnosis. As many pathologic diagnoses nowadays also include genetic studies, the most common genetic abnormalities in skull base tumors are presented.
In the paper presented are definitions of specific indicators of power which characterize the operation of the organic Rankine cycle (ORC) plant. These quantities have been presented as function of evaporation temperature for selected working fluids of ORC installation. In the paper presented also is the procedure for selection of working fluid with the view of obtaining maximum power. In the procedure of selection of working fluid the mentioned above indicators are of primary importance. In order to obtain maximum power there ought to be selected such working fluids which evaporate close to critical conditions. The value of this indicator increases when evaporation enthalpy decreases and it is known that the latent heat of evaporation decreases with temperature and reaches a value of zero at the critical point.
In the paper presented have been the results of the analysis of effectiveness of operation of binary power plant consisting of combined two Clausius-Rankine cycles, namely the binary cycle with water as a working fluid in the upper cycle and organic substance as a working fluid in the lower cycle, as well as a single fluid component power plant operating also in line with the C-R cycle for superheated steam, with water as a working fluid. The influence of the parameters of superheated steam in the upper cycle has been assessed as well as the type of working fluid in the lower cycle. The results of calculations have been referred to the single-cycle classical steam power plant operating at the same parameters of superheated steam and the same mass flow rate of water circulating in both cycles. On the basis of accomplished analysis it has been shown that the binary power plant shows a greater power with respect to the reference power plant.
This article presents an analysis of the efficiency of the ORC power plant with a wet circulating medium. The power plant is supplied from two heat sources, which are geothermal water streams obtained from the Lower Triassic and Middle Triassic Reservoirs. In the ORC system, it was assumed that one of these streams is directed to the superheater and the other to the evaporator. In the work, two variants of ORC power supply were considered. The first one, in which the maximum stream of water from the Middle Triassic Reservoir ṁg2 = 55 kg/s at a temperature of ${\rm{T}}_{{\rm{g1}}}^2$ = 104°C powers the evaporator, while the water stream from the Lower Triassic Reservoir ṁg1 = 25 kg/s at a temperature of ${\rm{T}}_{{\rm{g1}}}^1$$ = 128°C powers the superheater. In the second variant, the maximum water stream from the Lower Triassic Reservoir ṁg1 = 25 kg/s and a temperature of ${\rm{T}}_{{\rm{g1}}}^1$$ = 128°C feeds the evaporator, while the water stream from the Middle Triassic Reservoir ṁg2 at a temperature of ${\rm{T}}_{{\rm{g1}}}^2$ = 104°C supplies the superheater. In both variants, the geothermal water stream directed to the superheater is the size resulting from ORC plant operation and cannot exceed the maximum flow value for a given geothermal reservoir. The following working substances were taken into account in the analysis: cyclopropane, R143a, R32, propylene, R22, propane, R134a. The analysis carried out showed that in the ORC power plant with a two-source supply the maximum system power was obtained in the case of the first variant for the working medium R143a.
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