Environment impact of a concentrated solar power plant

More recently, there has been an increasing interest in the use of concentrated solar thermal energy for the production of electricity, but also for the use in cogeneration and trigeneration. In this sense, the increasing use of solar thermal energy in urban areas is expected, and its impact on the environment is inducing an increasing interest. The paper analyses the impact of concentrated solar power technology (linear Fresnel, parabolic trough, parabolic dish, and central tower) on the environment in terms of water consumption, land use, wasted heat, emissions of gases, emissions of pollutants that include the leakage of heat transfer fluid through pipelines and tanks, impact on flora and fauna, impact of noise and visual impact. The impact on the environment is different for different concentrated solar power technologies and depends on whether thermal energy storage is included in the plant. Water is mainly used for cooling the system, but also for cleaning the surface of the mirror. To reduce water consumption, other cooling technologies (e.g. air cooling) are being developed. The available data from the literature show large variances depending on the size of the plant, geographic location and applied technology

Višekriterijski model skladištenja rezervnih dijelova

Inventory control of spare parts is essential to many organizations. Excess inventory leads to high holding costs and a large commitment of funds. In the other hand stock outs can have a great impact on production or service. The paper proposes a methodology for spare parts inventory control applying multicriteria inventory model. It is based on ranking and classifying the spare parts in groups according to similar attributes. Each group of spares, depending on attributes of the spares that belong to it, joins the appropriate inventory policy model and forecasting demand model.Upravljanje skladištem rezervnih dijelova bitno je za mnoge tvrtke. Prevelika količina na zalihi vodi do velikih troškova skladištenja i velikog angažmana novčanih sredstava, a s druge strane nedostatak rezervnih dijelova na zalihi u vrijeme njihove potražnje može imati velike posljedice na proizvodnju ili usluge. Ovaj članak predlaže metodologiju upravljanja skladištem rezervnih dijelova primjenjujući višekriterijski model skladištenja. On se zasniva na rangiranju i svrstavanju rezervnih dijelova u skupine prema sličnim svojstvima. Svakoj skupini rezervnih dijelova, ovisno o karakteristikama dijelova koji joj pripadaju, pridružuje se odgovarajuća politika skladištenja te odgovarajući model predviđanja potražnje

Experimental Testing of PV Module Performance

This study compares the manufacturer\u27s technical data of several PV modules with real measured outdoor technical data. The irradiance effect on several PV modules is examined by the changing a tilt angle and comparing different meteorological situations of sky clearness (clouds) on the modules mounted outdoor and exposed to Sun. Also, the influence of temperature and dust on the performance of a PV panel is under research using measurement methods described in the paper. The measured current and voltage data at the clean surface of the PV module correspond to the declared data of the PV module manufacturer, and in the case of fouling of the module surface with dust, a power drop of 7.39% was measured

Modelling the Stages of Turbocharger Dynamic Reliability by Application of Exploitation Experience

Turbocharger is an important part of marine diesel engine installed as main propulsion on board. It is in operation from the outset and throughout the marine diesel engine exploitation. In order to meet high reliability criteria, a combination of mathematical, IT and simulation methods should be used. The original mathematical model of turbocharger has been shown in five stages. The paper presents database link from the AMOS maintenance software package, a mathematical model elaborated by using Markov chains and a systematic-dynamic simulation model elaborated in the POWERSIM simulation programme. Results will be used to monitor and predict reliability and availability of turbocharger in ship’s propulsion system

Unbalance Response Analysis of a Rotor Kit with Two Identical Discs Located Between Bearings

In this paper, the dynamic behavior of a rotor kit with two identical disks located between the plain bearings was analyzed. Modal and harmonic analysis of this rotor kit configuration were performed in the Ansys software package. To calibrate the bearing parameters (stiffness and damping) in the numerical model, experimental measurements of the rotor kit with a disc mounted at the midspan of the shaft were performed. As a result of modal analysis, natural frequencies and models were obtained. Using the Campbell’s diagram, the critical speeds and the influence of the gyroscopic effects on the natural frequencies were determined. The responses of the rotor kit to different unbalance distributions were considered by harmonic analysis

Vortex cooled air turning of induction-hardened raceway on the wind turbine-bearing ring

In the turning process of hard materials with CBN cutting inserts, metalworking fluid is not advisable as it results in poorer quality of finished surface and shortening of the tool life. Dry machining, otherwise, develops excessive heat, residual stresses in the workpiece material due to thermal stress, and therefore causes possible problems of achieving tolerances on larger workpieces. During the dry turning of induction hardened raceway on the wind turbine-bearing ring of 1500 mm in diameter, problems with achieving tolerances occurred. The vortex-cooled air implementation during turning resulted in achieving designing tolerances of the workpiece, with better surface roughness and with less tool wear. The result was 50% lower cost of cutting inserts and small operating costs associated with air consumption. The vortex-cooled air implementation makes it possible to extend the tool life of CBN cutting inserts and thus higher cost-effectiveness of machining

Finite Element Analysis of a Shrink Fitted Disc-Shaft Rotating System

In this paper, the shrink fit between the conical disk and the rotor shaft of a steam turbine was analysed with the aim of determining the rotor speed at which this fit is lost. The analysis was carried out numerically using the finite element method (FEM) in the Ansys software package. Three design values of disc-shaft joint interference were considered: minimum, maximum and mean. The rotor speed at which the shrink fit is lost is the lowest for minimum interference and the highest for maximum interference, which was expected. In other words, the rotor speed at which the shrink fit is lost is a linear function of the amount of interference (the allowance). The results of the analysis showed that the considered interferences of the shrink fit ensured the smooth transmission of torque in the range of speeds up to the operating speed and that the operation of the turbine is safe from that point of view

Transport emissions and electric mobility in private transport in the Republic of Slovenia

Since the ratification of the Kyoto Protocol more and more emphasis is laid on reducing greenhouse gas emissions. The article analyses the feasibility of introducing electric vehicles into traffic rather than vehicles with internal combustion engines. From standpoint of emission sources use of electricity for transport is analysed with stress on private cars and typical emissions from power sector by energy conversion in Slovenia. Results of research shows that electric car has a little more than twice better efficiency of the primary energy use, taking into account only efficiency in the energy chain. Electric mobility brings a more efficient use of energy in road transport with demand to reduce emission at power generation. So presented number can vary greatly, depending on the electrical energy source. In the present research problems connected with immediate initiation of the electric cars are not analysed

Environmental Impact of Geothermal Power Plants

Today, there is a growing awareness of the need for environmental protection and a healthy ecological environment. Given the growing popularity of renewable energy sources, they should be familiar with their environmental impact. Each renewable energy source has more or less environmental impacts that are most often compared to the influence of conventional fuels on the environment. The aim of this article is to show the potential impacts of geothermal power plants on the environment both in the construction phase and in the phase of regular work. Environmental impacts may be temporary or irreversible and include changes in habitats and land use, atmospheric emissions, increased noise, impact on surface and groundwater, land subsidence, occurrence of seismicity and solid waste disposal. The magnitude of the influence depends on the characteristics of the geothermal source, the applied thermodynamic cycle, and the applied abatement systems

Development of a new type of finned heat exchanger

Opisan je novi geometrijski oblik lamele (igličaste lamele) za orebrene cijevne izmjenjivače topline plin – tekućina pomoću kojeg se postiže veći koeficijent prijelaza topline, a time i manja masa izmjenjivačkih površina u odnosu na izmjenjivače topline s okruglim lamelama koji su u ovom slučaju poslužili kao baza za usporedbu. Za analizu izmjene topline i pada tlaka primijenjena je računalna dinamika fluida s programom ANSYS Fluent. Numerička simulacija provedena je za slučaj zagrijavanja zraka koji struji oko cijevi s lamelama novog geometrijskog oblika te oko cijevi s lamelama konvencionalnog kružnog oblika brzinama od 1 m/s do 5 m/s. Rezultati numeričke simulacije obzirom na izmijenjenu toplinu i pad tlaka za cijevi s okruglim lamelama provjereni su pomoću korelacija dostupnih u literaturi te su uspoređeni s rezultatima simulacije za cijevi s inovativnim lamelama. Rezultati pokazuju povećanje iznosa Nu značajke od 20 % do 30 % za 2300 > Re > 12000 uz smanjenje mase izmjenjivačkih površina od 23,8 %.A new geometric form of fins (needle fins) for finned heat exchangers of gas-liquid type is described. It achieves a higher heat transfer coefficient and lower mass of the heat exchange surface relative to the heat exchangers with circular fins which in this case served as a basis for comparison. For the analysis of the heat transfer, the computational fluid dynamics analysis with ANSYS Fluent software was applied. Numerical simulation was performed for the round fins and fins with a new, innovative geometric shape at air flow speeds of 1 m/s to 5 m/s. The results of numerical simulations, with regard to the exchanged heat and pressure drop were verified by the correlations available in the literature and compared to the simulation results for tubes with innovative fins. Results show an increase in the amount of Nu from 20 % to 30 % for 2300 >Re > 12000 while reducing mass of heat exchange surfaces of 23,8 %