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The ice in a triyalent system of energy production

100%

Hlavńa V.

tom Vol. 10, No. 1-2

33-38

Cogeneration is one of the rational technologies of use of primary energy stored in fuel. Actually four "cogeneration" cycles are used: with gas turbines (Brayton cycle), with endothermic sources (Diesel, Sbat or Otto cycle), with steam turbines {Rankin cycle) and a combination (combination of Brayton and Rankin cycle). The paper deals with a new solution - a combined cogeneration unit that uses a diesel tractor engine reconstructed to a gas engine

Flow modeling in a jet engine

63%

Hlavńa V. , Rajčan P.

tom Vol. 17, No. 4

191-197

It is possible to monitor effects related to flow in a jet aircraft engine by the three basic approaches - analytical, numerical and experimental Each approach has undergone changes and has been developed to the stage of its effective use. To efficiently manage the scientific and research work it is appropriate to use effective links among all three basic approaches. An experimental approach requires a test stand on which the characteristics of a usually geometrically reduced object or the actual object itself are verified. The principles of geometric and hydrodynamic similarities are applied. This approach is time and economically demanding and not all aerodynamic processes can be reliably simulated. Other disaavantages can be the occurrence of measurement errors, errors due to changes in the scale, influences of chemical reactions and influence of Reynolds number. Due to a very fast onset, development and challenges of IT, the numerical approach has become mostly used. It can provide sufficient information on an examined phenomenon in a particular object. It does not need any substantial simpliflcations, it is less financially demanding than the experimental approach, but it needs efficient processors with a huge memory capacity. Its disadvantage is a relatively large dependence of achieved results accuracy on the perfection of numerical models and models of turbulence in the areas with prevailing influence ofviscosity. The usage ofanalytical relations from mathematical andphysical analysis of the flow fleld is the fundamental of the analytical approach of observing the laws related to flowing. The paper deals with possibilities, procedures, advantages, and disadvantages of the mentioned approaches together with a presentation of some results from research and development activities carried out by the authors.

The influence of intensity of charge air intercooling on diesel engine gas

51%

Hlavńa V. , Kovalčik A. , Krakovsky J. , Labuda R.

tom Vol. 18, No. 2

177-184

The intercooling of charge air is one way of possible arrangements done while preparing fuel for diesel engines with the objective of lowering the environmental load. Such intercooling has other positive effects, e.g. the output increase, decrease in the maximal temperature of engine working cycle, decrease in thermal load of functional parts in the combustion space. Coolers of different constructions and versions are used for the charge air intercooling. As we have already presented in conferences and professional journals, we have been engaged in basic research into the non-conventional energetic system with the cooling combustion engine (the engine cooling circle is the ejector of absorption cooling). The obtained cold can be used for different purposes, e.g. for air conditioning of the maintenance room, cooling of goods storage space in trucks and also for more intensive intercooling of the charge air. Simultaneously with the mentioned topics we have been partially dealing with the influence of more intensive intercooling on the engine ecological parameters. We have presented some results of mathematical modelling connected with the mentioned topic. The paper is a continuation of previous publications and focuses on results of the experiment observing a two-stage charge air intercooling to lower temperatures. The air-to-air cooler was used as the first intercooling stage while the second stage was performed by means of the water-air intercooler.