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1

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

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

Journal of KONES

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2011

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Vol. 18, No. 2

177-184

EN

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.

2

Flow modeling in a jet engine

Hlavńa V., Rajčan P.

Journal of KONES

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2010

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Vol. 17, No. 4

191-197

EN

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.

3

Vehicle braking parameters influencing factors

Labuda R., Toporcer E., Hlavńa V.

Journal of KONES

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2009

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Vol. 16, No. 4

257-264

EN

In automotive technology attributes of the "driver-vehicle-environment" system are described as "vehicle handling". The driver has control of the vehicle generally by means of directional guidance, acceleration and braking, on the other side different influences as are side wind, road irregularities, road profile, sudden obstructions etc.from the environment affect on the vehicle. The task of research and development in the field of vehicle control is to adjust the vehicle handling to the driving ability of an average driver so that the active safety of the vehicle and passengers maximizes. Some selected vehicle characteristics and relations which influence the vehicle dynamics in braking modes are analysed in the paper. In particular vehicle influencing forces at braking, slip curve of the wheel, velocity course at braking, simplified parameters course, measurement preparation, measurement from the initial velocity ni =90 km.h-1, maximum braking deceleration dependence on tire pressure and velocity ni 1 on dry surface, maximum braking deceleration dependency on tire pressure and velocity ni 1 on wet surface, maximum braking deceleration dependency on velocity ni 1 tire pressure on dry surface, Maximum braking deceleration dependency on velocity ni 1nd tire pressure on wet surface are presented in the paper.

4

The emission factor and a vehicle run-in period

Hlavńa V., Krakovsky T.

Journal of KONES

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2009

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Vol. 16, No. 2

175-181

EN

During operation on road and due to gradual ageing ofa vehicle, the formation of gaseous pollutants undergoes certain evolution. At the start of the vehicle life the evolution is influenced mostly by the run-in period of the driving mechanism. Motor vehicle manufacturers state that the vehicle run-in period ends after the vehicle has run from 3,000-15,000 kilometers depending on the engine type and transmission mechanism. During the run-in period the fuel consumption decreases and the production of emissions slightly changes, which consequently influences the emission factor. (The emission factor is understood as the ratio between the pollutant produced and the amount of consumed fuel). A theoretical value of the difference in the fuel consumption between the new and run-in vehicle is about 8% in favor of the run-in vehicle. The European legislation does not specify after how many kilometers the vehicle stops to be considered new. This can lead to disputes when testing emissions from the new vehicle and those from the vehicle having the control software already installed. The contribution outlines apossibility of determining the coefficient for calculation of emissions and fuel consumption for the first tested vehicle and for the one that has coveredfrom 60 to 300 kilometres. It may contribute to the optimization of the control software installed in the vehicle.

5

Non-conventional energetic system for ships

Hlavńa V., Sojćak D.

Journal of KONES

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2004

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Vol. 11, No. 1-2

218-222

EN

The paper describes a possibility of implementation of a non-conventional energetic system for ships. The described system is a source of heat at three levels, cool, refined electric energy and mechanical energy. Individual secondary energies are acquired by means of transformation of primary chemically bound energy in fuel. Primary energy is transformed by means of a combustion engine used as a driving unit of ships designed for transportation of passengers and goods. The paper contains a brief illustration of efficiency criterion by means of Carnot circulation for non-conventional system using energy and, consequently, exergy produced by means of a combustion engine. Mechanical energy can be used to drive a ship and its equipment. Exergy as a source of heat and cool for technological equipment of a ship. The implementation of a non-conventional system of a ship offers more possibilities for effective usage and increases energetic evaluation of the combustion engine in this means of transport.

6

The ice in a triyalent system of energy production

Hlavńa V.

Journal of KONES

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2003

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Vol. 10, No. 1-2

33-38

EN

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