Wyniki wyszukiwania - BazTech

1

An optimization study on an eco-friendly engine cycle named as Dual-Miller cycle (DMC) for marine vehicles

Gonca G.

Polish Maritime Research

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2017

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nr 3

86--98

EN

The diesel engine is an indispensable part of technology and it is commonly used in land and marine vehicles. However, diesel engines release NOx emissions due to high combustion temperatures. They have harmful effects on the environment such as sources of photo-chemical fog and climate changes. Therefore, they must be reduced and limited. The Miller cycle application is a NOx control method and it is popular in the recent years to abate NOx produced from the internal combustion engines (ICEs). A performance investigation of a Dual-Miller cycle (DMC) engine in terms of power (PO), power density (PD) and effective efficiency (EE) has been performed using a new finite-time thermodynamics modeling (FTTM) in this study. The effects of engine design and operating parameters on the engine performance (EPER) have been examined. Additionally, the energy losses have been determined resulting from incomplete combustion (IC), friction (FR), heat transfer (HT) and exhaust output (EO). The results presented could be an essential tool for DMC marine engine designers.

2

Thermodynamic limits for work-assisted and solar assisted mass transfer operations

Sieniutycz S.

Archives of Thermodynamics

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2001

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Vol. 22, nr 3-4

17-36

EN

We displey a basic thermodynamic approach to endoreversible limits' of work that may be produced or consumed by a single resource flowing in an open system. To evaluate these limits we consider sequential work-assisted unit operations, in particular those of heating, evaporation and drying which run jointly with 'endoreversible' thermal machines (e.g. heat pumps.) We also compare structures of optimization criteria describing these limits in conventional operations of mass transfer and in work-assisted operations. Mathematical analogies between entropy production expressions in these two sorts of operations are helpful to formulate optimization criteria in both cases. In work-assisted unit operations, total power input is minimized at constraints which take into account dynamics of heat and mass transport and rate of work consumption. Finite-rate, endoreversible models include irreducible losses caused by thermal resistances to the classical exergy potential. Functions of extremum work, which incorporate residual minimum entropy production, are formulated in terms of initial and final states, total duration and (in discrete processes) number of stages. With a radiative engine as an example, extension of the present approach to thermodynamic limits of nonlinear processes is also discussed.

3

Thermodynamic Criteria for Optimization of Work-Assisted and Conventional Drying Operations

Sieniutycz S., Szwast Z.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2000

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Vol. 48, nr 3

315-332

EN

This work presents thermodynamic criteria for optimization of work-assisted drying operations and compares these criteria with those conventional drying operations in sequential systems. For the work-assisted operations, which run jointly with thermal machines, such as heat pumps, total power input is minimized at constrains which describe dynamics of energy and mass exchange. Finite-rate models take into account irreducible consumption of the classical exergy caused by lossy elements in the system. Optimal work functions, which incorporate a residual entropy production, are found in terms of end states, duration and (in discrete processes) number of stages. Mathematical analogies between entropy production expressions in work-assisted and conventional operations are helpful to formulate optimization criteria of the former.