Actual and Future Perspectives of Isothermal NSC-Engines

It is doubtless that the world population, energy consumption and worldwide environment and biosphere pollution are growing almost synchronously and exponentially and this fact is causing enormous environmental problems and will continue to do so (CO2, NOX and the consequences; global earth warming, global earth dimming, ozone hole, global climate changes etc. The energy reserves of the planet will be approx. until the end of the actual century well exhausted). One can deduce that the solutions for a number of mentioned problems are in the improvement of some of the primary causal factors, especially the current thermal engines. This can satisfactorily be achieved only: A) By developing new high efficiency thermal engine concepts, e.g. the newly-developed “NSC-Concept” (NSC=New Stirling engine Concept [1]), and on this concept based “Isothermal NSC-engines [4]”, geared for consequent use of actual conventional and alternative energy sources (e.g. all combustible gases - especially hydrogen, solar energy sources, geothermal and other energy sources and waste heat or waste cold sources). B) By invention and application of new energy sources and technologies, especially the industrial hydrogen production and in this way to start the “Hydrogen energy age” [3]. This topic and NSC-concept was thoroughly analysed by the first author (PhD Thesis [1]). Both authors reported about it several times and recently in [5], [6] and [12]. The research results show that new isothermal NSC-engines are and will be suitable for nearly all application fields of the actual thermal engines. The paper presents an overview of the latest results of the above-mentioned research and presents actual and possible future application perspectives of isothermal process based thermal NSC-engines

Performance Simulation of Marine Slow-Speed Diesel Propulsion Engine With Turbocharger Under Aggravated Conditions

The paper elaborates a mathematical model forming the basis for a computer-simulated model for a diesel propulsion engine. The model is applied in the analysis of steady and transient operating conditions of a turbocharged slow-speed diesel propulsion engine and a fixed blade propeller. Special attention has been paid to examining the stability and availability under aggravated operating conditions such as difficulties in scavenging and turbocharging system. The analysis of the results has established ultimate limits of affecting features and has defined safe operating conditions, in particular those of the turbocharging system. The analyses and the model can be used in finding better design characteristics and in expert operating systems which can analyse different conditions of the system beforehand and offer optimum operating conditions in order to prevent unwanted occurrences

STEADY STATE PERFORMANCES ANALYSIS OF MODERN MARINE TWO-STROKE LOW SPEED DIESEL ENGINE USING MLP NEURAL NETWORK MODEL

Compared to the other marine engines for ship propulsion, turbocharged two-stroke low speed diesel engines have advantages due to their high efficiency and reliability. Modern low speed ”intelligent” marine diesel engines have a flexibility in its operation due to the variable fuel injection strategy and management of the exhaust valve drive. This paper carried out verified zerodimensional numerical simulations which have been used for MLP (Multilayer Perceptron) neural network predictions of marine two-stroke low speed diesel engine steady state performances. The developed MLP neural network was used for marine engine optimized operation control. The paper presents an example of achieving lowest specific fuel consumption and for minimization of the cylinder process highest temperature for reducing NOx emission. Also, the developed neural network was used to achieve optimal exhaust gases heat flow for utilization. The obtained data maps give insight into the optimal working areas of simulated marine diesel engine, depending on the selected start of the fuel injection (SOI) and the time of the exhaust valve opening (EVO)

New Stirling Engine Concept (NSC-Engine) with Application of Direct Heat Introduction

Korisnost toplinskih motora izravno je ovisna o temperaturi i o razlici temperatura njihovih toplinskih spremnika (zagrijača i hladnjaka). Dosadašnja poboljšanja termičke korisnosti Stirlingovih motora postizavana su isključivo povišenjem temperature njihovih zagrijača, a mogućnosti poboljšanja korisnosti tih motora sniženjem temperature njihovih hladnjaka nisu bile ispitivane u dostatnoj mjeri. Znanstvenim radom Servisa ispitivan je utjecaj sniženja rashladnih spremnika topline do kriogeničkih temperatura na značajke Stirlingovih motora. Rezultati tih znanstvenih istraživanja pokazuju ujednačen, vrlo zamjetan porast korisnosti i snage ispitivanih motora do dubokoga, kriogeničkog područja temperatura hladnjaka motora. Na osnovi tog istraživanja bilo je moguće napraviti popis mjera za postizanje poboljšanja klasičnoga Stirlingova motora. Ta poboljšanja su postiziva primjenom načela izravnog dovođenja i odvođenja topline od procesa motora, realizacijom hlađenja motora ubrizgavanjem i naknadnim isparavanjem radnog medija u cilindru motora i hlađenjem motora do kriogeničkih temperatura. Primjena navedenih mjera rezultirala je razvojem “Novoga koncepta Stirlingovih motora (NKS-motor ≡ NSC-engine)”. To su motori tipa PROFIT0, PROFIT1 i PROFIT2, koji su zaštićeni patentima. NKS-motori, izvedeni po tom “Novom konceptu”, mogu postizati najviše moguće termičke korisnosti i snage, bitno veće nego današnji toplinski motori. Ti motori će, skoro neograničeno, moći koristiti razne izvore energije (kao i nositelje topline i hladnoće) i funkcionirati s “nultim” ili s “vrlo malim zagađivanjem” okoliša (bez ili s vrlo sniženim CO2- i NOx-emisija).The effi ciency of thermal engines is directly dependent on the temperatures and temperature differences of their heat reservoirs (heater and cooler). Up to now the improvements of the Stirling engine’s effi ciency have been exclusively achieved through the increase of the engine hot-side temperatures, whereas the possible improvements of the engine thermal effi ciency by lowering their cold-side temperatures, have not been thoroughly researched. In the research work of Wilhelm Servis the infl uence of lowering the engine cold-side temperature down to the deep, cryogenic temperature range on the Stirling engine performance was investigated. The research work results show a regular, very perceptible increase of thermal effi ciency and brake power by lowering the cold-side temperatures of the investigated engines down to the cryogenic temperature ranges. On the basis of this investigation it was possible to defi ne a list of measures to be taken to achieve improvements of the classic Stirling engine. These improvements were achieved through the application of the principle of the direct heat input and output from the engine process, the realisation of engine cooling through the injection and additional evaporation of liquefi ed working medium in the engine cylinder, and the engine cooling down to the cryogenic temperature range. The application of the mentioned measures has led to the development of the “New Stirling Engine Concept (NSC-engine ≡ NKS-motor)”. These are the engine types PROFIT0, PROFIT1 and PROFIT2, covered by pending and obtained patents. The NSC-engines, realised on the basis of this “New Concept” have the highest possible achievable thermal effi ciency and power production, substantially higher than the presently used thermal engines. These engines, will be able to use nearly any energy source (also porter of heat and cold) and also will be able to operate as real “class zero” or “class ultra low emission” engines (no or very low CO2- and NOx-emissions)

Quasi-dimensional diesel engine model with direct calculation of cylinder temperature and pressure

U ovom radu prikazan je kvazi-dimenzijski numerički model, implementiran u prethodno razvijeni 0D model. Prikazani model koristi direktan izračun jednadžbi za prirast tlaka i temperatura zona u cilindru, bez upotrebe numeričkih iteracija koje su uobičajene za ove modele. U modelu je prikazan proces usrednjavanja iz seta malih paketa (volumena) mlaza goriva u veliki paket, što je nužna pretpostavka numeričke stabilnosti modela. Model koristi oko pedeset podmodela. Simulacije su provedene za četiri najosjetljivija radna parametra u cilindru motora. Direktno rješavanje jednadžbi prirasta tlaka i temperature u cilindru, u kombinaciji sa usrednjavanjem paketa mlaza goriva, predstavlja doprinos u kvazi-dimenzijskom modeliranju procesa u dizelskom motoru.This paper describes the quasi-dimensional numerical model, implemented in previously developed 0D model. The presented model uses direct solution of equations for cylinder pressure and zone temperatures, without numerical iterations which are customary for these models. In the model there is shown a process of averaging from a set of small fuel spray packages (volumes) into big ones, which is a necessary precondition for the numerical stability. The model uses about fifty submodels. Simulations were performed in eight operating points, on four most sensitive engine cylinder operating parameters. Direct solution of temperature and pressure changes, in conjunction with the fuel spray packages averaging, represents a contribution to quasi-dimensional diesel engine process modelling

SIMULATION OF DIESEL ENGINE CYLINDER PROCESS USING QUASI-DIMENSIONAL NUMERICAL MODEL

This paper describes the developed quasi-dimensional numerical model, implemented in the 0D numerical model for direct injection diesel engine simulation. Quasi-dimensional model uses direct solution of equations for cylinder pressure and zone temperatures, without numerical iterations. Numerical model validation has been performed on measured working parameters of the diesel engine with direct fuel injection. After a successful validation, in which simulations have been examined, the movement of various operating parameters in the engine cylinder has been performed. Operating parameters movement for the whole cylinder and the zone without combustion is shown. Except the displayed operating parameters, numerical model monitors thermodynamic processes that occur in spray fuel packages (volumes), from the beginning of the fuel injection into the cylinder, until the opening of the exhaust valves. The developed numerical model goal is to monitor a large part of the engine operating parameters, which have a major impact on the engine working process. Some of them would be difficult or impossible to measure with the existing measuring equipment. Numerical model offers accuracy and precision in the engine operating parameters prognosis. Calculation of single engine process takes less than a minute on a conventional personal computer

Simulacija dinamičkih uvjeta rada dizelmotora s prednabijanjem kod pogona električnog generatora : doktorska disertacija

Sažetak disertacije "Simulacija dinamičkih uvjeta rada dizelmotora s prednabijanjem kod pogona električnog generatora" nije dostupan

Simulacija dinamičkih uvjeta rada dizelmotora s prednabijanjem kod pogona električnog generatora : doktorska disertacija

Sažetak disertacije "Simulacija dinamičkih uvjeta rada dizelmotora s prednabijanjem kod pogona električnog generatora" nije dostupan