Vedran Mrzljak

Vedran Mrzljak
University of Rijeka Faculty of Engineering

PhD

About

146
Publications
105,828
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1,442
Citations
Introduction
Energy and exergy analysis; Analysis and optimization of power plants; Energy systems and processes; Steam turbines; Gas turbines; Marine engineering; Marine power systems

Publications

Publications (146)
Article
Full-text available
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...
Article
Full-text available
Air heaters are commonly used devices in steam power plants. In base-loaded conventional power plants, air heaters usually use flue gases for air heating. In this paper, the air heater from a marine steam propulsion plant is analyzed, using superheated steam as a heating medium. In a marine propulsion plant, flue gases from steam generator are not...
Conference Paper
Full-text available
This paper presents an energy analysis of middle-power steam turbine with two cylinders (High Pressure Cylinder-HPC and Low Pressure Cylinder-LPC) and steam re-heater after the HPC (and before the LPC). Based on a steam operating parameters from the literature, performed energy analysis show that LPC develops higher power and has higher energy effi...
Conference Paper
Full-text available
In this paper, two-cylinder steam turbine, which operates in nuclear power plant is analyzed from the energy viewpoint. Along with the whole turbine, energy analysis is performed for each turbine cylinder (High Pressure Cylinder-HPC and Low Pressure Cylinder-LPC). A comparison of both cylinders shows that the dominant mechanical power producer is L...
Conference Paper
Full-text available
Gas emissions from power plants and gas turbines use fossil fuels as their energy source and have a detrimental effect on people and the environment, one of the harmful gases obtained by burning fossil fuels is Nitrogen Oxide which can have harmful effects on humans. This research boils down to the use of artificial intelligence algorithms from the...
Conference Paper
Full-text available
A standard maintenance methodology used in the majority of modern technical systems is corrective maintenance. This methodology is based on the removal of the malfunction by repairing or replacing broken components. Such an approach can be expensive due to the prolongate diagnostic and repair procedures. An alternative approach is to use predictive...
Conference Paper
Full-text available
In this paper is performed exergy analysis of steam reheating system, through all of its components, which operate in nuclear power plant. Analyzed reheating system consists of the moisture separator (MS) and two re-heaters (RH1 and RH2) and is observed in four different operating regimes. MS has significantly lower exergy destructions and signific...
Conference Paper
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This paper presents thermodynamic (energy and exergy) analysis of backpressure (BPT) and condensing (CT) steam turbines from cogeneration system. Based on the measurement data from exploitation it is performed calculation of main operating parameters for both turbines and its comparison. Analysis shows that BPT develops significantly lower mechanic...
Conference Paper
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This paper presents an exergy analysis of a complex four-cylinder steam turbine, which operate in a coal-fired power plant. Analyzed steam turbine consists of high pressure single flow cylinder (HPC), intermediate pressure dual flow cylinder (IPC) and two low pressure dual flow cylinders (LPC1 and LPC2). The highest part of cumulative mechanical po...
Conference Paper
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In this paper is performed energy evaluation of steam turbine from the solar-based combined cycle power plant which includes analysis of each cylinder and the whole turbine. Steam turbine has three cylinders-high, intermediate and low pressure cylinders (HPC, IPC and LPC). Observed turbine is interesting because it possesses steam cooling before it...
Article
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Bladder cancer is one of the most common malignancies in men in Croatia. It is characterized by a high recurrence rate and high metastatic potential. For this reason, accurate and timely diagnosis is needed in order to treat bladder cancer as successfully as possible. Cystoscopy as a diagnostic method shows poorer accuracy of Carcinoma in situ (CIS...
Article
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The paper presents steam turbine power, energy and exergy efficiencies and losses analysis during steam extractions opening/closing. The analyzed steam turbine can be used in steam power plant or in the marine steam propulsion system (low-power steam turbine). Steam extractions opening and closing can have a notable influence on various turbine ope...
Article
Full-text available
The scavenging process is an important part of the two-stroke engine operation. Its efficiency affects the global engine performance such as power, fuel consumption, and pollutant emissions. Slow speed marine diesel engines are uniflow scavenged, which implies inlet scavenging ports on the bottom of the liner and an exhaust valve on the top of the cy...
Article
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A thermodynamic analysis of CO2 closed-cycle gas turbine is presented in this paper. Two processes are investigated-base process and the same process upgraded with a heat regenerator. Maximum specific useful work is 159.94 kJ/kg for both observed processes. Involving of heat regenerator inside base CO2 closed-cycle gas turbine process requires atte...
Conference Paper
Full-text available
This paper presents an energy and exergy analyses of two steam turbines from geothermal double flash power system. Along with the calculation of efficiencies and losses, in the exergy analysis is performed variation of the ambient temperature to investigate its influence on the obtained results. Low pressure turbine (LPT) produces higher real mecha...
Conference Paper
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In this paper is performed energy analysis of the gas turbine upgraded with heat regenerator. The analysis is performed by using air and combustion gases operating parameters measured in the real exploitation, therefore all the losses are considered during calculations (only the mechanical losses which has low influence on the overall energy balanc...
Conference Paper
The shipping sector is becoming increasingly aware of global environmental impact of ships and is forced, by international legislation, to gradually reduce its emissions. International conventions (IMO) and energy efficiency standards set challenges to shipping sector, to ship owners and ship designers, to offer propulsion concepts which will effec...
Article
Full-text available
Urinary bladder cancer is one of the most common cancers of the urinary tract. This cancer is characterized by its high metastatic potential and recurrence rate. Due to the high metastatic potential and recurrence rate, correct and timely diagnosis is crucial for successful treatment and care. With the aim of increasing diagnosis accuracy, artifici...
Article
The maritime industry is becoming increasingly aware of the global environ- mental impact of ships and is being forced, by international legislation, to gradually reduce its emissions. International Maritime Organization conven- tions and energy efficiency standards set challenges to shipping sector, to ship owners and ship designers, and to offe...
Article
Full-text available
Inverse kinematic equations allow the determination of the joint angles necessary for the robotic manipulator to place a tool into a predefined position. Determining this equation is vital but a complex work. In this article, an artificial neural network, more specifically, a feed-forward type, multilayer perceptron (MLP), is trained, so that it co...
Conference Paper
Full-text available
In this paper is performed exergy analysis of three cylinder steam turbine from the supercritical coal-fired power plant. Exergy analysis parameters were calculated for the whole turbine and each cylinder for the ambient temperature range between 5 °C and 45 °C. The dominant mechanical power producer of all the cylinders is a low pressure cylinder...
Article
Full-text available
In this paper is performed energy and exergy analysis of waste heat recovery closed-cycle gas turbine system. Analyzed system can use waste heat from various main propulsors (gas turbines or internal combustion engines). Basically, the observed system operates by using CO 2 , what was the baseline for the analysis. It is investigated did the observ...
Article
Full-text available
The paper discusses the possibility of applying the trigeneration energy concept (cogeneration + absorption cooling) on diesel-powered refrigerated ships, based on systematic analyses of variable energy loads during the estimated life of the ship on a predefined navigation route. From a methodological point of view, mathematical modeling of predict...
Article
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This paper presents an exergy analysis of the whole turbine, turbine cylinders and cylinder parts in four different operating regimes. Analyzed turbine operates in nuclear power plant while three of four operating regimes are obtained by using optimization algorithms-SA (Simplex Algorithm), GA (Genetic Algorithm) and IGSA (Improved Genetic-Simplex...
Conference Paper
Full-text available
Inverse kinematics is one of the key parts of any industrial robotic manipulator modeling. Solving the inverse kinematics of a robotic manipulator in the classical analytical manner is fairly complex and error-prone. While previous research has shown the possibility of AI application for inverse kinematics solutions, such models have certain pitfal...
Preprint
Full-text available
This paper presents an exergy analysis of the whole turbine, turbine cylinders and cylinder parts in four different operating regimes. Analyzed turbine operates in nuclear power plant while three of four operating regimes are obtained by using optimization algorithms-SA (Simplex Algorithm), GA (Genetic Algorithm) and IGSA (Improved Genetic-Simplex...
Preprint
Full-text available
In this paper is performed exergy analysis of three cylinder steam turbine from the supercritical coal-fired power plant. Exergy analysis parameters were calculated for the whole turbine and each cylinder for the ambient temperature range between 5 °C and 45 °C. The dominant mechanical power producer of all the cylinders is a low pressure cylinder...
Preprint
Full-text available
This paper presents exergy analysis of the main steam condenser, which operates in nuclear power plant. The analysis is performed in four main condenser operating regimes (loads) for a variety of the ambient temperatures. It is found that the main steam condenser has the lowest exergy destruction (equal to 72091.56 kW) and the highest exergy effici...
Conference Paper
Full-text available
This paper presents a calculation of energy and exergy efficiency with energy and exergy losses of the entire nuclear power plant and all of its constituent components. The main idea of the performed analysis is to be a baseline for further improvements and optimizations of the entire nuclear power plant or any of its components. Assumed energy eff...
Conference Paper
Full-text available
This paper presents efficiencies and losses comparison of 5 different turbofan engines for aircraft propulsion. With some exceptions these turbofan engines were generally comprised of the following components: fan, low-pressure compressor, high-pressure compressor, combustion chamber, high-pressure turbine, and low-pressure turbine. The comparison...
Conference Paper
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The paper presents calculation results of carbon dioxide emissions from a ship's steam generator during the usage of different fuel types for 23 different loads. The calculation is done for the combined usage of HFO (Heavy Fuel Oil) and natural gas which is the standard working mode for the observed steam generator. After this, the calculation of C...
Conference Paper
Full-text available
This paper presents an analysis and comparison of a real open and closed cycle gas turbine process. Analysis is performed by using operating parameters of six different working mediums (air, helium, CO2, neon, argon, nitrogen). The most notable difference is that a real open cycle process uses air and contains a combustion chamber and its dissipate...
Article
Full-text available
In this paper, the publicly available dataset for the Combined Diesel-Electric and Gas (CODLAG) propulsion system was used to obtain symbolic expressions for estimation of fuel flow, ship speed, starboard propeller torque, port propeller torque, and total propeller torque using genetic programming (GP) algorithm. The dataset consists of 11,934 samp...
Conference Paper
Full-text available
In this paper is performed exergy analysis of high pressure feed water heating system and all of its components which operates in nuclear power plant. Four cases are observed: system operation in the base case and system operation in three optimized cases. Exergy analysis show that optimization by using different algorithms has a different influenc...
Conference Paper
Full-text available
In this paper is analyzed back-pressure steam turbine which operates in CHP (Combined Heat and Power) plant from the aspect of energy and exergy losses. Produced turbine power, used for electricity generator drive equals 62548.77 kW, while the turbine mechanical loss is 1934.50 kW. Exergy analysis of the turbine shows that cumulative exergy loss...
Conference Paper
Full-text available
In this paper is performed energy analysis of the whole low power steam turbine as well as energy analysis of all the turbine segments. Analysis of the whole turbine resulted with energy loss of 14642.48 kW and energy efficiency of 75.01%, what is in range with similar comparable low power steam turbines. Energy analysis of the turbine segments p...
Conference Paper
Full-text available
This paper presents an analysis and comparison of three steam turbines and its cylinders: from the conventional steam power plant, from nuclear power plant and from the marine propulsion plant. The best parameters for the comparison of whole turbines and its cylinders are: energy loss per unit of produced mechanical power, exergy destruction per...
Article
Full-text available
Urinary bladder cancer is one of the most common urinary tract cancers. Standard diagnosis procedure can be invasive and time-consuming. For these reasons, procedure called optical biopsy is introduced. This procedure allows in-vivo evaluation of bladder mucosa without the need for biopsy. Although less invasive and faster, accuracy is often lower....
Article
The thermodynamic (energy and exergy) analysis of a condensate heating system, its segments, and components from a marine steam propulsion plant with steam reheating is performed in this paper. It is found that energy analysis of any condensate heating system should be avoided because it is highly influenced by the measuring equipment accuracy and...
Article
Full-text available
This paper investigates the possibility of the implementation of Genetic Programming (GP) algorithm on a publicly available COVID-19 data set, in order to obtain mathematical models which could be used for estimation of confirmed, deceased, and recovered cases and the estimation of epidemiology curve for specific countries, with a high number of ca...
Article
Full-text available
This paper present energy and exergy analysis of the main marine steam turbine, which is used for the commercial LNG (Liquefied Natural Gas) carrier propulsion, at four different loads. Energy analysis is performed by using four different methods. The presented analysis allows distinguishing advantages and disadvantages of all observed energy analy...
Article
Full-text available
This paper presents an exergy analysis of marine waste heat recovery CO2 closed-cycle gas turbine system. Based on the operating parameters obtained in system exploitation, it is performed analysis of each system component individually, as well as analysis of the whole observed system. While observing all heat exchangers it is found that combustion...
Conference Paper
Full-text available
This paper presents a comparison of three methods for any pump energy analysis. Each method is used for the analysis of three different water pumps from the conventional steam thermal power plant-two feed water pumps (FWP1 and FWP2) and condensate pump (CP). For each pump three essential types of mechanical power which defines all energy analysis m...
Conference Paper
Full-text available
This paper present energy and exergy evaluation of CO 2 closed-cycle gas turbine process. The most important operating parameters of the whole observed cycle, as well as of each of its constituent components are presented and discussed. In the observed process, produced useful mechanical power for the power consumer drive is equal to 5189.78 kW, wh...
Article
Full-text available
The paper presents an analysis of two steam turbine operation regimes-regime with all steam extractions opened (base process) and regime with all steam extractions closed. Closing of all steam extractions significantly increases turbine real developed power for 5215.88 kW and increases turbine energy and exergy losses with simultaneous decrease of...
Conference Paper
Full-text available
In this paper is performed energy analysis of the dual-flow dissymmetrical low pressure steam turbine, which operates in a coal-fired power plant. Based on the measured operating parameters during exploitation it is calculated and presented an ideal and real power, energy losses and energy efficiencies of a whole turbine and both of its cylinders....
Preprint
Full-text available
This paper presents an exergy analysis of marine waste heat recovery CO2 closed-cycle gas turbine system. Based on the operating parameters obtained in system exploitation, it is performed analysis of each system component individually, as well as analysis of the whole observed system. While observing all heat exchangers it is found that combustion...
Conference Paper
Full-text available
COVID-19 (also known as coronavirus or SARS-CoV-2) is a highly infectious disease which has gripped the lives and minds of people across the world. Due to its high infection rate, as well as potentially deadly symptoms and long-lasting health risks involved with it, governments across the world have applied various measures to combat the spread of...
Article
Full-text available
This article presented an improvement of marine steam turbine conventional exergy analysis by application of neural networks. The conventional exergy analysis requires numerous measurements in seven different turbine operating points at each load, while the intention of MLP (Multilayer Perceptron) neural network-based analysis was to investigate th...
Chapter
In this chapter, a methodology for the utilization of edge-detector based hybrid artificial neural network (ANN) models for urinary bladder cancer is presented. The diagnosis of the bladder cancer can often be complex and it requires invasive diagnostic methods such as biopsy and histopatological evaluation. ANN utilization can provide faster and l...
Article
Full-text available
One of the challenges in medical data classification is the determination of the sufficient training dataset size. In this research, the effect of training dataset size on various artificial neural network (ANN) configurations is shown. All ANNs are trained and tested using Wisconsin Breast Cancer (Diagnostic) Dataset, which contains 569 samples. D...
Article
Full-text available
The atmospheric drain condensate system of a marine steam power plant is described and evaluated from the energetic and exergetic point of view at a conventional liquefied natural gas (LNG) carrier. Energy loss and exergy destruction rate were calculated for individual stream flows joined in an atmospheric drain tank with variations of the main tur...
Article
Full-text available
In this paper is presented an analysis of gland seals operation and their influence on the performance of low power steam turbine with two cylinders and steam reheating, which can be used in marine applications. Performed analysis presents a comparison of steam turbine main operating parameters when gland seals operation is neglected (as usual in t...
Article
Full-text available
This paper presents a comparison of conventional and heat balance based energy analyses of steam turbine. Both analyses are compared by using measured operating parameters from low power steam turbine exploitation. The major disadvantage of conventional steam turbine energy analysis is that extracted energy flow streams are not equal in real (polyt...
Conference Paper
Full-text available
Previous work has determined the ability of using the Multilayer Perceptron (MLP) type of Artificial Neural Network (ANN) to estimate the power output of a Combined Cycle Power Plant (CCPP) in which optimization did not focus on the solver parameter optimization. In previous work, the solvers used the default parameters. Possibility exists that opt...
Conference Paper
Full-text available
This paper present analysis of energy flow streams through the main steam turbine (the turbine is used for commercial LNG carrier propulsion) at three different loads. An increase in the propulsion plant (and proportionally increase in th