2018 - Repozytorium publikacji - Politechnika Gdańska

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Publikacje z roku 2018

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Experimental determination of general characteristic of internal combustion engine using mobile test bench connected via Power Take-Off unit
- Oskar Wysocki
- Jacek Kropiwnicki
- Tomasz Zajdziński
- Jacek Czyżewicz
2018
The general characteristics of the engine include information about the regions of the engine's operating area that are most efficient, where specific fuel consumption reaches the smallest values. Economic operation based on those characteristics can contribute to a significant reduction of fuel consumption and consequently less pollutant emissions and lower costs. The paper presents an experimental method of determination of general characteristic of internal combustion engine mounted in a truck chassis. Experimental tests focus on low torque and engine speed range, which is observed during operation of the body Refuse Collection Vehicle. To conduct the measurements, the specially designed test bench was used. The collected data from two engines was processed applying machine learning methods, which were described and compared to obtain best regression model. Determined general characteristic was used to evaluate fuel consumption in a time period of variable engine load. Finally, simulated total fuel used for both engines in different engine speeds and load were compared. Results show significant differences in total fuel consumption depend on engine speed, thus it is an evidence that there is a large field to improvement in propulsion system configuration.
EXPERIMENTAL EVALUATION OF DLC/STEEL SLIDING CONTACTS’ OPERATIONAL ENVELOPE
- Jacek Łubiński
- Michał Wasilczuk
2018 Pełny tekst TRIBOLOGIA
In an industrial project concerning sliding bearings, a sliding pair was selected of high alloy steel vs. industrial grade DLC coated high alloy steel as a basis for an innovative design of high performance sliding bearings lubricated with a synthetic oil for use in geared transmission units. The development process required credible data on the ultimate resistance of the sliding pair to very high contact stress. An experimental evaluation was undertaken in ring-on-ring contact with an incremental semi-steady state input parameters increase. Due to restrictions in time, economy, and manufacturing, the number of specimen sets available was limited. A flexible approach to specimen use and load/velocity/time combinations was employed to deliver required test results within the available resource limitations and at constantly updated project detailed goals.
Experimental examination and modification of chip suction system in circular sawing machine
- Jacek Barański
- Marcin Jewartowski
- Jan Wajs
- Kazimierz Orłowski
- Tomasz Pikała
2018 Pełny tekst Drvna Industrija
The article presents the results of experimental examination of the wood chip suction system in the existing sliding table saw before and after its modifi cation. The studies focused on the extraction hood of the mentioned system. The methodical experimental research of the pressure distribution inside the hood during wood chip removal for the selected rotational speed of saw blades of 3500 and 6000 min-1 with a diameter of 300 mm and 450 mm were carried out. The analysis of the results allowed estimating the areas with insufficient vacuum pressure hindering the organized transport of wood chips in the sliding table saw. That pressure was the main factor infl uencing the decision to adjust the hood construction. To achieve the efficient performance, several changes in the hood geometry were implemented. The results obtained from the experiments were used at the stage of shape modifi cation of the extraction hood. As a result, a new design of the chip suction system was obtained, vastly improving the chip extraction from the tool.
Experimental investigation of forced convection of water/EGAl2O3 nanofluids inside horizontal tube
- Janusz Cieśliński
- Przemysław Kozak
2018
In this paper, forced convection of water/EG-Al2O3 nanofluids inside horizontal stainless steel tube is studied experimentally. As base fluid served water/EG mixture of two ratios (60:50 and 50:50). Nanoparticle mass concentrations was 0.1% or and 1%. Transition and turbulent flow regimes were tested. Average heat transfer coefficient and pressure drop values were determined for nanofluids and compared to base fluids. Deterioration of heat transfer for all tested nanofluids has been recorded compared to base fluid. Negligible increase of pressure drop for nanofluids compared to base fluids has been observed.
Experimental Investigation of the Thermal Performance of a Wickless Heat Pipe Operating with Different Fluids: Water, Ethanol, and SES36. Analysis of Influences of Instability Processes at Working Operation Parameters
- Rafał Andrzejczyk
2018 Pełny tekst ENERGIES
In this study, the influences of different parameters on performance of a wickless heat pipe have been presented. Experiments have been carried out for an input power range from 50 W to 300 W, constant cooling water mass flow rate of 0.01 kg/s, and constant temperature at the inlet to condenser of 10 C. Three working fluids have been tested: water, ethanol, and SES36 (1,1,1,3,3-Pentafluorobutane) with different filling ratios (0.32, 0.51, 1.0). The wall temperature in different locations (evaporation section, adiabatic section, and condenser section), as well as operating pressure inside two phase closed thermosyphon have been monitored. The wickless heat pipe was made of 0.01 m diameter copper tube, which consists of an evaporator, adiabatic, and condensation sections with the same length (0.4 m). For all working fluids, a dynamic start-up effect caused by heat conduction towards the liquid pool was observed. Only the thermosyphon filled with SES36 was observed to have operation limitation caused by achieving the boiling limit in TPCTs (two-phase closed thermosyphons). The geyser boiling effect has been observed only for thermosyphon filled with ethanol and for a high filling ratio. The performance of the thermosyphon determined the form of the heat transfer resistance of the TPCT and it was found to be dependent of input power and filling ratio, as well as the type of working fluid and AR (aspect ratio). Comparison with other authors would seem to indicate that lower AR results in higher resistance; however, the ratio of condenser section length to inside diameter of pipe is also a very important parameter. Generally, performance of the presented thermosyphon is comparable to other constructions.
Experimental investigation of two-phase thermosyphon heat exchanger charged with acetone
- Janusz Cieśliński
- Maciej Fabrykiewicz
2018 Pełny tekst
This paper presents thermal characteristics of prototype of a two-phase thermosyphon heat exchanger (TPTHEx) charged with acetone as a working fluid. The TPTHEx consists of two horizontal cylindrical vessels connected by two risers and a downcomer. Tube bundles placed in the lower and upper cylinders work as an evaporator and a condenser, respectively. The tested TPTHEx operates in a vacuum. Therefore, the working liquid is boiled in temperatures ranging from 33ºC to 62ºC. The overall heat transfer coefficient (OHTC) of the tested TPTHEx was estimated by the use of the Wilson method and the modified Peclet equation. The results obtained indicate a superiority of water over acetone as a working fluid. Moreover, it was shown that having a lower pressure in the shell-side of TPTHEx results in a higher overall heat transfer coefficient. The Wilson method and the modified Peclet equation predict OHTC with satisfactory agreement.
Experimental investigation on straight and u-bend double tube heat exchanger with active and passive enhancement methods
- Rafał Andrzejczyk
- Tomasz Muszyński
- Przemysław Kozak
2018 Pełny tekst MATEC Web of Conferences
Authors in this work want to demonstrate the possibility to increase the heat transfer efficiency by using simple wire coil inserts to create turbulent flow in the boundary layer as well as air blowing into the annulus of the pipe. In the study, Wilson plot approach was applied in order to estimate heat transfer coefficients for all heat exchanger (HX) configurations. The study focuses on experimental values of heat transfer coefficient (HTC) and pressure drops. The primary objectives of the work are to: I. Provide an experimental comprehensive database for HTC and pressure drops; II. Analysis effect of different flow conditions e.g.. water mass flow rate, the void fraction on heat transfer and hydraulic performance of tested elements. III. Compare influences of both passive and active methods at the efficiency of simple heat exchangers constructions; IV. Validation experimental results with selected experimental models from the open literature.
Experimental investigations and simulations of the microturbine unit with permanent magnet generator
- Wojciech Włodarski
2018 Pełny tekst ENERGY
In dispersed power generation, low power devices are used for local combined generating of heat end electric power. There are developing concepts of micropower plants with electric generators driven by steam or gas microturbines. The paper presents the results of an experimental investigations of the microturbine set consists of the turbine with partial admission, permanent magnet generator and three phase AC-to-DC rectifier. The microturbine was designed for steam of HFE7100 as a working medium. The dynamic behavior of the microturbine unit was experimentally examined. Microturbine unit was tested during changes of the parameters of the working medium or the electrical load. Experiments were performed with compressed nitrogen as a working medium. The dynamic model of microturbine unit was developed. The examples of the comparison between experiment results and simulations are shown and discussed in the paper.
Experimental investigations on heat transfer enhancement in shell coil heat exchanger with VARIABLE Baffles GEOMETRY
- Rafał Andrzejczyk
- Tomasz Muszyński
- Marta Gosz
2018 CHEMICAL ENGINEERING AND PROCESSING
The paper presents the possibility of using passive intensification of heat transfer in the form of baffles to increase the energy efficiency of the shell and coil heat exchanger. The experiment was carried out by using a modular coil heat exchanger in the form of an electric heater. Water was used as a working fluid with constant thermal-flow parameters at the inlet of the module. It should be noted that experiments were made for a large range of power i.e. from 200 W to 1200 W and with mass flow rates from 0.01 kgs-1 to 0.03 kgs-1. For this flow range, Reynolds numbers were obtained in the field 150<Re<450. Consequently, all experiments were carried out for laminar flow conditions. This work shows, that due to the presence of mixed convection, natural convection has a significant effect on small values of Reynolds numbers and large values of Richard's numbers. Also, the baffles location has a significant influence on HX performance. The proposed solution of the shell coil exchanger with a baffle is characterized by better heat transfer efficiency on the shell side, but rather for lower values of Reynolds (Re <150) numbers and high values of heat fluxes. For all configurations is noticeable the influence of the supplied heat flux value on the rate of heat transfer. The paper presents new experimental Nusselt numbers correlation on the shell side of the heat exchanger with core-baffles. This correlation depends on Grashoff and Dean numbers as well as dimensionless shell diameter (C/D0), the correlation also includes Prandtl number. Experimental data were compared with selected correlations from literature as well as with own correlation. It was shown that only own semi-empirical correlation has satisfactory compliance with experimental results within 35% error band and with less than 8% of absolute deviation. The considered construction has markedly better heat transfer efficiency on the shell side for small Reynolds numbers (Re<150) comparing to the tube-in-tube exchanger with wire coil turbulator (over 20%).
Experimental Investigations On The Momentum Pressure Drop During Flow Boiling Of R134a
- Tomasz Muszyński
- Rafał Andrzejczyk
- Carlos Alberto Dorao
2018 Pełny tekst Journal of Physics : Conference Series
The article presents experimental investigations of the pressure drop during twophase flow. Experiments were performed for both adiabatic and heated flow of R134a. Obtained flow patterns were compared with the literature. Obtained data is used to validate momentum pressure drop predictions, a set of graphs showing comparisons, for a representative set of experimental conditions, of the two-phase frictional pressure gradients for the adiabatic and diabatic flow. The model proposed in the article allows to predict both values and peak pressure drop with very good accuracy. Verification of the momentum pressure drop predictions for two-phase adiabatic flow showed that all correlations have good agreement with experimental data.
EXPERIMENTAL RESEARCH ON INFLUENCE OF THE FUEL NOZZLE GEOMETRY ON THE FUEL CONSUMPTION OF THE MARINE 4-STROKE DIESEL ENGINE
- Jerzy Kowalski
- Jan Nagórski
- Gregorz Sikora
2018 Pełny tekst Journal of KONES
The article presents experimental research that has been carried out on a marine, 4-stroke, 3-cylinder, turbocharged engine. During testing, the engine operated at a constant rotational speed of 750 rpm and a load from 0 kW to 280 kW. The engine was fuelled by diesel oil of known specification and loaded by electric generator with water resistance. The fuel consumption was measured during the engine operation with fuel nozzles with different geometries. The measurement of the fuel consumption was carried out using a weighing system that was designed, constructed, and manufactured by the “KAIZEN” scientific research team at the Faculty of Mechanical Engineering at the Gdynia Maritime University. The results of measurements show changes in the fuel consumption by the engine with the geometry of the injected fuel spray. The research facility is Sulzer’s 3- cylinder, 4-stroke, turbocharged AL25/30 piston engine. The fuel system consists of Bosch injection pumps controlled by a rotation speed regulator. Fuel injectors are centrally located in the cylinder heads of the engine.
Experimental research on over-laminated steel sandwich panel connection to determine the form of fatigue failure
- Karol Niklas
- Janusz Kozak
2018 Pełny tekst AIP Conference Proceedings
The novel means of transport need to meet rising both the economic and ecologic requirements. In recent years the International Maritime Organization (IMO) introduced new measure of ship energy efficiency (the EEDI index), as well as new regulations regarding higher quality of fuel (so called Tier limits). It resulted in much higher interest of the technological development of ships. One of the solution having great potential is the reduction of structural mass. It has at least two positive consequences. The first is the reduction of fuel consumption, the second is possibility if increasing of a ship payload. Both aspect are very beneficious considering the need of meeting the EEDI requirements. The one very lightweight form of structure which is in use in many different branches are sandwich type structures. In a shipbuilding industry this solutions is also being constantly developed. One of the major issue for these thin walled structures is connection between panels and between panels and an ordinary ship structure. For rising fatigue resistance of the connection the over-laminated joint concept was introduced. In this article results of fatigue research on sandwich panels joint with the CFRP overlays are presented. The experimental research was performed in a full scale to identify the form of fatigue failure. On the basis of the research three characteristic stages of fatigue damage were identified.
Experimental study and numerical optimization of tensegrity domes – A case study
- Karol Winkelmann
- Filip Kłos
- Mateusz Rąpca
2018 Pełny tekst
The paper deals with the design, experimental analysis and numerical optimization of tensegrity dome models. Two structures are analyzed – a Geiger system dome (preliminary dome), with PVC-U bars and PA6/PP/PET tendons and a Fuller system dome (target dome), with wooden bars and steel cables as tendons. All used materials are experimentally tested in terms of Young's modulus and yield stress values, the compressed bars are also tested for the limit length demarcating the elastic buckling from plastic failure. The data obtained in experiments is then implemented in SOFiSTiK commercial software FE model. The model’s geometrical parameters are considered uniform random variables. Geometrically and materially nonlinear analysis is carried out. Based on the obtained structural response (displacements), a Monte Carlo simulation – based approach is incorporated for both structural design point formulation and the SLS requirements fulfillment analysis. Finally, an attempt is made to erect the Fuller dome model in order to compare the numerical results of an experimentally–derived model with the in situ measurements of an actual structure.
Experimental study of shear strength and failure mechanisms in RC beams scaled along height or length
- Jan Suchorzewski
- Ewelina Korol
- Andrzej Tejchman-Konarzewski
- Zenon Mróz
2018 ENGINEERING STRUCTURES
Artykuł omawia wyniki doświadczalne efektu skali w belkach żelbetowych bez zbrojenia pionowego. Belki żelbetowe były zeskałowane wzdłuż wysokości i długości. Zaobserwowane 3 różne mechanizmy zniszczenia w doświadczeniach. Wyniki efektu skali porównano z niektórymi wzorami analitycznymi z literatury.
Experimental study of the effect of vertical acceleration component on the slope stability
- Aleksandra Korzec
- Robert Jankowski
2018 Pełny tekst Journal of Measurements in Engineering
The paper deals with the stability of earth dams subjected to seismic and paraseismic excitations occurring in the close distance to the dam. The Newmark’s stability approach, classified as a simplified dynamic method, has been extended for two directional dynamic loading case and the evolution of the friction coefficient. The paper is focused on the experimental verification of the proposed method for harmonic and cyclic excitations generated by a simple oscillating device as well as by one-directional shaking table. Main assumptions of the proposed method have been proved and the effect of the vertical acceleration on the stability of the dam has been demonstrated. In the experiments conducted under cyclic loading, the impact of the vertical acceleration on the permanent displacement of the block was equal to 57 %. However, in general, the exact magnitude of this impact depends on many factors, such as the vertical to horizontal peak ground acceleration ratio or frequency range of the vertical component of the earthquake.
Experimental study of the use of electric car powered with stationary solar and electrochemical batteries in Northern Poland
- Dariusz Karkosiński
- Michał Pacholczyk
- Łukasz Sienkiewicz
2018 Pełny tekst
The subject of this paper is an experimental analysis of a Nissan LEAF electric car equipped with 24 kWh battery, powered from the standalone photo-voltaic (PV) charging station in Gdańsk, Poland. The calculations of charging process efficiency and range of test drives were conducted in two extreme situations (winter and summer) of sunlight and road conditions. Experiments were performed in the Laboratory of Innovative Power Technologies and Integration of Innovative Energy Sources (LINTE^2) at Gdańsk University of Technology. The car was night-charged with the stationary electrochemical battery, which, in turn, was powered with PV panels during the day. The impact of sunlight and ambient temperature changes on daily urban and highway drive ranges was analysed. The efficiency of energy conversion in multiple current converters was determined.
Experimental study on the seepage flow through the ice jam
- Tomasz Kolerski
- Małgorzata Bratnikow
2018 Pełny tekst
In light of the observed climate change, there is a need for better understanding of river ice processes for managing water resources in the cold regions. Ice jams produce significant resistance which may cause rise of water level and flooding. The jam resistance is only referred to the roughness of its underside, and this approach lead to exceptional roughness coefficients which has no physical explanation. Number of evidences and facts showed the analogy between the seepage flow in the ice jam and flow in open channel over rough, permeable bed. Base on the experiments where flow over rough, gravel bed was investigated it was concluded that the velocity over the bed is not zero, thus the seepage flow in the gravel exists. Taking all this into consideration, experiments conducted on ice jam model can help to develop theories on gravel bed, as well as during the study some theories from permeable bed can be adopted. This paper describes the first approach to gain preliminary understanding on the flow resistance of river ice jams. The study was carried out using the facilities at Gdansk University of Technology (GUT) where all hydraulic experiments were conducted. Experiments were proceed in hydraulic laboratory as a scale model of the real ice jam, because measurements in rivers are extremely dangerous and nearly impossible due to the risk of ice jam release during the surveying of the water velocity. Therefore scale model was set up to reproduce the typical condition observed in rivers. Since the facility on Gdansk University of Technology has no possibility to lower the room temperature to below freezing, the material similar to the ice was used instead (polypropylene, PP). Results shown that significant amount of water discharge formed the seepage flow through the jam voids.
Experimental validation of pressure drop models during flow boiling of R134a – effect of flow acceleration and entrainment
- Tomasz Muszyński
- Rafał Andrzejczyk
- Carlos Alberto Dorao
2018 Pełny tekst MATEC Web of Conferences
A crucial step to assure proficient work of power and process apparatus is their proper design. A wide array of those devices operates within boiling or condensation of the working fluid to benefit from high heat transfer rates. Two-phase flows are associated with high heat transfer coefficients because of the latent heat of evaporation and high turbulence level between the liquid and the solid surface. Predicting heat transfer coefficient and pressure drop is a challenging task, and has been pursued by researchers for decades. In the case of diabatic flows, the total pressure drop is due to the change in kinetic and potential energy. The article presents detailed boiling pressure drops data for R134a at a saturation temperature of 19.4oC. Study cases have been set for a mass flux varying from 300 to 500 kg/m2s. Presented data along with the data reduction procedure was used to obtain the momentum pressure drop values during flow boiling. The study focuses on experimental values of momentum pressure drop component and its prediction based on various void fraction models and entrainment effects.
Experimental verification of visual method for measuring displacements of contact line elements
- Jacek Skibicki
2018 Pełny tekst MATEC Web of Conferences
The increase of rail vehicles speed, as well as the increase of their power, puts high demands on the power delivery system for traction vehicles The most critical point in the vehicle's power supply circuit is the contact between the current collector and contact wires. Ensuring a reliable co-operation of the current collector and contact line, requires technical development of the contact line and current collector construction, as well as improvement of diagnostic systems of these components. This is translated into the need to develop new measurement methods, which allow for more complete definition of the parameters of these elements of traction vehicle power supply system. Each new measurement method requires verification, performed by calibrating or comparing the results with another measurement method which has already been tested. The article presents results of experimental verification of a visual method for measuring the displacement of contact wires, with a proven method based on short range laser rangefinders and calliper as reference measurement.
Expert opinion on the effectiveness of protection against electric shock in case of fault in an installation for electric vehicles charging
- Stanisław Czapp
2018
The opinion concerns the use of residual current devices for protection against electric shock by automatic disconnection of supply in a Norwegian installation intended for charging of electric vehicles.