Experimental and Theoretical Research on Pressure Drop Changes in a Two-Stage Air Filter Used in Tracked Vehicle Engine

Differences in Performance and Conductivity Persistence of New Reduced Graphene Oxide Air Filter Materials before and after Eliminating Static Electricity

Improving the filtration efficiency of air filter materials is an ongoing research goal. This study conducted in-depth research on a new reduced graphene oxide air filter material, and the differences in its performance and conductivity durability before and after eliminating static electricity were tested and analyzed. The results showed that the filtration efficiency of the reduced graphene oxide air filter material significantly decreased after eliminating static electricity. The maximum decrease in filtration efficiency was observed at a filtration velocity of 0.8 m/s, with PM10 > PM1.0 > PM2.5. In this case, the filtration efficiency decreased by 11.8%, 7.98%, and 7.17%, respectively. The maximum difference in filtration efficiency of 0.29 μm particulates was about 12.7%. Eliminating static electricity slightly increased the resistance (2.5~15.5 Pa). In addition, the new reduced graphene oxide air filter material exhibited good conductivity and stability after continuous testing. This study provides data support for the application of subsequent electrification sterilization, reference values for multi-angle applications, and the development of new composite air filter materials.

Experimental Studies of Welded Joints in Structures Subject to High Impact Vibrations Using Destructive and Non-Destructive Methods

This article presents the issues of control and quality assurance of high-strength railway rail joints. Selected test results and requirements for rail joints made by welding with stationary welders on the basis of the requirements included in the PN-EN standards have been described. In addition, destructive and non-destructive tests of weld quality were performed, including visual tests, geometrical measurements of irregularities, magnetic particle and penetration tests, fracture tests, observations of micro- and macro-structure and hardness measurements. The scope of these studies included conducting tests, monitoring the process and evaluating the results obtained. Laboratory tests on the rail joints confirmed the good quality of the rail joints from the welding shop. Increasingly less damage to the track in places of new welded joints is proof that the methodology of laboratory qualification tests is correct and fulfils its task. The presented research will help educate engineers on the welding mechanism and the importance of quality control of rail joints during their design. The results of this study are of key importance for public safety and will improve knowledge on the correct implementation of the rail joint and how to conduct quality control tests in accordance with the requirements of the currently applicable standards. It will help engineers choose the right welding technique and choose solutions to minimize cracks.

Experimental Study of the Effect of Air Filter Pressure Drop on Internal Combustion Engine Performance

The paper presents the problem of the effect of air filter pressure drop on the operating parameters of a modern internal combustion engine with compression ignition. A literature analysis of the results of investigations of the effect of air filter pressure drop on the filling, power and fuel consumption of carburetor and diesel engines with classical injection system was carried out. It was shown that each increase in the air filter pressure drop Δpf by 1 kPa results in an average decrease in engine power by SI 1–1.5% and an increase in specific fuel consumption by about 0.7. For compression ignition engines, the values are 0.4–0.6% decrease in power and 0.3–0.5% increase in specific fuel consumption. The values of the permissible resistance of the air filter flow Δpfdop determined from the condition of 3% decrease in engine power are given, which are at the level of 2.5–4.0 kPa—passenger car engines, 4–7 kPa—truck engines and 9–12 kPa—special purpose vehicles. Possibilities of decreasing the pressure drop of the inlet system, which result in the increase of the engine filling and power, were analyzed. The program and conditions of dynamometer engine tests were worked out in respect to the influence of the air filter pressure drop on the operation parameters of the six-cylinder engine of the swept volume Vss = 15.8 dm3 and power rating of 226 kW. Three technical states of the air filter were modeled by increasing the pressure drop of the filter element. For each technical state of the air filter, measurements and calculations of engine operating parameters, including power, hourly and specific fuel consumption, boost pressure and temperature, were carried out in the speed range n = 1000–2100 rpm. It was shown that the increase in air filter pressure drop causes a decrease in power (9.31%), hourly fuel consumption (7.87%), exhaust temperature (5.1%) and boost pressure (3.11%). At the same time, there is an increase in specific fuel consumption (2.52%) and the smoke of exhaust gases, which does not exceed the permissible values resulting from the technical conditions for admission of vehicles to traffic.

A Method of Analyzing the Residual Values of Low-Emission Vehicles Based on a Selected Expert Method Taking into Account Stochastic Operational Parameters

Increasing the market share of low-emission vehicles in relation to individual mobility is one of the main postulates of modern transport policy. In the discussion on low-emission and the new structure of the car fleet, the role of new vehicles is emphasized above all, ignoring the importance of the secondary market. In recent years, both in Poland and in other European Union countries, there has been a noticeable dynamic development of electromobility implementation processes in urban areas, the initial effect of which is increasing market accessibility to commercial vehicles with electric EV/BEV, hybrid HEV/PHEV and fuel cell powered FCEV. As in the case of vehicles powered by conventional ICEV fuels, also in relation to those defined as low-emission, their residual value is lost along with the operational process. Information on this variable is important both for the owner of a newly purchased vehicle, which after the period of its operation will decide to sell it as well as to the future buyer. The scientific aim of the study is to analyze the residual values of selected vehicle models from the primary and secondary market, with particular emphasis on stochastic operational phenomena. The subject of the research is to obtain extensive knowledge on the achieved changes in the residual values of low-emission vehicles in relation to ICEVs. For this purpose, a comparative analysis of the commercial program, data approximated from auction portals and own numerical modeling tool based on a neural network was performed. The research sample included, among others, selected models of passenger cars, the purchase offer of which included the choice of a drive unit powered by conventional and low-emission fuels. The use of this method allowed to answer the question whether low-emission vehicles are characterized by a greater or lesser loss of value in relation to conventionally powered vehicles ICEV.