GAS DISTRIBUTION PHASES HYDRAULIC CONTROLLED INTERNAL COMBUSTION ENGINE VALVES

The efficiency of an agricultural car or tractor depends on the characteristics of the engine determined by the gas distribution mechanism (GRM). Traditional timing with fixed valve timing does not provide high-quality gas exchange at all engine operating modes. The aim of the work is to improve the characteristics of the engine by using the hydraulic drive of the timing valves. The drive allows you to turn off individual valves, set the moments of their opening and closing in an arbitrary way, provide several triggering of the internal combustion engine valves during the operating cycle. The drive is controlled by an electronic control unit (ECU). The advantage of the drive is its ease of integration into the internal combustion engine. The hydraulic drive ensures that the timing valves are lifted to a height of about 14 mm. The law of displacement of the valve, revealed experimentally, is close to trapezoidal. The use of a hydraulic valve drive has a positive effect on the "time-section" factor in the area of low and medium crankshaft rotational speeds. The increment of the factor "time-section" is due to the significant speeds of opening and closing the valves. Due to the peculiarities of the kinematic characteristics of the movement of the valves when using a hydraulic drive for their movement, the use of serial phases of gas distribution of the engine is impractical. Numerical modeling of the operation of the internal combustion engine determined the regularity of the change in valve timing from the high-speed operating mode of the engine. Optimization criterion is the achievement of maximum engine power. When choosing the valve timing, the possibility of meeting the intake and exhaust valves with the engine piston was excluded. The use of optimal phases leads to an increase in power up to 4.5% at a low crankshaft speed. With an increase in the speed mode, the increase in power decreases, and with a high frequency of rotation of the crankshaft, its slight decrease (1.4%) is observed. An increase in torque, up to a power utilization factor of 0.9, and its subsequent decrease, allow stabilizing the vehicle speed on a road with variable resistance. An increase in the working pressure in the hydraulic drive of the valves makes it possible to intensify gas exchange even at a high speed of rotation of the crankshaft

Improving the energy efficiency of a 6ChN13/15 gas engine with a Miller cycle by optimizing the valve timing

Introduction (problem statement and relevance). The object of research in this work is an inline six-cylinder gas engine 6ChN13/15 with a Miller thermodynamic cycle. On the basis of its computer model studies minimization of the specific effective fuel consumption has been reached due to variation study of gas distribution and air supply systems parameters.The purpose of the study was to investigate the parameters regulation effect of gas distribution and air supply systems on the performance of a 6ChN13/15 gas engine with a Miller cycle on the external speed characteristic basing on numerical modeling.Methodology and research methods. The research was carried out by the method of computer simulation. Numerical modeling was made on the basis of data obtained during a full-scale experiment of a 6ChN13/15 gas engine with Miller thermodynamic cycle.Scientific novelty and results. A comparative analysis of a gas engine optimization results has been carried out. The results obtained will be used to create a gas engine and its further optimization by controlling the working process and the air supply system.Practical significance. The results obtained may be of interest to truck car manufacturers and engine specialists.

Service Quality in Natural Gas Distribution: A Study

Purpose: Using the SERVQUAL model in the Natural Gas Distribution business context, the research paper examines and compares the quality of service parameters of two City Gas Distribution (CGD) companies engaged in Piped Natural Gas (PNG) distribution- one from public and other from the private sector. Research Design/Approach: Mapping of various activities pertaining to domestic (household) PNG service on the SERVQUAL dimensions was undertaken. Based on the mapping, a relevant data collection tool was deployed to collect the data on PNG service quality parameters from the respondents, who were current consumers of these companies. Hypotheses regarding various components of SERVQUAL model were tested towards the comparison of service quality of these companies. Data were analyzed by employing an appropriate statistical tool. Findings: Statistical results reveal a significant difference between the companies in terms of the quality of services offered by them. Interpretation of study results, managerial implications and suggestions have been discussed in the paper. Practical Implications: The study shall help in designing and implementing the quality of service parameters and subsequently devising or revising Service Level Agreements (SLA) for the domestic PNG customers of CGD companies. Originality/Value: Not much relevant research work on service quality issues has been undertaken in the CGD Sector in general and in the domestic Piped Natural Gas (PNG) sub-sector in particular. One of the outcomes of the study is also the mapping of various activities pertaining to domestic PNG service on the SERVQUAL dimensions.

Methodology of hydrogen embrittlement study of long-term operated natural gas distribution pipeline steels caused by hydrogen transport

A methodology of experimental research on hydrogen embrittlement of pipe carbon steels due to the transportation of hydrogen or its mixture with natural gas by a long-term operated gas distribution network is presented. The importance of comparative assessments of the steel in the as-received and operated states basing on the properties that characterize plasticity, resistance to brittle fracture and hydrogen assisted cracking is accentuated. Two main methodological peculiarities are pointed out, (i) testing specimens should be cut out in the transverse direction relative to the pipe axis; (ii) strength and plasticity characteristics should be determined using flat tensile specimens with the smallest possible thickness of the working part. The determination of hydrogen concentration in metal, metallographic and fractographic analyses have been supplemented the study. The effectiveness of the proposed methodology has been illustrated by the example of the steel research after its 52-year operation.

Determination of the maximum traction force of the screw working body when piercing the soil

Laying of gas distribution pipelines, water mains, sewerage systems, power cables and communication cables is performed both by laying it in an open trench and by trenchless methods.