Measurement of Inductance of Liquefied Natural Gas

The peculiarities of application of various means of measuring gas mass are being considered. We study the dependence of the inductance of a gas cylinder from the quantity of liquefied gas in the tank and the ambient temperature. The results of experiments are presented. The scheme of device for determining the amount of liquefied gas in the cylinder has been proposed

High-Voltage Ignition Circuit For Compressed Natural Gas Direct Injection Engine

Ignition system of an internal combustion engine is an important part of the overall engine management system. It is a means to provide enough high-voltage, minimum around 20 kV to form an arc across the gap of a spark plug and to control the ignition timing. Thus, it can provide a right time to burn the air-fuel mixture inside the engine. With advances in technology, the ignition system has progressed from a contact point ignition system to an electronic ignition system and then to a digital distributorless ignition system. The increased growth of the ignition system design in both size and complexity has brought about the need for a simple and reliable ignition system to provide high-voltage output to be delivered to the spark plug and at the same time to adapt with the natural gas engine environment. Therefore, with the development of an economical and reliable ignition system, there is a growing interest in developing digital distributorless ignition system, which is programmable making it more flexible and superior to other conventional system. This thesis presents the development of an ignition circuit for a coil-on plug ignition system of a natural gas engine. The main specification of the circuit is the implementation of the ignition power-switching device at the primary side of the circuit to provide high switching speed to turn on and off the device. The chosen power-switching device was Insulated Gate Bipolar Transistor or IGBT, which is more suitable to be implemented inside the circuit design compared to other power-switching devices. The selected IGBT, IRGB14C40L are specifically design for a ignition applications and small engine ignition circuit. It has low saturation voltage and high self-clamped inductive switching energy. The modelling and optimization of the ignition IGBT parameters is done in the PSPICE software to fulfill the real ignition power-switching device requirements. The other specification of the circuit design is the implementation of the snubber circuit, which can provide over-voltage protection at the primary side of the power-switching device. Finally, the testing of the circuit is done by applying a control signal at the input source terminal or at the gate terminal of the ignition IGBT. The complete circuit design is integrated with the high-voltage ignition coil and a special designed long neck spark plug for the natural gas engine purpose. The circuit has been tested to make sure it can provide the desired voltage so it can ignite the mixture of the air and compressed natural gas in the right cylinder and at the right time. From the test results of the ignition circuit, it demonstrates that the performances of the ignition parameters such as the primary current and secondary voltage are highly affected by the device parameters like the ignition IGBT parameters, specifications of the high-voltage ignition coil as well as the control strategy of the switching-time to ignite the spark plug

Migration from Gasoline to Gaseous Fuel for Small-scale Electricity Generation Systems

This paper describes a study that gives a consideration to change fuel source for electriccity generator from gasoline to combustible gas. A gaseous fuel conversion technology is presented and its performance is compared with gasoline. In the experiment, two types of load were tested, resistive and resistive-inductive. By using both fuels mostly the power factor (Cos φ) of resistive-inductive load variations were greater than 0.8, and they had slight difference on operational voltage. The drawback of using gaseous fuel is the frequency of the electricity might be not reach the standard frequency (i.e. 50 Hz). In the lab scale experiment, the gasoline consumption increased proportionally with the load increase, while using gaseous fuel the consumption of gas equal also increased where the average consumption value is 100 gram per 15 minutes operation for the tested load in the experiment. The main advantage using gaseous fuel (liquefied petroleum gas or biogas) compared to gasoline is a cleaner emitted gas after combustion

NASA Tech Briefs Index, 1977, volume 2, numbers 1-4

Announcements of new technology derived from the research and development activities of NASA are presented. Abstracts, and indexes for subject, personal author, originating center, and Tech Brief number are presented for 1977

Technical-economic analysis of Gas Insulated Lines

The increasing electric demand shows the need of a grid reinforcement which is going to be accomplished in the following years. These new lines will have to be designed focusing on efficiency and sustainability in order to improve the performance of the power grid. These new parameters give us the opportunity to talk about Gas Insulated Lines (GIL) due to its low transmission losses, and high transmission capacity [1]. This project presents a technical-economic analysis for GIL, to approximate the total cost of a GIL infrastructure with its singular technical arrangements, both initial investment costs and long term costs due to the operation. To accomplish it all cost components have been approached as function of nominal values of a GIL project; for this reason a study has been done for each single cost component to relate the technical solution with costs. A number of parameters (such as geometric measures, mass of insulator gas, conductor resistance, capacitance or inductance) of the installation have been obtained by statistic regressions based on data from available sources. These parameters have been needed to come up with the installation price. In addition a case study is presented, where different technologies are compared in terms of cost. The objective is to show differences in the price for each component between the different technology arrangements for the given case. It can be seen that there are significant differences between technologies in the initial inversion cost and the life-long operation cost. With the case study which is referred to a regular installation, can be seen which is the cheapest electric solution and which is the higher cost efficient technology, which leads to a low price investment and operating expenses

Experimental Assessment of Cryogenic Cooling Impact on Induction Motors

In this work, an experimental assessment of the influence of cryogenic cooling in a conventional induction motor is presented. The performance of a fractional kilowatt induction motor is evaluated when submerged in liquid nitrogen. Using the single-phase equivalent electric circuit, the influence of the temperature and skin-effect is analyzed in the variation of the machine's parameters, under ambient and cryogenic conditions. Also, the variation of the iron core and mechanical losses are evaluated. An analytical methodology is proposed to estimate the change of motor performance under cryogenic conditions. For the analyzed induction motor, measurements are performed to verify the predicted machine performance. The experimental tests in cryogenic conditions show the possibility of achieving higher efficiency levels with more than double the nominal torque. Also, due to the cryogenic environment, there was no thermal constraint in the operation of the induction motor

Experimental Model-Based Linearization of a S.I. Engine Gas Injector Flow Chart

Experimental tests previously executed by the authors on the simultaneous combustion of gasoline and gaseous fuel in a spark ignition engine revealed the presence of strong nonlinearities in the lower part of the gas injector flow chart. These nonlinearities arise via the injector outflow area variation caused by the needle impacts and bounces during the transient phenomena that take place in the opening and closing phases of the injector and may seriously compromise the air-fuel mixture quality control for the lower injection times, thus increasing both fuel consumption and pollutant emissions. Despite the extensive literature about the operation and modelling of fuel injectors, there are no known studies focused on the nonlinearities of the gas injector flow chart and on the way they can be reduced or eliminated. The authors thus developed a mathematical model for the prediction of mass injected by a spark ignition (S.I.) engine gas injector, validated through experimental data. The gas injector has been studied with particular reference to the complex needle motion during the opening and closing phases, which may strongly affect the amount of fuel injected. In this work, the mathematical model previously developed has been employed to study and determine an appropriate injection strategy in order to linearize the injector flow chart to the greatest degree possible. The injection strategy proposed by the authors is based on minimum injection energy considerations and may be easily implemented in current engine control units (ECU) without any hardware modification or additional costs. Once calibrated by means of simulation, this strategy has been validated by experimental data acquired on an appropriately equipped injector test bench. As a result, the real injector flow chart has been substantially improved, reducing its deviation from linearity to one third of the original flow chart, which is an excellent result, especially if the typical measurement dispersion of the injected mass is taken into account. The injection strategy proposed by the authors could extend the linear behaviour of gas injectors and improve the fuel supply by means of a simple software update of the ECU, thus obtaining higher engine efficiency and lower pollutant emissions

Operational Performance Analysis of the Cryogenic Electrical Machine for Submerged Liquefied Natural Gas Pumps

The electrical machine is one of the key components for submerged liquefied natural gas (LNG) pumps. This study deals with a cryogenic permanent magnet synchronous motor (CPMSM) for submerged LNG pumps. An 18.5-kW CPMSM prototype was developed according to the needs of users. The basic design of the CPMSM was proposed by using a cryogenic temperature (CT) design method. To analyze the operational performance accurately, simulation modeling and analysis are carried out, and a liquid nitrogen (−196°C) experimental platform is built. The test results verify the rationality of the design and the accuracy of the simulation. Based on the simulation and experimental data, the working characteristics and mechanical properties of the prototype in liquid nitrogen are analyzed. In addition, the performance of the prototype operating in liquid nitrogen (−196°C) and LNG (−161°C) are compared and analyzed, and the results show that the operating characteristics of the prototype in the two fluid environments are similar