The Potential of a Separated Electric Compound Spark Ignition Engine for Hybrid Vehicle Application

In-cylinder expansion of internal combustion engines based on Diesel or Otto cycles cannot be completely brought down to ambient pressure, causing a 20% theoretical energy loss. Several systems have been implemented to recover and use this energy such as turbocharging, turbo-mechanical and turbo-electrical compounding, or the implementation of Miller Cycles. In all these cases however, the amount of energy recovered is limited allowing the engine to reach an overall efficiency incremental improvement between 4% and 9%. Implementing an adequately designed expander-generator unit could efficiently recover the unexpanded exhaust gas energy and improve efficiency. In this work, the application of the expander-generator unit to a hybrid propulsion vehicle is considered, where the onboard energy storage receives power produced by an expander-generator, which could hence be employed for vehicle propulsion through an electric drivetrain. Starting from these considerations, a simple but effective modelling approach is used to evaluate the energetic potential of a spark-ignition engine electrically supercharged and equipped with an exhaust gas expander connected to an electric generator. The overall efficiency was compared to a reference turbocharged engine within a hybrid vehicle architecture. It was found that, if adequately recovered, the unexpanded gas energy could reduce engine fuel consumption and related pollutant emissions by 4% to 12%, depending on overall power output.

Heating of natural gas before expander - generator unit

The article discusses the replacement of throttling at the stations of technological lowering of the pressure of main natural gas by an expander-generator technology that allows the production of a cheap one with high environmental indicators. The disadvantage of this method of generating electricity is a significant cooling of the gas at the outlet of the expander, which necessitates its heating. The efficiency of the expander-generator set is largely determined by the adopted gas heating scheme. Achieving such heating temperatures is possible only by using high-potential energy resources, which are present in the technological equipment of gas distribution stations in the form of gas heaters with an intermediate heat carrier, designed to heat gas before expansion. Calculations of the amount of fuel gas required for heating the main natural gas in front of the expander-generator unit at the gas distribution stations under consideration have been carried out. The results of the study of the influence of the temperature of gas heating in front of the expander on the consumption of fuel gas supplied for heating and the numbers of heaters are presented. An analytical dependence of the electric power of the heat pump installation on the difference between the total power consumption of the compressor and the power of the air turbine is obtained.

The Analysis of a Generator Shaft Crack Cause by Torsional Vibration due to SSR

Abstract.This paper introduces the serious crack accident of the rotor of a 600 MW turbo-generator unit in Vietnam, which leads to the rotor scrapped. After excluding the material and design reasons, it is considered that the electrical torque is the possibility. Through the operation parameters and theoretical calculation of the unit, the fault reason is positioned as Sub-synchronous resonance. The most important criterion is that the vibration of Unit 1 increases simultaneously with that of Unit 2, which is physically isolated from Unit 1. Further theoretical calculation shows that the natural frequencies of torsional vibration are 13.74 Hz, 26.23 Hz and 30.30 Hz, which are complementary to the grid frequency at that time cause of the change of grid structure.

Experimental investigations of the processes in gas generator of hydrogen-air energy storage

This paper describes the results of experimental investigation of the sample of the hydrogen-air gas generator unit with the expected average power of 65 kW. In total 5 test runs were made. Two tests showed that the mass flow and outlet gas temperature was in an agreement with the designed parameters. Additional attention should be paid to the cooling system design for the combustion chamber. In future such a gas generator in couple with the suitable gas turbine unit could be a part of the renewable energy accumulation system e.g. of hydrogen-air energy storage.

Development of a mathematical model of diesel-generator units with a valve-inductor generator

The paper presents a comprehensive mathematical model of a diesel-generator units with a valve-inductor generator. The calculated data obtained using this model allows optimizing the operation of fuel injectors and adjust the injection characteristics. The electromagnetic part of the model allows taking into account the power losses and efficiency of the generator, calculating the phase windings and their connection schemes, methods for setting the voltage or current of any shape that feeds the windings of the valve-inductor generator, as well as the characteristics of the rotor, stator, and winding materials to obtain the most effective operation parameters of the engine in various operating modes as part of the generator unit.

Analisis Pengaruh Temperatur Stator terhadap Rugi-Rugi Daya Generator Unit 2 PLTP Kamojang

Kenaikan temperatur lilitan stator dapat menyebabkan penurunan keandalan generator, sehingga peran sistem pendingin generator yang berfungsi untuk menjaga keandalan generator agar kenaikan temperatur lilitan stator tidak melampaui batas kemampuan generator. Metode pengukuran generator dengan menggunakan DCS. Hasil pengukuran beban, temperatur lilitan stator, temperatur inti stator, dan temperatur pendingin generator akan diolah dan dianalisis apakah besar perubahan beban akan berdampak pada kinerja generator dan besar temperatur masih berada di batas aman kelas isolasi. Berdasarkan hasil dari penelitian ini titik terendah pada temperatur lilitan 90,17 oC pada daya aktif 46 MW dan menghasilkan rugi tembaga 115,19 kW. Titik tertinggi pada temperature lilitan 105,83oC pada daya aktif 56,1 MW dan menghasilkan rugi tembaga 120,39 kW. Hasil pengukuran temperatur lilitan stator berada dibawah standar kelas isolasi yaitu 130°C.