The dynamics of microturbines lubricated using unconventional agents

Abstract

Abstract. The paper presents the research results of the microturbines dynamics with power of a few to several hundred KW. They are combined heat and power (CHP) units (generating heat and electricity) for houses and for municipalities in the form of Autonomous Energy Regions (ARE). These are key technologies for energy sector with respect to the distributed generation and for small-scale eco-power engineering. The following examples will refer only to the several selected research projects coordinated by the IMP PAN (Institute of FluidFlow Machinery of the Polish Academy of Sciences) in Gdansk. The paper will focus on the dynamics of rotors and bearings lubricated by means of low boiling agents, i.e., by means of turbine working medium. Analysis of hydrodynamic instability phenomena, including the development of oil whirl and oil whip has also been carried out.Key words: rotor dynamics, microurbines, distributed energy generation. Preliminary remarksThe presented in the paper examples refer to the several selected research projects coordinated by the IMP PAN (Institute of Fluid-Flow Machinery of the Polish Academy of Sciences) in Gdansk. However, thy are the largest research projects in the country regarding the field of RES-based eco-power engineering.This article focuses on the results of the work related to so-called "energy-plus" technologies and small & microcombined heat and power units. These results are the effect of research conducted at the institute and in cooperation with industrial partners (mainly the Capital Group ENERGA) and more than a dozen research teams from different research centers across the country. The study focuses on the future implementation and is addressed to individual and municipal consumers.When it comes to the ongoing studies, the construction of the CHP ORC plant is planned (the blocks consisting of a boiler and a microturbine operating with a low-boiling agent using an Organic Rankine Cycle (ORC) with the electric power of several kW and tens of kW of thermal power. Within the framework of the another project it is planned to build CHP ORC units of higher power (hundreds of kW of electrical power, thermal power up to several MW).The results of these projects is thus addressed to individual customers in the form of domestic CHP units, and to the municipal customer as Municipal Energy Centers or Autonomous Energy Regions (ARE).Tracking the discussions in the EU it can be concluded that the domestic CHP units, Autonomous Energy Regions and generally distributed energy systems (DES) based on renewable energy sources (RES) play a big role in energy policy and especially in the so-called energy mix not only in Poland but also in EU Countries [1][2][3][4][5][6][7][8][9][10][11].Microturbines constitute the most important part of the small devices like DES/RES. Analysis of the work of microturbines and microbearings, their construction and operation is a challenge for many centers around the world. Research objectsThe IMP PAN group (that means: IMP PAN, Lodz University of Technology...

Investigation of Gas Foil Bearings With an Adaptive and Non-Linear Structure

“…This also applies to devices used in distributed power generation, which additionally should be small in size and have a low impact on the surrounding environment (i.e., low noise and emissions). As far as cogeneration systems and trigeneration systems (in which heat energy is generated simultaneously with electricity and cold) are concerned, such requirements can easily be met by using high-speed fluid-flow machines such as microturbines (Kiciński, 2015, Kosowski et al, 2018, Włodarski, 2018. In order to enable microturbine rotors to operate at increasingly higher rotational speeds, novel bearing systems must be developed.…”

Experimental Study of the Thermal and Wear Characteristics of a Foil Bearing Lubricated with a Low-Boiling Liquid

“…The history of foil bearings is also linked to the growing popularity of high-speed rotating machines such as microturbines and turboexpanders [6][7][8]. A lot of research and development work is currently being carried out on the application of foil bearings in aviation [9,10], small-scale cogeneration [11][12][13] and the automotive industry [14][15][16]. Well-designed foil bearings have many advantages, such as the absence of external lubrication, low friction losses, low noise and vibration levels, long service life, and the ability to operate at high speeds and temperatures [17].…”

“…In our study, we established a correlation between the thermal characteristics of the tested bearing variants, their design and the quality of the mating surfaces. The experimental test rig used allows for conducting start/stop tests in the presence of any fluids, such as low-boiling liquids used in vapour microturbines [12,13,39,40]. In this context, the research presented in this article is a significant novelty, since the experimental studies on foil bearings presented in other publications were mostly conducted under gas or other liquid lubrication conditions.…”

Experimental Characterization of a Foil Journal Bearing Structure with an Anti-Friction Polymer Coating

“…Although these types of bearings have been known for several decades, it was only in the last two decades that they have seen their heyday, driven by demand resulting from the rapid development of various types of high-speed machines such as microturbines [6][7][8]. That is why a lot of research and development work is being carried out to use foil bearings in the aircraft industry [9,10], distributed power generation [11][12][13] or the automotive industry, where attempts have been made to use them to support the rotor of a turbocharger [14][15][16]. Properly matched to the operating conditions, foil bearings can have many advantages, such as the absence of oil lubrication, low friction losses, reduced vibration level, high durability, and the possibility to increase the speed and operating temperature [17].…”