Numerical investigation of a GTM-140 turbojet engine

The paper presents three-dimensional numerical simulations of combustion in the GTM-140 miniature turbine engine. The main aim of the work is to understand the processes occurring in the combustion chamber. The coupling of chemical kinetics, thermochemistry, transport of mass, energy and momentum, and fluid mechanics is a challenge for the engineers. The knowledge of these issues is essential to achieve a high performance product. The k- ϵ (RANS) Turbulence Model and Non-Premixed Model for the combustion was used. The particles of fluid droplets were described by the Discrete Phase Model

Individual differences in police dog handlers

The Polish adaptation of the NEO-FFI inventory (see Costa & McCrea, 1989; 1992b; Zawadzki et al. 2007) was used in the present study to assess the personality of dog handlers. For diagnosis of the emotional intelligence, the Polish scale Popular Questionnaire of Emotional Intelligence was used (Jaworowska & Matczak, 2005). There were 601 participants out of the total estimated number of 1408 police dog handlers in Poland. The results were compared with normalization tests for the measures used. The personality profile and emotional intelligence of dog handlers differ significantly from general population. Described in the NEO-FFI terms, police dog handlers are characterized by very low neuroticism, slightly above average extraversion, slightly below average openness to experience, a little above average agreeableness, and very high conscientiousness. In terms of emotional intelligence, they demonstrate higher control and understanding of emotions. It seems that the results obtained in the study may become relevant for the recruitment and training of police officers

Mała energetyka domowa

Polska energetyka i  ciepłownictwo stoi przed szeregiem wyzwań związanych z zanieczyszczeniem środowiska, brakiem mocy i  ubóstwem znacznej części społeczeństwa. Mikrosiłownie kogeneracyjne zasilane lokalnymi paliwami stałymi i węglem moją szansę stać się remedium na te problemy. Artykuł jest opisem działań jakie prowadziły do powstania pierwszej domowej mikrosiłowni kogeneracyjnej w Polsce oraz prezentuje potencjał jaki jest związany z tworzeniem energetyki rozproszonej. Przedstawiono działającą instalację badawczą oraz przedsięwzięcie IMP PAN i  SARK sp. z o.o. zmierzające do zbudowania pierwszej komercyjnej mikrosiłowni ORC. Według zapowiedzi SARK sp. z  o.o. przewidywana cena takiego urządzenia zaopatrującego dom w energię cieplną i elektryczną będzie mieścić się w zakresie 30÷40 tys. zł. Obszar sprzedaży mikrosiłownie kogeneracyjne na paliwo stałe nie ogranicza się tylko do terenu Polski, lecz może obejmować inne kontynenty, zaś same mikrosiłownie mają szansę stać się polską specjalnością i naszą marką narodową

A case study of working fluid selection for a small-scale waste heat recovery ORC system

The paper illustrates a case study of fluid selection for an internal combustion engine heat recovery organic Rankine cycle (ORC) system having the net power of about 30 kW. Various criteria of fluid selection are discussed. Particular attention is paid to thermodynamic performance of the system and human safety. The selection of working fluid for the ORC system has a large impact on the next steps of the design process, i.e., the working substance affects the turbine design and the size and type of heat exchangers. The final choice is usually a compromise between thermodynamic performance, safety and impact on natural environment. The most important parameters in thermodynamic analysis include calculations of net generated power and ORC cycle efficiency. Some level of toxicity and flammability can be accepted only if the leakages are very low. The fluid thermal stability level has to be taken into account too. The economy is a key aspect from the commercial point of view and that includes not only the fluid cost but also other costs which are the consequence of particular fluid selection. The paper discusses various configurations of the ORC system – with and without a regenerator and with direct or indirect evaporation. The selected working fluids for the considered particular power plant include toluene, DMC (dimethyl carbonate) and MM (hexamethyldisiloxane). Their advantages and disadvantages are outlined

Comparison of an impulse and a reaction turbine stage for an ORC power plant

Turbine stages can be divided into two types: impulse stages and reaction stages. The advantages of one type over the second one are generally known based on the basic physics of turbine stage. In this paper these differences between mentioned two types of turbines were indicated on the example of single stage turbines dedicated to work in organic Rankine cycle (ORC) power systems. The turbines for two ORC cases were analysed: the plant generating up to 30 kW and up to 300 kW of net electric power, respectively. Mentioned ORC systems operate with different working fluids: DMC (dimethyl carbonate) for the 30 kW power plant and MM (hexamethyldisiloxane) for the 300 kW power plant. The turbines were compared according to three major issues: thermodynamic and aerodynamic performance, mechanical and manufacturing aspects. The analysis was performed by means of the 0D turbomachinery theory and 3D computational aerodynamic calculations. As a result of this analysis, the paper indicates conclusions which type of turbine is a recommended choice to use in ORC systems taking into account the features of these systems

Design and numerical study of turbines operating with MDM as working fluid

Design processes and numerical simulations have been presented for a few cases of turbines designated to work in ORC systems. The chosen working fluid isMDM. The considered design configurations include single stage centripetal reaction and centrifugal impulse turbines as well as multistage axial turbines. The power outputs vary from about 75 kW to 1 MW. The flow in single stage turbines is supersonic and requires special design of blades. The internal efficiencies of these configurations exceed 80% which is considered high for these type of machines. The efficiency of axial turbines exceed 90%. Possible turbine optimization directions have been also outlined in the work

Analysis of the use of waste heat from a glass melting furnace for electricity production in the organic Rankine cycle system

In most production plants, waste heat is usually discharged into the environment, contributing to a reduction in the energy efficiency of industrial processes. This is often due to the low thermal parameters of the carriers in which this energy is contained, such as oils, water, exhaust gases or other post-process gases, which means that their use for electricity production in a conventional Rankine cycle may prove to be economically unprofitable. One of the technologies enabling the use of lowand medium-temperature waste heat carriers is the organic Rankine cycle (ORC) technology. The paper present results of calculations performed to evaluate potential electricity production in ORC using waste heat from a natural gas-fired glass melting furnace. The analysis was carried out assuming the use of a single-stage axial turbine, whose efficiency was estimated using correlations available in the literature. The calculations were carried out for three working fluids, namely hexamethyldisiloxane, dimethyl carbonate, and toluene for two scenarios, i.e. ORC system dedicated only to electricity production and ORC system working in cogeneration mode, where heat is obtain from cooling the condenser. In each of the considered cases, the ORC system achieves the net power output exceeding 300 kW (309 kW for megawatts in the cogenerative mode to 367 kW for toluene in the non-cogenerative mode), with an estimated turbine efficiency above 80%, in range of 80,75 to 83,78%. The efficiency of the ORC system, depending on the used working fluid and the adopted scenario, is in the range from 14.85 to 16.68%, achieving higher efficiency for the non-cogenerative work scenario