9 research outputs found
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