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Wyświetlanie 1-8 z 8
Tytuł:
Heat transfer in falling film evaporators during the industrial process of apple juice concentrate production
Autorzy:
Cyklis, P.
Powiązania:
https://bibliotekanauki.pl/articles/240517.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer
falling film evaporator
industrial
transport
ciepło
przemysł
Opis:
Falling film, shell-tube type evaporators are commonly used heat exchangers for the production of fruit juice concentrate. The main problem in the design of the exchanger is a reliable estimation of wall heat transfer coefficients for all effects in real operating conditions. Most literature sources for the overall heat transfer coefficients are based on laboratory measurements, where the tubes are usually short, no fouling exists and the flow rate is carefully adjusted. This paper shows the heat transfer estimated in real industrial operating conditions, compared to literature sources. Paper is based on the author’s own experience in designing and launching several evaporators for juice concentrate production into operation. As a summary, the design heat transfer coefficients are provided with relation to sugar content in juice concentrate.
Źródło:
Archives of Thermodynamics; 2018, 39, 3; 3-13
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Waste heat recovery from the air preparation room in a paint shop
Autorzy:
Adamkiewicz, Andrzej
Nikończuk, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/240142.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
waste heat recovery
air compression
paint shop
ciepło odpadowe
sprężanie powietrza
lakiernia
Opis:
The policy of sustainable development seeks to improve energy efficiency of industrial equipment. Efforts to improve energy efficiency also apply to the paint shops, where the recovery of waste heat is sought. The main source of a large amount of low-temperature waste heat in the paint shop is the spray booth. The second place where a large amount of low temperature waste heat is released is the room where the compressed air is prepared. Low energy efficiency of air compressors requires a large electric power supply. As a result, the emitted large heat fluxes become waste energy of the technological process. Heat is equivalent to up to 93% of the electric power supplied in the air compression process. There are solutions for recovering heat from compressors coming from the oil cooling water, but then the waste heat from the cooling of the compressed air and from the electric motor is released into air in the room. A method for recovering low-temperature waste heat from the air preparation room by means of an air-source heat pump has been proposed. An energy balance of the air compression and dehumidification process for the paint shop was made. A Matlab’s built-in numerical model includes air compressor and dehumidifier, heat recovery and accumulation for the purposes of use in the spray booth. A simulation experiment was carried out on the effectiveness of heat recovery from the air preparation room. The use of combined energy management in paint shops was proposed.
Źródło:
Archives of Thermodynamics; 2019, 40, 3; 229-241
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exergy analysis of the Szewalski cycle with a waste heat recovery system
Autorzy:
Kowalczyk, T.
Ziółkowski, P.
Badur, J.
Powiązania:
https://bibliotekanauki.pl/articles/240278.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Szewalski cycle
binary vapour cycle
exergy analysis
waste heat
idea Szewalskiego
analiza egzergii
ciepło odpadowe
Opis:
The conversion of a waste heat energy to electricity is now becoming one of the key points to improve the energy efficiency in a process engineering. However, large losses of a low-temperature thermal energy are also present in power engineering. One of such sources of waste heat in power plants are exhaust gases at the outlet of boilers. Through usage of a waste heat regeneration system it is possible to attain a heat rate of approximately 200 MWth, under about 90°C, for a supercritical power block of 900 MWel fuelled by a lignite. In the article, we propose to use the waste heat to improve thermal efficiency of the Szewalski binary vapour cycle. The Szewalski binary vapour cycle provides steam as the working fluid in a high temperature part of the cycle, while another fluid – organic working fluid – as the working substance substituting conventional steam over the temperature range represented by the low pressure steam expansion. In order to define in detail the efficiency of energy conversion at various stages of the proposed cycle the exergy analysis was performed. The steam cycle for reference conditions, the Szewalski binary vapour cycle as well as the Szewalski hierarchic vapour cycle cooperating with a system of waste heat recovery have been comprised.
Źródło:
Archives of Thermodynamics; 2015, 36, 3; 25-48
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
First principles calculations of thermodynamic properties of ZrB2
Autorzy:
Wani, T. A.
Das, B. K.
Powiązania:
https://bibliotekanauki.pl/articles/240687.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
TMB2
thermal expansion
Gruneisen parameter
debye temperature
specific heat
ekspandowanie termiczne
ciepło właściwe
rozszerzalność termiczna
Opis:
The thermodynamic properties, which are the important bulk properties for solids, have been investigated for ZrB2 under pressure through the quasi harmonic Debye model. The dependences of thermal expansion, Gruneisen parameter, Debye temperature and specific heat on pressure P are successfully obtained. The obtained results are in a good agreement with the available experimental and other theoretical data.
Źródło:
Archives of Thermodynamics; 2018, 39, 4; 113--124
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of an impulse and a reaction turbine stage for an ORC power plant
Autorzy:
Zaniewski, Dawid
Klimaszewski, Piotr
Witanowski, Łukasz
Jędzejewski, Łukasz
Klonowicz, Piotr
Lampart, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/240056.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
CFD
waste heat recovery
steam turbine
organic Rankine cycle
ciepło odpadowe
odzysk ciepła
ORC
organiczny cykl Rankine'a
Opis:
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.
Źródło:
Archives of Thermodynamics; 2019, 40, 3; 137-157
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bidirectionally stretched flow of Jeffrey liquid with nanoparticles, Rosseland radiation and variable thermal conductivity
Autorzy:
Archana, M.
Gireesha, B. J.
Rashidi, M. M.
Prasannakumara, B. C.
Gorla, R. S. R.
Powiązania:
https://bibliotekanauki.pl/articles/240409.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat mass transfer
jeffrey nanofluid
variable thermal conductivity
rosseland approximation
suction
ciepło
masa
zmienna przewodność cieplna
aproksymacja
ssanie
Opis:
Heat and mass transfer stretched flow of an incompressible, electrically conducting Jeffrey fluid has been studied numerically. Nanoparticles are suspended in the base fluid and it has many applications such as cooling of engines, thermal absorption systems, lubricants fuel cell, nanodrug delivery system and so on. Temperature dependent variable thermal conductivity with Rosseland approximation is taken into account and suction effect is employed in the boundary conditions. The governing partial differential equations are first transformed into set of ordinary differential equations using selected similarity transformations, which are then solved numerically using Runge-Kutta-Felhberg fourth-fifth order method along with shooting technique. The flow, heat and mass transfer characteristics with local Nusselt number for various physical parameters are presented graphically and a detailed discussion regarding the effect of flow parameters on velocity and temperature profiles are provided. It is found that, increase of variable thermal conductivity, radiation, Brownian motion and thermophoresis parameter increases the rate of heat transfer. Local Nusselt number has been computed for various parameters and it is observed that, in the presence of variable thermal conductivity and Rosseland approximation, heat transfer characteristics are higher as compared to the constant thermal conductivity and linear thermal radiation.
Źródło:
Archives of Thermodynamics; 2018, 39, 4; 33--57
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A case study of working fluid selection for a small-scale waste heat recovery ORC system
Autorzy:
Klimaszewski, Piotr
Zaniewski, Dawid
Witanowski, Łukasz
Suchocki, Tomasz
Klonowicz, Piotr
Lampart, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/240748.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
waste heat recovery
organic Rankine cycle
ORC fluids
heat exchangers
turboexpander
ciepło odpadowe
odzysk ciepła
ORC
organiczny cykl Rankine'a
wymienniki ciepła
turboekspander
Opis:
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.
Źródło:
Archives of Thermodynamics; 2019, 40, 3; 159-180
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of the effective thermal conductivity of solid fuels by the laser flash method
Autorzy:
Kosowska-Golachowska, M.
Gajewski, W.
Musiał, T.
Powiązania:
https://bibliotekanauki.pl/articles/240915.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
effective thermal conductivity
effective thermal diffusivity
specific heat
laser flash method
hard coal
brown coal
anthracite
efektywna przewodność cieplna
dyfuzja cieplna
ciepło właściwe
laserowa metoda impulsowa
węgiel kamienny
węgiel brunatny
antracyt
Opis:
In this study, a new laser flash system was proposed for the determination of the thermal conductivity of brown coal, hard coal and anthracite. The main objective of the investigation was to determine the effect of coal rank, composition, physical structure and temperature on thermal conductivity. The solid fuels tested were medium conductors of heat whose determined thermal conductivities were in the range of 0.09 to 0.23 W/(m K) at room temperature. The thermal conductivity of the solid fuels tested typically increased with the rank of coal and the measurement temperature. The results of this study show that the physical structure of solid fuels and temperature have a dominant effect on the fuels' thermal conductivity.
Źródło:
Archives of Thermodynamics; 2014, 35, 3; 3-16
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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