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Wyszukujesz frazę "Andrzejczyk, R." wg kryterium: Autor


Wyświetlanie 1-7 z 7
Tytuł:
Performance analyses of helical coil heat exchangers. The effect of external coil surface modification on heat exchanger effectiveness
Autorzy:
Andrzejczyk, R.
Muszyński, T.
Powiązania:
https://bibliotekanauki.pl/articles/240706.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
effectiveness
heat transfer intensification
number of transfer unit
helical coil
skuteczność
intensyfikacja wymiany ciepła
liczba jednostek przesyłowych
spirala
Opis:
The shell and coil heat exchangers are commonly used in heating, ventilation, nuclear industry, process plant, heat recovery and air conditioning systems. This type of recuperators benefits from simple construction, the low value of pressure drops and high heat transfer. In helical coil, centrifugal force is acting on the moving fluid due to the curvature of the tube results in the development. It has been long recognized that the heat transfer in the helical tube is much better than in the straight ones because of the occurrence of secondary flow in planes normal to the main flow nside the helical structure. Helical tubes show good performance in heat transfer enhancement, while the uniform curvature of spiral structure is inconvenient in pipe installation in heat exchangers. Authors have presented their own construction of shell and tube heat exchanger with intensified heat transfer. The purpose of this article is to assess the influence of the surface modification over the performance coefficient and effectiveness. The experiments have been performed for the steady-state heat transfer. Experimental data points were gathered for both laminar and turbulent flow, both for co current- and countercurrent flow arrangement. To find optimal heat transfer intensification on the shell-side authors applied the number of transfer units analysis.
Źródło:
Archives of Thermodynamics; 2016, 37, 4; 137-159
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative study of flow condensation in conventional and small diameter tubes
Autorzy:
Mikielewicz, D.
Andrzejczyk, R.
Powiązania:
https://bibliotekanauki.pl/articles/240398.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
kondensacja w przepływie
minikanały
wymiana ciepła
flow condensation
heat transfer
minichannels
Opis:
Flow boiling and flow condensation are often regarded as two opposite or symmetrical phenomena. Their description however with a single correlation has yet to be suggested. In the case of flow boiling in minichannels there is mostly encountered the annular flow structure, where the bubble generation is not present. Similar picture holds for the case of inside tube condensation, where annular flow structure predominates. In such case the heat transfer coefficient is primarily dependent on the convective mechanism. In the paper a method developed earlier by the first author is applied to calculations of heat transfer coefficient for inside tube condensation. The method has been verified using experimental data from literature on several fluids in different microchannels and compared to three well established correlations for calculations of heat transfer coefficient in flow condensation. It clearly stems from the results presented here that the flow condensation can be modeled in terms of appropriately devised pressure drop.
Źródło:
Archives of Thermodynamics; 2012, 33, 2; 67-83
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The performance of H2O, R134a, SES36, ethanol, and HFE7100 two-phase closed thermosyphons for varying operating parameters and geometry
Autorzy:
Andrzejczyk, R.
Muszyński, T.
Powiązania:
https://bibliotekanauki.pl/articles/240401.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
two-phase closed thermosiphon
heat pipe
energy efficiency
NTU
number of heat transfer units
heat recovery
zamknięty termosyfon dwufazowy
rura cieplna
efektywność energetyczna
liczba jednostek przepływu ciepła
odzysk ciepła
Opis:
In this study, the influences of different parameters at performance two-phase closed thermosiphon (TPCT) was presented. It has been confirmed that the working fluid, as well as operating parameters and fill ratio, are very important factors in the performance of TPCT. The article shows characteristics of gravitational tube geometries, as well as the technical characteristic of the most important system components, i.e., the evaporator/condenser. The experiment’s plan and the results of it for the two-phase thermosiphon for both evaluated geometries with varying thermal and fluid flow parameters are presented. Experiments were performed for the most perspective working fluids, namely: water, R134a, SES36, ethanol and HFE7100. Obtained research proves the possibility to use TPCT for heat recovery from the industrial waste water.
Źródło:
Archives of Thermodynamics; 2017, 38, 3; 3-21
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zastosowanie korelacji opisujących wymianę ciepła w obszarze uderzających mikrostrug do projektowania kompaktowych wymienników ciepła: cz. 1. Budowa modelowego wymiennika ciepła i jego charakterystyka
Applicability of correlations of heat transfer in arrays of microjets to design compact heat exchangers: part 1. Model heat exchanger design and its characteristics
Autorzy:
Muszyński, T.
Andrzejczyk, R.
Powiązania:
https://bibliotekanauki.pl/articles/151400.pdf
Data publikacji:
2014
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
mikrostrugi
wymiennik ciepła
intensyfikacja wymiany ciepła
microjets
heat exchanger
heat transfer intensification
Opis:
W artykule przedstawiono konstrukcję prototypowego, modułowego mikrostrugowego wymiennika ciepła. Przeprowadzone badania cieplno przepływowe w układzie woda-woda, umożliwiają określenie efektywności wymiany ciepła, charakterystyk cieplno przepływowych, oraz wielkości współczynnika przejmowania ciepła. Eksperymenty w dalszej części publikacji posłużą do weryfikacji stosowalności istniejących korelacji opisujących wymianę ciepła w obszarze uderzającej mikrostrugi.
The article presents experimental studies on a compact heat exchanger with heat transfer intensification by means of impinging microjets. The pursuit to provide high performance of heat exchangers is a response to the demand both in economics and in the universal tendency to miniaturization of industrial equipment. This paper presents the design of a prototype, modular microjet heat exchanger. The modular design of the heat exchanger allows to change its geometrical dimensions, as well as changing the heat exchange membrane material. Schematics, view of test section and design of the heat exchanger are shown in Figures 1 to 4. The study of heat transfer in water-water flow, allows to determine the heat transfer efficiency, the characteristics of heat transfer, and the heat transfer coefficient values. Data were collected for the pressure drops in heat exchanger not exceeding 15 kPa, i.e. such as in conventional heat exchangers. Hydraulic characteristics of a model heat exchanger are shown in Figures 5 and 6. Additionally for the two experimental series, comparison of the performance of tested heat exchanger with standard pipe in the pipe heat exchanger has been made, as shown in Figure 9. Conducted experimental research, in the following part of publication will be used to verify the applicability of the existing correlations of heat transfer in microjet impingement area.
Źródło:
Pomiary Automatyka Kontrola; 2014, R. 60, nr 11, 11; 1021-1024
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations on mixture preparation for two phase adiabatic pressure drop of R134a flowing in 5 mm diameter channel
Autorzy:
Muszyński, T.
Andrzejczyk, R.
Dorao, C. A.
Powiązania:
https://bibliotekanauki.pl/articles/240440.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
adiabatic flow
frictional pressure drop
two-phase flow
flow pattern map
R134a
przepływ adiabatyczny
tarciowy spadek ciśnienia
przepływ dwufazowy
mapy przepływu
Opis:
The article presents detailed two-phase adiabatic pressure drops data for refrigerant R134a. Study cases have been set for a mass flux varying from 200 to 400 kg/m2s, at the saturation temperature of 19.4°C. Obtained experimental data was compared with the available correlations from the literature for the frictional pressure drop during adiabatic flow. Influence of mixture preparation on pressure drop was investigated, for varying inlet subcooling temperature in the heated section. The flow patterns have also been obtained by means of a high-speed camera placed in the visualization section and compared with literature observations.
Źródło:
Archives of Thermodynamics; 2017, 38, 3; 101-118
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative study of heat transfer and pressure drop during flow boiling and flow condensation in minichannels
Autorzy:
Mikielewicz, D.
Andrzejczyk, R.
Jakubowska, B.
Mikielewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/240815.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
two-phase pressure drops
heat transfer coefficient
boiling
condensation
dwufazowy spadek ciśnienia
współczynnik przenikania ciepła
wrzenie
kondensacja
Opis:
In the paper a method developed earlier by authors is applied to calculations of pressure drop and heat transfer coefficient for flow boiling and also flow condensation for some recent data collected from literature for such fluids as R404a, R600a, R290, R32,R134a, R1234yf and other. The modification of interface shear stresses between flow boiling and flow condensation in annular flow structure are considered through incorporation of the so called blowing parameter. The shear stress between vapor phase and liquid phase is generally a function of nonisothermal effects. The mechanism of modification of shear stresses at the vapor-liquid interface has been presented in detail. In case of annular flow it contributes to thickening and thinning of the liquid film, which corresponds to condensation and boiling respectively. There is also a different influence of heat flux on the modification of shear stress in the bubbly flow structure, where it affects bubble nucleation. In that case the effect of applied heat flux is considered. As a result a modified form of the two-phase flow multiplier is obtained, in which the nonadiabatic effect is clearly pronounced.
Źródło:
Archives of Thermodynamics; 2014, 35, 3; 17-37
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wpływ osłony bocznej drzewostanu na wzrost dębu bezszypułkowego (Quercus petraea) i grabu pospolitego (Carpinus betulus) w fazie uprawy
Effect of lateral shelter on a height growth of sessile oak (Quercus petraea) and common hornbeam (Carpinus betulus) in young growth phase
Autorzy:
Andrzejczyk, T.
Dzwonkowski, M.
Pawłowski, M.
Działak, R.
Powiązania:
https://bibliotekanauki.pl/articles/990860.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
hodowla lasu
uprawy lesne
dab bezszypulkowy
Quercus petraea
grab pospolity
Carpinus betulus
wzrost roslin
przyrost wysokosci
oslona boczna
sciana lasu
oak silviculture
hornbeam
height growth
mixed stands
mixture form
Opis:
We investigated annual height increment of sessile oak and common hornbeam planted on clear−cut in respect to the distance to the adjacent mature Scots pine stand. The study area was divided into 3 zones (I−III) each of 20 m width. The four analyzed treatments were defined on a basis of a mingling form: W1 – a monoculture of oak (control plot), W2 and W3 – two types of row mixture, W4 – single tree mixture. Two years after planting an annual height increment of both tree species was significantly higher in the zone I (adjacent to the mature pine stand from the SW side) than in two other zones. The same significant differences were also found at the other inventories. Although hornbeam was on average higher than oak, a growth inhibition of oak by hornbeam was not significant. The annual height increment of both species was correlated with the precipitation in June and July.
Źródło:
Sylwan; 2014, 158, 10; 723-732
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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