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Tytuł:
Thermal analysis of a gravity-assisted heat pipe working with zirconia-acetone nanofluids: An experimental assessment
Autorzy:
Abdolhossein Zadeh, Amin
Nakhjavani, Shima
Powiązania:
https://bibliotekanauki.pl/articles/240484.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat pipe
zirconia-acetone nanofluid
tilt angle
filling ratio
Opis:
An experimental investigation was performed on the thermal performance and heat transfer characteristics of acetone/zirconia nanofluid in a straight (rod) gravity-assisted heat pipe. The heat pipe was fabricated from copper with a diameter of 15 mm, evaporator-condenser length of 100 mm and adiabatic length of 50 mm. The zirconia-acetone nanofluid was prepared at 0.05–0.15% wt. Influence of heat flux applied to the evaporator, filling ratio, tilt angle and mass concentration of nanofluid on the heat transfer coefficient of heat pipe was investigated. Results showed that the use of nanofluid increases the heat transfer coefficient while decreasing the thermal resistance of the heat pipe. However, for the filling ratio and tilt angle values, the heat transfer coefficient initially increases with an increase in both. However, from a specific value, which was 0.65 for filling ratio and 60–65 deg for tilt angle, the heat transfer coefficient was suppressed. This was attributed to the limitation in the internal space of the heat pipe and also the accumulation of working fluid inside the bottom of the heat pipe due to the large tilt angle. Overall, zirconia-acetone showed a great potential to increase the thermal performance of the heat pipe.
Źródło:
Archives of Thermodynamics; 2020, 41, 2; 65-83
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A data assimilation approach for estimating strength of steel pipes reinforced with composite sleeves under unsteady pressure-flow conditions
Autorzy:
Witek, Maciej
Uilhoorn, Ferdinand
Powiązania:
https://bibliotekanauki.pl/articles/1845453.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pipe wall metal loss
composite sleeve
pipe fracture
gas dynamics
data assimilation
Opis:
The aim of this paper is twofold: to estimate the unsteady pressure-flow variations in gas transmission pipelines using the ensemblebased data assimilation approach and to analyse the strength of steel tubes reinforced with composite sleeves containing localized part-wall thickness loss caused by corrosion while taking into consideration a safe operating pressure of the pipeline. For a steel thin-walled cylinder containing a partwall metal loss, a flexible wrap of fibreglass as well as carbon glass with epoxy resin are determined. The strength of the repaired pipeline with two kinds of materials for sleeves is investigated taking into consideration the internal pressure at the defect location. For the case study, a section of the Yamal transit pipeline on the Polish territory is selected. The results enable pipeline operators to evaluate the strength of corroded steel pipelines and develop optimal repair activities, which are of vital importance for the maintenance and operation of underground steel networks.
Źródło:
Archives of Thermodynamics; 2020, 41, 4; 3-22
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A data assimilation approach for estimating strength of steel pipes reinforced with composite sleeves under unsteady pressure-flow conditions
Autorzy:
Witek, Maciej
Uilhoorn, Ferdinand
Powiązania:
https://bibliotekanauki.pl/articles/1845456.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pipe wall metal loss
composite sleeve
pipe fracture
gas dynamics
data assimilation
Opis:
The aim of this paper is twofold: to estimate the unsteady pressure-flow variations in gas transmission pipelines using the ensemblebased data assimilation approach and to analyse the strength of steel tubes reinforced with composite sleeves containing localized part-wall thickness loss caused by corrosion while taking into consideration a safe operating pressure of the pipeline. For a steel thin-walled cylinder containing a partwall metal loss, a flexible wrap of fibreglass as well as carbon glass with epoxy resin are determined. The strength of the repaired pipeline with two kinds of materials for sleeves is investigated taking into consideration the internal pressure at the defect location. For the case study, a section of the Yamal transit pipeline on the Polish territory is selected. The results enable pipeline operators to evaluate the strength of corroded steel pipelines and develop optimal repair activities, which are of vital importance for the maintenance and operation of underground steel networks.
Źródło:
Archives of Thermodynamics; 2020, 41, 4; 3-22
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of the influence of capillary effect on operation of the loop heat pipe
Autorzy:
Mikielewicz, D.
Błauciak, K.
Powiązania:
https://bibliotekanauki.pl/articles/240739.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
loop heat pipe
capillary forces
waste heat recovery
rurka ciepła z pętlą obiegową
siły kapilarne
wykorzystanie energii odpadowej
Opis:
In the paper presented are studies on the investigation of the capillary forces effect induced in the porous structure of a loop heat pipe using water and ethanol ad test fluids. The potential application of such effect is for example in the evaporator of the domestic micro-CHP unit, where the reduction of pumping power could be obtained. Preliminary analysis of the results indicates water as having the best potential for developing the capillary effect.
Źródło:
Archives of Thermodynamics; 2014, 35, 3; 59-80
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental investigation of gravity-assisted wickless heat pipes (thermosyphons) at low heat inputs for solar application
Autorzy:
Al-Joboory, Hassan Naji Salman
Powiązania:
https://bibliotekanauki.pl/articles/240582.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wickless heat pipe
adiabatic section
solar heat pipe
fill charge ratio
working fluid inventory
inclination angle
Opis:
The performance of ten wickless heat pipes without adiabatic sections is investigated experimentally at low heat inputs 120 to 2000 W/m2 for use in solar water heaters. Three heat pipe diameter groups were tested, namely 16, 22, and 28.5 mm. Each group had evaporator lengths of 1150, 1300, and 1550 mm, respectively, with an extra evaporator length of 1800 mm added to the second group. The condenser section length of all heat pipes was 200 mm. Ethanol, methanol, and acetone were utilized as working fluids, at inventory of 25%, 50%, 70%, and 90% by evaporator volume respectively. The 22 mm diameter pipes were tested at inclination angles 30°, 45°, and 60°. Other diameter groups were tested at 45° only. Experiments revealed increased surface temperatures and heat transfer coefficients with increased pipe diameter and evaporator length, and that increased working fluid inventory caused pronounced reduction in evaporator surface temperature accompanied by improved heat transfer coefficient to reach maximum values at 50% inventory for the selected fluids. Violent noisy shocks were observed with 70% and 90% inventories with the tested heat pipes and the selected working fluids with heat flux inputs from 320–1900 W/m2. These shocks significantly affected the heat pipes heat transfer capability and operation stability. Experiments revealed a 45° and 50% optimum inclination angle of fill charge ratio respectively, and that wickless heat pipes can be satisfactorily used in solar applications. The effect of evaporator length and heat pipe diameter on the performance was included in data correlations.
Źródło:
Archives of Thermodynamics; 2020, 41, 2; 257-276
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New expression to calculate quantity of recovered heat in the earth-pipe-air heat-exchanger operating in winter heating mode
Autorzy:
Molcrette, Vincent F. A.
Autier, Vincent R. B.
Powiązania:
https://bibliotekanauki.pl/articles/240792.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
earth-pipe-air heat-exchanger
analytical model
air heating
Opis:
A new expression is proposed to calculate the earth-energy of an earth-air-pipe heat exchanger during winter heating for three kinds of soil in France. An analytical model is obtained by using numerical computation developed in Scilab – a free open source software. The authors showed the comparison between their simple analytical model and experimental results. They showed the influence of different parameters to specify the size of the heat exchanger.
Źródło:
Archives of Thermodynamics; 2020, 41, 2; 103-117
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Visualization of heat transport in heat pipes using thermocamera
Autorzy:
Nemec, P.
Caja, A.
Lenhard, R.
Powiązania:
https://bibliotekanauki.pl/articles/239979.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
rura cieplna
termowizja
heat pipe
thermovision
Opis:
Heat pipes, as passive elements show a high level of reliability when taking heat away and they can take away heat flows having a significantly higher density than systems with forced convection. A heat pipe is a hermetically closed duct, filled with working fluid. Transport of heat in heat pipes is procured by the change of state of the working fluid from liquid state to steam and vice versa and depends on the hydrodynamic and heat processes in the pipe. This study have been focused on observing the impact these processes have on the heat process, the transport of heat within the heat pipe with the help of thermovision. The experiment is oriented at scanning the changes in the surface temperatures of the basic structural types of capillary heat pipes in vertical position.
Źródło:
Archives of Thermodynamics; 2010, 31, 4; 125-132
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of pressure drop during refrigerant condensation in pipe minichannels
Autorzy:
Sikora, M.
Bohdal, T.
Powiązania:
https://bibliotekanauki.pl/articles/240860.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
minichannels
pressure drop
refrigerant
condensation
minikanał
spadek ciśnienia
chłodziwo
kondensacja
Opis:
Investigations of refrigerant condensation in pipe minichannels are very challenging and complicated issue. Due to the multitude of influences very important is mathematical and computer modeling. Its allows for performing calculations for many different refrigerants under different flow conditions. A large number of experimental results published in the literature allows for experimental verification of correctness of the models. In this work is presented a mathematical model for calculation of flow resistance during condensation of refrigerants in the pipe minichannel. The model was developed in environment based on conservation equations. The results of calculations were verified by authors own experimental investigations results.
Źródło:
Archives of Thermodynamics; 2017, 38, 4; 15--28
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of temperature distribution in a pipe with inner mineral deposit
Autorzy:
Joachimiak, M.
Ciałkowski, M.
Bartoszewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/240495.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
mineral deposit
inverse problem
złoża kopalin
zagadnienie odwrotne
Opis:
The paper presents the results of calculations related to determination of temperature distributions in a steel pipe of a heat exchanger taking into account inner mineral deposits. Calculations have been carried out for silicate-based scale being characterized by a low heat transfer coefficient. Deposits of the lowest values of heat conduction coefficient are particularly impactful on the strength of thermally loaded elements. In the analysis the location of the thermocouple and the imperfection of its installation were taken into account. The paper presents the influence of determination accuracy of the heat flux on the pipe external wall on temperature distribution. The influence of the heat flux disturbance value on the thickness of deposit has also been analyzed.
Źródło:
Archives of Thermodynamics; 2014, 35, 2; 37-49
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Challenges in operating and testing loop heat pipes in 500–700 K temperature ranges
Autorzy:
Szymański, Paweł
Mikielewicz, Dariusz
Powiązania:
https://bibliotekanauki.pl/articles/2091372.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
loop heat pipe
working fluid
material compatibility
Opis:
The potential applications of loop heat pipes (LHPs) are the nuclear power space systems, fuel cell thermal management systems, waste heat recovery systems, medium temperature electronic systems, medium temperature military systems, among others. Such applications usually operate in temperature ranges between 500–700 K, hence it is necessary to develop an LHP system that will meet this requirement. Such a thermal management device require to meet various technical problems and challenges currently existing in the development of LHP working in medium temperatures, including: (1) selection of appropriate working fluid; (2) selection of appropriate LHP construction material; (3) construction of suitable test rig capable of testing at elevated temperatures; (4) development of new testing methods. Currently, there are no proven working fluids that can be used in LHPs in medium temperature ranges. Water can be applicable only at temperatures up to 570 K. Caesium can be applicable at temperatures above 670 K. Organic fluids usually tend to generate non-condensable gasses and/or decompose at elevated temperatures and their viscosity dramatically increases. For halides, most of them are very reactive or toxic and their full property data are not available or the majority of the physical properties are predicted, also live tests and their environmental impact data are not adequate. As for casing/LHP construction material, there are no full chemical compatibility tables with most of the medium temperature working fluids and the reactivity of fluids significantly limits the potential materials. Also, testing such an LHP is an endeavour as the reactivity of medium temperature fluids and the use of obscure metals create new challenges. Altogether creates multiple challenges in the development, testing, handling and operating of LHP in the medium temperature range.
Źródło:
Archives of Thermodynamics; 2022, 43, 2; 61--73
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Loss coefficients of ice slurry in sudden pipe contractions
Autorzy:
Mika, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/240917.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
opór przepływu
przepływ zawiesiny lodowej
straty ciśnienia
Współczynnik strat lokalnych
flow resistance
Ice slurry flow
Local loss coefficient
Pressure losses in contraction
Opis:
In this paper, flow systems which are commonly used in fittings elements such as contractions in ice slurry pipelines, are experimentally investigated. In the study reported in this paper, the consideration was given to the specific features of the ice slurry flow in which the flow behaviour depends mainly on the volume fraction of solid particles. The results of the experimental studies on the flow resistance, presented herein, enabled to determine the loss coefficient during the ice slurry flow through the sudden pipe contraction. The mass fraction of solid particles in the slurry ranged from 5 to 30%. The experimental studies were conducted on a few variants of the most common contractions of copper pipes: 28/22 mm, 28/18 mm, 28/15 mm, 22/18 mm, 22/15 mm and 18/15 mm. The recommended (with respect to minimal flow resistance) range of the Reynolds number (Re about 3000-4000) for the ice slurry flow through sudden contractions was presented in this paper.
Źródło:
Archives of Thermodynamics; 2010, 31, 3; 78-86
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental and theoretical investigation of an evacuated tube solar water heater incorporating wickless heat pipes
Autorzy:
Al-Joboory, Hassan Naji Salman
Powiązania:
https://bibliotekanauki.pl/articles/240588.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wickless heat pipe
fill charge
electrical analogy
evacuated tube solar collector
water heater
performance
Opis:
The present work involved an extensive outdoor performance testing program of a solar water heating system that consists of four evacuated tube solar collectors incorporating four wickless heat pipes integrated to a storage tank. Tests were conducted under the weather conditions of Baghdad, Iraq. The heat pipes were of 22 mm diameter, 1800 mm evaporator length and 200 mm condenser length. Three heat pipe working fluids were employed, ethanol, methanol, and acetone at an inventory of 50% by volume of the heat pipe evaporator sections. The system was tested outdoors with various load conditions. Results showed that the system performance was not sensitive to the type of heat pipe working fluid employed here. Improved overall efficiency of the solar system was obtained with hot water withdrawal (load conditions) by 14%. A theoretical analysis was formulated for the solar system performance using an energy balance based iterative electrical analogy formulation to compare the experimental temperature behavior and energy output with theoretical predictions. Good agreement of 8% was obtained between theoretical and experimental values.
Źródło:
Archives of Thermodynamics; 2020, 41, 3; 3-31
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pressure drop during condensation of refrigerants in pipe minichannels
Autorzy:
Bohdal, T.
Charun, H.
Sikora, M.
Powiązania:
https://bibliotekanauki.pl/articles/240165.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
kompaktowy kondensator
przepływ
skraplanie
skraplaniea w minikanałach
spadek ciśnienia
compact condenser
condensation in minichannels
pressure drop during flow in condensation
Opis:
The present paper describes results of experimental investigations of pressure drop during the condensation of R134a, R404a and R407C refrigerants in pipe minichannels with internal diameter 0.31-3.30 mm. The results concern investigations of the mean and local pressure drop in single minichannels. The results of experimental investigations were compared with the calculations according to the correlations proposed by other authors. A pressure drop during the condensation of refrigerants is described in a satisfactory manner with Friedel and Garimella correlations. On the basis of the experimental investigations, the authors proposed their own correlation for calculation of local pressure drop during condensation in single minichannels.
Źródło:
Archives of Thermodynamics; 2012, 33, 1; 87-106
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation for convective heat transfer of nanofluid laminar flow inside a circular pipe by applying various models
Autorzy:
Saeed, Farqad Rasheed
Al-Dulaimi, Marwah Abdulkareem
Powiązania:
https://bibliotekanauki.pl/articles/1845502.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
convective heat transfer
Reynolds number
nanofluid
single-phase flow
thermophysical properties
Opis:
The work presents a numerical investigation for the convective heat transfer of nanofluids under a laminar flow inside a straight tube. Different models applied to investigate the improvement in convective heat transfer, and Nusselt number in comparison with the experimental data. The impact of temperature dependence, temperature independence, and Brownian motion, was studied through the used models. In addition, temperature distribution and velocity field discussed through the presented models. Various concentrations of nanoparticles are used to explore the results of each equation with more precision. It was shown that achieving the solution through specific models could provide better consistency between obtained results and experimental data than the others.
Źródło:
Archives of Thermodynamics; 2021, 42, 1; 71-95
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical modeling of heat transfer in Al2O3/H2O nanofluid flowing through a Bessel-like converging pipe
Autorzy:
Iweka, Chukwuka S.
Fadodun, Olatomide G.
Powiązania:
https://bibliotekanauki.pl/articles/1845460.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nanofluid
Nusselt number
response surface methodology
Reynolds number
convergence
index
Opis:
This paper studies hydrodynamic and heat transfer performance of Al2O3/H2O nanofluid flowing through a Bessel-like converging pipe in laminar flow regime using the computational fluid dynamic approach. A parametric study was carried out on the effect of Reynolds number (300– 1200), convergence index (0-3) and nanoparticle concentration (0–3%) on the both hydrodynamic and thermal fields. The results showed the pressure drop profile along the axial length of the converging pipes is parabolic compared to the downward straight profile obtained in a straight pipe. Furthermore, an increase in convergence index, Reynolds number and nanoparticle concentration were found to enhance convective heat transfer performance. Also, a new empirical model was developed to estimates the average Nusselt number as a function of aforementioned variables. Finally, the result of the thermohydraulic performance evaluation criterion showed that the usage of Bessel-like converging pipes is advantageous at a low Reynolds number.
Źródło:
Archives of Thermodynamics; 2021, 42, 2; 121-153
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł

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