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Tytuł:
Influence of working position for thermal performance of the capillary heat pipe
Autorzy:
Kosa, L.
Jobb, M.
Nemec, P.
Malcho, M.
Powiązania:
https://bibliotekanauki.pl/articles/402189.pdf
Data publikacji:
2014
Wydawca:
Politechnika Świętokrzyska w Kielcach. Wydawnictwo PŚw
Tematy:
capillary heat pipe
thermal performance
working position
Opis:
This experiment is concentrated on working position for optimization of capillary heat pipe. The main objective was to find optimal working position for capillary heat pipe. Working position is an important part for function of the heat pipe. A change in working position should change thermal performance of capillary heat pipe.
Źródło:
Structure and Environment; 2014, 6, 1; 46-48
2081-1500
Pojawia się w:
Structure and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal efficiency and hydraulic performance evaluation on Ag–Al2O3 and SiC–Al2O3 hybrid nanofluid for circular jet impingement
Autorzy:
Datta, Abanti
Halder, Pabitra
Powiązania:
https://bibliotekanauki.pl/articles/1845498.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
hybrid nanofluid
thermal performance factor
pumping power
merit number
Opis:
Hybrid nanofluids is obtained by dispersing more than one nanoparticle into a base fluid. The work is concerned with a detailed numerical investigation of the thermal efficiency and hydraulic performance of hybrid nanofluids for circular jet impinges on a round plate. For this paper, a metal (Ag), a metal oxides (Al2O3) and a metal carbides (SiC) nanoparticle and their water based hybrid nanofluids are considered to analyse numerically with varying significant dimensionless parameters, i.e., the jet-to-plate spacing ratio, Reynolds number and volume fraction of nanoparticles. The results demonstrated that the efficiency of heat transfer of all nanofluids is increased by the addition of nanoparticle to the dispersed in water at constant Reynolds number. Moreover, the results illustrate that heat transfer efficacy and pumping power penalty both increased as jet-to-plate spacing ratio reduced. The jet-to-plate spacing ratio equal to 4 is the best as the percentage enhance heat transfer is maximum in this situation. Since both the heat transfer effect and pumping penalty increase using hybrid nanofluids, thermal performance factor increases or decreases depends on nanoparticles of nanofluids. It is evident that the analysis of these hybrid nanofluids will consider both the increase in heat efficiency and the pumping capacity. The best flow behaviour is achieved for SiC–Al2O3 hybrid nanofluids. New merit number is introduced for additional clarification.
Źródło:
Archives of Thermodynamics; 2021, 42, 1; 163-182
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Budynki z konstrukcją przysłupową. Termomodernizacja ścian zewnętrznych i dachu
Buildings with a corner timbered-framework. Thermal performance improvement of external walls and roof
Autorzy:
Chądzyński, A.
Piróg, M.
Powiązania:
https://bibliotekanauki.pl/articles/293668.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
konstrukcja przysłupowa
termomodernizacja
corner timbered-framework construction
thermal performance improvement
Opis:
Tematem artykułu jest termomodernizacja przegród zewnętrznych (dachu i ścian) budynków drewnianych o konstrukcji przysłupowej. Zagadnienie to dotyczy obiektów liczących w większości kilkadziesiąt i więcej lat. W artykule poruszono kwestię konieczności ich remontów i dostosowania przegród do współczesnych wymagań w zakresie izolacyjności termicznej. Na podstawie analizy formy budynków drewnianych z konstrukcją przysłupową zaproponowano sposoby wykonania docieplenia zewnętrznych ścian wieńcowych, ryglowych i połaci dachu. Przedstawiono kierunek postępowania w tym procesie, biorąc szczególnie pod uwagę rodzaj materiału, jakim jest drewno, wyjątkowy charakter budynków o konstrukcji przysłupowej oraz ich znaczenie dla krajobrazu kulturowego.
The subject of the article is thermal performance improvement of external partitions (roof and walls) of wooden buildings with a corner timbered-framework structure. This problem concerns objects which are several dozen and more years old. The article discusses the need of renovation and adapting partitions to modern requirements in the field of thermal insulation. Based on the analysis of the form of wooden buildings with a timbered structure, methods of thermal insulation of external corrugated walls, timbered walls and roof slopes have been proposed. The article presents the course of action in this process, taking into account in particular the type of material which is wood, the unique character of the buildings with a corner timbered-framework structure and their meaning for the cultural landscape.
Źródło:
Architectus; 2018, 3 (55); 101-110
1429-7507
2084-5227
Pojawia się w:
Architectus
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comprehensive review on energy and exergy analysis of solar air heaters
Autorzy:
Ghritlahre, Harish Kumar
Sahu, Piyush Kumar
Powiązania:
https://bibliotekanauki.pl/articles/240351.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
solar energy
energy
exergy analysis
solar air heater
thermal performance
Opis:
For economic growth of nation, the energy plays an important role. The excessive use of fossil fuels results the increase in global warming and depleting the resources. Due to this reason, the renewable energy sources are creating more attraction for researchers. In renewable energy sector, solar energy is the most abundant and clean source of energy. In solar thermal systems, solar air heater (SAH) is the main system which is used for heating of air. As it is simple in construction and cheaper in cost, it is of main interest for the researchers. The concept of first law and second law of thermodynamics is used for the study of the energy and exergy analysis respectively. The energy analysis is of great importance for the study of process effectiveness while the exergetic analysis is another significant concept to examine the actual behavior of process involving various energy losses and internal irreversibility. For efficient utilization of solar energy, the exergy analysis is very important tool for optimal design of solar air heaters. The aim of the present work is to review the works related to energy and exergy analysis of various types of solar air heaters and to find out the research gap for future work.
Źródło:
Archives of Thermodynamics; 2020, 41, 3; 183-222
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solar air heater performance prediction using artificial neural network technique with relevant input variables
Autorzy:
Ghritlahre, Harish Kumar
Chandrakar, Purvi
Ahmad, Ashfaque
Powiązania:
https://bibliotekanauki.pl/articles/240435.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
artificial neural network
solar air heater
thermal performance
multilayer perceptron
Opis:
Solar air heater (SAH) is an important device for solar energy utilization which is used for space heating, crop drying, timber seasoning etc. Its performance mainly depends on system parameters, operating parameters and meteorological parameters. Many researchers have been used these parameters to predict the performance of SAH by analytical or conventional approach and artificial neural network (ANN) technique, but performance prediction of SAH by using relevant input parameters has not been done so far. Therefore, relevant input parameters have been considered in this study. Total ten parameters were used such as mass flow rate, ambient temperature, wind speed, relative humidity, fluid inlet temperature, fluid mean temperature, plate temperature, wind direction, solar elevation and solar intensity to find out the relevant parameters for ANN prediction. Seven different neural models have been constructed using these parameters. In each model 10 to 20 neurons have been selected to find out the optimal model. The optimal neural models for ANN-I, ANN-II, ANN-III, ANN-IV, ANN-V, ANN-VI and ANN-VII were obtained as 10-17-1, 8-14-1, 6-16-1, 5- 14-1, 4-17-1, 3-16-1 and 2-14-1, respectively. It has been found that ANN-II model with 8-14-1 is the optimal model as compared to other neural models. Values of the sum of squared errors, mean relative error, and coefficient of determination were found to be 0.02138, 1.82% and 0.99387, respectively, which shows that the ANN-II developed with mass flow rate, ambient temperature, inlet and mean temperature of air, plate temperature, wind speed and direction, relative humidity, and relevant input parameters performed better. The above results show that these eight parameters are relevant for prediction.
Źródło:
Archives of Thermodynamics; 2020, 41, 3; 255-282
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of serrated circular rings on heat transfer augmentation of circular tube heat exchanger
Autorzy:
Kharkwal, Himanshi
Singh, Satyendra
Powiązania:
https://bibliotekanauki.pl/articles/2091375.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer rate
friction factor
thermal performance factor
serrated circular ring
Opis:
Limiting energy resources has led researchers to find new innovative ways to enhance heat exchanging devices thermal performance in power generating systems. Thus, the present paper analyzes passive techniques of enhancing the thermal performance of a single tube heat exchanger. Experimental and numerical investigation on heat transfer enhancement using aserrated circular ring with twisted tape is carried out. The work incorporates the determination of Nusselt number, friction factor, thermal performance factor for serrated circular ring with twisted tape with variation in diameter ratio (0.8 and 0.85) and pitch ratio (2 and 3). Air is used as a working fluid with Reynolds number 6000–24000. The experiment is conducted by providing a constant wall heat flux of 1000 W/m2 to the system and thereby taking results at a steady state. The experimental and computational findings obtained for the smooth tube case are compared with the standard correlations of Dittus–Boelter and Blasius. Based on experimental and numerical investigation, there is 5.16 times augmentation in heat transfer and 3.05 times improvement in thermal performance factor over the smooth tube heat exchanger. In addition, the study of entropy generation rate for every geometrical parameter has been conducted, and their influence on the system’s thermal behaviour is presented. The results obtained in the present study may help the researchers of the same research area to find similar inserts and new ways of enhancing the thermal performance of heat exchangers.
Źródło:
Archives of Thermodynamics; 2022, 43, 2; 129--155
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Internal Heat Generation on the Thermal Stability of a Porous Fin
Autorzy:
Sobamowo, M. G.
Jayesimi, L. O.
Waheed, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/1031875.pdf
Data publikacji:
2020
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Differential Transformation Method
Porous Fin
Temperature-Dependent Internal Heat Generation
Thermal analysis
Thermal performance
Opis:
In this study, the effects of internal heat generation on thermal stability of porous fin is theoretical investigated using differential transform method. The parametric studies reveal increase in the internal heat generation leads to increase in the value or the range of the thermal stability of the fin. The internal heat generation can be used to control the thermal instability in the fin. Also, as the porosity parameter increase, the rate of heat transfer from the base of the fin and consequently improve the efficiency of the fin increase. However, a high value or an excessive internal heat generation results in an undesirable situation where some of the heat energy cannot escape to the sink and instead ends up flowing into the prime surface and the fin tends to store heat rather than dissipating it. This scenario defeats the prime purpose of the cooling fin. Therefore, the operational parameters must be carefully selected to ensure that the fin retains its primary purpose of removing heat from the primary surface.
Źródło:
World Scientific News; 2020, 149; 110-127
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of filling ratio on thermal performance and thermal parameters of closed loop pulsating heat pipes
Autorzy:
Kolková, Z.
Malcho, M.
Powiązania:
https://bibliotekanauki.pl/articles/402056.pdf
Data publikacji:
2013
Wydawca:
Politechnika Świętokrzyska w Kielcach. Wydawnictwo PŚw
Tematy:
closed loop pulsating heat pipe
thermal performance
evaporation
condensation
filling ratio
thermal resistance
temperature
Opis:
Improving the performance of electrical components needs higher heat removal from these systems. One of the solutions available is to use a sealed heat pipe with a throbbing filling, where development meets the current requirements for intensification of heat removal and elimination of moving parts cooling systems. Heat pipes operate using phase change working fluid, and it is evaporation and condensation. They have a meandering shape and are characterized by high intensity of heat transfer, high durability and reliability. Advantage of these tubes is that it is not necessary to create the internal capillary structure for transporting liquid and they need no pump to the working fluid circulation. They have a simple structure, low cost, high performance, and they can be used for various structural applications. The choice of working fluid volume and performance affects thermal performance. Distilled water, ethanol and acetone were used in the performance ranges of 0-80%.
Źródło:
Structure and Environment; 2013, 5, 4; 37-40
2081-1500
Pojawia się w:
Structure and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Method of research for solar cookers performance characteristics- analysis and comparison
Autorzy:
Raghav, Geetanjali
Sharma, Pankaj Kumar
Kumar, Suresh
Maithani, Rajesh
Powiązania:
https://bibliotekanauki.pl/articles/1833748.pdf
Data publikacji:
2021
Wydawca:
Centrum Badań i Innowacji Pro-Akademia
Tematy:
solar cookers
cooking
plate temperature
thermal performance
kuchenka słoneczna
gotowanie
wydajność cieplna
Opis:
Cooking is one of the most common activity in day-to-day life of every woman. In rural areas the transportation of fuel is major problem and the increasing demand of energy for cooking applications is gaining importance and various investigations are being carried out for performance enhancement of the solar cooker. The box-type solar cooker has a complex thermal analysis due to the transient heat transfer phenomenon involved in three dimensions. A comparison of the standard correlation available are analysed for accuracy of predicted results with experimental data. The investigation involves the experimental determination of the parameters viz. wind heat transfer coefficient, side and bottom loss coefficient, inner and outer glass temperature. The extensive data is analysed with that of standard correlations and the significance of the experimental data is checked. Analysis found to have deviation of 3%-20% in experimental and correlation data, which indicates that for accuracy of performance analysis the studied parameters should be determined experimentally.
Źródło:
Acta Innovations; 2021, 39; 54--66
2300-5599
Pojawia się w:
Acta Innovations
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An overview of heat transfer enhancement based upon nanoparticles influenced by induced magnetic field with slip condition via finite element strategy
Autorzy:
Hafeez, Muhammad B.
Krawczuk, Marek
Shahzad, Hasan
Powiązania:
https://bibliotekanauki.pl/articles/2105987.pdf
Data publikacji:
2022
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
magnetohydrodynamic flow
porous medium
nanofluids
heat transfer
thermal performance
convective boundary conditions
FEM
Opis:
The mathematical model of heat generation and dissipation during thermal energy transmission employing nanoparticles in a Newtonian medium is investigated. Dimensionless boundary layer equations with correlations for titanium dioxide, copper oxide, and aluminium oxide are solved by the finite element method. Parameters are varied to analyze their impact on the flow fields. Various numerical experiments are performed consecutively to explore the phenomenon of thermal performance of the combination fluid. A remarkable enhancement in thermal performance is noticed when solid structures are dispersed in the working fluid. The Biot number determines the convective nature of the boundary. When the Biot number is increased, the fluid temperature decreases significantly. Among copper oxide, aluminium oxide, and titanium oxide nanoparticles, copper oxide nanoparticles are found to be the most effective thermal enhancers.
Źródło:
Acta Mechanica et Automatica; 2022, 16, 3; 200--206
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of back propagation neural network to predict the thermal performance of porous bed solar air heater
Autorzy:
Ghritlahre, Harish Kumar
Prasad, Radha Krishna
Powiązania:
https://bibliotekanauki.pl/articles/240570.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
solar air heater
porous bed
thermal performance
artificial neural network
Levenberg-Marquardt algorithm
Opis:
The objective of present work is to predict the thermal performance of wire screen porous bed solar air heater using artificial neural network (ANN) technique. This paper also describes the experimental study of porous bed solar air heaters (SAH). Analysis has been performed for two types of porous bed solar air heaters: unidirectional flow and cross flow. The actual experimental data for thermal efficiency of these solar air heaters have been used for developing ANN model and trained with Levenberg-Marquardt (LM) learning algorithm. For an optimal topology the number of neurons in hidden layer is found thirteen (LM-13).The actual experimental values of thermal efficiency of porous bed solar air heaters have been compared with the ANN predicted values. The value of coefficient of determination of proposed network is found as 0.9994 and 0.9964 for unidirectional flow and cross flow types of collector respectively at LM-13. For unidirectional flow SAH, the values of root mean square error, mean absolute error and mean relative percentage error are found to be 0.16359, 0.104235 and 0.24676 respectively, whereas, for cross flow SAH, these values are 0.27693, 0.03428, and 0.36213 respectively. It is concluded that the ANN can be used as an appropriate method for the prediction of thermal performance of porous bed solar air heaters.
Źródło:
Archives of Thermodynamics; 2019, 40, 4; 103-128
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Comparison of the Sensitivity and Performance Characteristics of Melt-pour Explosives with TNT and DNAN Binder
Autorzy:
Trzciński, W.
Cudziło, S.
Dyjak, S.
Nita, M.
Powiązania:
https://bibliotekanauki.pl/articles/358284.pdf
Data publikacji:
2014
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
insensitive explosives
thermal analysis and performance
Opis:
Some sensitivity and performance characteristics for pure 2,4-dinitroanisole (DNAN) and 2,4,6-trinitrotoluene (TNT), as well as for meltpour composites containing 40% of DNAN or TNT, 20% of RDX, and 40% of NTO were determined (under the same conditions) and compared.
Źródło:
Central European Journal of Energetic Materials; 2014, 11, 3; 443-455
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of solar cooker with thermal storage for remote hilly areas: determination of heating and cooling characteristic time
Autorzy:
Raghav, Geetanjali
Sharma, Pankaj Kumar
Kumar, Suresh
Maithani, Rajesh
Iung, Alexis
Quentin, Mercier
Powiązania:
https://bibliotekanauki.pl/articles/2142896.pdf
Data publikacji:
2021
Wydawca:
Centrum Badań i Innowacji Pro-Akademia
Tematy:
solar energy
solar cookers
thermal storage
thermal performance
energia słoneczna
kuchenka słoneczna
magazynowanie ciepła
wydajność cieplna
Opis:
Solar cooking finds a major application in rural areas of Uttarakhand, India, yet its utilization is still limited due to certain limitation such as intermittent nature of solar radiations. This drawback limits solar cooker in becoming a viable alternate solution of LPG and other pollution causing resources such as wood. In order to cater this problem a numerical analysis of box type solar cooker with storage is carried out. The energy stored in the storage material will keep the cooker warm up to the time when food is consumed. Charging and discharging time analysis is performed in with an aim to understand the effect of storage on solar cooker. Heating and cooling characteristic time are being evaluated and analysed with storage. Thermal performance of box type solar cooker is measured in terms of figures of merit according to BIS standards. The effect of storage has also been analysed in terms of charging and discharging time and first figure of merit of box type solar cooker.it has been observed that during discharging the heat is stored for more duration as compared to the charging time as discharge time is approx. 4-5 hours while charging time for the same amount of insolation is around 3-4 hours.
Źródło:
Acta Innovations; 2021, 40; 5-18
2300-5599
Pojawia się w:
Acta Innovations
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Performance Assessment of Heat Resistant Fabrics Based on a New Thermal Wave Model of Skin Heat Transfer
Autorzy:
Zhu, F.
Zhang, W.
Song, G.
Powiązania:
https://bibliotekanauki.pl/articles/90033.pdf
Data publikacji:
2006
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
thermal performance
skin burn
skin simulant sensor
heat resistant fabrics
thermal wave skin model
ciepło
temperatura skóry
oparzenie
Opis:
A thermal wave skin model incorporating surface heat flux from a skin simulant sensor is developed to characterize the thermal performance of heat resistant fabrics covering the skin simulant sensor. Comparisons of time to 2nd-degree skin burn and temperature elevation of skin beneath a layer of fabric between the Pennes’ equation and the newly developed thermal wave skin model are performed in this research. Results of tolerance time from the Stoll criterion method are also compared with those from 2 skin models in a thermal protective performance calorimeter. It is concluded that the thermal properties of heat resistant fabrics can be characterized more precisely than previously.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2006, 12, 1; 43-51
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comparative study for double pass solar air collector utilizing medial glass panel
Autorzy:
Salih, Hussein M.
Powiązania:
https://bibliotekanauki.pl/articles/27309858.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
solar air collector
double-pass
CFD
finite volume
thermal performance
kolektor powietrza słonecznego
skończona objętość
wydajność cieplna
Opis:
A numerical investigation of thermal prediction of double-pass solar air heater of-counter flow is developed in the present study. The main idea of the current study is that the collector consists of two layers of glass so that the middle layer is glass instead of the usual metal plate. The performance of double-pass solar air heater is studied for a wide range of solar radiation intensities (600, 750 and 900 W/m 2). A FORTRAN-90 program is built to simulate the mathematical model of double-pass solar air heater based on solving steady state two-dimensional Navier-Stokes equations and energy equation based on finite volume method. Turbulence effect is simulated by two equations k-ε module. The results are compared with the results of a previous experimental study and a good agreement was found. From compression calculating efficiency of the present and traditional collector for each solar intensity, it was found that the efficiency of the current collector is higher than that of the traditional one, where the efficiency of the current collector at the solar intensity of (600, 750 and 900) W/m 2 are (0.529, 0.514 and 0.503), respectively, while those of the traditional collector (0.508, 0.492 and 0.481), respectively. In addition to this, the effect of the mass flow rate on the temperature difference of the current proposed collector was studied. Three values of the mass flow rate were studied (0.009,0.018, and 0.027) kg/s at solar intensity of 750 W/m 2. From this it was found that the temperature difference decreases with increasing mass flow rate. Accordingly, the efficiency decreases
Źródło:
Archive of Mechanical Engineering; 2022, LXIX, 4; 729--747
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Natural convection and radiation in a radial porous fin with variable thermal conductivity
Autorzy:
Darvishi, M. T.
Kani, F.
Gorla, R. S. R.
Powiązania:
https://bibliotekanauki.pl/articles/955178.pdf
Data publikacji:
2014
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
konwekcja naturalna
promieniowanie
wydajność cieplna
metoda kolokacji
porous radial fin
natural convection
radiation
thermal performance
spectral collocation method
Opis:
In this study, the effects of radiation and convection heat transfer in a radial porous fin are considered. The geometry considered is that of a rectangular profile fin. The porous fin allows the flow to infiltrate through it and solid-fluid interaction takes place. This study is performed using Darcy’s model to formulate the heat transfer equation. The thermal conductivity is assumed to be a function of temperature. The effects of the natural convection parameter Nc , radiation parameter Nr and thermal conductivity parameter m on the dimensionless temperature distribution and heat transfer rate are discussed. The results suggest that the radiation transfers more heat than a similar model without radiation.
Źródło:
International Journal of Applied Mechanics and Engineering; 2014, 19, 1; 27-37
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal performance analysis of manned airships in a thermally variable environment
Autorzy:
Shi, Hong
Liu, Meinan
Chen, Jiamin
Zou, Yitao
Powiązania:
https://bibliotekanauki.pl/articles/2173708.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
manned airship
thermal performance
nacelle
temperature difference
flight position
sterowiec załogowy
wydajność cieplna
gondola
różnica temperatur
pozycja lotu
Opis:
The safety and reliability of the manned airship depend to a considerable extent on its thermal performance. In this paper, heat balance equations are developed and solved in the C++ programming language. The temperature variation of the enclosure, gasbag, and nacelles of the manned airship is investigated. In addition, the effects of season, latitude, and orientation on the thermal performance of the manned airship and the airship nacelle are investigated. The results show that: (1) The average temperature difference of the nacelle surface at the same time is 25 K, while the maximum temperature difference in the nacelle is 29 K during the day, (2) the temperature distribution in the nacelle is similar in spring and autumn, with maximum temperature between 306 K and 309 K. The maximum temperature in the nacelle is between 300 K and 303 K in winter while the maximum temperature in the nacelles is between 309 K and 315 K in summer, (3) as the flight position of the manned airship changes from 20°N to 60°N, the average nacelle temperature varies slightly by about 1 K. However, as the latitude increases, the high- temperature region shifts from the bottom of the nacelle to the side of the nacelle, and (4) the temperature distribution of the upper envelope of the airship varies considerably with orientation. However, the average temperature of the nacelle is less impacted by orientation. These results are useful for understanding the thermal performance of manned airships.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 5; art. no. e143105
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Energy saving measures to improve the microclimate in poultry facilities
Oszczędność energii w celu poprawy mikroklimatu w obiektach drobiarskich
Autorzy:
Spodyniuk, Nadiia
Pshenychna, Oksana
Powiązania:
https://bibliotekanauki.pl/articles/2175037.pdf
Data publikacji:
2021
Wydawca:
Politechnika Częstochowska
Tematy:
infrared heating
poultry’s location
thermal performance of the heater
ogrzewanie na podczerwień
lokalizacja drobiu
wydajność cieplna nagrzewnicy
Opis:
The provision of a microclimate for poultry houses with the help of radiant heating systems has become widespread. Infrared heating systems, unlike other systems for providing the microclimate of poultry houses, provide local heating. When placed correctly, infrared heaters heat only the area where the poultry is located. When using infrared heaters, it is possible to achieve the necessary conditions in the location of the poultry, without increasing the temperature of the indoor air, and if possible, reducing it. Studies were conducted on a system that combined an infrared emitter for local heating and an exhaust umbrella to remove gaseous harmful substances from the up-per part of the poultry’s location. From the results of the experiment and the obtained graphical and analytical dependences, the optimum air temperature in the poultry’s location was determined.
Zapewnienie mikroklimatu dla kurników za pomocą systemów ogrzewania promiennikowego stało się powszechne. Systemy ogrzewania na podczerwień, w przeciwieństwie do innych systemów zapewniających mikroklimat kurników, zapewniają lokalne ogrzewanie. Przy prawidłowym umieszczeniu promienniki podczerwieni ogrzewają tylko obszar, w którym znajduje się drób. Stosując promienniki na podczerwień, możliwe jest osiągnięcie niezbędnych warunków w lokalizacji drobiu, bez zwiększania temperatury powietrza w pomieszczeniu, a jeśli to możliwe, jej obniżania. Przeprowadzono badania nad systemem, który łączył promiennik podczerwieni do lokalnego ogrzewania i parasol wyciągowy w celu usunięcia szkodliwych substancji gazowych z górnej części stanowiska drobiu. Na podstawie wyników doświadczenia oraz uzyskanych zależności graficznych i analitycznych wyznaczono optymalną temperaturę powietrza w miejscu przebywania drobiu.
Źródło:
Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo; 2021, 27 (177); 230-233
0860-7214
Pojawia się w:
Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Further Study on Thermal Performance of Porous Fin with Temperature-Dependent Thermal Conductivity and Internal Heat Generation using Galerkin’s method of Weighted Residual
Autorzy:
Sobamowo, M. G.
Kamiyo, O. M.
Adeleye, O. A.
Powiązania:
https://bibliotekanauki.pl/articles/1046542.pdf
Data publikacji:
2019
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Galerkin’s method of weighted residual
Porous Fin
Surface convective heat transfer
Temperature-Dependent Thermal Conductivity and Internal Heat Generation
Thermal performance
Opis:
This work is presented as a further study to our previous work, “Thermal performance analysis of a natural convection porous fin with temperature-dependent thermal conductivity and internal heat" published in "Thermal Science and Engineering Progress. 1 (2017) 39–52”, where it was assumed that the surface convection is negligible and heat is transferred only by natural convection in the porous fin. In this present study, such an assumption has been relaxed. Also, effects of surface convective heat transfer on the thermal performance of porous fin with temperature-dependent thermal conductivity and internal heat generation have been investigated using Galerkin’s method of weighted residual. The results of the Galerkin’s method of weighted residual show excellent agreement with the results of numerical method using shooting method coupled with Runge-Kutta method and also with the results of homotopy perturbation method. Thereafter, the developed analytical solutions are used to investigate the influences of the thermal model parameters on the thermal performance of the porous fin. It is found as the with the other model parameters that as the convective parameter increases, the rate of heat transfer from the base of the fin increases and consequently, the porous fin efficiency improves. However, increase in the nonlinear thermal conductivity parameter decreases the temperature distribution in the fin. Based on the high accuracy of the Galerkin’s method of weighted residual as displayed in this work, it is hoped that the simple analytical solutions given by the approximate analytical method will enhance the analysis of extended surfaces and also assist the designers.
Źródło:
World Scientific News; 2019, 138, 2; 167-191
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of thermal performance factor for solar air heaters with artificially roughened channels
Autorzy:
Siddique, Waseem
Raheem, Aneeq
Aqeel, Muhammad
Qayyum, Sualeh
Salamen, Tareq
Waheed, Khalid
Qureshi, Kamran
Powiązania:
https://bibliotekanauki.pl/articles/1845043.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
turbulence promoter
solar air heater
heat transfer enhancement
thermal performance factor
słoneczny grzejnik powietrzny
intensyfikacja wymiany ciepła
współczynnik wydajności cieplnej
Opis:
Heat transfer augmentation has become the utmost industrial desire. Turbulence promoters seems to be a better option for better heat transfer but at the expense of enormous pressure drop. In the current study, experimental optimization of heat transfer and pressure drop in various configurations of ribbed and corrugated surfaces on the bottom wall of the Solar Air Heater channel, having aspect ratio of 26:5 was performed. The results were evaluated in terms of enhancement in heat transfer (Nu/Nu s), friction factor ratio (f/f s) and thermal performance factor ( η). Three different cases and nine configurations with a pitch to rib/corrugation height ratio of 4.0 were studied. Case A consists of a smooth, continuous square rib, inline and staggered broken ribs. Case B comprises 30°, 45°, 60° and 90° trapezoidal corrugated geometries while Case C is the comparison of smooth, wavy corrugated and the best configurations of cases A and B. The results show that rectangular duct with staggered broken ribs and trapezoidal corrugation at 45° are the best configurations for case A and B, respectively. The 45° corrugated configuration is the best one amongst all, with values of 1.53, 1.5 and 1.33% for Nu/Nu s, f/f s and η respectively.
Źródło:
Archive of Mechanical Engineering; 2021, LXVIII, 2; 195-225
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Energy-related conditions and envelope properties for sustainable buildings
Autorzy:
Geryło, R.
Powiązania:
https://bibliotekanauki.pl/articles/201891.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
sustainability of construction works
requirements development
primary energy
embodied energy
thermal performance
thermal stability
trwałość obiektów budowlanych
rozwój wymagań
energia pierwotna
wydajność cieplna
stabilność termiczna
Opis:
The assessment methodology for the sustainability of buildings is based on the analysis of environmental, social and economic performance. The main purpose of the paper is the presentation of energy-related conditions and envelope properties as well as methodology aspects. The first part of the paper presents the literature review on sustainability and zero-energy buildings. The second part is devoted to describe different energy indicators for the evaluation of primary energy requirements and energy characteristic. The last section describes the general methodology for characterization of energetic properties of the building envelope and gives examples from literature of the effect of applications in a building’s envelope an aerogel based thermal insulation for higher thermal transmittance and a PCM for higher latent heat capacity with general description of results obtained by other authors. The crucial measure is the use of high thermal performance components for the building’s envelopes combined with the heat storage potential. In the context of sustainability, energy related conditions constitute a new set of indicators for identifying the usefulness and the efficiency of new technologies.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2016, 64, 4; 697-707
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhancement of thermal efficiency of nanofluid flows in a flat solar collector using CFD
Autorzy:
Zarda, Falah
Hussein, Adnan Mohammed
Danook, Suad H.
Mohamad, Barhm
Powiązania:
https://bibliotekanauki.pl/articles/2146747.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
solar collector flat-plate
diamond/H2O nanofluids
thermal performance
computational fluid dynamics
płaski kolektor słoneczny
właściwości cieplne
numeryczna mechanika płynów
Opis:
Flat plate solar collector (FPSC) is popular for their low cost, simplicity, and ease of installation and operation. In this work, FPSC thermal performance was analyzed. It's compared to diamond/H2O nanofluids. The volume percentage and kind of nanoparticles are analyzed numerically that validation with experimental data available in the literature. The hot climate of Iraq is employed to approximate the model. The numerical study is performed by using ANSYS/FLUENT software to simulate the case study of problem. Due to less solar intensity after midday, temperatures reduction. The greatest collector thermal efficiency is 68.90% with 1% ND/water nanofluid, a 12.2% increase over pure water. The efficiency of 1% nanofluid is better than other concentrations because of a change in physical properties and an increase in thermal conductivity. Since the intensity of radiation affects the outlet temperature from the solar collector and there is a direct link between them, this increases the efficiency of the solar collector, especially around 12:30 pm at the optimum efficiency.
Źródło:
Diagnostyka; 2022, 23, 4; art. no. 2022411
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhancing the Thermal Protective Performance of Firefighters Protective Fabrics by Incorporating Phase Change Materials
Polepszenie właściwości termicznych odzieży ochronnej strażaków poprzez zastosowanie materiałów zmiennofazowych
Autorzy:
Zhu, F L
Feng, Q Q
Liu, R
Yu, B
Zhou, Y
Powiązania:
https://bibliotekanauki.pl/articles/231560.pdf
Data publikacji:
2015
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
phase change material
fire protective clothing
thermal protective performance
materiał zmiennofazowy
odzież ochronna
ochrona termiczna odzieży
Opis:
A composite fabric consisting of an outer shell, moisture barrier, thermal liner and comfort layer used for firefighters’ protective clothing, was incorporated with shape-stabilised phase change material (PCM) powder in order to improve the thermal protection capability provided by thermal protective clothing. Then we conducted a series of FTP (fire testing protection) experiments to investigate the effects of PCM location and phase change temperature on the heat protection efficiency of firefighters’ protective fabrics (FFPFs). Simultaneously the thermoregulation performance of the composite fabrics with PCMs was evaluated by using step-cooling experimental technology during the cooling process. Data from the FTP tests were also compared with those from the existing enthalpy formulation model of heat transfer through FFPFs embedded with PCMs. It was concluded that the use of PCMs could improve the heat buffering capacity. However, as PCM has a moderate melting temperature, it is better than the other two samples because they have a lower and higher melting temperature. Therefore PX 52 PCMs (melting temperature: 47 - 53 °C) could provided the maximum heat protection time compared with the other two kinds of PCMs.
W celu zwiększenia zdolności ochrony termicznej odzieży ochronnej dla strażaków, przy użyciu stabilizowanego materiału zmiennofazowego w postaci proszku, stworzono materiał kompozytowy składający się z powłoki zewnętrznej, warstwy stanowiącej barierę dla wilgoci, wkładki termicznej i warstwy zapewniającej komfort. W celu zbadania wpływu umieszczenia materiału zmiennofazowego i temperatury przemiany fazowej na efektywność ochrony cieplnej przeprowadzono serię eksperymentów (testy ochrony przeciwpożarowej). Jednocześnie oceniono zdolność termoregulacji tkanin kompozytowych, oceny tej dokonano stosując technikę stopniowego chłodzenia. Dane z badań porównano z danymi teoretycznymi. Stwierdzono, że stosowanie materiałów zmiennofazowych może poprawić zdolność buforowania ciepła. Określono optymalny rodzaj materiału zmiennofazowego.
Źródło:
Fibres & Textiles in Eastern Europe; 2015, 2 (110); 68-73
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wpływ materiału zmiennego fazowo na właściwości wytrzymałościowe i cieplne zapraw budowlanych
Influence of phase changing materials on endurance and thermal properties of building mortars
Autorzy:
Rucińska, Teresa
Adamczuk, Magdalena
Ciesiński, Błażej
Powiązania:
https://bibliotekanauki.pl/articles/160518.pdf
Data publikacji:
2020
Wydawca:
Polski Związek Inżynierów i Techników Budownictwa
Tematy:
materiał zmiennofazowy
MFZ
zaprawa budowlana
właściwości wytrzmałościowe
właściwości cieplne
akumulacja ciepła
pojemność cieplna
badanie laboratoryjne
phase changing material
PCM
mortar
strength properties
thermal performance
heat accumulation
thermal capacity
laboratory test
Opis:
W artykule przedstawiono możliwości wykorzystania materiałów zmiennych fazowo jako przykład poprawienia zdolności akumulacji energii cieplnej wyrobów budowlanych, a także wyniki eksperymentu w zakresie oceny skuteczności działania materiału zmiennego fazowo w postaci mikrokapsułek Micronal®PCM firmy BASF, wprowadzonego w zróżnicowanej ilości do składu materiałów kompozytowych z matrycą gipsową i cementową. Oznaczono objętościową pojemność i przewodność cieplną w zmiennych warunkach temperaturowych, a także wykonano badania podstawowych parametrów technicznych analizowanych zapraw. Opisane rezultaty badań zaczerpnięto z prac dyplomowych, magisterskiej i inżynierskiej, zrealizowanych na Wydziale Budownictwa i Inżynierii Środowiska ZUT w Szczecinie.
The article presents the possibilities of using phase changing materials as an example of improvement of thermal energy accumulation capacity of construction products, as well as results of an experiment regarding assessment of effectiveness of a phase changing material in the form of Micronal®PCM microcapsules, manufactured by the BASF company, introduced in varying amounts to the composition of composite materials with a gypsum and cement matrix. The volumetric capacity and heat conductivity were determined in changing temperature conditions, and the basic technical parameters of the analysed mortars were tested. The described research results have been taken from master's and engineer's dissertations, written at the Faculty of Civil and Environmental Engineering, at the West Pomeranian University of Technology in Szczecin.
Źródło:
Przegląd Budowlany; 2020, 91, 9; 44-53
0033-2038
Pojawia się w:
Przegląd Budowlany
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Method of calculation of air temperature in the open air layer
Metoda obliczania temperatury powietrza w otwartej warstwie powietrznej
Autorzy:
Piotrowski, J.Z.
Olenets, M.
Starzomska, M.
Zaborek, R.
Powiązania:
https://bibliotekanauki.pl/articles/402493.pdf
Data publikacji:
2012
Wydawca:
Politechnika Świętokrzyska w Kielcach. Wydawnictwo PŚw
Tematy:
open air layer
thermal performance
mathematical model
convective heat flux
radiant heat flux
heat transfer
otwarta warstwa powietrzna
wydajność cieplna
model matematyczny
konwekcyjny strumień ciepła
radiacyjny strumień cieplny
wymiana ciepła
Opis:
The building envelopes with the open air layer are common in building energy-efficient houses. In such buildings, air gap is used for moisture elimination from a surface of external wall, which improves its thermal properties. To improve the thermal quality of building envelopes with open air layer and reduce the heat transfer rate during the cold period, it is necessary to conduct more in-depth study of heat exchange in the ventilated layer of air. The article presents a mathematical model of heat transfer through building envelopes with an open air layer for the cold season. In the proposed mathematical model connective and radiant heat fluxes were considered separately.
Źródło:
Structure and Environment; 2012, 4, 4; 43-48
2081-1500
Pojawia się w:
Structure and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-25 z 58

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