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1
Content available Experimental setup and measurements of heat transfer rate during newborn brain cooling process
100%
Bandoła D. , Rojczyk M. , Ostrowski Z. , Łaszczyk J. , Walas W. , Nowak A. J.
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2
Content available Effect of serrated circular rings on heat transfer augmentation of circular tube heat exchanger
100%
Kharkwal H. , Singh S.
Archives of Thermodynamics
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2022
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tom Vol. 43, no 2
129--155
EN
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.
3
An application of electrochemical technique in analysis of heat distribution in a tube bank during gas-liqiud two-phase flow
75%
Siejka K. , Ulbrich R.
Turbulence : international journal
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2007
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tom Vol. 12
105-113
EN
Electrochemical technique was applied to analyze the heat distribution in a tube bank in a bubbling gas-liquid flow column reactor. Results of the research on distribution of heat transfer rate on the surface of horizontal oriented tube bundles with two-phase gas-liquid crosswise flow in shell side of heat exchangers were presented in the paper. Basing on the obtained results, authors recognize electrochemical technique as very useful and of a great potential. It's noteworthy since it provides for finding mean and local heat transfer coefficients that result from conditions in both hydraulic and thermal developing region. Moreover, this technique seems to be low cost one and is the most accurate of all indirect methods of determining heat transfer coefficient.
4
Content available Numerical simulation of flow and heat transfer in hydromagnetic micropolar fluid between two stretchable disks with viscous dissipation effects
75%
Ali K. , Ahmad S. , Ashraf M.
Journal of Theoretical and Applied Mechanics
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2016
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tom Vol. 54 nr 2
633--643
EN
A study of magnetohydrodynamic (MHD) flow with viscous dissipation and heat transfer in an electrically conducting laminar steady viscous incompressible micropolar fluid between two infinite uniformly stretching disks is presented. The transformed self similar nonlinear ODEs are first linearized using a quasi linearization method and then solved by employing a combination of a direct and an iterative method. The study may be beneficial to flow and thermal control of polymeric processing.
5
Content available Performance estimation of blended nano-refrigerants’ thermodynamic characteristics and refrigeration efficacy
75%
Mystkowski A. , Śmierciew K. , Dudar A. , Gundabattini E. , Katoch A. , Razak F. A. , Suresh A. , Bibin B. S. , Farina A. R. , Cirillo L.
Acta Mechanica et Automatica
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2024
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tom Vol. 18, no. 2
282--290
EN
The use of nanoparticle-infused blended refrigerants is essential for achieving an effective sustainable system. This investigation analyses the efficiency of three nano-refrigerants (CuO-R152a, TiO2-R152a and TiO2-R113a) on the basis of the thermal performance and energy usage of the compressor using MATLAB-Simulink in the vapour compression refrigeration cycle with a two-phase flow domain. Also, nanoparticle volume concentrations of 0.1%–0.5% in the basic refrigerants are investigated. In the Simulink model, the outcomes are calculated mathematically. Using the NIST chemistry webbook, the thermo-physical characteristics of base refrigerants were calculated, and different numerical models were used to compute the characteristics of nano-enhanced refrigerants. MS Excel was used to perform the liquid–vapour interpolation. It was discovered that refrigerants with nanoparticles have superior heat-transfer properties and operate most excellently at an optimal volume fraction of 0.1% for TiO2-R152a and CuO-R152a with a coefficient of performance (COP) as 10.8. However, the other blended nano-refrigerant TiO2-R113a performed the best at 0.5% of nano-particle volume fraction with a COP value of 5.27.
6
Content available Experimental investigation of augmented thermal and performance characteristics of solar air heater ducts due to varied orientations of roughness geometry on the absorber plate
75%
Sahu M. K. , Matheswaran M. M. , Bishnoi P.
Archives of Thermodynamics
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2020
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tom Vol. 41, no 3
147--182
EN
This paper presents the outdoor experimental results for thermal performance analysis of artificially roughened solar air heaters (SAHs). Circular wire ribs have been arranged to form arc shape geometry on the absorber plates and have been tested for two configurations of SAHs named as arc shape apex-downstream flow and arc shape apex-upstream flow SAH. Roughness parameters have been taken as relative roughness pitch in the range of 8–15, angle of attack 45°–75°, and for fixed relative roughness height of 0.0454, duct width to duct height ratio of 11. During the experimental analysis the mass flow rate varied from 0.0100 to 0.0471 kg/s. Based on the experimental results it was found that roughness with apexupstream flow SAH is having higher value of thermal efficiency, heat removal factor and collector efficiency factor as compared to roughness with apexdownstream flow SAH and simple absorber plate SAH. In the range of the operating parameters investigated the maximum of thermal efficiency, heat removal factor, and collector efficiency factor have been found.
7
Content available Universal method of calculation of radiation recuperators with microfinned surface
63%
Karczewski K.
Metallurgy and Foundry Engineering
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2005
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tom Vol. 31, No 2
185-200
EN
Universal method of calculation of radiation recuperators with microfinned surface were elaborated. The algorithm of method applied: model investigations of heat transfer and hydraulic resistance on recuperator elements with microfins, the surface ratio and micro-fin efficiency. The universal method of calculation developed in the paper makes possible the recuperator's design to industrial furnace.
PL
Opracowano ogólną metodę obliczeń rekuperatorów radiacyjnych z mikroużebrowaniem. W algorytmie obliczeń zastosowano badania modelowe intensyfikacji wnikania ciepła i oporów przepływu elementów rekuperatorowych z mikroużebrowaniem, stosunek mikroużebrowania i sprawność mikrożebra. Ogólna metoda obliczeń umożliwiła wykonanie konstrukcji rekuperatora radiacyjnego do pieca przemysłowego.
8
Content available remote Modified zonal model of radiation recuperators with microfinned surface
63%
Karczewski K.
Metallurgy and Foundry Engineering
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2004
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tom Vol. 30, No 1
43-59
EN
Modified zonal model of radiation recuperators with microfinned surface was elaborated. The model equations are describing the function between walls, furnace gas and preheating air temperatures. In equations model researches heat transfer and hydraulic resistance of recuperator microfinned elements was applied. To calculate the recuperator wall temperature the rule of falsi method was used. Modified zonal model makes possible the projects of radiation recuperators with microfinned surface to industrial furnace.
PL
Opracowano zmodyfikowany strefowy model rekuperatorów radiacyjnych z mikroużebrowaniem. Równania modelu opisują zależności pomiędzy temperaturami ścian przegród, spalin i podgrzanego powietrza. W równaniach wykorzystano badania wymiany ciepła i oporów przepływu elementów rekuperatorowych z mikroużebrowaniem. Do obliczenia temperatury ścianki rekuperatora dostosowano metodę „reguła falsi". Zmodyfikowany strefowy model umożliwia projektowanie rekuperatorów radiacyjnych z mikroużebrowaniem dla pieców przemysłowych.
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Content available Modified single-zone model of radiation recuperator with microfinned surface
63%
Karczewski K.
Metallurgy and Foundry Engineering
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2007
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tom Vol. 33, no. 2
129-139
EN
Modified single-zone model of radiation recuperator with microfinned surface were elaborated. In this model the researches of heat transfer and hydraulic resistance microfinned elements were applied. To calculate the recuperator wall temperature weight mean temperature was used. By elaborated model radiation recuperator with microfinned surface to glass furnace were calculated. Single-zone model makes possible the project of small overall dimensions recuperators to industrial furnaces.
PL
Opracowano zmodyfikowany jednostrefowy model rekuperatora radiacyjnego z mikroużebrowaniem. W modelu wykorzystano badania wymiany ciepła i oporów przepływu mikroużebrowanych elementów rekuperatorowych. Temperaturę ścianki przegrody rekuperatora obliczono średnią ważoną. Według opracowanego modelu zaprojektowano rekuperator radiacyjny z mikroużebrowaniem do pieca szklarskiego. Model jednostrefowy umożliwia projektowanie małych gabarytowo rekuperatorów radiacyjnych do pieców przemysłowych.
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