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1

Powłoki natryskiwane plazmowo dla potrzeb przemysłu chemicznego

Morel Sławomir

Przemysł Chemiczny

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2023

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T. 102, nr 4

355--361

PL

Opisano przeznaczenie i zakres zastosowań powłok natryskiwanych cieplnie. Scharakteryzowano plazmę stosowaną do natryskiwania powłok. Dokonano ogólnej charakterystyki najczęściej stosowanych materiałów powłokowych i wyszczególniono ważniejsze właściwości powłok decydujące o ich przydatności dla potrzeb przemysłu i gospodarki. Przytoczono ważniejsze przykłady eksploatacji urządzeń pracujących z natryskanymi powłokami, zamieszczając osiągnięte efekty oddziaływania powłok na wzrost trwałości i efektywności pracy cieplnej.

EN

A review, with 14 refs, of the range of applications of thermal sprayed coatings using plasma. The plasma used for spraying coatings was characterized. The general characteristics of the most commonly used coating materials were presented, and the most important coating properties detg. their suitability for industrial applications were indicated. Examples of the operation of devices working with sprayed coatings were given, including the effects of coatings on increasing the durability and efficiency of thermal operation.

2

Całkowite przenikanie ciepła przez elementy obudowy budynku

Pawłowski Krzysztof

Izolacje

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2023

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T. 28, nr 2

34--38

PL

W artykule przedstawiono procedury obliczeniowe wraz z przykładem obliczeniowym w zakresie określania strat ciepła przez przenikanie przez elementy obudowy budynku.

EN

The article presents calculation procedures together with a calculation example in the field of determining heat loss by penetration through elements of the building envelope.

3

Surface Imaging of Temperature – Research Method of Heat Transfer

Szafran Krzysztof, Łusiak Tomasz, Jeziorek Łukasz, Korzec Izabela

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 1

243--251

EN

The method does not differ in difficulty from the standard surface temperature imaging method, which is its unquestionable advantage. The disadvantage is the need to use test models made of materials transmitting visible light in the full range (blue light for excitation and red as a recorded result), which, with more complex shapes, makes the model more expensive. Nevertheless, the presented method is a valuable supplement to the set of methods and techniques used so far for imaging temperature fields and estimating the heat flux in the steady state.

4

Fractional order, state space model of the temperature field in the pcb plate

Oprzędkiewicz Krzysztof, Mitkowski Wojciech, Rosół Maciej

Acta Mechanica et Automatica

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2023

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Vol. 17, no. 2

180--187

EN

In the paper the fractional order, state space model of a temperature field in a two-dimensional metallic surface is addressed. The proposed model is the two dimensional generalization of the one dimensional, fractional order, state space of model of the heat transfer process. It uses fractional derivatives along time and length. The proposed model assures better accuracy with lower order than models using integer order derivatives. Elementary properties of the proposed model are analysed. Theoretical results are experimentally verifed using data from industrial thermal camera.

5

Influence of structural characteristics of porous materials on the coefficient of thermal conductivity

Cheilytko Andrii

Journal of New Technologies in Environmental Science

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2022

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Vol. 6, nr 3

104--112

EN

The existing dependences of the effective coefficient of thermal conductivity of the material depending on the size and location of pores in it are analyzed and compared with each other and with previously obtained experimental data. It is shown that the resulting thermophysical properties of the material are affected not only by the porosity, but also by the location of the pores in the volume of the material. The disadvantages of the existing dependences of determining the effective thermal conductivity of the material on the type of porosity (both for porous material and for dispersed systems) are shown. Also, the most reliable dependences of the thermal conductivity coefficients on the porosity of dispersed systems for backfill materials and the need for their correction by empirical coefficients are determined. Complex indicators that fully describe the porous structure and on which the mathematical model of heat exchange processes in a porous medium should be based are proposed.

6

Application of phase change materials in ventilation systems - a review

Galiszewska Beata

Journal of New Technologies in Environmental Science

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2022

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Vol. 6, nr 1

15--27

EN

Heat losses caused by ventilation systems significantly affect energy consumption in buildings. Therefore, it seems reasonable to look for solutions to improve the efficiency of heat recovery and storage in ventilation systems. One example of such solutions are thermal energy storage systems using phase change materials (PCM), which can be a way to improve the thermal performance of a building. Utilizing the increased energy absorption capacity of phase transition temperatures through phase change materials, increases the efficiency of energy accumulation and subsequent release. The use of sensible and latent heat of PCM materials can significantly affect the efficiency of heat recovery and storage in ventilation systems. The paper presents an overview of various applications PCM in ventilation systems. The study presents the method of conducting selected research and the results achieved.

7

Exact solution for heat conduction inside a sphere with heat absorption using the regularized Hilfer-Prabhakar derivative

Elhadedy Hager, Latif Mohamed S. Abdel, Nour Hamed M., Kader Abbas H. Abdel

Journal of Applied Mathematics and Computational Mechanics

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2022

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Vol. 21, nr 2

27--37

EN

In this article, we utilize the finite Sine-Fourier transform and the Laplace transform for solving fractional partial differential equations with regularized Hilfer-Prabhakar derivative. These transforms are used to get analytical solutions for the time fractional heat conduction equation (TFHCE) with the regularized Hilfer-Prabhakar derivative associated with heat absorption in spherical coordinates. Two cases of Dirichlet boundary conditions are considered by obtaining an analytical solution in each case. The effect of the parameters of the regularized Hilfer-Prabhakar derivative on the heat transfer inside the sphere is discussed using some figures.

8

Unsteady electro-magneto hydrodynamic flow and heat transfer of two ionized fluids in a rotating system with Hall currents

Raju T. Linga, Rao B. Venkat

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 1

125--145

EN

An unsteady flow and heat transmission of ionized gases via a horizontal channel enclosed by non-conducting plates in a rotating framework with Hall currents is examined using electro-magnetohydrodynamic (EMHD) two-fluid heat flow. The Hall current impact is taken into account by assuming that the gases are totally ionized, the applied transverse magnetic field is very strong. For temperature and velocity distributions in two-fluid flow regions, the governing equations are solved analytically. For numerous physical parameters such as the Hartmann number, Hall parameter, rotation parameter, viscosity ratio, and so on, numerical solutions are visually displayed. It was discovered that an increase in temperature in the two regions is caused by the thermal conductivity ratio. It was also realized that an increase in rate of heat transfer coefficient at the plates is caused by either the Hartman number or the Hall parameter.

9

The Hall effect on MHD 2-fluid unsteady heat transfer flow of plasma in a rotating system via a straight channel between conducting plates

Raju T. Linga, Rao B. Venkata

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 3

137--162

EN

Hall currents are used to investigate MHD unsteady two fluid flows and heat transport of plasma along a straight channel of conducting plates. In the two liquid zones, the velocity and temperature fields for the case of conducting side plates are obtained by solving the governing equations using a two-term series under the specified conditions. The distribution profiles are graphically resolved and examined. The distributions are thought to be dependent on the electron-to-total pressure ratio. The flow and heat transfer factors are also influenced by other parameters such as the Hartmann number, Hall parameter, rotation parameter, thermal conductivity and viscosity ratio.

10

An effect of binary fluid on the thermal performance of pulsation heat pipe

Barrak Anwar S., Ali Nawfal M, Ali Hussein Hayder Mohammed

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 1

21--34

EN

A pulsation heat pipe is an efficient heat pipe used in many engineering applications. This study aims to test the effect of working fluids on the thermal performance of pulsation heat pipe. Seven turned pulsation heat pipes were designed and manufactured from a copper pipe with a 3.5 mm inner diameter. The lengths of an evaporation part, an adiabatic passage, and a condenser part were 300 mm, 210 mm, and 300 mm, respectively. In this study, three different fluids were used as the working fluid: distilled water, methanol, and binary fluid (a mixture of water and methanol) with a 50% filling ratio. Compared to water, the experimental results suggested that methanol had a better thermal performance when used as a working fluid in the PHP. On the other hand, a binary fluid enhanced the lower thermal performance of water (29% reduction in the thermal resistance and a 20% increase in the effective thermal conductivity of the PHP).

11

Wpływ struktury przepływu na wymianę ciepła w procesie skraplania proekologicznych czynników chłodniczych w minikanałach

Sikora Małgorzata, Bohdal Tadeusz

Instal

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2022

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nr 5

20--26

PL

Podczas procesu skraplania w minikanałach następuje zmiana mechanizmów przenoszenia ciepła i masy wynikająca ze zmiany stopnia suchości x i stopnia zapełnienia φ, które wpływają na proces formowania się różnych struktur przepływu. Miarą efektywności energetycznej procesu jest współczynnik przejmowania ciepła α, który zależy od charakteru przepływu dwufazowego. W niniejszym artykule zaprezentowano wpływ formujących się struktur przepływu dwufazowego na proces wymiany ciepła podczas procesu skraplania czynników chłodniczych w poziomych minikanałach rurowych. Badania przeprowadzono dla trzech proekologicznych czynników niskociśnieniowych HFE7000, HFE7100, Novec649, o niskich wskaźnikach ODP i GWP. Proces skraplania zachodził w minikanałach rurowych o średnicy wewnętrznej dh = 2,0; 1,2; 0,8; 0,5 mm.

EN

During the condensation process in the mini-channels, the heat and mass transfer mechanisms change, resulting from the change in the vapor quality x and the void fraction φ, which in turn affect the process of formation of various flow structures. The measure of the energy efficiency of the process is the heat transfer coefficient α, which depends on the kind of the two-phase flow. This article presents the influence of the two-phase flow structures formed during the condensation process in horizontal pipe mini-channels on the heat transfer process. The research was carried out on three pro-ecological low-pressure refrigerants with low ODP and GWP coefficients, HFE7000, HFE7100, and Novec649. The condensation process took place in pipe mini-channels with an internal diameter of dh = 2.0; 1.2; 0.8; 0.5 mm

12

Experimental and Numerical Study of Photo Voltaic Thermal Phase Change Material Heat Transfer Augmentation with Encapsulation of Embedded Material/Fins

Kameswara Rao Dommeti, Reddy Keesari Sudhakar, Subba Rao V. V.

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 4

149--161

EN

Nonconventional energy sources like natural gas, coal, fossil fuels and petroleum are using extensively, leads to clean energy / renewable energy importance. Power generation with burning of fossil fuels can be changed using solar energy input source. Solar radiation incident on Photo voltaic Thermal (PVT) panel raises its temperaturę which tends to decrease the electrical output. Heat enhancement in Photo voltaic Thermal (PVT) panel can be reduced by attaching Phase Change Material (PCM) container on rear side of PV panel which increases the PVT efficiency. Novel technique and promising media for better thermal energy storage using PCM with fins, porous materials. Thermal conductivity of PCMs was low creates problem for energy storage and rate of retrieval. Improvement of thermal conductivity in PCMs and heat transfer enhancement can be done efficiently with the help of fins and porous materials of different designs. Present study provides optimum design of PCM container depth, fin height along with length of fin. Enhancement of heat transfer in Photo voltaic Thermal- Phase Change Material (PVT-PCM) will done by addition of Nano particles (Tio2, Sio2 and Al etc.)of high thermal conductivity along with PCM. Porous materials / fins can be made with metallic based materials nickel, copper, aluminum and carbon materials like graphite. These porous materials gave good results and efficient in heat transfer / thermal conductivity enhancement by 50–600 times than the conventional one. This paper gives the recommendations and conclusions to discuss research gap in this area PCM heat transfer enhancement to reduce the PVT panel temperature.

13

Artificial Neural Network Technique for Estimating the Thermo-Physical Properties of Water-Alumina Nanofluid

Ravi Babu Sajja, Krishna Varma K. P. V., Mohan Kunapuli Siva Satya

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 2

97--106

EN

With its superior thermo-physical characteristics to the carrier fluid, nanofluid is the most impactful heat transfer fluid. Thermal conductivity, density, viscosity, specific heat, coefficient of volumetric expansion, and other thermo-physical parameters play an important part in the thermal management of any heat transfer application. This thermal management governs the service life of an equipment or apparatus, which dissipates heat during its operation. If the equipment is well-managed thermally, then its service life will be extended. Otherwise the equipment stops functioning due to excess heat. Thermo-physical properties of nanofluid vary with the change in the concentration of nanoparticles. Estimation of the properties with the varying concentrations of the nanoparticles is time consuming and is economically not viable. There were many empirical models available in the literature for determining the thermo-physical properties of nanofluids. However, each model provides different values of thermo-physical properties and choosing the best model among the models available is a complex task. In this regard, to avoid the complication in choosing the best model, and in order to envisage the thermo-physical properties of the nanofluid, the Artificial Neural Network (ANN) technique was used. This technique is widely used among the researchers for various applications. The ANN approach was utilized in this work to estimate viscosity and thermal conductivity of water-based Al2O3 nanofluid for volume fractions between 0.01% and 0.1%. For thermal conductivity, mean square error (MSE) was observed as 4.504e-09 and for viscosity, it was observed as 6.4742e-09. Training times were 5 seconds and 4 seconds for thermal conductivity and viscosity datasets, respectively.

14

Odzysk i transfer ciepła z Data Center

Żuk Maciej

Chłodnictwo i Klimatyzacja

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2022

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nr 6

48--50

PL

Jakie rozwiązania dotyczące chłodzenia serwerowni są w ostatnim czasie coraz częściej rozważane przez inwestorów i dlaczego? Co mówią prognozy na przyszłość? Jako projektant postaram się w tym artykule odpowiedzieć na te i kilka innych pytań związanych z projektowaniem systemów chłodzenia pomieszczeń Data Center oraz wskazać zalecenia, które warto wziąć pod uwagę przy w procesie planowania.

15

Enhancement of heat transfer in helical coil heat exchangers using nano-fluids

Parveez Malik, Hanief Mohammad

Chemical and Process Engineering

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2022

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Vol. 43, nr 2

279--283

EN

Investigation for heat transfer behaviour of Al2O3 and CuO nano-fluid in helical coil heat exchangers was carried out in this study. The thermo-physical properties of the fluids have temperature dependent nature. The main emphasis was to depict the influence of nano-particle concentration by volume on the characteristics of temperature, rate of heat transfer and heat transfer coefficients (convective). In order to enhance efficiency, density and thermal conductivity are considered to be the most important variables. In comparison to water and for equal flow rate, the rate of heat transfer of nano-fluid increases conspicuously. Efficiency of the helical coil heat exchanger increased by 38.80%.

16

Simulations of Heat Transfer through Multilayer Protective Clothing Exposed to Flame

Puszkarz Adam K., Machnowski Waldemar

Autex Research Journal

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2022

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Vol. 22, no. 3

298--304

EN

In this paper, the safety and thermal comfort of protective clothing used by firefighters was analyzed. Three-dimensional geometry and morphology models of real multilayer assemblies used in thermal protective clothing were mapped by selected Computer-Aided Design (CAD) software. In the designed assembly models, different scales of the resolution were used for the particular layers – a homogenization for nonwoven fabrics model and designing the geometry of the individual yarns in the model of woven fabrics. Then, the finite volume method to simulate heat transfer through the assemblies caused by their exposure to the flame was applied. Finally, the simulation results with experimental measurements conducted according to the EN ISO 9151 were compared. Based on both the experimental and simulation results, parameters describing the tested clothing protective features directly affecting the firefighter’s safety were determined. As a result of the experiment and simulations, comparable values of these parameters were determined, which could show that used methods are an efficient tool in studying the thermal properties of multilayer protective clothing.

17

Numerical Investigation of Heat Transfer in Garment Air Gap

Zhang Yijie, Jia Juhong

Autex Research Journal

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2022

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Vol. 22, no. 1

89--95

EN

This article aimed to study the characteristics and mechanisms of 3D heat transfer through clothing involving the air gap. A three-dimensional finite volume method is used to obtain the coupled conductive, convective, and radiative heat transfer in a body-air-cloth microclimate system. The flow contours and characteristics of temperature, heat flux, and velocity have been obtained. The reason for the high flux and temperature regions was analyzed. Computational results show that the coupled effect of the air gap and the airflow between the skin and garment strongly influences the temperature and heat flux distribution. There are several high-temperature regions on the clothing and high heat flux regions on the body skin because the conductive heat flux can cross through the narrow air gap and reach the cloth surface easily. The high-speed cooling airflow brings about high forced convective heat flux, which will result in the temperature increase on the upper cloth surface. The radiative heat flux has a strong correlation with the temperature gradient between the body and clothing. But its proportion in the total heat flux is relatively small.

18

Investigation of Heat Transfer in Seersucker Woven Fabrics using Thermographic Method

Zgórniak P., Matusiak M., Frącczak L.

Autex Research Journal

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2022

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Vol. 22, no. 3

282--289

EN

Seersucker woven fabrics are characterized by unconventional structure and surface topography. Their crucial feature is a three-dimensional puckered effect created by puckered and flat strips occurring in the warp direction. Such a structure influences the basic mechanical and utility properties of the fabrics. The aim of the presented work is to analyze the heat transfer in seersucker woven fabrics. Measurement of the heat transfer was done using an infrared camera. Thermograms created for different seersucker woven fabrics, as well as for flat and puckered areas of the seersucker woven fabrics, were analyzed from the aspect of heat exchange between a hot plate and the environment through the fabric. The results showed that the linear density of the weft yarn influences the heat transfer through seersucker woven fabrics. The results allowed the comparison of the heat transfer through the seersucker woven fabrics in both flat and puckered areas. The investigations performed confirmed that the thermographic method can be applied to complex analyses of the heat transfer through seersucker woven fabrics.

19

Thermal performance evaluation of an earth-to-air heat exchanger for the heating mode applications using an experimental test rig

Ahmad Saif Nawaz, Prakash Om

Archives of Thermodynamics

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2022

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Vol. 43, no 1

185--207

EN

This paper presents the experimental investigation of an earth-to-air heat exchanger for heating purposes in the Patna region of India, using an experimental test rig. In the view of the author, real field experiments have several limitations such as lack of repeatability and uncontrolled conditions. It also takes more time for the response of parameters that depends on nature and climate. Moreover, earth-to-air heat exchangers may be expensive to fabricate and require more land area. Thus, in this work authors executed their experimental work in indoor controllable environments to investigate the thermal performance of an earth-to-air heat exchanger. The actual soil conditions were created and maintained the temperature at 26°C throughout the soil in the vicinity of pipes. Three horizontal PVC pipes of equal lengths and diameters of 0.0285 m, 0.038 m and 0.0485 m were installed in the test rig. The experiments were performed for different inlet air velocities at ambient air temperature. This study acknowledges that the maximum rise in outlet temperature occurs at a lower speed for smaller pipes. Also, the maximum effectiveness of 0.83 was observed at 2 m/s for the smallest diameter pipe.

20

Numerical study of car radiator using dimple roughness and nanofluid

Thapa Robin Kumar, Bisht Vijay Singh, Bhandari Prabhakar, Rawat Kamal Singh

Archives of Thermodynamics

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2022

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Vol. 43, no 3

125--140

EN

Thermal augmentation in flat tube of car radiator using different nanofluids has been performed more often, but use of artificial roughness has been seldom done. Artificial roughness in the form of dimple is used in the present research work. Present study shows the impact of dimple shaped roughness and nanofluid (Al2O3/pure water) on the performance of car radiator. The pitch of dimples is kept at 15 mm (constant) for all the studies performed. The Reynolds number of the flow is selected in the turbulent regime ranging from 9350 to 23 000 and the concentration of the nanofluid is taken in the range of 0.1–1%. It has been found that the heat transfer rate has improved significantly in dimpled radiator tube on the expense of pumping power. Furthermore, the heat transfer rate also increases with increase in nanoparticle concentration from 0.1% to 1.0%. The highest heat transfer enhancement of 79% is observed at Reynolds number 9350, while least enhancement of 18% is observed for Reynolds number of 23 000.