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1

Requirement of pressure relief dampers for clean rooms

Hrnková Bronislava, Hečko Dávid, Kapjor Andrej, Mičko Pavol, Vantúch Martin

Structure and Environment

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2021

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Vol. 13, no. 2

55--58

EN

The clean room is designed and used to minimize the entry, generation and deposition of pollutants. Proper flow control is an important factor in determining the efficiency of clean rooms. It is important that the air stream entrains from the space all the particles that are released when people move, but also from equipment and various materials. Therefore, in the following article we will deal with the need for pressure dampers in clean rooms.

PL

Pomieszczenie czyste jest zaprojektowane i wykorzystywane w taki sposób, aby zminimalizować wnikanie, generowanie i osadzanie się zanieczyszczeń. Właściwa kontrola przepływu powietrza jest istotnym czynnikiem określającym efektywność pomieszczeń czystych. Ważne jest, żeby strumień powietrza porywał z przestrzeni wszystkie cząstki, które są uwalniane podczas ruchu ludzi, ale także ze sprzętu i różnych materiałów. W związku z powyższym w niniejszym artykule zajmiemy się potrzebą stosowania klap nadciśnieniowych w pomieszczeniach czystych.

2

Analiza numeryczna spadku ciśnienia w zaworze maksymalnym układu smarowania pojazdów spalinowych

Mazur Klaudia

Journal of TransLogistics

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2021

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Vol. 7, nr 1

85--98

PL

W poniższej pracy przedstawiono analizę przepływu oleju przez zawór przelewowy typu UDZB firmy PONAR Wadowice wykorzystywany w układach smarowania. Ma to na celu przedstawienie zachodzących zjawisk podczas zmiany wielkości szczeliny w zaworze. W pracy zawarte są informacje dotyczące spadku ciśnienia – czym jest spowodowany oraz jakie mogą być jego skutki.

EN

The paper below presents an analysis of the oil flow through the PONAR Wadowice UDZB overflow valve used in lubrication systems. Its aim is to present the phenomena occurring when changing the size of the gap in the valve. The paper contains information on the pressure drop – why does it happen and what its effects may be.

3

Problems of selecting filter partition in passenger car engine intake air filters

Dziubak Tadeusz, Bąkała Leszek

Combustion Engines

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2021

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R. 60, nr 2

44--58

EN

The aim of this study was to verify the criteria for selecting pleated filter partitions used in passenger car engine filters. The paper presents the problem of optimizing pleated air filters in the direction of minimizing pressure drop, which is the source of engine energy losses. Two criteria for selection of a paper filter partition for specific operating conditions of the filter and the engine are presented: criterion of permissible separation speed and criterion of permissible pressure drop. The actual filtration area of 44 paper pleated filter elements used in passenger cars and the air stream flowing through the filter were determined, which made it possible to calculate separation speed. In 62% of the analyzed filter inserts, the calculated separation speeds are within the speed range recommended by the constructors, ʋFmax = 0.06-0.12 m/s. Exceeding permissible separation speed ʋFmax = 0.12 m/s was found mainly in supercharged engines. Negative effects of engine operation with an air filter with too small separation area are presented, in the form of increased pressure drop and energy loss of the engine as well as shorter car mileage to reach permissible pressure drop.

4

Theoretical and experimental analysis on the interaction properties between tracks and sediments considering sand content for unmanned underwater tracked bulldozer

Li Yong, He Dingchang, Si Qiaorui

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 1

art. no. e136036

EN

The unmanned underwater tracked bulldozer (UUTB) is an indispensable equipment for dredging and cleaning obstacles on the river bed in the flood season. The investigation on the interaction properties between the UUTB tracks and sediments provides foundation for the evaluation of operation performance when it works on the inland river bed. Based on the current worldwide research, the sediments mixed by sand, bentonite and water with sand content 0%, 10% and 20% were configured in this study to replace the real sediments on the inland river bed in China. The current pressure-sinkage model and shear stress-shear displacement model were discussed. Three different tracks were tested for the pressure-sinkage and the shear stress-shear displacement on the platform. The relationship between pressure and sinkage under sand content 0%, 10% and 20% are revealed based on the experimental results. The modulus of cohesive deformation and friction deformation of the sediments under said sand content are presented. The curves of shear stress and shear displacement are also obtained, which demonstrates the properties between the tracks and configured sediments under sand content 0%, 10% and 20%. The relationship between the tractive force and slip ratio with three different tracks under said sand content is also presented based on the quantitative analysis, which provides reference for the dynamics control and performance evaluation of UUTB on the inland river bed.

5

Rheological behavior of fly ash suspension with additive for hydraulic conveyance

Kumar K.

International Journal of Applied Mechanics and Engineering

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2020

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Vol. 25, no. 2

202--210

EN

In the present work, rheological behaviour of a fine particulate fly ash slurry suspension is studied with and without addition of an additive. Rheological experiments are performed for the range of shear rate from 50 to 200 s1.Sodium sulfate is used as an additive in the fraction of 0.2, 0.4 and 0.6% (by weight). Addition of sodium sulfate to the fly ash slurry suspension leads to an improvement of its rheological characteristics. A reduction in relative viscosity and pressure drop is more pronounced with the addition of sodium sulfate in proportion of 0.4%, while marginal with 0.2 and 0.6% (by weight). The analysis reveals that the fly ash suspension has a potential to for being transported in a slurry pipeline with higher concentration and minimum energy consumption.

6

Model of forced turbulence for pulsing flow

Dmytriv Vasyl

Diagnostyka

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2020

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Vol. 21, No. 1

89--96

EN

The article deals with fluid motion along an infinite hose. Taking into consideration the Stokes equation, the tangential friction stresses according to Newton and the Reynolds equation, the differential equation of the velocity change in radius is developed taking into account the pulsating component of the friction forces in the turbulent flow. Turbulence is defined as the impulse component of a flow, characterized by a pressure drop along a dynamic length of flow, a frequency response, and an oscillation amplitude of the pressure drop of pulse (which is given by the time equation of the oscillation). The velocity distribution along the radius of the hose in the time interval of one second was modelled for pressure drops in the range from 6000 to 18000 Pa and the amount of transported medium in the range from 1.667·10-5 to 6.667·10-5 m3 , which corresponded to the length of pulse plug. The dynamic viscosity of the medium (milk) of 1.79 · 10-3 Pa·s and its density of 10273 N·s2 /m4 were accounted at the simulation. The developed analytical dependence of the velocity of the forced turbulence of the pulsating flow allows to calculate the absolute value of the velocity at a given point of crosssection of the pipeline, and characterizes the physical process of flow of Newtonian fluids and gases in the pipeline.

7

Study on the Relationship Between Structure Parameters and Filtration Performance of Polypropylene Meltblown Nonwovens

Xiao Yuanxiang, Sakib Nazmus, Yue Zhonghua, Wang Yan, Cheng Si, You Jianmin, Militky Jiri, Venkataraman Mohanapriya, Zhu Guocheng

Autex Research Journal

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2020

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Vol. 20, no. 4

366--371

EN

In this study, polypropylene meltblown nonwoven fabrics with different structure parameters such as fiber diameter, pore size, and areal density were prepared by the industrial production line. The morphology of meltblown nonwoven fibers was evaluated by using scanning electron microscope, and the diameter of fibers was analyzed by using image-pro plus software from at least 200 measurements. The pore size of nonwoven fabric was characterized by a CFP-1500AE type pore size analyzer. The filtration efficiency and pressure drop were evaluated by TSI8130 automatic filter. The results showed that the pressure drop of nonwoven fabrics decreased with the increase in pore size; the filtration efficiency and the pressure drop had a positive correlation with the areal density. However, when the areal density is in the range of 27–29 g/m2, both filtration efficiency and pressure drop decreased with the increase of areal density; when the areal density was kept constant, the filtration efficiency decreased as the pore size decreased; when the pore size of the meltblown nonwoven fabric is less than 17 μm, the filtration efficiency increased as the pore diameter decreased; when the pore diameter of the nonwoven fabric is larger than 17 μm. In a wide range, the pressure drop decreased as the fiber diameter decreased.

8

Optimization of compressed heat exchanger efficiency by using genetic algorithm

Ghorbani M., Ranjbar S. F.

International Journal of Applied Mechanics and Engineering

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2019

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Vol. 24, no. 2

461--472

EN

Due to the application of coil-shaped coils in a compressed gas flow exchanger and water pipe flow in airconditioner devices, air conditioning and refrigeration systems, both industrial and domestic, need to be optimized to improve exchange capacity of heat exchangers by reducing the pressure drop. Today, due to the reduction of fossil fuel resources and the importance of optimal use of resources, optimization of thermal, mechanical and electrical devices has gained particular importance. Compressed heat exchangers are the devices used in industries, especially oil and petrochemical ones, as well as in power plants. So, in this paper we try to optimize compressed heat exchangers. Variables of the functions or state-of-the-machine parameters are optimized in compressed heat exchangers to achieve maximum thermal efficiency. To do this, it is necessary to provide equations and functions of the compressed heat exchanger relative to the functional variables and then to formulate the parameter for the gas pressure drop of the gas flow through the blades and the heat exchange surface in relation to the heat duty. The heat transfer rate to the gas-side pressure drop is maximized by solving the binary equation system in the genetic algorithm. The results show that using optimization, the heat capacity and the efficiency of the heat exchanger improved by 15% and the pressure drop along the path significantly decreases.

9

Properties of material with nanofiber layer used for filtering the inlet air of internal combustion engines

Dziubak Tadeusz

Combustion Engines

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2019

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R. 58, nr 2

66--75

EN

Nanofiber properties, and the possibilities of their application in industry, including the production of car air intake filtration materials for vehicle engines are discussed. The attention is paid to the low efficiency of standard filtration materials based on cellulose in the range of dust grains below 5 μm. The properties of filtration materials with nanofibers addition are described. The conditions, and methodology of material filter paper tests at the station with particle counter were developed. Studies on the filtration characteristics, such as: efficiency, accuracy, as well as pressure drop of filtration materials differing in structure were made: standard paper, cellulose, and these materials with the addition of nanofibers. These are commonly used filter materials for filter inserts production of car air intake systems. Test results show significantly higher values of the efficiency, and filtration accuracy of materials with nanofiber layer addition of dust grains below 5 μm in comparison with standard filter paper. It was found that there are 16 μm dust grains in the air flow behind the insert made out of cellulose, which may be the reason for the accelerated wear of the engine's "piston-piston ring-cylinder" association. Lower values of dust mass loading coefficient km for filtration materials with the addition of nanofiber layer, in relation to standard filter paper were observed.

10

Numeryczne wyznaczanie spadku ciśnienia i wydatku mieszaniny gazów w kanale ze zwężką

Tiutiurski P., Kardaś D.

Inżynieria i Aparatura Chemiczna

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2018

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Nr 1

16--18

PL

Przedstawiono wyniki obliczeń CFD dotyczących przepływu przez zwężkę pomiarową z odbiorem przy tarczowym. Obliczenia wykonano za pomocą programu Ansys Fluent 16.0 przy użyciu modelu Species transport oraz modelu turbulencji k-ω SST. Podano wartości spadków ciśnień obliczone dla pięciu wydatków objętościowych mieszaniny gazów. Porównano je z wynikami uzyskanymi za pomocą oprogramowania TNflow 3.10, które jest specjalistycznym narzędziem do projektowania zwężek pomiarowych. Błąd względny porównywanych wyników mieścił się w zakresie 10,6÷3,7%.

EN

The paper focuses on CFD simulations included results of llow through the orifice with the close-to-plate tapping. The presented calculations were made with the use of commercial CFD code Ansys Fluent 16.0. Additionally, Species transport model and k-ω SST turbulence model applied in simulations. The pressure drop for five values of gas mixture volumetric flow rate is given. Numerical results were compared with TNflow 3.10 software being a tool dedicated to the orifice design. The relative error of compared results was in a rangę 10.6÷13.7%.

11

Numerical analysis of erosion wear and pressure drop for turbulent multiphase slurry flow

Kannojiya V., Darshan M. B., Chandra Y. P.

Archive of Mechanical Engineering

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2018

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Vol. LXV, nr 3

361--378

EN

The disposal of ash in a thermal plant through the slurry pipe is subjected to some erosion wear due to the abrasive characteristics of the slurry. A simulation study of particle-liquid erosion of mild steel pipe wall based on CFD-FLUENT that considers the solid-liquid, solid-solid and solid-wall interaction is presented in this work.The multi-phase Euler-Lagrange model with standard k- ϵ turbulence modeling is adopted to predict the particulate erosion wear caused by the ﬂow of bottom ash water suspension. Erosion rate for diﬀerent particle size and concentration is evaluated at variable ﬂow rate. It is observed that the pressure drop and erosion rate share direct relationships with ﬂow velocity, particle size and concentration. The ﬂow velocity is found to be the most inﬂuencing parameter. A model capable of predicting the erosion wear at variable operating conditions is presented.The simulation ﬁndings show good agreement with the published ﬁndings.

12

Porównanie korelacji spadku ciśnienia dla przepływu dwufazowego w kanałach o małej średnicy

Pietrzak M., Płaczek M., Witczak S.

Przemysł Chemiczny

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2017

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T. 96, nr 3

592--597

PL

Przeprowadzono gruntowny przegląd literatury na temat korelacji spadku ciśnienia, opracowano bank danych doświadczalnych obejmujący szeroki zakres zmian parametrów przepływowych oraz dokonano weryfikacji możliwości przewidywania wartości spadków ciśnienia w przepływach dwufazowych gaz-ciecz w minikanałach. Porównano wartości spadków ciśnienia obliczone zgodnie z dostępnymi w literaturze korelacjami z wartościami eksperymentalnymi. Analiza uzyskanych wyników obliczeń wykazała, że większość korelacji ma bardzo ograniczony zakres ważności i nie opisuje danych doświadczalnych z zadowalającą dokładnością. Zaproponowano równania do obliczania spadku ciśnienia w przepływie w minikanałach, i to niezależnie od rodzaju przepływu.

EN

Fundamentals and a review, with 17 refs., of pressure drop correlations and exp. pressure drop data. Performance of the correlations in correctly predicting the diverse data sets was verified. Most of the correlations developed are very restricted in terms of handling a wide variety of data sets.

13

Bubble boiling in flow of refrigerating media

Bohdal T.

Journal of Mechanical and Energy Engineering

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2017

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Vol. 1, No 1

57--64

EN

The paper describes results of investigations of heat transfer and pressure drop during bubbly boiling of refrigerating media. In this article were presented of authors own experimental studies and were proposed new simple calculation model describing bubble boiling in the tubular channel. The author attempts to put forward a simplified description of the process of bubble boiling in a straight pipe. The two-phase one-component (liquid-vapour) system is treated as a continuum governed by the laws of conservation of energy, momentum and mass. The continuum is characterised by parameters that describe the two-phase system, such as density of the two-phase mixture, static void fraction or static equilibrium dryness fraction. In view of engineering applications, a one-dimensional model is used where physical quantities are cross-section averaged. This way the average velocity, pressure, temperature, and so on, are introduced. The results of the proposed model have been compared with the results of the experimental research with satisfactory compliance.

14

An investigation of heat transfer coefficient during refrigerants condensation in vertical pipe microchannel

Bohdal T., Kruzel M., Sikora M.

Journal of Mechanical and Energy Engineering

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2017

|

Vol. 1, No 2

163--169

EN

This article presents the results of experimental research of R404A, R407C and R410A high-pressure refrigerants condensation in vertical pipe microchannels with an internal diameter dw below 1 mm. The study determined the local and average heat transfer coefficient in the full range of vapor quality, x = 1-0. On the basis of experimental investigations, the dependence of heat transfer coefficient on the vapor quality x, the mass flux density G and the channel internal diameter dw was obtained.

15

Analiza dokładności obliczeń hydraulicznych przesyłu gazu

Kowalski R., Liszka K., Łaciak M., Oliinyk A., Szurlej A.

Gaz, Woda i Technika Sanitarna

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2017

|

Nr 4

131--133

PL

Istnieje wiele algorytmów matematycznych, których głównym zadaniem jest określenie spadku ciśnienia w gazociągu przesyłowym. W artykule zostały dokładnie przeanalizowane najczęściej stosowane na świecie algorytmy do obliczenia spadku ciśnienia w gazociągach przesyłowych, a uzyskane wyniki obliczeniowe porównano z rzeczywistymi. W artykule przedstawiono wpływ poszczególnych modułów obliczeniowych na dokładność wybranych modeli matematycznych do wyznaczenia spadku ciśnienia w gazociągach przesyłowych.

EN

There are many mathematical algorithms, whose main task is to determine the pressure drop in the transmission pipeline. In the article was carefully analyzed the most used in the world algorithms to calculate pressure drop in transmission pipelines, and the obtained results were compared with actual data. In the article present impact of deferent algorithms on the accuracy of the selected mathematical models to calculation of pressure drop in transmission pipelines.

16

Selected studies of flow maldistribution in a minichannel plate heat exchanger

Dąbrowski P., Klugmann M., Mikielewicz D.

Archives of Thermodynamics

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2017

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Vol. 38, no. 3

135--148

EN

Analysis of the state of-the-art in research of minichannel heat exchangers, especially on the topic of flow maldistribution in multiple channels, has been accomplished. Studies on minichannel plate heat exchanger with 51 parallel minichannels with four hydraulic diameters, i.e., 461 μm, 574 μm, 667 μm, and 750 μm have been presented. Flow at the instance of filling the microchannel with water at low flow rates has been visualized. The pressure drop characteristics for single minichannel plate have been presented along with the channels blockage, which occurred in several cases. The impact of the mass flow rate and channels’ cross-section dimensions on the flow maldistribution were illustrated.

17

Modeling of pressure drop during refrigerant condensation in pipe minichannels

Sikora M., Bohdal T.

Archives of Thermodynamics

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2017

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Vol. 38, no. 4

15–-28

EN

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.

18

Cooling of High Heat Flux Flat Surface with Nanofluid Assisted Convective Loop. Experimental Assessment

Arya A., Shahmiry S., Nikkhah V., Sarafraz M.M.

Archive of Mechanical Engineering

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2017

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Vol. LXIV, nr 4

519--531

EN

Experimental investigation was conducted on the thermal performance and pressure drop of a convective cooling loop working with ZnO aqueous nanofluids. The loop was used to cool a flat heater connected to an AC autotransformer. Influence of different operating parameters, such as fluid flow rate and mass concentration of nanofluid on surface temperature of heater, pressure drop, friction factor and overall heat transfer coefficient was investigated and briefly discussed. Results of this study showed that, despite a penalty for pressure drop, ZnO/water nanofluid was a promising coolant for cooling the micro-electronic devices and chipsets. It was also found that there is an optimum for concentration of nanofluid so that the heat transfer coefficient is maximum, which was wt. % = 0.3 for ZnO/water used in this research. In addition, presence of nanoparticles enhanced the friction factor and pressure drop as well; however, it is not very significant in comparison with those of registered for the base fluid.

19

Numerical analysis of pressure drop and acoustic attenuation performance of two helicoidal resonators arranged in parallel ducts with different rotation angles

Łapka W.

Vibrations in Physical Systems

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2016

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Vol. 27

237--244

EN

The paper presents a numerical analysis of pressure drop and acoustic attenuation performance (transmission loss) of two identical acoustic helicoidal resonators arranged in parallel ducts with different rotation angles. The air stream is divided from one cylindrical duct of a diameter D=140mm to a two parallel cylindrical ducts of diameter d=125mm with two helicoidal resonators inside – one per one duct. The ratio of helicoidal pitch s of helicoidal resonators to a cylindrical duct diameter d equals s/d=1,976. Other geometrical relationships of helicoidal resonators, as a mandrel diameter dm to duct diameter ratio dm/d=0.024, thickness g of helicoidal profile g/d=0.0024, and the number of helicoidal turn n=0,695 for both resonators. The investigated range of rotation angles covered the three characteristic positions of helicoidal resonators gaps, when considering the air stream distribution from central large duct with diameter D. The value of normal inflow velocity v[m/s] equaled 1 for all investigated cases.

20

Ocena wpływu blokowania się kanałów przepływowych w mikrokanałowym wymienniku ciepła na wymianę ciepła i spadek ciśnienia

Mikielewicz J., Rybiński W., Kiciński J.

Technika Chłodnicza i Klimatyzacyjna

|

2016

|

nr 1-2

22--25

PL

W artykule przedstawiono prosty model matematyczny wymiany ciepła oraz modyfikacji spadku ciśnienia w kanale, w którym uwzględniono modyfikację charakterystyki cieplno-przepływowej wymiennika na skutek zatykania się kanałów. Model porównano z własnymi danymi eksperymentalnymi prototypu wymiennika mikrokanałowego. Model ten jest szczególnie użyteczny w przypadku konieczności oceny pracy wymiennika, w którym występuje zagadnienie jego zatykania się, bez konieczności rozbierania takiego wymiennika. Jest to zatem nieniszcząca metoda wyznaczenia stopnia zatkania kanalików wymiennika.

EN

In the paper a simple mathematical model of heat transfer and flow resistance is given for heat exchangers with partially blocked channels. The predictions are compared with own experimental data for a prototype micro channel heat exchanger. Presented model is particularly useful for evaluation of a heat exchanger performance with partially blocked channels without its dismantling. Determination of the blockage degree is then possible with this model.