Cooling liquid flow boiling heat transfer in an annular minigap with an enhanced wall

Piasecka, Magdalena; Musiał, Tomasz; Piasecki, Artur

doi:10.1051/epjconf/201921302066

Cited by 7 publications

(5 citation statements)

References 28 publications

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“…The boundary conditions for which the MSEs have not been shown in Table 3 were satisfied with similar accuracy. (6), (8), and (9).…”

Section: Resultsmentioning

confidence: 99%

“…Several recent authors' papers have been published to address the issues of heat transfer in flow boiling in annular minigaps of the same dimensions as presented in this work [7][8][9][10] and minichannels of rectangular cross-sections, like in [11][12][13][14][15][16]. The aim of Reference [7] was to present mathematical models of heat transfer in flow boiling in a 1-3-mm-wide minigap.…”

Section: Introductionmentioning

confidence: 99%

“…Both approaches gave similar results. The results from experiments with HFE-649 flowing in an annular minigap were illustrated in [9]. This gap of a 1 mm width was created between the metal pipe with an enhanced surface contacting fluid and the external glass pipe.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Solution of Axisymmetric Inverse Heat Conduction Problem by the Trefftz Method

Hożejowska

Piasecka

2020

Energies

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In this paper, the issue of flow boiling heat transfer in an annular minigap was discussed. The main aim of the paper was determining the boiling heat transfer coefficient at the HFE-649 fluid–heater contact during flow along an annular minigap. The essential element of the experimental stand was a test section vertically oriented with the minigap 2 mm wide. Thermocouples were used to measure the temperature of the heater and fluid at the inlet and the outlet to the minigap. The mathematical model assumed that the fluid flow was laminar and the steady–state heat transfer process was axisymmetric. The temperatures of the heated surface and of the flowing fluid were assumed to fulfill energy equations with adequate boundary conditions. The problem was solved by the Trefftz method. The local heat transfer coefficients at the fluid–test surface interface were calculated due to the third kind boundary condition at the saturated boiling. Graphs were used to illustrate: the measurement of the heater surface temperature, 2D temperature distributions in the pipe and fluid, and the heat transfer coefficient as a function of the distance from the minigap inlet. The measurement uncertainties and accuracy of the heat transfer coefficient determination were estimated.

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“…The boundary conditions for which the MSEs have not been shown in Table 3 were satisfied with similar accuracy. (6), (8), and (9).…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Numerical Solution of Axisymmetric Inverse Heat Conduction Problem by the Trefftz Method

Hożejowska

Piasecka

2020

Energies

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“…Main of authors earlier works concerned steady state studies on flow boiling heat transfer in minigaps of different geometry: in an annular minigap [1,2] and in minichannels of rectangular cross sections [2][3][4][5][6]. It was also noticed that the use of enhanced surfaces often increases the intensification of heat transfer both in flow boiling [2][3][4][5][6] and in pool boiling research [7][8][9]. Maciejewska and Piasecka focused on flow boiling heat transfer under unsteady state conditions in minichannels [10,11].…”

Section: Introductionmentioning

confidence: 99%

Development of a two-dimensional mathematical model of flow boiling heat transfer in micro- and minichannels

Hożejowska

Piasecka

Piasecki³

2022

EPJ Web Conf.

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The paper concerns flow boiling heat transfer in micro- and minichannels. In the mathematical model, the steady state heat transfer process in a single asymmetrically heated minichannel was considered. Calculations with the use of Trefftz functions were based on the data from own experiments. The temperature of the heater and the refrigerant were assumed to satisfy the Laplace equations and the energy equation respectively. The problem was solved by the Trefftz method using two sets of Trefftz functions. The known heater and refrigerant temperature distributions were used to determine the heat transfer coefficient at the heater – refrigerant contact. To verify the proposed mathematical model, data from experiments were applied to calculations. The essential part of the experimental stand was the test section which comprises a minichannel heat sink. The heated element for Fluorinert FC-72 flowing along minichannels was a thin foil. The temperature of its outer side was measured using infrared thermography. Thermocouples and pressure transducers installed at the inlet and outlet of the test section monitored fluid temperature and pressure. Mass flow rate, the current supplied to the heater and the voltage drop were also recorded. The resulting graphs presented thermograms of measured temperature on outer surface of the heater, temperature distributions of fluid temperature and local values of the heat transfer coefficient.

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“…As for minigaps, such a single wide minichannel is a progressive option for dealing with high heat fluxes, mainly in electronic systems. Investigations into minigaps of different geometries (e.g., rectangular [21] or annular [22]) usually focus on the thermal performance (e.g., local heat transfer coefficients [23], Nusselt number [24], or temperature distribution [25]). Flow distribution in minigaps is discussed rarely, and if so, then usually as a side experimental observation [26] or in the form of numerical analyses using computational fluid dynamics (CFD) [27].…”

Section: Introductionmentioning

confidence: 99%

Experimentally Verified Flow Distribution Model for a Composite Modelling System

Fialová

Jegla

2021

Energies

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Requirements of modern process and power technologies for compact and highly efficient equipment for transferring large heat fluxes lead to designing these apparatuses as dense parallel flow systems, ranging from conventional to minichannel dimensions according to the specific industrial application. To avoid operating issues in such complex equipment, it is vital to identify not only the local distribution of heat flux in individual parts of the heat transfer surface but also the uniformity of fluid flow distribution inside individual parallel channels of the flow system. A composite modelling system is currently being developed for accurate design of such complex heat transfer equipment. The modeling approach requires a flow distribution model enabling to yield accurate-enough predictions in reasonable time frames. The paper presents the results of complex experimental and modeling investigation of fluid flow distribution in dividing headers of tubular-type equipment. Different modeling approaches were examined on a set of header geometries. Predictions obtained via analytical and numerical models were validated using data from the experiments conducted on additively manufactured header samples. Two case studies employing parallel flow systems (mini-scale systems and a conventional-size heat exchanger) demonstrated the applicability of the distribution model and the accuracy of the composite modelling system.

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Cooling liquid flow boiling heat transfer in an annular minigap with an enhanced wall

Cited by 7 publications

References 28 publications

Numerical Solution of Axisymmetric Inverse Heat Conduction Problem by the Trefftz Method

Numerical Solution of Axisymmetric Inverse Heat Conduction Problem by the Trefftz Method

Development of a two-dimensional mathematical model of flow boiling heat transfer in micro- and minichannels

Experimentally Verified Flow Distribution Model for a Composite Modelling System

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