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Applied Sciences
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Two-Phase Heat Transfer in Industrial Engineering
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Two-Phase Heat Transfer in Industrial Engineering

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Applied Thermal Engineering".

Deadline for manuscript submissions: closed (20 July 2022) | Viewed by 10296

Special Issue Editors

Dr. Andrea Diani

E-Mail Website
Guest Editor
Department of Industrial Engineering, University of Padova, Via Venezia 1, 35131 Padova, Italy
Interests: heat transfer; flow boiling; condensation; thermal engineering; low-GWP refrigerants; PCMs
Special Issues, Collections and Topics in MDPI journals
Dr. Luca Viscito

E-Mail Website
Guest Editor
Department of Industrial Engineering, University of Naples Federico II, 80138 Napoli, NA, Italy
Interests: thermodynamics; refrigeration; two-phase flow; heat transfer
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Two-phase heat transfer inside tubes is involved in many different applications, among which evaporators and condensers for HVAC and refrigeration equipment. The industry is now facing with the growing number of HVAC and refrigeration systems worldwide, and, at the same time, must deal with the reduction of greenhouse gases, with the aim of controlling the global warming. New equipment involving lower Global Warming Potential refrigerants and highly efficient systems are in great demand nowadays. The transition from HFC refrigerants to lower GWP refrigerants is ongoing: natural fluids, such as HydroCarbons (HCs) or carbon dioxide, HydroFluoroOlefins (HFOs), and new refrigerants mixtures have been proposed as new alternative refrigerants with lower values of GWPs.

New experimental data are needed to better understand the behavior of these new refrigerants during two-phase heat transfer. These experimental data can also be used to develop and verify reliable models for the estimation of thermal and hydraulic performances of tubes during two-phase heat transfer of these new lower GWP refrigerants. In this context, this Special Issue of Applied Sciences aims at collecting contributions related to (but not limited to) two-phase heat transfer, i.e. evaporation and/or condensation, of new lower GWP pure refrigerants or refrigerants mixtures inside/outside smooth and/or enhanced tubes. Experimental, numerical and/or modelling contributions are welcome in this Special Issue in order to give a deeper insight about the topic.

Dr. Andrea Diani
Dr. Luca Viscito
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • flow boiling
  • evaporation
  • boiling
  • condensation
  • smooth tube
  • enhanced tube
  • dryout
  • heat transfer coefficient
  • pressure drop
  • empirical correlation

Published Papers (5 papers)

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Research

21 pages, 5320 KiB  
Article
Flow Boiling of R450A, R515B, and R1234ze(E) Inside a 7.0 mm OD Microfin Tube: Experimental Comparison and Analysis of Boiling Mechanisms
by Yuce Liu, Luisa Rossetto and Andrea Diani
Appl. Sci. 2022, 12(23), 12450; https://doi.org/10.3390/app122312450 - 05 Dec 2022
Cited by 3 | Viewed by 1152
Abstract
A comparative analysis of the flow boiling characteristics of R450A, R515B, and R1234ze(E) inside a 7.0 mm OD microfin tube was performed. The mass velocity was explored from low values, starting from 50 kg m−2 s−1, up to 400 kg [...] Read more.
A comparative analysis of the flow boiling characteristics of R450A, R515B, and R1234ze(E) inside a 7.0 mm OD microfin tube was performed. The mass velocity was explored from low values, starting from 50 kg m−2 s−1, up to 400 kg m−2 s−1, and the heat flux was tested in the range of 10–50 kW m−2, keeping a constant saturation temperature of 30 °C at the inlet of the test section. R515B and R1234ze(E) showed similar values of the heat transfer coefficient and frictional pressure gradient under all the investigated working conditions. R450A showed lower values of the heat transfer coefficient, especially at low heat flux and high mass velocity, compared to R515B and R1234ze(E), but the gap of the heat transfer performance between the three fluids reduced at high heat flux. The frictional pressure drops of R450A were generally lower than those of R515B and R1234ze(E). In the end, some correlations for the evaluation of both the heat transfer coefficient and the pressure drop were selected, and the estimated values were compared against the experimental counterpart. Furthermore, the effects of nucleate boiling and of convective boiling, as well as of the temperature glide for R450A, were analyzed and estimated. Full article
(This article belongs to the Special Issue Two-Phase Heat Transfer in Industrial Engineering)
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23 pages, 531 KiB  
Article
Numerical Prediction of Internal Flows in He/LOx Seals for Liquid Rocket Engine Cryogenic Turbopumps
by Lorenzo Maritano, Francesco Maria Marin, Cristina Bertani, Dario Pastrone, Maddalena Angelucci and Giuseppe Caggiano
Appl. Sci. 2022, 12(21), 10776; https://doi.org/10.3390/app122110776 - 24 Oct 2022
Viewed by 1675
Abstract
Cryogenic turbopumps are used in high-performance, lightweight liquid rocket engines for space applications. The development of bearings and shaft seals for cryogenic turbopumps requires detailed characterization of the internal flow, taking into account the effects of boiling and multi-component two-phase flow. Here, a [...] Read more.
Cryogenic turbopumps are used in high-performance, lightweight liquid rocket engines for space applications. The development of bearings and shaft seals for cryogenic turbopumps requires detailed characterization of the internal flow, taking into account the effects of boiling and multi-component two-phase flow. Here, a flow network solver was developed to analyse the secondary flow circuit of a cryogenic turbopump where the propellant is mixed with high-temperature helium after bearing cooling. The network solver is based on an extension of a classic 1D homogeneous model, originally developed for a pure substance, to the case of two-phase multi-component flow. The solver is capable of predicting pressures, temperatures, flow rates, and species concentrations in a complex two-phase flow in the presence of non-condensable gases. The unsteady mass, momentum, and energy conservation equations are implemented in conjunction with the thermodynamic equations of state using a general-purpose finite volume formulation, where the pressure drop and the heat transfer are calculated using correlations. The numerical tool was validated by comparing its predictions with experimental data obtained during tests on the secondary circuit of an oxygen turbopump developed at Avio S.p.A. A number of engine operating conditions were considered (inlet helium temperature in the range of 250–280 K, helium/liquid oxygen drain in the range of 165–230 K). The predicted temperature values showed good agreement with the experimental data in most conditions. Full article
(This article belongs to the Special Issue Two-Phase Heat Transfer in Industrial Engineering)
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14 pages, 3646 KiB  
Article
Experimental Investigation of Thermal Contact Conductance in a Bundle of Flat Steel Bars
by Rafał Wyczółkowski, Vazgen Bagdasaryan and Marek Gała
Appl. Sci. 2022, 12(14), 6977; https://doi.org/10.3390/app12146977 - 09 Jul 2022
Viewed by 1103
Abstract
The phenomenon of thermal contact conduction in two-phase (fluid-solid) media determines many technological processes. An example of such a process is heat treatment of steel bars, when a heated charge has a form of a packed bundle. In order to determine the optimal [...] Read more.
The phenomenon of thermal contact conduction in two-phase (fluid-solid) media determines many technological processes. An example of such a process is heat treatment of steel bars, when a heated charge has a form of a packed bundle. In order to determine the optimal heating curve it is necessary to have knowledge about the intensity of transfer through contact areas of the bars. This phenomenon is quantified by the thermal contact conductance hct. The article describes the methodology of determining the hct coefficient for bundles of flat steel bars. The starting point for the analysis is the measurement of the effective thermal conductivity kef performed for 5 × 20 mm and 10 × 20 mm bars. Individual samples of the same bars differed in arrangement. The analytical investigation used the concept of an elementary cell. This approach consisted in analysing resistances for individual heat transfer types: conduction, contact conduction and radiation. Based on the performed calculations it has been established that the value of the hct coefficient for the analysed samples is within the range 128–472 W/(m2 K). Changes of the hct coefficient in the temperature range 25–700 °C can be described with a second degree polynomial. It has been established that hct assumes maximum values in the temperature range from 300 °C to 400 °C. Full article
(This article belongs to the Special Issue Two-Phase Heat Transfer in Industrial Engineering)
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17 pages, 5544 KiB  
Article
R1234ze(E) Flow Boiling inside a 2.5 mm ID Smooth Tube and Comparison against an Equivalent Microfin Tube
by Andrea Diani and Luisa Rossetto
Appl. Sci. 2021, 11(6), 2627; https://doi.org/10.3390/app11062627 - 16 Mar 2021
Cited by 2 | Viewed by 1696
Abstract
The air conditioning and refrigeration industry is now dealing with an imminent substitution of widely implemented refrigerants having a non-negligible global warming impact. Among the proposed hydrofluoroolefins, R1234ze(E) has thermodynamic and transport properties close to those of R134a, and thus it can be [...] Read more.
The air conditioning and refrigeration industry is now dealing with an imminent substitution of widely implemented refrigerants having a non-negligible global warming impact. Among the proposed hydrofluoroolefins, R1234ze(E) has thermodynamic and transport properties close to those of R134a, and thus it can be one of its substitutes. This paper experimentally analyzes R1234ze(E) flow boiling inside a smooth tube with an internal diameter of 2.5 mm. Mass velocity is investigated from 200 to 600 kg m−2 s−1, for vapor quality from 0.15 to 0.99. The test tube is electrically heated by the Joule effect, by supplying heat fluxes from 12 to 60 kW m−2. Heat transfer coefficients and frictional pressure drops were evaluated from the experimental tests, and compared against values estimated by empirical correlations. Additional experimental tests permitted the comparison between the thermal and hydraulic characteristics of the smooth tube and those of a microfin tube with an inner diameter at the fin tip of 2.4 mm. The comparison revealed the higher contribution of convective boiling for the microfin tube compared to the smooth tube for all of the investigated working conditions. Full article
(This article belongs to the Special Issue Two-Phase Heat Transfer in Industrial Engineering)
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15 pages, 3901 KiB  
Article
Validation of Heat-Level Vapor Phase Soldering Process and Workspace Leakage Detection with Applied Pressure Sensors
by Mohamed Amine Alaya, Balázs Illés, David Bušek and Attila Géczy
Appl. Sci. 2021, 11(4), 1755; https://doi.org/10.3390/app11041755 - 16 Feb 2021
Cited by 4 | Viewed by 2297
Abstract
Electronic manufacturing principles are continuously developing, further improving assembly quality and productivity. There is a continuous need to apply novel and improved methods of process monitoring to provide accurate measurement and control during assembling. In this paper, a new principle for monitoring filmwise [...] Read more.
Electronic manufacturing principles are continuously developing, further improving assembly quality and productivity. There is a continuous need to apply novel and improved methods of process monitoring to provide accurate measurement and control during assembling. In this paper, a new principle for monitoring filmwise condensation-based heat-level—vapour phase soldering (HL-VPS) is presented to improve the process control. The experiment is based on thermocouple sensors in fusion with a sensitive gauge type pressure sensor. The aim is to precisely identify the steps of condensation-based reflow heat transfer process with commercially available components and the mindset of possible retrofitting in the generally used HL-VPS soldering ovens. It was found that the gauge sensor can follow the state of the workspace more precisely as the thermocouples, by monitoring the hydrostatic state of the vapour. The pressure (time) function gives information about the build-up of the vapour column, highlighting four characteristic steps (phases) of the process, meaning: immersion of the sample to be soldered, condensation-based heat transfer, solder-break, and cooling. Combined application with thermocouples enables more precise control, improving soldering quality and can reduce idle time of the oven. In addition, it was showed that the gauge type sensors could highlight any failure in the oven sealing by a sensor signal threshold detection. The original concept of workspace identification also fits the present and future industry 4.0 directives. Full article
(This article belongs to the Special Issue Two-Phase Heat Transfer in Industrial Engineering)
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