Special Issue "Heat Transfer Optimization in Physical Processes, Thermal Systems, and Pollutant Reduction"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "Thermal Management".

Deadline for manuscript submissions: 15 December 2021.

Special Issue Editor

Dr. Guido Marseglia
E-Mail Website1 Website2
Guest Editor
Research Department, Link Campus University, Rome, Italy& University of Seville (IMUS), Seville, Spain
Interests: energy conversion processes; circular economy; numerical model; sustainable buildings and infrastructures; sustainable transports; physical processes in experimental tests; heat transfer; pollutant emissions; engine efficiency; combustion process; thermal systems; alternative fuels; waste management; climate changes; smart cities
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Special Issue Information

Dear Colleagues,

 

As highlighted in the seventh Sustainable Development Goal, of the 17 SDGs defined in the 2030 Agenda of the United Nations, the development of clean and affordable energy in different areas of the world is a necessity. The heat transfer optimization in thermal systems is fundamental to obtaining more efficient and environmentally friendly solutions.

This Special Issue will collect a series of scientific articles that report important actions taken to improve aspects of thermal performance optimization and pollution reduction, which may include all energy processes as biomass conversion, waste, engines, combustion, CHP, and CCPP systems, and also the thermal comfort and the environmental impact of infrastructure and buildings. Articles are invited from all countries.

Dr. Guido Marseglia
Guest Editor

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 papers will be 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. Energies 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 2000 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

  • Thermal systems
  • circular economy
  • heat transfer
  • sustainable buildings and infrastructures
  • pollution reduction
  • renewable energies
  • thermal comfort
  • heat exchange

Published Papers (4 papers)

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Research

Article
Direct Analytical Modeling for Optimal, On-Design Performance of Ejector for Simulating Heat-Driven Systems
Energies 2021, 14(10), 2819; https://doi.org/10.3390/en14102819 - 14 May 2021
Viewed by 522
Abstract
This paper describes an ejector model for the prediction of on-design performance under available conditions. This is a direct method of calculating the optimal ejector performance (entrainment ratio or ER) without the need for iterative methods, which have been conventionally used. The values [...] Read more.
This paper describes an ejector model for the prediction of on-design performance under available conditions. This is a direct method of calculating the optimal ejector performance (entrainment ratio or ER) without the need for iterative methods, which have been conventionally used. The values of three ejector efficiencies used to account for losses in the ejector are calculated by using a systematic approach (by employing CFD analysis) rather than the hit and trial method. Both experimental and analytical data from literature are used to validate the presented analytical model with good agreement for on-design performance. R245fa working fluid has been used for low-grade heat applications, and Engineering Equation Solver (EES) has been employed for simulating the proposed model. The presented model is suitable for integration with any thermal system model and its optimization because of its direct, non-iterative methodology. This model is a non-dimensional model and therefore requires no geometrical dimensions to be able to calculate ejector performance. The model has been validated against various experimental results, and the model is employed to generate the ejector performance curves for R245fa working fluid. In addition, system simulation results of the ejector refrigeration system (ERS) and combined cooling and power (CCP) system have been produced by using the proposed analytical model. Full article
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Article
Numerical Simulation of the Thermally Developed Pulsatile Flow of a Hybrid Nanofluid in a Constricted Channel
Energies 2021, 14(9), 2410; https://doi.org/10.3390/en14092410 - 23 Apr 2021
Cited by 1 | Viewed by 336
Abstract
Heat transfer analysis of the pulsatile flow of a hybrid nanofluid through a constricted channel under the impact of a magnetic field and thermal radiation is presented. Hybrid nanofluids form a new class of nanofluids, distinguished by the thermal properties and functional utilities [...] Read more.
Heat transfer analysis of the pulsatile flow of a hybrid nanofluid through a constricted channel under the impact of a magnetic field and thermal radiation is presented. Hybrid nanofluids form a new class of nanofluids, distinguished by the thermal properties and functional utilities for improving the heat transfer rate. The behaviors of a water-based copper nanofluid and water-based copper plus a single-wall carbon nanotube, i.e., (CuSWCNT/water), hybrid nanofluid over each of velocity, wall shear stress, and temperature profiles, are visualized graphically. The time-dependent governing equations of the incompressible fluid flow are transformed to the vorticity-stream function formulation and solved numerically using the finite difference method. The laminar flow simulations are carried out in 2D for simplicity as the flow profiles are assumed to vary only in the 2D plane represented by the 2D Cartesian geometry. The streamlines and vorticity contours are also shown to demonstrate the flow behviour along the channel. For comparison of the flow characteristics and heat transfer rate, the impacts of variations in Hartmann number, Strouhal number, Prandtl number, and the thermal radiation parameter are analyzed. The effects of the emerging parameters on the skin friction coefficient and Nusselt number are also examined. The hybrid nanofluid is demonstrated to have better thermal characteristics than the traditional one. Full article
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Article
Impact of Lorentz Force in Thermally Developed Pulsatile Micropolar Fluid Flow in a Constricted Channel
Energies 2021, 14(8), 2173; https://doi.org/10.3390/en14082173 - 13 Apr 2021
Cited by 3 | Viewed by 413
Abstract
This work aimed to analyze the heat transfer of micropolar fluid flow in a constricted channel influenced by thermal radiation and the Lorentz force. A finite difference-based flow solver, on a Cartesian grid, is used for the numerical solution after transforming the governing [...] Read more.
This work aimed to analyze the heat transfer of micropolar fluid flow in a constricted channel influenced by thermal radiation and the Lorentz force. A finite difference-based flow solver, on a Cartesian grid, is used for the numerical solution after transforming the governing equations into the vorticity-stream function form. The impact of various emerging parameters on the wall shear stress, axial velocity, micro-rotation velocity and temperature profiles is discussed in this paper. The temperature profile is observed to have an inciting trend towards the thermal radiation, whereas it has a declining trend towards the Hartman and Prandtl numbers. The axial velocity profile has an inciting trend towards the Hartman number, whereas it has a declining trend towards the micropolar parameter and Reynolds number. The micro-rotation velocity escalates with the micropolar parameter and Hartman number, whereas it de-escalates with the Reynolds number. The Nusselt number is observed to have a direct relationship with the Prandtl and Reynolds numbers. Full article
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Article
Thermofluid Characterization of Nanofluid Spray Cooling Combining Phase Doppler Interferometry with High-Speed Visualization and Time-Resolved IR Thermography
Energies 2020, 13(22), 5864; https://doi.org/10.3390/en13225864 - 10 Nov 2020
Cited by 5 | Viewed by 659
Abstract
Spray impingement on smooth and heated surfaces is a highly complex thermofluid phenomenon present in several engineering applications. The combination of phase Doppler interferometry, high-speed visualization, and time-resolved infrared thermography allows characterizing the heat transfer and fluid dynamics involved. Particular emphasis is given [...] Read more.
Spray impingement on smooth and heated surfaces is a highly complex thermofluid phenomenon present in several engineering applications. The combination of phase Doppler interferometry, high-speed visualization, and time-resolved infrared thermography allows characterizing the heat transfer and fluid dynamics involved. Particular emphasis is given to the use of nanofluids in sprays due to their potential to enhance the heat transfer mechanisms. The results for low nanoparticle concentrations (up to 1 wt.%) show that the surfactant added to water, required to stabilize the nanofluids and minimize particle clustering, affects the spray’s main characteristics. Namely, the surfactant decreases the liquid surface tension leading to a larger wetted area and wettability, promoting heat transfer between the surface and the liquid film. However, since lower surface tension also tends to enhance splash near the edges of the wetted area, the gold nanospheres act to lessen such disturbances due to an increase of the solutions’ viscosity, thus increasing the heat flux removed from the spray slightly. The experimental results obtained from this work demonstrate that the maximum heat convection coefficients evaluated for the nanofluids can be 9.8% to 21.9% higher than those obtained with the base fluid and 11.5% to 38.8% higher when compared with those obtained with DI water. Full article
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Heat Transfer Analysis of A Counterflow Heat Exchanger with Two Rectangular Minichannels
Authors: Magdalena Piasecka*, Dariusz Strąk, Sylwia Hożejowska, Anna Pawińsk
Affiliation: Kielce University of Technology, Poland
Abstract: This paper presents the results of research on heat transfer during fluid flow in a counterflow heat exchanger with two rectangular minichannels. In one channel there was a flow of Fluorinert FC-72 while in the other distilled water was circulated. Refrigerant FC-72 was heated by the outer heating wall. In the second minichannel, there was a countercurrent flow of distilled water. The channels were separated by a copper plate. Thermal imaging cameras were used to measure the temperature distribution of the outer surfaces of the heat exchanger. The experiments involved measuring the heat flux supplied to the heating wall and the temperature and pressure of the fluids at the inlet and outlet to/from each channel. The purpose of the calculations was to determine the heat transfer coefficients at the contact surfaces: the heating wall - FC-72 and the copper plate - distilled water. Two approaches to describe the heat flow in the heat exchanger have been proposed: one-dimensional (1D) and two-dimensional (2D). In the 1D approach, only the heat flow direction perpendicular to the fluid flow direction was assumed. The 2D approach additionally involved the direction along the flow. In this model, it was assumed that the temperature of the heating plate and the copper partition meets the Poisson and Laplace equations, respectively, supplemented by the boundary conditions system. Trefftz functions were used in numerical calculations. The results were presented in the form of graphs of heat transfer coefficients as a function of the distance from the inlet. The analysis of the results showed that the values and distributions of the heat transfer coefficient determined using both models were similar. An application of the proposed heat exchanger with minichannels concept for cooling PV cells has been proposed.

Title: A New Direct Analytical Model of Ejector for On-Design Optimal Performance Prediction of Heat Driven Cooling Systems
Authors: Fahid Riaz1,2,*, Fu Zhi Yam1, Muhammad Abdul Qyyum3*, Saqib Anwar4, Ahmed M. El-Sherbeeny4, Poh Seng Lee1
Affiliation: 1 Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, 117575, Singapore; [email protected] (F.R); [email protected] (F. Z. Y); [email protected] (P. S. L) 2 Department of Mechanical Engineering, University of Engineering and Technology, Lahore, Pakistan 3 School of Chemical Engineering, Yeungnam University, Dae-dong 712-749, Republic of Korea 4 Industrial Engineering Department, College of Engineering, King Saud University, P.O. Box 800, Riyadh, 11421, Saudi Arabia; [email protected] (S. A); [email protected] (A. M. E) * Correspondence: [email protected] (M.A.Q)
Abstract: Abstract: This paper describes an ejector model for the prediction of on-design performance under available conditions. This is a more direct method of estimating the ejector performance without the need for iterations. This model avoids using ideal gas assumption for the working fluid and uses real fluid properties in calculations. The ideal gas assumption is used only to predict the pressure of the mixing chamber having lower-pressure vapour. Three efficiencies are used to account for losses in the ejector and their values are found out by using CFD analysis. Both experimental and analytical data from literature are used to validate the presented analytical model with good agreement for on-design performance. R245fa has been used as a suitable working fluid for low-grade heat applications. Engineering Equation Solver has been used to program the proposed model. This presented model is suitable for system optimization because of its direct and simpler calculation method. This model does not consider geometrical dimensions and hence cannot be used for off-design performance and detailed design of ejectors. For detailed design, CFD or experimental investigation is required. A systematic approach for using CFD for detailed design and sizing of ejectors is also presented.

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