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Thermal Systems

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

Deadline for manuscript submissions: closed (30 June 2020) | Viewed by 31253

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Dr. Brian Agnew

E-Mail Website
Guest Editor
NewRail - Newcastle Centre for Railway Research, Newcastle University, Newcastle upon Tyne NE17RU, UK
Interests: thermal power systems; refrigeration; combined cycles; internal combustion engines; finite time thermodynamics
Special Issues, Collections and Topics in MDPI journals
Dr. Ivan CK Tam

E-Mail Website
Guest Editor
Associate Professor in Marine Engineering Design & Technology, Newcastle University, Newcastle Research & Innovation Institute, 80 Jurong East Street 21, #05-04, Singapore, Singapore
Interests: engine combustion process; exhaust emission control; energy management; renewable energy; cryogenic technology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

We live in interesting times in which life as we know it is being threatened by manmade changes to the atmosphere in which we live. On the global scale, concern is focused on climate change due to greenhouse gas emissions, and on a national scale, atmospheric pollution produced by combustion processes is of concern. To meet the dual challenges presented by these factors, consideration needs to be given to energy efficiency and pollution reduction in transport and energy conversion processes. A possible approach is through the development of new ideas, processes, and practices.

In this Special Issue on " Thermal Systems”, we welcome review articles and original research papers, fundamental or applied and theoretical, numerical, or experimental, which explore new concepts in thermal systems and energy utilization. Topics of interest include, but are not limited to, the following:

  • Combined cycles (CHP and cooling);
  • Organic Rankine cycles;
  • Component performance;
  • Combustion processes;
  • Solar power;
  • Geothermal energy;
  • Bio-fuels;
  • Heat transfer;
  • Finite time thermodynamics;
  • Exergy and Second Law analysis;
  • Energy efficiency;
  • Nano-fluids.
Prof. Dr. Brian Agnew
Dr. Ivan CK Tam
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. 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 2600 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

  • combined cycles (CHP and cooling)
  • organic rankine cycles
  • component performance
  • combustion processes
  • solar power
  • geothermal energy
  • bio-fuels
  • heat transfer
  • finite time thermodynamics
  • exergy and second law analysis
  • energy efficiency
  • nano-fluids.

Published Papers (11 papers)

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Editorial

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3 pages, 152 KiB  
Editorial
Thermal Systems—An Overview
by Ivan CK Tam and Brian Agnew
Energies 2021, 14(1), 175; https://doi.org/10.3390/en14010175 - 31 Dec 2020
Cited by 1 | Viewed by 1392
Abstract
We live in interesting times in which life as we know it is being threatened by human-made changes to the atmosphere we live [...] Full article
(This article belongs to the Special Issue Thermal Systems)

Research

Jump to: Editorial

23 pages, 10165 KiB  
Article
A Study on the Application Possibility of the Vehicle Air Conditioning System Using Vortex Tube
by Younghyeon Kim, Seokyeon Im and Jaeyoung Han
Energies 2020, 13(19), 5227; https://doi.org/10.3390/en13195227 - 08 Oct 2020
Cited by 6 | Viewed by 4441
Abstract
Since refrigerants applied to vehicle air conditioning systems exacerbate global warming, many studies have been conducted to supplement them. However, most studies have attempted to maximize the efficiency and minimize the environmental impact of the refrigerant, and thus, an air conditioning system without [...] Read more.
Since refrigerants applied to vehicle air conditioning systems exacerbate global warming, many studies have been conducted to supplement them. However, most studies have attempted to maximize the efficiency and minimize the environmental impact of the refrigerant, and thus, an air conditioning system without refrigerant is required. The vortex tube is a temperature separation system capable of separating air at low and high temperatures using compressed air. When applied to an air conditioning system, it is possible to construct an eco-friendly system that does not use a refrigerant. In this paper, various temperature changes and characteristics of a vortex tube were identified and applied to an air conditioning system simulation device. Additionally, an air conditioning system simulation device using indirect heat exchange and direct heat exchange methods was constructed to test the low-temperature air flow rate (yc), according to the temperature and pressure. As a result of the experiment, the temperature of the indirect heat exchange method was found to be higher than the direct heat exchange method, but the direct heat exchange method had low flow resistance. As a result, the direct heat exchange method can easily control the temperature according to the pressure and the low-temperature air flow rate (yc). Therefore, it was judged that the direct heat exchange method is more feasible for use in air conditioning systems than the indirect heat exchange method. Full article
(This article belongs to the Special Issue Thermal Systems)
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14 pages, 3863 KiB  
Article
Application of the 2-D Trefftz Method for Identification of Flow Boiling Heat Transfer Coefficient in a Rectangular MiniChannel
by Mirosław Grabowski, Sylwia Hożejowska, Beata Maciejewska, Krzysztof Płaczkowski and Mieczysław E. Poniewski
Energies 2020, 13(15), 3973; https://doi.org/10.3390/en13153973 - 02 Aug 2020
Cited by 7 | Viewed by 2082
Abstract
The study presents the experimental and numeric heat transfer investigations in flow boiling of water through an asymmetrically heated, rectangular and horizontal minichannel, with transparent side walls. A dedicated system was designed to record images of two-phase flow structures using a high-speed video [...] Read more.
The study presents the experimental and numeric heat transfer investigations in flow boiling of water through an asymmetrically heated, rectangular and horizontal minichannel, with transparent side walls. A dedicated system was designed to record images of two-phase flow structures using a high-speed video camera with a synchronous movement system. The images were analyzed with Matlab 2019a scripts for determination of the void fraction for each pattern of two-phase flow structures observed. The experimental data measured during the experimental runs included inlet and outlet temperature, temperature at three internal points of the heater body, volume flux of the flowing water, inlet pressure, pressure drop, current and the voltage drop in the heater power supply. The flows were investigated at Reynolds number characteristic of laminar flow. The mathematical model assumed the heat transfer process in the measurement module to be steady-state with temperature independent thermal properties of solids and flowing fluid. The defined two inverse heat transfer problems were solved with the Trefftz method with two sets of T- functions. Graphs were used to represent: the boiling curves, the local void fraction values, the boiling heat transfer coefficients and the errors of both of them for selected mass fluxes and heat fluxes. Full article
(This article belongs to the Special Issue Thermal Systems)
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15 pages, 3975 KiB  
Article
Applicability of Swaging as an Alternative for the Fabrication of Accident-Tolerant Fuel Cladding
by Dae Yun Kim, You Na Lee, Joon Han Kim, Yonghee Kim and Young Soo Yoon
Energies 2020, 13(12), 3182; https://doi.org/10.3390/en13123182 - 19 Jun 2020
Cited by 5 | Viewed by 2163
Abstract
We suggest an alternative to conventional coating methods for accident-tolerant fuel (ATF) cladding. A Zircaloy-4 tube was inserted into metal tubes of different materials and the inserted tubes were subjected to physical force at room temperature. The manufactured tube exhibited a pseudo-single tube [...] Read more.
We suggest an alternative to conventional coating methods for accident-tolerant fuel (ATF) cladding. A Zircaloy-4 tube was inserted into metal tubes of different materials and the inserted tubes were subjected to physical force at room temperature. The manufactured tube exhibited a pseudo-single tube (PST) structure and had higher thermal stability than a Zircaloy-4 tube. Optical microscopy and scanning electron microscopy images showed that the PST had a uniform and well-bonded interface structure, i.e., no gaps or voids were found at the interface between the inner and outer tubes. Energy-dispersive X-ray spectroscopy analysis confirmed that the metal components did not interdiffuse at the interface of the PST, even after being kept at 600 and 900 °C for 1 h and rapidly cooled to room temperature. Unlike pure Zircaloy-4 tubes, Zircaloy-4/stainless use steel (SUS) 316 PST did not show significant structural collapse, even after being stored at 1200 °C for 1 h. Based on these results, if a PST was fabricated using a Zircaloy-4 tube thinner than the Zircaloy-4 tube used in this study and an outer tube of micron-scale thickness, swaging may be a feasible alternative to Zircaloy-4-based ATF cladding. Full article
(This article belongs to the Special Issue Thermal Systems)
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23 pages, 2790 KiB  
Article
Feasibility Study of a Centralised Electrically Driven Air Source Heat Pump Water Heater to Face Energy Poverty in Block Dwellings in Madrid (Spain)
by Roberto Barrella, Irene Priego, José Ignacio Linares, Eva Arenas, José Carlos Romero and Efraim Centeno
Energies 2020, 13(11), 2723; https://doi.org/10.3390/en13112723 - 28 May 2020
Cited by 8 | Viewed by 3459
Abstract
Energy poverty can be defined as the inability to pay the bills that are required for maintaining the comfort conditions (usually in winter) in dwellings. The use of energy efficient systems is one way forward to mitigate this problem, with one option being [...] Read more.
Energy poverty can be defined as the inability to pay the bills that are required for maintaining the comfort conditions (usually in winter) in dwellings. The use of energy efficient systems is one way forward to mitigate this problem, with one option being the electrically driven air source heat pump water heater. This paper assesses the performance of a centralised heat pump (200 kW of heating capacity) to meet the space heating demand of block dwellings in Madrid (tier four out of five in winter severity in Spain). Two models have been developed to obtain the following variables: the hourly thermal energy demand and the off-design heat pump performance. The proposed heat pump is driven by a motor with variable rotational speed to modulate the heating capacity in an efficient way. A back-up system is also considered to meet the peak demand. A levelised cost of heating of 92.22 €/MWh is obtained for a middle-level energy efficiency in housing (class E, close to D). Moreover, the following energy-environmental parameters have been achieved: more than 74% share of renewable energy in primary energy and 131.7 g CO2 avoided per kWh met. A reduction of 60% in the heating cost per dwelling is obtained if an energy retrofit is carried out, improving the energy performance class from E to C. These results prove that the proposed technology is among the most promising measures for addressing energy poverty in vulnerable households. Full article
(This article belongs to the Special Issue Thermal Systems)
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17 pages, 5591 KiB  
Article
Design Evaluation for a Finned-Tube CO2 Gas Cooler in Residential Applications
by Charalampos Alexopoulos, Osama Aljolani, Florian Heberle, Tryfon C. Roumpedakis, Dieter Brüggemann and Sotirios Karellas
Energies 2020, 13(10), 2428; https://doi.org/10.3390/en13102428 - 12 May 2020
Cited by 2 | Viewed by 2704
Abstract
Towards the introduction of environmentally friendlier refrigerants, CO2 cycles have gained significant attention in cooling and air conditioning systems in recent years. In this context, a design procedure for an air finned-tube CO2 gas cooler is developed. The analysis aims to [...] Read more.
Towards the introduction of environmentally friendlier refrigerants, CO2 cycles have gained significant attention in cooling and air conditioning systems in recent years. In this context, a design procedure for an air finned-tube CO2 gas cooler is developed. The analysis aims to evaluate the gas cooler design incorporated into a CO2 air conditioning system for residential applications. Therefore, a simulation model of the gas cooler is developed and validated experimentally by comparing its overall heat transfer coefficient. Based on the model, the evaluation of different numbers of rows, lengths, and diameters of tubes, as well as different ambient temperatures, are conducted, identifying the most suitable design in terms of pressure losses and required heat exchange area for selected operational conditions. The comparison between the model and the experimental results showed a satisfactory convergence for fan frequencies from 50 to 80 Hz. The absolute average deviations of the overall heat transfer coefficient for fan frequencies from 60 to 80 Hz were approximately 10%. With respect to the gas cooler design, a compromise between the bundle area and the refrigerant pressure drop was necessary, resulting in a 2.11 m2 bundle area and 0.23 bar refrigerant pressure drop. In addition, the analysis of the gas cooler’s performance in different ambient temperatures showed that the defined heat exchanger operates properly, compared to other potential gas cooler designs. Full article
(This article belongs to the Special Issue Thermal Systems)
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11 pages, 1709 KiB  
Article
Experimental Validation of Heat Transport Modelling in Large Solar Thermal Plants
by Kevin Sartor and Rémi Dickes
Energies 2020, 13(9), 2343; https://doi.org/10.3390/en13092343 - 08 May 2020
Cited by 2 | Viewed by 1481
Abstract
Solar thermal plants are often considered as a convenient and environmentally friendly way to supply heat to buildings or low temperature industrial processes. Some modelling techniques are required to assess the dynamic behaviour of solar thermal plants in order to control them correctly. [...] Read more.
Solar thermal plants are often considered as a convenient and environmentally friendly way to supply heat to buildings or low temperature industrial processes. Some modelling techniques are required to assess the dynamic behaviour of solar thermal plants in order to control them correctly. This aspect is reinforced while large plants are considered. Indeed, some atmospheric conditions, such as local clouds, could have significant influence on the outlet temperature of the solar field. A common modelling approach to assess the heat transport in pipes is the one-dimensional finite volume method. However, previous work shows limitations in the assessment of the temperatures and in the computational time required for simulating large pipe networks. In this contribution, a previous alternative method developed and validated in a district heating network is used and extended to a solar thermal plant considering the thermal solar gain and the inertia of the pipes. The present contribution intends to experimentally validate this model on an existing solar plant facility available at the Plataforma Solar de Almeria in Spain. Full article
(This article belongs to the Special Issue Thermal Systems)
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15 pages, 6869 KiB  
Article
Heat Transport Capacity of an Axial-Rotating Single-Loop Oscillating Heat Pipe for Abrasive-Milling Tools
by Ning Qian, Yucan Fu, Marco Marengo, Jiuhua Xu, Jiajia Chen and Fan Jiang
Energies 2020, 13(9), 2145; https://doi.org/10.3390/en13092145 - 30 Apr 2020
Cited by 13 | Viewed by 2143
Abstract
In order to enhance heat transfer in the abrasive-milling processes to reduce thermal damage, the concept of employing oscillating heat pipes (OHPs) in an abrasive-milling tool is proposed. A single-loop OHP (SLOHP) is positioned on the plane parallel to the rotational axis of [...] Read more.
In order to enhance heat transfer in the abrasive-milling processes to reduce thermal damage, the concept of employing oscillating heat pipes (OHPs) in an abrasive-milling tool is proposed. A single-loop OHP (SLOHP) is positioned on the plane parallel to the rotational axis of the tool. In this case, centrifugal accelerations do not segregate the fluid between the evaporator and condenser. The experimental investigation is conducted to study the effects of centrifugal acceleration (0–738 m/s2), heat flux (9100–31,850 W/m2) and working fluids (methanol, acetone and water) on the thermal performance. Results show that the centrifugal acceleration has a positive influence on the thermal performance of the axial-rotating SLOHP when filled with acetone or methanol. As for water, with the increase of centrifugal acceleration, the heat transfer performance first increases and then decreases. The thermal performance enhances for higher heat flux rises for all the fluids. The flow inside the axial-rotating SLOHP is analyzed by a slow-motion visualization supported by the theoretical analysis. Based on the theoretical analysis, the rotation will increase the resistance for the vapor to penetrate through the liquid slugs to form an annular flow, which is verified by the visualization. Full article
(This article belongs to the Special Issue Thermal Systems)
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15 pages, 4942 KiB  
Article
A Li-Ion Battery Thermal Management System Combining a Heat Pipe and Thermoelectric Cooler
by Chuanwei Zhang, Zhan Xia, Bin Wang, Huaibin Gao, Shangrui Chen, Shouchao Zong and Kunxin Luo
Energies 2020, 13(4), 841; https://doi.org/10.3390/en13040841 - 14 Feb 2020
Cited by 35 | Viewed by 4015
Abstract
The temperature of electric vehicle batteries needs to be controlled through a thermal management system to ensure working performance, service life, and safety. In this paper, TAFEL-LAE895 100Ah ternary Li-ion batteries were used, and discharging experiments at different rates were conducted to study [...] Read more.
The temperature of electric vehicle batteries needs to be controlled through a thermal management system to ensure working performance, service life, and safety. In this paper, TAFEL-LAE895 100Ah ternary Li-ion batteries were used, and discharging experiments at different rates were conducted to study the surface temperature increasing characteristics of the battery. To dissipate heat, heat pipes with high thermal conductivity were used to accelerate dissipating heat on the surface of the battery. We found that the heat pipe was sufficient to keep the battery temperature within the desired range with a midlevel discharge rate. For further improvement, an additional thermoelectric cooler was needed for a high discharge rate. Simulations were completed with a battery management system based on a heat pipe and with a combined heat pipe and thermoelectric cooler, and the results were in line with the experimental results. The findings show that the combined system can effectively reduce the surface temperature of a battery within the full range of discharge rates expected in the battery used. Full article
(This article belongs to the Special Issue Thermal Systems)
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18 pages, 4236 KiB  
Article
Advance Exergo-Economic Analysis of a Waste Heat Recovery System Using ORC for a Bottoming Natural Gas Engine
by Guillermo Valencia Ochoa, Jhan Piero Rojas and Jorge Duarte Forero
Energies 2020, 13(1), 267; https://doi.org/10.3390/en13010267 - 05 Jan 2020
Cited by 36 | Viewed by 3362
Abstract
This manuscript presents an advanced exergo-economic analysis of a waste heat recovery system based on the organic Rankine cycle from the exhaust gases of an internal combustion engine. Different operating conditions were established in order to find the exergy destroyed values in the [...] Read more.
This manuscript presents an advanced exergo-economic analysis of a waste heat recovery system based on the organic Rankine cycle from the exhaust gases of an internal combustion engine. Different operating conditions were established in order to find the exergy destroyed values in the components and the desegregation of them, as well as the rate of fuel exergy, product exergy, and loss exergy. The component with the highest exergy destroyed values was heat exchanger 1, which is a shell and tube equipment with the highest mean temperature difference in the thermal cycle. However, the values of the fuel cost rate (47.85 USD/GJ) and the product cost rate (197.65 USD/GJ) revealed the organic fluid pump (pump 2) as the device with the main thermo-economic opportunity of improvement, with an exergo-economic factor greater than 91%. In addition, the component with the highest investment costs was the heat exchanger 1 with a value of 2.769 USD/h, which means advanced exergo-economic analysis is a powerful method to identify the correct allocation of the irreversibility and highest cost, and the real potential for improvement is not linked to the interaction between components but to the same component being studied. Full article
(This article belongs to the Special Issue Thermal Systems)
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18 pages, 2374 KiB  
Article
Thermo-Economic Assessment of a Gas Microturbine-Absorption Chiller Trigeneration System under Different Compressor Inlet Air Temperatures
by Guillermo Valencia Ochoa , Carlos Acevedo Peñaloza and Jorge Duarte Forero
Energies 2019, 12(24), 4643; https://doi.org/10.3390/en12244643 - 06 Dec 2019
Cited by 41 | Viewed by 2552
Abstract
This manuscript presents a thermo-economic analysis for a trigeneration system integrated by an absorption refrigeration chiller, a gas microturbine, and the heat recovery steam generation subsystem. The effect of the compressor inlet air temperature on the thermo-economic performance of the trigeneration system was [...] Read more.
This manuscript presents a thermo-economic analysis for a trigeneration system integrated by an absorption refrigeration chiller, a gas microturbine, and the heat recovery steam generation subsystem. The effect of the compressor inlet air temperature on the thermo-economic performance of the trigeneration system was studied and analyzed in detail based on a validated model. Then, we determined the critical operating conditions for which the trigeneration system presents the greatest exergy destruction, producing an increase in the costs associated with loss of exergy, relative costs, and operation and maintenance costs. The results also show that the combustion chamber of the gas microturbine is the component with the greatest exergy destruction (29.24%), followed by the generator of the absorption refrigeration chiller (26.25%). In addition, the compressor inlet air temperature increases from 305.15 K to 315.15 K, causing a decrease in the relative cost difference of the evaporator (21.63%). Likewise, the exergo-economic factor in the heat exchanger and generator presented an increase of 6.53% and 2.84%, respectively. Full article
(This article belongs to the Special Issue Thermal Systems)
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