Thermo

Open AccessReview

A Review on Thermal Energy Modelling for Optimal Microgrids Management

and

Thermo 2021, 1(1), 63-76; https://doi.org/10.3390/thermo1010006 - 25 Apr 2021

Abstract

Microgrids have become increasingly popular in recent years due to technological improvements, growing recognition of their benefits, and diminishing costs. By clustering distributed energy resources, microgrids can effectively integrate renewable energy resources in distribution networks and satisfy end-user demands, thus playing a critical role in transforming the existing power grid to a future smart grid. There are many existing research and review works on microgrids. However, the thermal energy modelling in optimal microgrid management is seldom discussed in the current literature. To address this research gap, this paper presents a detailed review on the thermal energy modelling application on the optimal energy management for microgrids. This review firstly presents microgrid characteristics. Afterwards, the existing thermal energy modeling utilized in microgrids will be discussed, including the application of a combined cooling, heating and power (CCHP) and thermal comfort model to form virtual energy storage systems. Current trial programs of thermal energy modelling for microgrid energy management are analyzed and some challenges and future research directions are discussed at the end. This paper serves as a comprehensive review to the most up-to-date thermal energy modelling applications on microgrid energy management. Full article

(This article belongs to the Special Issue Thermal Energy Modelling for Renewable Energy Applications)

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Open AccessEditorial

A New Research Journal on Thermal Sciences: Thermo

Johan Jacquemin

Thermo 2021, 1(1), 61-62; https://doi.org/10.3390/thermo1010005 - 06 Apr 2021

Abstract

I am honored to take on the role of Editor-in-Chief of Thermo (ISSN 2673-7264) effective from February 2021 [...] Full article

Open AccessFeature PaperReview

The Basic Theorem of Temperature-Dependent Processes

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Thermo 2021, 1(1), 45-60; https://doi.org/10.3390/thermo1010004 - 19 Mar 2021

Abstract

The basic theorem of isokinetic relationships is formulated as “if there exists a linear correlation “structure∼properties” at two temperatures, the point of their intersection will be a common point for the same correlation at other temperatures, until the Arrhenius law is violated”. The theorem is valid in various regions of thermally activated processes, in which only one parameter changes. A detailed examination of the consequences of this theorem showed that it is easy to formulate a number of empirical regularities known as the “kinetic compensation effect”, the well-known formula of the Meyer–Neldel rule, or the so-called concept of “multi-excitation entropy”. In a series of similar processes, we examined the effect of different variable parameters of the process on the free energy of activation, and we discuss possible applications. Full article

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Open AccessArticle

Numerical Integration of Weight Loss Curves for Kinetic Analysis

Juan A. Conesa

Thermo 2021, 1(1), 32-44; https://doi.org/10.3390/thermo1010003 - 05 Mar 2021

Abstract

Research abounds in the literature on kinetic analyses using thermogravimetric (TG) runs. Many of these studies use approximations of integral or derivative forms of the kinetic law and all of them use programmed temperatures. In the present work, a numerical integration procedure was discussed and applied to different examples. We focused on materials presenting a single decomposition curve as well as other materials with more complex processes. Different examples were explored, and the methodology was applied to a number of wastes such as coffee husks, polystyrene and polyethylene. In all cases, the actual temperature measured by thermocouples close to the sample is used, and several runs are fitted using the same kinetic parameters, giving robustness to the results. Full article

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Open AccessArticle

Thermochemistry, Bond Energies and Internal Rotor Potentials of Acetic Acid Hydrazide, Acetamide, N-Methyl Acetamide (NMA) and Radicals

Sumit Charaya

and

Joseph W. Bozzelli

Thermo 2021, 1(1), 15-31; https://doi.org/10.3390/thermo1010002 - 02 Mar 2021

Abstract

Structures, thermochemical properties, bond energies, and internal rotation potentials of acetic acid hydrazide (CH₃CONHNH₂), acetamide (CH₃CONH₂), and N-methyl acetamide (CH₃CONHCH₃), and their radicals corresponding to the loss of hydrogen atom, have been studied. Gas-phase standard enthalpies of formation and bond energies were calculated using the DFT methods B3LYP/6-31G(d,p), B3LYP/6-31G(2d,2p) and the composite CBS-QB3 methods employing a series of work reactions further to improve the accuracy of the ΔH_f°(298 K). Molecular structures, vibration frequencies, and internal rotor potentials were calculated at the DFT level. The parent molecules’ standard formation enthalpies of CH₃–C=ONHNH₂, CH₃–C=ONH_2, and CH₃–C=ONHCH₃ were evaluated as −27.08, −57.40, and −56.48 kcal mol⁻¹, respectively, from the CBS–QB3 calculations. Structures, internal rotor potentials, and C–H and N–H bond dissociation energies are reported. The DFT and the CBS-QB3 enthalpy values show close agreement, and this accord is attributed to the use of isodesmic work reactions for the analysis. The agreement also suggests this combination of the B3LYP/work reaction approach is acceptable for larger molecules. Internal rotor potentials for the amides are high, ranging from 16 to 22 kcal mol⁻¹. Full article

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Open AccessArticle

Interaction of a Low-Power Laser Radiation with Nanoparticles Formed over the Copper Melt in Rarefied Argon Atmosphere

Leonid A. Dombrovsky

and

Vladimir Ya. Mendeleyev

Thermo 2021, 1(1), 1-14; https://doi.org/10.3390/thermo1010001 - 16 Dec 2020

Abstract

Two effects have been recently observed by the authors for the copper sample melted in a rarefied argon atmosphere. The first of these effects is a strong decrease in the normal reflectance of a copper sample with time just after the beginning of melting. A partially regular crystal structure was also formed on the surface of the solid sample after the experiment. Both effects were explained by generation of a cloud of levitating nanoparticles. Additional experiments reported in the present paper show that the rate of decrease in reflectance increases with pressure of argon atmosphere and the surface pattern on the solid sample after the experiment depends on the probe laser radiation. It is theoretically shown for the first time that the dependent scattering effects in the cloud of copper nanoparticles are responsible for the abnormal decrease in normal reflectance and also for the observed significant role of light pressure in deposition of nanoparticles on the sample surface. The predicted minimum of normal reflectance is in good agreement with the experimental value. Full article

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