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Whence Dynamical Systems
Published in LM Pismen, Working with Dynamical Systems, 2020
Arrhenius law. A common autocatalytic agent in chemical processes is heat. Heat released in an exothermic reaction increases the temperature of the reacting mixture, which, in turn, accelerates the reaction. The ratio of the reaction heat to the heat capacity of the reacting mixture can be viewed as a “stoichiometric coefficient” of temperature. Denoting it as v0, we can write, analogous to (1.34), the dynamic equation for temperature, complementing kinetic equations of chemical species: T˙=v0f(C,T).
Additional Topics
Published in Anthony Peter Gordon Shaw, Thermitic Thermodynamics, 2020
Spontaneous chemical reactions can be put to work in two different ways. Batteries and fuel cells perform electrical work directly. Alternatively, an exothermic reaction can be used to produce heat, and this heat can be used by a heat engine to do mechanical work. In turn, dynamos and motors can be used to interconvert mechanical and electrical work, and all types of work are eventually converted into heat. All of these processes are ultimately governed by the laws of thermodynamics. But, practical considerations impose additional limitations, and the best course of action will always depend on the peculiarities of a given situation.
Basic Concepts: Chemical Processes and Unit Operations
Published in Victor H. Edwards, Suzanne Shelley, Careers in Chemical and Biomolecular Engineering, 2018
Victor H. Edwards, Suzanne Shelley
Instead, for practical purposes, mass and energy are conserved in chemical and biomolecular reactions. By way of explanation: in most chemical reactions, there is either a release of heat (exothermic reaction) or an uptake of heat (endothermic reaction). In an exothermic reaction, heat is released as the reaction proceeds from reactants to products. By contrast, in an endothermic reaction, energy must be provided from the environment to drive the reaction forward. The magnitude of the heat of a reaction is the same for the forward and the reverse reactions; only the direction of energy transfer to or from the surroundings differs.
Experimental Analysis of Partially Premixed Charge in a Diesel Engine with Jatropha Oil Methyl Ester and Diesel Blends
Published in Distributed Generation & Alternative Energy Journal, 2019
In HCCI combustion well mixed fuel and oxidizer (typically air) are compressed to the point of auto-ignition controlled by means of a combustion initiator. As in other forms of combustion, this exothermic reaction releases chemical energy into a sensible form that can be translated by an engine into work and heat [2][3]. Since obtaining very lean homogenous mixture is hard, it becomes difficult to sustain HCCI mode over the operating range of varying speeds and loads, to effectively control the HCCI combustion over the operating range a modified form of homogenous charge compression ignition mode combustion known as Premixed Charge Compression Ignition-Direct Injection (PCCI) can be used [4]. The major advantage of PCCI mode combustion over that of HCCI mode combustion is that, after achieving homogenous charge PCCI mode combustion employs a pilot injection as the combustion initiator there by establishing a effective control over the combustion in variable load and speed [5]. Although all the inherit characteristics of HCCI mode combustion cannot be obtained in this mode of combustion, it still performs better than the conventional mode of combustion.
Thermogravimetric and combustion efficiency analysis of Jatropha curcas biodiesel and its derivatives
Published in Biofuels, 2022
Vinay Atgur, G. Manavendra, G. P. Desai, B. Nageswara Rao, I. M. Rizwanul Fattah, Badr A. Mohamed, Nazaruddin Sinaga, H. H. Masjuki
Generally, the combustion of hydrocarbons exhibits an exothermic reaction. The DSC thermogram of diesel (Figure 8) indicates an endothermic reaction at 34–100 °C. This is known as an evaporation zone, and it is where the fuel prepares for combustion by evaporating a small fraction occurring through one step endothermic cracking reaction. It is termed diesel distillation [41,42]. Combustion peak temperature occurs at 250.4 °C with enthalpy 130.4 J/g as diesel consists of C5–C12 with a boiling range of 180–371 °C. Further, it starts burning and dissipating more energy to the environment.
Thermal behavior of diesel, honge oil methyl ester and ITS B-20 blend in atmospheric air and oxygen
Published in International Journal of Sustainable Engineering, 2022
Vinay Atgur, G. Manavendra, G.P. Desai, N. R. Banapurmath, Chandramouli Vadlamudi, Sanjay Krishnappa, B. Nageswara Rao
DSC thermogram of diesel (see Figure 4) indicates the endothermic reaction in the evaporation zone of 34–100°C. As fuel prepares for combustion, small fraction of diesel volatilise up. Only one step endothermic cracking reaction occurs (which is termed as distillation of the diesel). Combustion curve of hydrocarbons exhibits endothermic reaction initially in evaporation zone. Heat flow continues to environment indicating exothermic reaction. Higher heat release rate with premixed burning phase occurs during diesel combustion resulting in high thermal efficiency.