Introduction to chemical engineering thermodynamics

Flash point is the most important variable used to characterize fire and explosion hazard of liquids. Herein, partially miscible mixtures are presented within the context of liquid-liquid extraction processes. This paper describes development of a model for predicting the flash point of binary partially miscible mixtures of flammable solvents.To confirm the predictive efficacy of the derived flash points, the model was verified by comparing the predicted values with the experimental data for the studied mixtures: methanol + octane; methanol + decane; acetone + decane; methanol + 2,2,4-trimethylpentane; and, ethanol + tetradecane. Our results reveal that immiscibility in the two liquid phases should not be ignored in the prediction of flash point. Overall, the predictive results of this proposed model describe the experimental data well. Based on this evidence, therefore, it appears reasonable to suggest potential application for our model in assessment of fire and explosion hazards, and development of inherently safer designs for chemical processes containing binary partially miscible mixtures of flammable solvents.

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“…(1) - (2). The iterative procedure is analogous to that used for calculating the boiling and dew points of mixtures [26].…”

Section: Mathematical Formulationmentioning

confidence: 99%

Flash-point prediction for binary partially miscible mixtures of flammable solvents

Liaw

Gerbaud

et al. 2008

Journal of Hazardous Materials

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“…Another benefit of this liquid is that it has a greater capacity to heat up with a smaller change in energy when compared to specific heating capacity of water, thereby increasing the SWHS's capacity to store energy [28]. It should be noted that SWHS configurations similar to that shown in fig.3.1 have been considered in other studies.…”

Section: Problem Formulationmentioning

confidence: 99%

Optimal flow control of a forced circulation solar water heating system with energy storage units and connecting pipes

2016

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Degree:Master of Engineering (Electrical Engineering)Keywords: Flat plate solar collector, flow rate optimization, maximum energy extraction, system thermal losses, thermal comfort.Solar water heating systems (SWHS) have fast become a suitable alternative to conventional water heating systems due to growing energy demands. A SWHS generally consists of a solar collector (which is used to convert solar radiation to heat), a water storage tank, and a flow control device such as a pump in the case of forced circulation SWHS. Extensive research and analysis on the operation and performance of these systems has been conducted, and results show that optimal flow control is an important factor that can be used to improve the performance and efficiency of SWHS.This study focuses on pump flow rate optimization for forced circulation SWHS with pipes.The system analyzed consists of an array of flat plate solar collectors, two storage tanks (one for the circulation fluid and one for the water), a heat exchanger, two pumps, and connecting pipes which are considered as one of the components of the SWHS so as to account for their thermal effects. The proposed model is developed using mainly the first and second laws of thermodynamics. The model is used to maximize the difference between the energy extracted from the solar collector and the combined sum of the energy extracted by the heat exchanger and corresponding energies used by the pumps in the primary and secondary loops. The objective function maximizes the overall system energy gain whilst minimizing the sum of the energy extracted by the heat exchanger and energy used by the corresponding pumps in the secondary loop to conserve the stored energy and meet the user requirement of water tank temperatures.The model is solved using the fmincon solver in MATLAB's optimization toolbox. When compared to other flow control techniques, in particular the most suitable energy efficient control strategy, the results of this study show a significant increase in the system's overall energy gain. The results also illustrate the effects of system pipe thermal losses for the different control strategies, hence highlighting the importance of developing a model that takes such losses into account so as to improve the overall accuracy of the model. Sonenergie-waterverwarmingstelsels (SWV) het vinnig 'n geskikte alternatief vir konvensionele waterverwarmingstelsels geword, weens die groeiende vraag na energie. 'n SWV bestaan gewoonlik uit 'n sonkollektor wat gebruik word om sonstraling om te skakel na hitte, 'n opgaartenk vir water, en 'n vloeibeheertoestel soos 'n pomp, in die geval van geforseerde sirkulasie SWV. Uitgebreide navorsing en ontleding op die werking en prestasie van hierdie stelsels is uitgevoer en die resultate toon dat die optimale vloeibeheer 'n belangrike faktor is wat gebruik kan word om die prestasie en doeltreffendheid van SWV verbeter. OPSOMMINGHierdie studie fokus op die optimering van die vloeitempo van 'n pomp vir geforseerde sirkulasie sonenergie-waterverwarmingste...

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“…An adiabatic compressor with an isentropic efficiency of 0.72 was used (Smith et al, 1996) for the proposed configuration. A vertical thermosyphon reboiler similar to the existing configuration was suggested, as shown in Figure 3.…”

Section: Industrial Casementioning

confidence: 99%

Exergetic and economic analysis of an industrial distillation column

Araújo

Vasconcelos

Fossy

et al. 2007

Braz. J. Chem. Eng.

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-In this work, applications of exergy and economic concepts to compression, heat exchange, and separation processes were used for calculation of the irreversibility rate, thermodynamic efficiency, and internal rate of return (IRR) of the profitability. A case study based on a real process, the purification of 1,2-dichloroethane (DCE) in a high-purity distillation column, is presented. This column has the highest steam flow rate in any vinyl chloride monomer (VCM) plant. A configuration using a vapor compression heat pump is proposed for improvement of the energy efficiency without having to make important process modifications. Existing and proposed configurations were implemented using the Aspen Plus™ commercial simulator; the results of the existing configuration were validated with data extracted from the plant. The objective of this work was to compare the existing configuration with the proposed one, using a thermodynamic and an economic approach.

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Introduction to chemical engineering thermodynamics

Cited by 1,544 publications

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Flash-point prediction for binary partially miscible mixtures of flammable solvents

Flash-point prediction for binary partially miscible mixtures of flammable solvents

Optimal flow control of a forced circulation solar water heating system with energy storage units and connecting pipes

Exergetic and economic analysis of an industrial distillation column

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