Prediction of the freezing point of multicomponent liquid refrigerant solutions (original) (raw)
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Journal of Food Engineering, 2007
Immersion chilling and freezing (ICF) of foods use aqueous solutions at low temperature that are considered secondary refrigerants. These solutions contain solutes such as NaCl, CaCl 2 , KCl, ethanol, glucose, etc. The ICF processes have several advantages over the conventional food chilling and freezing methods. The aim of this work was to study the behavior of an excess Gibbs energy model for predicting thermodynamic properties of mixtures of electrolytes and non-electrolytes, considering the physical conditions used in immersion chilling and freezing of foods. The extended UNIQUAC model was used. Data obtained from literature for heat capacity, density and freezing point for binary aqueous solutions of NaCl, CaCl 2 , KCl and ethanol were compared with predicted values. Additional parameters for the density estimation were included into the model. In general, the model accuracy was satisfactory.
Calculation of thermodynamic properties and vapor-liquid equilibria of refrigerants
Chemical Engineering Science, 1978
A?Mract-Saturated state thermodynaimc propeNes of ref~rants are prcdrctcd from cnt~cal coordmates and normaI bodmg pomts by usmg Soave's equabon of state Bmary vapor-hquni cqtuhbna are correlated by determmmg mteraction parameters for the followmg SEX systems CC12FJCH3CHF2. CCIJ;JCHCIF~, CHF&X3F3, CClF&Xl~F, CCIZFJCCIS, CFXHS On the whole the method gves rehable results over broad temperature and pressure ranges for pracbcal engmeermg uses IN'WODUCI'ION Temperature Pressure References points range W) range (atm) klz UP (atm) uY CC12FJCH1CHF-Refrtgerant 500
Freeze-drying of aqueous solutions: Maximum allowable operating temperature
Cryobiology, 1972
Freeze-drying (Iyophilization) is a two-step dehydration process by which a substance is first frozen, and then water is removed by sublimation under vacuum. Freeze-drying has a diverse range of application, including the preparation of biological samples, pharmaceutical manufacture, and food preservation. Freeze-dried liquids show an abrupt, loss in product quality when the temperature of the subliming interface during drying is maintained above a critical value, t'he "collapse" temperature (6). Drying above this temperature gives a distorted (collapsed) product with poor solubility, low drying rates, uneven drying, and loss of texture and volatile substances. We find that, in the absence of solute crystallization, the collapse temperature depends principally upon the viscosity of the unfrozen port,ion of the solution. -4 simple theory, presentcd below, shows that increasing solute molecular weight gives higher collapse temperatures, and predict's observed collapse temperatures quantitatively.
2008
Progressive freeze concentration (PFC) is believed to be able to overcome the weaknesses of conventional suspension freeze concentration (SFC), in which among all, can reduce the capital cost involved. PFC produces ice crystals as a single ice block instead of a suspension of small crystals in the mother liquor, hence reducing the number of unit operations to separate the crystals from the concentrated solution. The design of the heat exchanger where crystallization of ice should occur is among important factors in ensuring a PFC process with high efficiency. A new apparatus called crystallisation chamber (CC) for the purpose of crystallisation of ice has been designed in this research, made of copper and helical in shape. The effect of two operating conditions on the performance of the newly designed crystallisation chamber was then investigated, which are the initial concentration of solution and coolant temperature. Effective partition constant, K, was used as an indication of the system efficiency, calculated from the volume and concentration of the solid and liquid phase.
Boiling and Condensation of Alternative Refrigerants in a Horizontal Smooth Tube
~mean inside diameter [m] C mass velocity [kgl (m 2 s) ] 2d} Ca Galileo number, ( gp 2 1 ) fl hfg latent heat of evaporation or condensation [JIkg] H Phase-change number, ( Cpz( T sat -TWI» hfg K heat-flux-fraction factor, (= qnb) q ( ad.) Nu Nusselt number,P pressure [MPa] Pc critical pressure [MPa] Pr reduced pressure, (= PIPc) Pr Prandtl number, (= Cpil) fl Re Reynolds number, (= Cd l ) fl Reto Reynolds number of liquid-only flow, ( C(l-x)~) fl q heat flux [W1m 2 ]
HOLOS, 2011
This paper makes a comparative analysis of the thermophysical properties of ice slurry with conventional single-phase secondary fluids used in thermal storage cooling systems. The ice slurry is a two-phase fluid consisting of water, antifreeze and ice crystals. It is a new technology that has shown great energy potential. In addition to transporting energy as a heat transfer fluid, it has thermal storage properties due to the presence of ice, storing coolness by latent heat of fusion. The single-phase fluids analyzed are water-NaCl and water-propylene glycol solutions, which also operate as carrier fluids in ice slurry. The presence of ice changes the thermophysical properties of aqueous solutions and a number of these properties were determined: density, thermal conductivity and dynamic viscosity. Data were obtained by software simulation. The results show that the presence of 10% by weight of ice provides a significant increase in thermal conductivity and dynamic viscosity, withou...
A correlation of densities of liquid polar and nonpolar refrigerants from critical temperature
Physics and Chemistry of Liquids, 2018
We developed an equation of state based on statistical-mechanical perturbation theory for polar and nonpolar refrigerants. The equation is that the Ihm, Song and Mason, in which the three temperature dependant parameters are, calculated by means of the corresponding states correlations. In this work, it is shown that using the critical constants of fluids as scale constants would correlate the temperature-dependent parameters of the equation of state with sufficient accuracy. We have tested the predicted equation of state against the experimental data for a large number of haloalkanes including a number of the environmentally acceptable HFCs (R23,
Quantitative Modeling for Prediction of Critical Temperature of Refrigerant Compounds
The quantitative structure-property relationship (QSPR) method is used to develop the correlation between structures of refrigerants (198 compounds) and their critical temperature. Molecular descriptors calculated from structure alone were used to represent molecular structures. A subset of the calculated descriptors selected using a genetic algorithm (GA) was used in the QSPR model development. Multiple linear regressions (MLR) were utilized to construct the linear prediction model. The prediction result agrees well with the experimental value of this property. The comparison results indicate the superiority of the presented model and reveal that it can be effectively used to predict the critical temperatures of refrigerant compounds from the molecular structures alone. The stability and predictivity of the proposed model were validated using internal validation, external validation and Y-scrambling. Application of the developed model to a testing set of 39 organic compounds demonstrates that the new model is reliable with good predictive accuracy and simple formulation. The R 2 , RMSEtr and Q 2 loo values for the training set were 0.9752, 13.8994 and 0.9742; Q 2 ext and RMSEpr for test set were 0.9766 and 12.8654 for GA-MLR model, respectively. The prediction results are in good agreement with the experimental values. In addition, the applicability domain (AD) of the model was analyzed based on the Williams plot.
Refrigeration Science and Technology" proceedings series
2017
In 2014, European F-gas directive plans the prohibition of fluorinated working fluids with GWP of 2500 or more from 2020. Consequently, new working fluids have to be considered in the future such as HydroFluoroOlefin, carbon dioxide or mixture of HFO with hydro-fluoro-carbon or CO 2. The knowledge of the thermo-physical properties of working fluid is essential for the evaluation of performance of heat pumps, ORC and refrigeration. Herein, several "French" laboratories proposed to investigate the thermo-physical properties of the R744 + R1234yf binary system. In 2014, Juntarachat et al. measured and correlated vapour liquid equilibria including mixture critical point. New experimental determinations for density and viscosity using vibrating densitometer and capillary viscometer are presented. Also, enthalpies of mixing are determined using BT-215 Calvet calorimeters. In addition, molecular simulation based on empirical force have been realized. Several thermodynamic and tra...