The impact of temperature, pressure, and chemical potential on the isobaric coefficient of volumetric expansion of water and argon

One of the main components of a closed ice slurry system is the heat exchanger in which ice slurry absorbs heat resulting in the melting ice crystals. Design calculations of heat exchangers are mainly based on heat transfer coefficient and pressure drop data. But experiments presented in this paper show the effect of ice slurry mass flux on heat transfer rate and heat transfer coefficient during melting. For the experiments, ice slurry was made from 6.5% ethylene glycol–water solution, flowing through a 16.91mm internal diameter, 1500mm long horizontal copper tube. The ice slurry was heated by hot water circulated at the annulus gap of the heat exchanger. Experiments of the melting process were conducted with changing the ice slurry mass flux and the ice fraction from 800 to 3500kgm−2s−1 and 0 to 25%, respectively. During the experiment, it was found that the measured heat transfer rates increase with the mass flow rate and ice fraction; however, the effect of ice fraction appears not to be significant at high mass flow rate. At the region of low mass flow rates, a sharp increase in the heat transfer coefficient was observed when the ice fraction was more than a certain value. Experiments were also conducted to investigate the effect of hot water temperature on the heat transfer coefficient. Copyright © 2006 John Wiley & Sons, Ltd.

Investigation on flow and heat transfer characteristics of ice slurry without additives in a plate heat exchanger

An expression for the chemical potential due to Kirkwood & Boggs is adapted to give rigorous expressions for Henry’s coefficient (H) for the solubility of a gas in a liquid and for the temperature dependence of this coefficient, in terms of radial distribution functions (g) and a molecular coupling parameter. If the solute-solvent and solvent-solvent molecular interactions are similar in strength the expression forTdlnH/dTreduces toTdlnH/ dT=L/RT+ (1+αT) InP° /H(i) whereL, aandp° are the molar latent heat, the coefficient of thermal expansion and the vapour pressure of the pure solvent. Equation (i) is closely obeyed by the simple systems Ar-CH4, Ar-O2and Ar—N2, though it becomes markedly less accurate when applied to the solubilities of common gases in liquids. This is to be expected since the solute-solvent and solvent—solvent intermolecular force fields are then very different. By assuming these force fields to be of the Lennard-Jones type and making simplifying assumptions relatinggfor the solute in the solvent togfor the pure solvent, the equationTdlnH/ dT=L/RT+ (1 +αT) InP° /H-Q0(1 -ε°αβσ3αβ/ε°ββσ3ββ(ii) is then obtained in whichQ0=L/RT- 1 +αT(1 +αT) InP°Vβ/RT, whereVβis the molar volume of the solvent,ε°ββ,σββ,ε°αβandσαβare the Lennard-Jones force constants for the solvent-solvent and solute—solvent interactions respectively. This equation is found to predictTdlnH/ dTfor gases dissolved in common liquids with sufficient accuracy to be of practical value The equationTdlnH/ dT= 2-αT+ (1 +αT) InRT/VβH, valid at solvent reduced temperatures between about 0.5 and 0.65, is found in practice to provide a useful approximation to (ii) both for simple systems and for the permanent gases dissolved in common solvents. Expression (i) is shown to be related to an expression previously developed by Longuet-Higgins.

The objective of the present study was the evaluation of the effect of slurry ice, as an alternative cooling medium during harvesting and transportation, on the quality parameters (e.g., microbiological stability, sensory attributes, physicochemical changes) and shelf life of fish. The effect of seasonal variability of seawater temperature on fish preservation using the tested cooling media was also investigated. Gilthead sea bream (Sparus aurata) was slaughtered and transported in different mixtures of conventional flake ice and slurry ice for 24 h. Three mixtures of ice were tested as T: slaughtered in flake ice and transported in flake ice (control), TC: slaughtered in slurry ice and transported in flake ice, T50: slaughtered and transported in slurry ice 50%–flake ice 50%. Samples were subsequently stored isothermally at 0 °C for shelf-life evaluation. Three independent experiments were performed at three different periods, i.e., January, April, and September, referring to a sea water temperature range of 13.3–26.8 °C. Higher sea water temperatures at catching led to lower microbial growth rates and proteolytic enzyme activities and longer shelf life of refrigerated whole fish. The partial replacement of conventional flake ice with slurry ice improved the quality and extended the shelf life of fish at 0 °C by 2–7 days. The results of the study support that the use of slurry ice may enable better quality maintenance and significant shelf-life extension of whole gilthead sea bream.

Vital Signs: Deficiencies in Environmental Control Identified in Outbreaks of Legionnaires’ Disease—North America, 2000–2014

Vaname shrimp and other crustacean have problems with the quality deterioration process that can be a problem in the fishing industry and marketing of fisheries whose farmland is far from the center of sales and processing. One method that can be used to preserve shrimp is the cooling mechanism and seawater-based ice slurry is an option as a cooling agent used in this study. This study aims to determine the value of the optimum parameters in producing ice slurry and the resulting ice slurry is used as a shrimp cooling medium to test its cooling and preservation ability. The experimental condition with higher scraper RPM result in slower ice slurry generation and the higher the pump RPM the faster the sea water temperature decreases. The test results on White Shrimp for 21 days of storage showed acceptable results according to the freshness standard of 5 x 105 colonies at storage under 14 days.

Heat transfer model of slurry ice melting on external surface of helical coil

The state condition of a fluid is described as a function of two intensive properties and the properties of the fluid can be represented also as a function of two independent properties. Figure 2.1.1 [1] shows the PVT surface of water in which the relation of pressure, volume and temperature of water is described. The critical point is shown as an open circle labeled C.P. The critical temperature of water is T C = 647.096 K, the critical pressure is P C = 22.064 MPa and the critical volume is V C= 0.003106 m3/kg. A list of critical and basic constants for selected fluids is given in Appendix A. The saturated liquid line and the saturated vapor line meet at the critical point. The dome-shaped region under the saturated liquid and vapor lines is the two-phase coexistence region of liquid and vapor. The region above the dome-shaped region is a single-phase homogeneous region which may be divided into three regions by the critical isotherm and critical isobar. The region at high pressure and low temperature is the compressed liquid region and the region at high temperature and low pressure is the superheated vapor or gas region. The supercritical fluid (SCF) region covers the states at which temperature is higher than the critical temperature, and pressure is higher than the critical pressure. In the SCF region, the phase separation can no longer be observed by compression of the vapor or expansion of the liquid.

Measurements are presented of the vapor pressure of supercooled water utilizing infrared spectroscopy, which enables unambiguous verification that the authors’ data correspond to the vapor pressure of liquid water, not a mixture of liquid water and ice. Values of the vapor pressure are in agreement with previous work. Below −13°C, the water film that is monitored to determine coexistence of liquid water (at one temperature) and ice (at another, higher, temperature) de-wets from the hydrophilic silicon prism employed in the authors’ apparatus. The de-wetting transition indicates a quantitative change in the structure of the supercooled liquid.

Mass transfer characteristics of gases in aqueous and organic liquids at elevated pressures and temperatures in agitated reactors

Adhesion characteristics of ice in urea aqueous solution for efficient slurry formation in cold storage

Abstract. Heterogeneous ice nucleation is thought to be the primary pathway for the formation of ice in mixed-phase clouds, with the number of active ice-nucleating particles (INPs) increasing rapidly with decreasing temperature. Here, molecular-dynamics simulations of heterogeneous ice nucleation demonstrate that the ice nucleation rate is also sensitive to pressure and that negative pressure within supercooled water shifts freezing temperatures to higher temperatures. Negative pressure, or tension, occurs naturally in water capillary bridges and pores and can also result from water agitation. Capillary bridge simulations presented in this study confirm that negative Laplace pressure within the water increases heterogeneous-freezing temperatures. The increase in freezing temperatures with negative pressure is approximately linear within the atmospherically relevant range of 1 to −1000 atm. An equation describing the slope depends on the latent heat of freezing and the molar volume difference between liquid water and ice. Results indicate that negative pressures of −500 atm, which correspond to nanometer-scale water surface curvatures, lead to a roughly 4 K increase in heterogeneous-freezing temperatures. In mixed-phase clouds, this would result in an increase of approximately 1 order of magnitude in active INP concentrations. The findings presented here indicate that any process leading to negative pressure in supercooled water may play a role in ice formation, consistent with experimental evidence of enhanced ice nucleation due to surface geometry or mechanical agitation of water droplets. This points towards the potential for dynamic processes such as contact nucleation and droplet collision or breakup to increase ice nucleation rates through pressure perturbations.

Thermodynamic characteristics of gas-liquid phase change investigated by lattice Boltzmann method

Thermal analysis of slurry ice production system using direct contact heat transfer of carbon dioxide and water mixture

This study is devoted to the impurity concentration–temperature phase diagram of a substance (A) contain-ing an impurity (B) and featuring a liquid–liquid phasetransition A1 A2, which is manifested by a sharpchange in the short-order structure of the α solutionbased on component A. This transition is caused byvariation of the solution composition or temperatureand results in a phase separation, which is basically dif-ferent from the usual separation of a liquid into the αsolution based on the main component A and a β solu-tion based on impurity B. Intersection of the two-phaseregion of phase separation in a liquid α solution with atwo-phase region of the liquid–solid system leads tonew, previously unknown binary phase diagrams, thetypes of which can be established using thermody-namic analysis.1. INTRODUCTIONThere are many simple substances exhibiting pres-sure-induced first-order phase transitions in the liquidstate at the melting line on the phase diagram. Anexhaustive review of the corresponding experimentaldata can be found in [1]. These transitions are mani-fested by a sharp change in characteristics of the localstructure of the melt, such as the average interatomicdistance and coordination number, and are accompa-nied by anomalous variation of their physical propertiesboth in the pretransition state and immediately on thephase transition line [1–3]. On the temperature–pressure plane of thermody-namic variables, the first-order phase transition linebegins at the triple point on the melting line (featuringthe coexistence of the two types of liquids and the crys-tal) and is usually terminated by the point of the sec-ond-order phase transition, which was predicted as the“structural boiling” point by Katayama et al. [4]. Thisphase transition line can also be terminated at the pointof intersection with the line of liquid–gas phase transi-tion or with the line of another liquid–liquid phase tran-sition that originates either at the melting line (as, e.g.,in bismuth) or at the liquid–gas equilibrium line [5]. Inthe latter case, the phase diagram exhibits a triple pointin the region of liquid states.In order to describe the phase diagrams of pure sub-stances on the pressure–temperature plane, with contin-uation of the phase transition line to the region of liquidstates and termination at the “structural boiling” point,we have developed a model that was described in [6–9].There is a natural question as to how the structuraltransformation in a pure melt will be influenced by anadditional thermodynamic factor—the presence of asecond component (impurity) in the system—that is, bythe passage to the binary system. The aim of this studywas to elucidate this question.2. A TWO-PHASE REGION ON THE CONCENTRATION–TEMPERATURE DIAGRAMLet us consider a phase transition in a liquid solutionrepresenting a melt of the main component A. Consid-ering the concentration of impurity B as a preset exter-nal parameter and assuming that it is not redistributedbetween phases, we would obtain a line on the temper-ature–concentration diagram (similar to that on thepressure–temperature diagram), which terminates atthe “structural boiling” point ( T