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In the current study, we propose a novel hybrid system which consists of the solar heliostat field, gas turbine cycle and re-heat Rankine cycle and is capable of producing power and hot water simultaneously. A thermodynamic analysis of the current system is carried out to assess its performance both energetically and exergetically. A detailed parametric study is undertaken to study the effect of changing concentration ratio, ambient temperature, and time and day of the year on both energetic and exergetic efficiencies of the current system for Toronto, Canada. The best possible energy and exergy efficiencies for the receiver are 0.81 and 0.76 at a concentration ratio of 1600 and at 12:00pm on the 180th day of the year. The receiver efficiency is observed to vary from 0.71 to 0.763 with a variation in ambient temperature from 260 to 320 K. [ABSTRACT FROM AUTHOR]

It is very important to have quantitative data regarding the temperature distributions of lithium-ion batteries at different discharge rates in order to design thermal management systems and also for battery thermal modellers. In this paper, the surface temperature distributions on a superior lithium polymer battery (SLPB) with lithium manganese nickel cobalt oxide (LiMnNiCoO) cathode material (16 Ah capacity) at C/8, C/4, C/2, 1C, 2C, and 3C discharge rates are presented. Additionally, a battery thermal model is developed for this battery using a neural network approach with the Bayesian Regularization method and the simulated results are compared with experimental results in terms of temperature and voltage profiles at C/8, C/4, C/2, 1C, 2C, and 3C discharge rates. Thermal images, which were also captured during experiments with an IR camera at various discharge rates, and are reported in the paper. The results of this study show that the increased discharge rates between C/8 and 3C results in increased surface temperature distributions on the principal surface of the battery and decreased discharge capacity. [ABSTRACT FROM AUTHOR]

We aim to reveal the influence of pH values of the working solution on spatial arrangement of metal-containing inclusions in the monolayer coatings prepared by Langmuir-Blodgett (LB) technology and transferred to solid substrates with consequent modification of surface electrical properties. Consequently, films with inclusions in the form of dendrites and cluster shapes have been obtained. Submicron and micron lead-containing formations in Langmuir-Blodgett films have been characterized by using the atomic force microscopy, Kelvin probe microscopy, and scanning electron microscopy methods. The results show that increasing pH value of the subphase has caused the significant changes in the shape and composition of the inclusions in Langmuir-Blodgett films. The synthesized inclusions on the solid substrate surface resulted in formation of the regions with the local electric fields and, as consequence, to significant modification of the structure and electrical properties. The location and length of the regions with surface potential disturbance depend on the shape of inclusions, and consequently, on pH value of the subphase used in LB technology. [ABSTRACT FROM AUTHOR]

Transient operation of a co-current heat exchanger is analyzed in this paper, using a new predictive formulation for laminar and turbulent flows with mass discharge from the heat exchanger. The model includes time-varying mass discharge due to pressure regulated gas outflow. The temperature variations of the working fluid, heating fluid and the wall are predicted and validated against past data. It is found that the temperature of the working fluid rises sharply to a peak and then gradually decreases over time, due to mass discharge effects. The wall temperature decreases exponentially, and the temperature of the heating fluid falls sharply, and then gradually decreases. A benchmark case of a step change in the mass flow rate of the incoming fluid is analyzed and compared against past data for validation, after which results are presented and discussed for transient step changes of the incoming mass flow rate. [ABSTRACT FROM AUTHOR]

This paper examines a passive thermal management system for electric vehicle batteries, consisting of encapsulated phase change material (PCM) which melts during a process to absorb the heat generated by a battery. A new configuration for the thermal management system, using double series PCM shells, is analyzed with finite volume simulations. A combination of computational fluid dynamics (CFD) and second law analysis is used to evaluate and compare the new system against the single PCM shells. Using a finite volume method, heat transfer in the battery pack is examined and the results are used to analyse the exergy losses. The simulations provide design guidelines for the thermal management system to minimize the size and cost of the system. The thermal conductivity and melting temperature are studied as two important parameters in the configuration of the shells. Heat transfer from the surroundings to the PCM shell in a non-insulated case is found to be infeasible. For a single PCM system, the exergy efficiency is below 50%. For the second case for other combinations, the exergy efficiencies ranged from 30-40%. The second shell content did not have significant influence on the exergy efficiencies. The double PCM shell system showed higher exergy efficiencies than the single PCM shell system (except a case for type PCM-1). With respect to the reference environment, it is found that in all cases the exergy efficiencies decreased, when the dead-state temperatures rises, and the destroyed exergy content increases gradually. For the double shell systems for all dead-state temperatures, the efficiencies were very similar. Except for a dead-state temperature of 302 K, with the other temperatures, the exergy efficiencies for different combinations are well over 50%. The range of exergy efficiencies vary widely between 15 and 85% for a single shell system, and between 30-80% for double shell systems. [ABSTRACT FROM AUTHOR]

This paper presents a new predictive model of droplet flow and heat transfer from molten salt droplets in a direct contact heat exchanger. The process is designed to recover heat from molten CuCl in a thermochemical copper-chlorine (Cu-Cl) cycle of hydrogen production. This heat recovery occurs through the physical interaction between high temperature CuCl droplets and air. Convective heat transfer between droplets and air is analyzed in a counter-current spray flow heat exchanger. Numerical results for the variations of temperature, velocity and heat transfer rate are presented for two cases of CuCl flow. The optimal dimensions of the heat exchanger are found to be a diameter of 0.13 m, with a height of 0.6 and 0.8 m, for 1 and 0.5 mm droplet diameters, respectively. Additional results are presented and discussed for the heat transfer effectiveness and droplet solidification during heat recovery from the molten CuCl droplets. [ABSTRACT FROM AUTHOR]

Longitudinal two-dimensional strain deformation is a novel technique which evaluates global and regional left ventricular (LV) function with high reproducibility. The aim of the study was to investigate the global and regional systolic function using this method in patients with pure mitral stenosis (MS). Conventional echocardiography and longitudinal two-dimensional strain analysis were performed in 60 patients (41 +/- 5 years, 48 women) with mild to moderate MS (mitral valve area: 1.9 +/- 0.5 cm(2)), and 52 healthy controls (40 +/- 7 years, 37 women). For strain analysis standard apical views were obtained, and by using a software system peak systolic strain and strain rate were calculated off-line in each segment. In all, 88% of the segments could be optimally tracked by the software system. Despite normal LV systolic function as assessed by ejection fraction (66 +/- 8%), mean global longitudinal strain (GLS) and global longitudinal strain rate (GLSR) were significantly reduced in patients with isolated MS (GLS -17 +/- 3.3 vs. -19 +/- 2.5%, P = 0.006 and GLSR -1.3 +/- 0.3 vs. -1.5 +/- 0.3 s(-1), P < 0.0001). Regional analysis demonstrated that patients with MS had a significantly reduced longitudinal peak strain and strain rate in all basal, and some mid (inferior, anteroseptal, interventricular septum) segments of the left ventricle. For other segments longitudinal peak strain and strain rate values were similar among the groups. Evaluation of LV systolic function by longitudinal two-dimensional strain deformation identified early abnormalities in MS patients who had apparently normal standard systolic function. [ABSTRACT FROM AUTHOR]

Cooling technology is widely used in a variety of engineering applications ranging from cooling of electronic devices to food cooling. It makes this industry play an important role in the economies. In practice there is an urgent need to design a cooling system with the optimum processing conditions and to provide energy saving along with the high quality products. In this respect, accurate determination of the heat transfer parameters for the cooling operation is essential. In this paper, recently developed models and correlations, e.g., thermal diffusivity and heat transfer coefficient models, and Nusselt–Reynolds and Fourier–Reynolds correlations to determine the cooling process and heat transfer parameters are presented with an illustrative example. Another important point is that the cooling parameters are incorporated into the heat transfer parameters and correlations. It is believed that these models and correlations are of great significance to refrigeration industry. [ABSTRACT FROM AUTHOR]

This article presents an analytical technique for determining the moisture diffusivities and moisture transfer coefficients for slab shaped woods subjects to drying process. The analysis of transient moisture diffusion is carried out on the basis of two important practical criteria: 0.1100. The drying coefficients and lag factors are defined for wood-drying applications and incorporated into the models. In order to verify the present models, the model results are compared with experimental measurements taken from the literature and good agreement was found. Results show that the technique presented here is capable of determining the moisture diffusivities and moisture transfer coefficients for slab woods in a simple and accurate manner for practical applications and will be beneficial to the relevant wood␣drying industries. This approach can be extended to␣different wood products of regular and irregular shapes. [ABSTRACT FROM AUTHOR]

In this paper, an analysis of transient heat transfer during heat sterilization and cooling processes of a cylindrical canned product is presented. In the analysis, most practical case including the boundary condition of third kind (i.e., convection boundary condition, leading to 0.1 ≤ Bi ≤ 100) was employed. A simple analytical model for determining effective heat transfer coefficients for such products is developed. For the heat sterilization process, heating coefficient is incorporated into heat transfer coefficient model. An experimental study was performed to measure the thermal center temperatures of the short-cylindrical canned products (i.e., Tuna fish) during heat sterilization at the retort medium temperatures of 115∘C and 121∘C, and during cooling process at 16∘C. The effective heat transfer coefficient model used the experimental temperature data. Using these effective heat transfer coefficients the center temperature distributions were calculated and compared with the experimental temperature distributions. Agreement was found considerably high. The results of the present study indicate that the heat-transfer analysis technique and heat-transfer coefficient model are reliable, and can provide accurate results for such problems. [ABSTRACT FROM AUTHOR]

The present paper deals with the development of simple analytical models for determining thermal diffusivities, thermal conductivities and heat transfer coefficients of solid objects being refrigerated in any medium. Experimental data taken from the author's previous works were used to validate the present models. Three classifications of transient heat transfer namely Bi<0.1, 0.1≤Bi≤100, and Bi>100 were investigated and the corresponding models were obtained. In the modelling, the objects were considered as infinite slabs, infinite cylinders or spheres. The calculation results demonstrated that the thermal properties are strongly dependent cooling process parameters in terms of the lag factor and refrigeration coefficient. The present models will be beneficial to the refrigeration industry and other relevant sectors. [ABSTRACT FROM AUTHOR]

In this paper, the development of new models to determine heat and mass transfer parameters (HMTPs) in terms of the thermal diffusivity, heat transfer coefficient, moisture diffusivity and moisture transfer coefficient for slab, cylindrical, and spherical products being deep-fried was presented. In the model development, two cases of the Biot number, i.e., 0< Bi<100, and Bi≥100 in the transient heat and mass transfer were considered. In order to verify the models, frying experiments were performed using the cylindrically shaped potatoes as test samples, and these samples were fried in a deep fryer at 180°C. The lag factor and frying coefficient for a frying process, which affect heat and mass transfer parameters, were first-defined and considered most important process parameters. By using the temperature and moisture measurements, the frying coefficient and lag factor were determined and incorporated into the models. The HMTPs were determined in a simple and effective manner. In this respect, we can conclude that the present models are useful tools for determining the HMTPs for the products during frying and will be beneficial to the practical applications. In der Arbeit werden Modelle vorgestellt, über die sich Wärme- und Stoffübergangsparameter als Funktionen der Temperatur- und Feuchteleitfähigkeit und der Wärme- und Stoffübergangskoeffizienten für platten-, zylinder- und kugelförmige Nahrungsmittel beim Tauchgaren bestimmen lassen. Im instationären Wärme- und Stoffaustauschmodell werden zwei Bereiche der Biot-Zahl betrachtet: 0≤ Bi≤100 und Bi≥100. Die Modellvorstellungen konnten durch Garexperimente bei 180°C an zylindrisch vorgeformten Kartoffelstücken verifiziert werden. Als wichtigste Prozeßparameter wurden über Temperature- und Feuchtegehaltsmessungen ein Verzögerungsfaktor und ein Garkoeffizient ermittelt und hieraus, in sehr einfacher und effektiver Weise, die interessierenden Wärme- und Stoffaustauschparameter. Es zeigte sich, daß die vorgeschlagenen Modelle recht gut geeignet sind, um die relevanten Wärme- und Stoffübergangsparameter für zum Tauchgaren bestimmte Produkte ermitteln zu helfen. [ABSTRACT FROM AUTHOR]