Narrow Results

In the present study, local condensation heat transfer coefficients of the R1234ze(E) inside a vertical plate heat exchanger (PHE) were investigated experimentally. In the experiment, three vertical flow channels are formed in the test section where refrigerant flows downward in the middle channel and cooling water flows upward in other two channels. The test section consists of eight plates: two of them form a channel of chevron type PHE for refrigerant flow channel, other two flat plates are set for heat transfer measurements, and another consist on cooling water flow channel. Down flow of the condensing refrigerant R1234ze(E) in the center channel releases heat to other channels of cooling water. In order to measure local heat transfer characteristics, a total of 60 thermocouples were set at middle of flow direction and also in the right and left sides of plates in test section. Experiments were conducted for mass fluxes ranging from 10kg/m²s to 50kg/m²s. The measurement results show that local heat transfer coefficients decrease with increase of wetness with different values in horizontal direction. Further, characteristics of local heat flux and wall temperature distribution as a function of distance from inlet to outlet of refrigerant channel were explored in detail.

In this paper, we consider the generalization of Gross Pitaevskii equation for condensate of bosons with nonextensive statistics. First, we use the non-additive methods and formalism to obtain the well-known Schrödinger equation. Using a suitable Hamiltonian for condensate phase and minimizing the free energy of the system by non-additive formalism, we work out the nonextensive Gross Pitaevskii equation.

We review recent interactions between mathematical theory of two-dimensional topological order and operator algebras, particularly the Jones theory of subfactors. The role of representation theory in terms of tensor categories is emphasized. Connections to two-dimensional conformal field theory are also presented. In particular, we discuss anyon condensation, gapped domain walls and matrix product operators in terms of operator algebras.

A [3+2] acid-catalyzed condensation of a tetra-functionalized pyrene fluorophore (4) with dipyrromethane dicarbinol (5) resulted in the unprecedented formation of two bis-calix[5]phyrins (bis-calix[5]-1 and bis-calix[5]-2). The solution state structure of both bis-calix[5]phyrins was found to be similar with slight variations as confirmed by NMR spectral studies. Interestingly, two different linkages between the pyrene subunits with dipyrromethane dicarbinols led to two different calix[5]phyrin systems. Although the optical features seem to be similar, the single crystal X-ray structure obtained for bis-calix[5]-1 provided the structural proof showing a non-planar, half-chair conformation with two meso-sp³ carbons. DFT studies were carried out to compare the HOMO-LUMO energy levels of both bis-calix[5]phyrins with the targetted conjugated bis-macrocycle (bis-N${}_8)$. Further, both the calix[5]-phyrins showed high Stokes shift (5404 cm${}^{-1})$ and fluorescence quantum yield efficiency of around 90%.

Condensation heat transfer coefficients and pressure drops of HFC refrigerants R-134a and R-410A have been investigated experimentally in smooth and micro-fin tubes (helix angles 18${}^{\circ }$ and 15${}^{\circ }$) of outer diameter 9.52mm at mass fluxes from 200 to 600kg/m${}^2\cdot$s, vapor qualities between 0.1 and 0.9 and at saturation temperatures of 35${}^{\circ }$C and 40${}^{\circ }$C. Results showed that the heat transfer coefficients of R-134a and R-410A inside micro-fin tubes were 1.21–1.82 and 1.15–1.47 times higher and frictional pressure drops were 2.11–2.56 and 1.62–2.12 times higher than those of smooth tubes. These experimental results are compared with the existing heat transfer and frictional pressure drop correlations proposed by different researchers. The comparison showed fairly good agreement with these existing correlations within $\pm$30%. A new correlation has also been proposed for predicting heat transfer coefficient in micro-fin tubes. The oil concentrations measured for refrigerants R-134a and R-410A varied in the range of 1.3–1.5%, respectively.

Following our earlier work on the perturbative thermodynamic geometry of nonextensive quantum and classical gases [H. Mohammadzadeh, F. Adli and S. Nouri, Phys. Rev. E94 (2016) 062118], we study $q$-generalized Bose–Einstein, Fermi–Dirac and classical statistics nonperturbatively. We define $q$-generalized polylogarithm functions and evaluate thermodynamics quantities such as internal energy and particle number. We construct the thermodynamic geometry of nonextensive Bose (Fermi) ideal gas and show that the thermodynamic curvature is positive(negative) in full physical range as the same as ordinary statistics. Also, we show that the thermodynamic geometry of nonextensive ideal classical gas is flat, similar to the ordinary one. Therefore, the nonextensive parameter does not change the nature of intrinsic statistical interactions. We argue that the nonextensive boson gas might be more stable than the boson gas due to conjectural interpretation of thermodynamic curvature. In the following, we extract the singular points of thermodynamic curvature of nonextensive Bose gas and relate it to the condensation. We evaluate some thermodynamic quantities such as heat capacities, compressibility and $q$-dependent phase transition temperature. We show that the heat capacity is not differentiable at critical temperature, $T_c^q$ which is reduced by increasing nonextensive parameter $q$. Moreover, the critical temperature and possibility of condensation is investigated for different values of nonextensive parameter in various dimensions.

In this paper, condensation and evaporation characteristics of low global warming potential (GWP) refrigerants such as R-1234yf and R-1234ze series are reviewed. This review focuses on heat transfer and pressure drop in plate heat exchangers. Mass flux is considered as an important factor while saturation temperature is not for condensation and evaporation process in plate heat exchangers. The dryout phenomenon occurs occasionally and gives greatly harmful impact on evaporation heat transfer. It is found that R-1234yf and R-1234ze(E) give slightly lower heat transfer performance than R-134a for both condensation and evaporation processes. Generally, low GWP refrigerants presented in this review give lower heat transfer coefficient and higher frictional pressure drop than the conventional refrigerants. Nevertheless, R-1234ze(Z) gives superior heat transfer performance than other refrigerants in condensation. R-32 gives remarkable performance in evaporation, but it gives relatively high GWP compared to other low GWP refrigerants.

A numerical algorithm is used to solve the bare and the effective potential for the scalar ϕ⁴ model in the local potential approximation. An approximate dynamical Maxwell-cut is found which reveals itself in the degeneracy of the action for modes at some scale. This result indicates that the potential develop singular field dependence as far as one can see it by an algorithm of limited numerical accuracy.

We analytically describe the properties of the s-wave holographic superconductor with the exponential nonlinear electrodynamics in the Lifshitz black hole background in four-dimensions. Employing an assumption the scalar and gauge fields backreact on the background geometry, we calculate the critical temperature as well as the condensation operator. Based on Sturm–Liouville method, we show that the critical temperature decreases with increasing exponential nonlinear electrodynamics and Lifshitz dynamical exponent, $z$, indicating that condensation becomes difficult. Also we find that the effects of backreaction has a more important role on the critical temperature and condensation operator in small values of Lifshitz dynamical exponent, while $z$ is around one. In addition, the properties of the upper critical magnetic field in Lifshitz black hole background using Sturm–Liouville approach is investigated to describe the phase diagram of the corresponding holographic superconductor in the probe limit. We observe that the critical magnetic field decreases with increasing Lifshitz dynamical exponent, $z$, and it goes to zero at critical temperature, independent of the Lifshitz dynamical exponent, $z$.

In this paper, we explore the dynamics of quantum correlations in an isolated physical quantum under the influence of intrinsic coherence. We characterize the quantum correlations in the hybrid system using the granular model to investigate the amount of coherent-chaotic fractions, and we particularly use the spherical droplets to measure the specific correlations. Likewise, we examine the effect of coherence on the source evolution of these quantifiers within engineering applications. In particular, the behavior of the multiparticle correlations in terms of the system parameters and the coherence rate is investigated and analyzed in detail to explore the source intrinsic dimensions. We found that the correlations with genuine interferences behave slightly unsymmetrical for identical parameters characterizing the considered complex system and that the genuine correlations are more meaningful than primary interference which probed the chaotic peculiarities against the coherence phenomena. Our results also show that the robustness of quantum correlations can be modulated by adjusting the coherent rate, source physical properties and the initial conditions.

We establish natural criteria under which normally iterable premice are iterable for stacks of normal trees. Let $\mathrm{\Omega }$ be a regular uncountable cardinal. Let $m<\omega$ and $M$ be an $m$-sound premouse and $\mathrm{\Sigma }$ be an $(m,\mathrm{\Omega }+1)$-iteration strategy for $M$ (roughly, a normal $(\mathrm{\Omega }+1)$-strategy). We define a natural condensation property for iteration strategies, inflation condensation. We show that if $\mathrm{\Sigma }$ has inflation condensation then $M$ is ${(m,\mathrm{\Omega },\mathrm{\Omega }+1)}^{\ast }$-iterable (roughly, $M$ is iterable for length $\le \mathrm{\Omega }$ stacks of normal trees each of length $<\mathrm{\Omega }$), and moreover, we define a specific such strategy ${\mathrm{\Sigma }}^{\mathrm{\text{st}}}$ and a reduction of stacks via ${\mathrm{\Sigma }}^{\mathrm{\text{st}}}$ to normal trees via $\mathrm{\Sigma }$. If $\mathrm{\Sigma }$ has the Dodd-Jensen property and $\mathrm{\text{card}}(M)<\mathrm{\Omega }$ then $\mathrm{\Sigma }$ has inflation condensation. We also apply some of the techniques developed to prove that if $\mathrm{\Sigma }$ has strong hull condensation (introduced independently by John Steel), and $G$ is $V$-generic for an $\mathrm{\Omega }$-cc forcing, then $\mathrm{\Sigma }$ extends to an $(m,\mathrm{\Omega }+1)$-strategy ${\mathrm{\Sigma }}^{+}$ for $M$ with strong hull condensation, in the sense of $V[G]$. Moreover, this extension is unique. We deduce that if $G$ is $V$-generic for a ccc forcing then $V$ and $V[G]$ have the same $\omega$-sound, $(\omega ,\mathrm{\Omega }+1)$-iterable premice which project to $\omega$.

A new mathematical model for non-equilibrium evaporation/condensation including boiling effect is proposed. A simplified differential-algebraic system of equations is obtained. A code to solve numerically this differential-algebraic system has been developed. It is designed to solve both systems of equations with and without the boiling effect. Numerical calculations of ammonia–water systems with various initial conditions, which correspond to evaporation and/or condensation of both components, have been performed. It is shown that, although the system evolves quickly towards a quasi-equilibrium state, it is necessary to use a non-equilibrium evaporation model to calculate accurately the evaporation/condensation rates, and consequently all the other dependent variables.

R-410A condensation heat transfer and pressure drop data are provided for a 5.0 mm O.D. microfin tube having 40 fins with 18 degree helix angle and 40 degree fin apex angle. Tests were conducted for a range of quality (0.2 ~ 0.8), mass flux (346 ~ 692 kg/m²s) and saturation temperature (45 ~ 55°C). Data are compared with smooth tube counterpart. It was found that both heat transfer coefficient and pressure drop increased as mass flux increased. The range of pressure drop penalty factor (1.83 ~ 2.62) was slightly larger than that of heat transfer enhancement factor (1.24 ~ 1.66). Data are compared with available heat transfer and pressure drop correlations.

The present study experimentally investigated the condensation heat transfer characteristics and condensate flow mode of R245fa on horizontal low-finned and microscopic-grooved tubes. Five low-finned tubes and a microscopic-grooved tube with tube diameters at the fin tip of approximately 19 mm were used. Experiments were conducted at a saturation temperature of 40°C. The fundamental heat transfer characteristics of the low-finned and microscopic-grooved tubes were experimentally investigated to clarify the flow modes of the condensate and the efficacy of the enhanced heat transfer.

The syntheses of indium, gallium and aluminum porphyrin dimers with a single hydroxo-bridge, $\{$[M(Porph)]₂(OH)${\}}^{+}$, are described. Emphasis is given to indium and gallium derivatives. The X-ray structures for $\{$ [Ga(OEP)]₂(OH)$\}$ ClO₄ and $\{$ [In(OEP)]₂(OH)$\}$ ClO₄ (two forms) are presented. The dimeric molecules can be synthesized by the acid-treatment of the corresponding hydroxo-ligated monomeric complexes [M(OEP)(OH)] and [M(TPP)(OH)]. The nature of the starting material (the hydroxo-ligated monomer) was first suggested by IR spectroscopy and further proved by proton-deuterium exchange followed by ¹H NMR spectroscopy. The structure of a monomeric indium hydroxide complex, [In(OEP)(OH)], is also presented. The synthesis of the dimer for all metals can be monitored by UV-vis spectroscopy, which clearly demonstrates that a blue-shift of the Soret band accompanies formation of the dimer from the monomer. A strong $\pi$–$\pi$interaction between the two porphyrin rings of these $\mu$-hydroxo-bridged dimers is confirmed both by solution state studies (¹H NMR and UV-vis spectroscopy) and the X-ray structures of $\{$ [M(OEP)]₂(OH)$\}$ ClO₄ (M = In, Ga). In addition, exposure of methylene chloride solutions of these bridged complexes to white light afforded the corresponding chloro derivatives, [M(Porph)Cl]. The stereochemistry of a range of $\mu$-hydroxo dimers is discussed and DFT simulations at the HSEH1PBE/SDD level of theory provide suitable structural models and further electronic structure insights on selected [Ga(Porph)(OH)] and $\{$ [Ga(Porph)]₂(OH)$\}$${}^{+}$ derivatives.

In this study, we have prepared new tripyrranes embedded with azulene bearing two meso-pentafluorophenyl substituents. They were obtained as diastereomers in high yield which were separated using conventional column chromatography. Their distinct solution structures were unambiguously confirmed by NMR and mass analysis. Our synthetic strategy is simple and straightforward due to the reactivity of 1,3-positions of azulene, which underwent Lewis acid-catalyzed condensation with pyrrole-2-carbinol. These diastereomers were further subjected to acid-catalyzed (CF₃COOH) condensation with pyrrole dicarbinol to afford the target N-confused azuliporphyrin (reduced form) in trace amount. However, we obtained the tris-meso-pentafluorophenyl substituted azulicorrole (AzCorA) as major product due to an unprecedented scrambling of the azulitripyrranes. The structural characterization of newly synthesized key precursors and macrocycles was done with the aid of high-resolution mass analyses, and ¹H and 2D NMR analyses. The single crystal X-ray structure obtained for AzCorArevealed that the azulene subunit is tilted by 34.03${}^{\circ }$ due to the steric congestion of inner-NHs.

R-404A condensation heat transfer and pressure drop data are provided for 7.0mm O.D. smooth and microfin tubes. Tests were conducted for a range of mass fluxes (from 80 to 200kg/m²s) and quality (from 0.2 to 0.8). The heat flux was 6kW/m² and saturation temperature was 45${}^{\circ }$C. It was found that both the heat transfer enhancement factor and the pressure drop penalty factor increase as mass flux increases. The range of pressure drop penalty factor (0.99–1.27) was smaller than that of heat transfer enhancement factor (1.21–1.96). Smooth tube heat transfer coefficients and pressure drops are reasonably predicted by Shah [An improved and extended general correlation for heat transfer during condensation in plain tubes, Int. J. HVAC&R Res.15 (2009) 889–913] and Jung and Radermacher [Prediction of pressure drop during horizontal annular flow boiling of pure and mixed refrigerants, Int. J. Heat Mass Transfer32 (1989) 2435–2446] correlation, respectively. For the microfin tube, however, all the existing correlations do not adequately predict the present data. Poor predictions may be attributed to the lack of R-404A and low mass flux data in their database.

Internal combustion (IC) engines are a major contributor to the total particulate emissions inventory, especially in urban areas. Recent epidemiological studies suggesting links between fine particles and negative health effects have sparked an increased interest in this subject. While particulate emissions from IC engines have been the focus of research for many years, a great deal of information crucial to our understanding of this subject still remains unknown. In this paper the authors address some of these unknowns, focusing primarily on the process and consequences of aerosol dilution strategy. The thermodynamics of dilution are considered, and the inadequacy of conventional constant-volume sampling dilution tunnels for ultrafine particle characterization are demonstrated using experimental data. Finally, time-resolved data demonstrating the variation in concentration of pollutants in a vehicle moving in traffic are used as an example of the difficulties in setting legislation aimed at controlling exposure to ultrafine particles.