Energy Flow Rate Research Articles

Design and heat flow analysis of a commercial energy efficient in-line water heating system

In this paper, the authors provide the design, heat flow analysis and pressure analysis of a commercial energy efficient in-line water heating system in South Africa. The designed commercial in-line water heating system captures the energy consumption, flow rate, temperature and pressure during operation and accordingly responds on these values to increase the energy efficiency of the system. The user is constantly aware of the energy consumption and cost during operation and can choose to switch to a more economical setting to conserve energy. A central processor with PID control was used to optimize the energy consumption of the in-line water heating system. An overview on the design and results of the heat flow analysis and pressure analysis are provided.

Fairness in Wireless Networks:Issues, Measures and Challenges

The pervasiveness of wireless technology has indeed created massive opportunity to integrate almost everything into the Internet fabric. This can be seen with the advent of Internet of Things and Cyber Physical Systems, which involves cooperation of massive number of intelligent devices to provide intelligent services. Fairness amongst these devices is an important issue that can be analysed from several dimensions, e.g., energy usage, achieving required quality of services, spectrum sharing, and so on. This article focusses on these viewpoints while looking at fairness research. To generalize, mainly wireless networks are considered. First, we present a general view of fairness studies, and pose three core questions that help us delineate the nuances in defining fairness. Then, the existing fairness models are summarized and compared. We also look into the major fairness research domains in wireless networks such as fair energy consumption control, power control, topology control, link and flow scheduling, channel assignment, rate allocation, congestion control and routing protocols. We make a distinction amongst fairness, utility and resource allocation to begin with. Later, we present their inter-relation. At the end of this article, we list the common properties of fairness and give an example of fairness management. Several open research challenges that point to further work on fairness in wireless networks are also discussed. Indeed, the research on fairness is entangled with many other aspects such as performance, utility, optimization and throughput at the network and node levels. While consolidating the contributions in the literature, this article tries to explain the niceties of all these aspects in the domain of wireless networking.

Analysis of non-Fourier conduction and volumetric radiation in a concentric spherical shell using lattice Boltzmann method and finite volume method

Application of the lattice Boltzmann method (LBM) has been extended to formulate and solve the energy equation of a non-Fourier conduction and radiation heat transfer problem in a concentric spherical shell. The enclosed conducting-radiating medium is absorbing, emitting and scattering. The non-Fourier conduction effect is induced by thermally perturbing one of the boundaries and incorporating the finite propagation speed of the thermal wave front in Fourier’s law of heat conduction. The volumetric radiative information needed in the energy equation has been computed using the finite volume method (FVM). To establish the accuracy of the LBM approach, with volumetric radiative information obtained from the FVM, the energy equation is also solved using the FVM. Effects of extinction coefficient, scattering albedo, conduction–radiation parameter, emissivity, radius ratio and the magnitude of thermal perturbations are studied on transient temperature distributions. Effects of the aforesaid parameters on the steady-state conduction, radiation and total energy flow rates are also studied. Steady-state LBM and FVM results are compared. In all the cases, the LBM results compare exceedingly well with the FVM results, and LBM has a faster convergence than the FVM.

Economic Consequence Analysis of Fire and Explosion in Petrochemical Feed and Product Pipelines Network

planning. Objectives: The purpose of this study was to estimate economic loss due to fire and explosion in petrochemical feed and product pipelines. Materials and Methods: The present study which performed on 47 pipelines of a petrochemical special zone, pertinent pipeline selected by chemical energy potential, flow rate and capital density. Pipeline hazard factor and material factor were determined, and fire and explosion index (F&EI) was calculated. After determination of F&EI, the area of exposure and replacement value in exposure area was determined. Finally, actual maximum probable property damage and business interruption were computed. Results: In the fire and explosion, radius of exposure in adjacent of pipeline was 41.5 meter, and damage factor was 0.87. On the other hand, actual maximum probable property damage was $ M 3.9, and business interruption was $ M 767. Conclusions: Since, Butadiene pipeline has the highest grade of risk in which the degree of fire and explosion is severe, appropriate control actions are required to reduce the risks. Therefore, considering the economic costs and consequences, a comprehensive risk analysis and emergency response planning is highly important for the Petrochemical feed pipelines.

Combustion and emissions performance of a hydrogen engine at idle and lean conditions

SUMMARY Hydrogen is the most promising alternative fuel for spark-ignited engines. This paper experimentally investigated the performance of a pure hydrogen-fueled SI engine at idle and lean conditions. The experiment was carried out on a four-cylinder gasoline-fueled SI engine equipped with an electronically controlled hydrogen port-injection system and a hybrid electronic control unit which was used to govern the hydrogen injection duration. The engine original electronic control unit was used to adjust the opening of idle bypass valve and spark timing to enable the engine to be run around its target idle speed. The test results showed that the fuel energy flow rate was reduced with the increase of excess air ratio for the pure hydrogen-fueled engine at idle and lean conditions. When excess air ratio increased from 2.08 to 3.2, the hydrogen energy flow rate was decreased from 11.79 to 9.97 MJ/h. Both the flame development and propagation periods were increased with the increase of excess air ratio. Because of the increased opening of idle bypass valve and dropped cylinder temperature, both pumping and cooling losses were reduced when the engine was leaned out. NOx and CO emissions were negligible, but HC and CO2 were still existed for the pure hydrogen-fueled SI engine due to the possible burning of the blow-by lubricant oil gas. Copyright © 2013 John Wiley & Sons, Ltd.

Analysis of non-Fourier conduction and radiation in a cylindrical medium using lattice Boltzmann method and finite volume method

Combined mode heat transfer in a conducting–radiating participating medium bounded by a concentric cylindrical enclosure is studied. The finite propagation speed of heat transfer by conduction is accounted by modifying the Fourier’s law of heat conduction. The energy equation is formulated and solved using the lattice Boltzmann method. The finite volume method is used to compute the volumetric radiative information needed in the energy equation. Radial distributions of temporal temperature and the steady-state conductive, radiative and total energy flow rates are analyzed for a wide range of parameters, such as the extinction coefficient, the scattering albedo, the conduction–radiation parameter, the emissivity and the radius ratio. With volumetric radiative information computed using the finite volume method, in all cases, the steady-state temperature distributions from the lattice Boltzmann method are compared with those obtained by solving the energy equation using the finite difference method. An excellent comparison is obtained.

Improving the gas barrier properties of a-SiOxCyNz film at low temperature using high energy and suitable nitrogen flow rate

Amorphous silicon oxycarbonitride thin films were synthesized on polyethylene terephthalate (PET) substrates at low temperatures (∼80 °C) by plasma-enhanced chemical vapor deposition (PECVD). A high ion flux and suitable nitrogen flow rate improved the gas barrier properties and deposition rate of the resulting a-SiOxCyNz film. The a-SiOxCyNz films were deposited at a high deposition rate and low water WVTR properties as a result of the high ion flux and nitrogen chemistry. The high ion flux modified the chemical structure and nitrogen atomic composition of the resulting a-SiOxCyNz film coatings. The substrate temperature was characterized using a thermometer. In addition, the coating properties were characterized by Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS) and the water vapor transmission rate (WVTR).

Mechanical properties and bonding structure of boron carbon nitride films synthesized by dual ion beam sputtering

The BCN films were synthesized on Si (110) wafers by using dual ion beam sputtering deposition from boron carbide target. The influences of ion assist source energy and N2 relative flow rate on the surface roughness, mechanical properties and chemical bonding structure of BCN films were investigated systematically. The surface roughness was measured using non-contact optical surface profilometer and the mechanical properties of BCN films were evaluated with nano-indenter. The BCN films were characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. The results showed that the BCN films' surface roughness varied in the range of 5–15 nm, and their hardness and reduced elastic modulus fluctuated in the scope of 18–29 GPa and 192–229 GPa, respectively. When the BCN films' surface roughness varied in the range of 8–12 nm, the values of hardness and reduced elastic modulus were fluctuated slightly. The BCN films with the smoothest surface (Ra = 5 nm) and the highest hardness of 28 GPa were obtained at the ion assist source energy of 200 eV and the N2 relative flow rate of 50%. The BCN films were amorphous and contained several bonding states such as B–N, B–C and C–N with B–C–N hybridization.

The cold start performance of a spark-ignited dimethyl ether engine

Dimethyl ether (DME) seems to be a potential approach for improving the cold start performance for spark-ignited (SI) engines. In this paper, the cold start performance of an SI engine fueled with pure DME was experimentally investigated and compared with that of the original SI gasoline engine. The engine was successfully cold started with pure DME and pure gasoline, respectively. The test results demonstrated that, the fuel energy flow rate of the SI DME engine was only 30% of that of the original SI gasoline engine whereas the imep (indicated mean effective pressures) of the SI DME engine was effectively enhanced in the first 5 cycles. The SI DME engine had a shortened flame development period compared with the original SI gasoline engine. Meanwhile, the HC emissions were averagely decreased by 80% under the pure DME mode. The instantaneous CO and NOx emissions from the SI DME engine were slightly increased in the initial seconds after the onset of cold start and then markedly reduced compared with those from the original SI gasoline engine. In view of the above, starting an SI engine with pure DME could improve the combustion and emissions performance.

Study of the aerodynamic sealing of a cold store – Experimental and numerical approaches

An experimental study was conducted in a laboratory scale model in order to characterize the airflow generated by an air curtain device (ACD) on the aerodynamic sealing of refrigerated spaces. The laboratory scale model consists of two similar adjacent rooms connected by a door over which the ACD device was installed. The tracer gas technique was used to calculate the sealing effect achieved with the air curtain at different jet velocities.A three-dimensional numerical model was also developed to simulate the heat and mass transfer phenomena, as well as the aerodynamic sealing performance of an ACD. The numerical study was carried out using a commercial CFD code (ANSYS-CFX®) and the turbulence effects were approached by two different turbulence models (k–ɛ and k–ω SST).The experimental and numerical results show a good agreement for validation purposes. No significant differences were found in the results obtained with the two turbulence models, although the k–ω SST model seems to be more appropriate for the simulations. The existence of an optimum discharge air jet velocity was confirmed. The results also indicate that the air curtain is more efficient in reducing the mass transfer than the energy flow rate across the doorway.

Development of convective heat transfer correlations for common designs of solar dryer

The knowledge of convective heat transfer coefficient hcpf (absorber plate to flowing air) is necessary to predict or evaluate thermal performance of any solar dryer. In order to determine hcpf, laboratory models of direct (cabinet), indirect and mixed mode solar dryer are designed and constructed to perform no-load steady state experiments for natural and forced air circulation. The dryers are operated under indoor simulation conditions for absorbed thermal energy and air flow rate for the range of 300–800W/m2 and 1–3m/s, respectively. Separate methods depending on mode of heat utilisation are proposed for determination of hcpf for different dryers. Correlations of hcpf in terms of dimensionless numbers are developed for each dryer operating under natural and forced convection. Levenberg–Marquardt algorithm is used to develop temperature dependent correlations. A close agreement between experimental and predicted hcpf values obtained from proposed correlations for natural convection dryers demonstrates their reliability. However, for forced convection dryers, there is a need to use temperature dependent Nu–Re correlation for more accurate results. The low uncertainty ranging from 0.3% to 0.8% in the determination of hcpf confirms the accuracy of experimental data obtained for various dryer designs operated under different conditions.

Mass Spectrometric Identification of Silver Nanoparticles: The Case of Ag32(SG)19

Mass spectrometry has played a key role in identifying the members of a series of gold clusters, which has enabled the development of magic-number cluster theory. The successes of the gold cluster system have yet to be repeated in another metal cluster system, however. Silver clusters in particular have proven to be challenging due to their relative instability compared with gold clusters. Using the well-characterized gold nanocluster, Au(25)(SG)(18), we present optimized electrospray ionization mass spectrometry (ESI-MS) instrumental parameters for the maximal transmission of the intact cluster. Parameters shown to have the largest effect on intact cluster transmission/detection include trap and transfer collision energy, source temperature, and cone gas flow rate. Herein we describe a general strategy to acquire mass spectra of fragile metal clusters with reliable mass assignments. By also optimizing sample solution conditions, high-quality ESI mass spectra of a prototypical silver:glutathione (Ag:SG) cluster were obtained without significant fragmentation. By using gentle conditions and solution conditions designed to stabilize the clusters, fragmentation was dramatically reduced and mass spectra with isotopic resolution were measured. Using this strategy, we have made the first formula assignment for a ligand-protected Ag cluster of Ag(32)(SG)(19).

Comparative Thermal Performance Study of Indirect and Mixed-mode Solar Dryers

In the present study, simple performance evaluation method of solar dryers is proposed. The methodology based on steady state heat balance concept applied to the absorber surface of collectordryer assembly is proposed for identification of dimensionless parameter called effectiveness of dryer, e. No-load experiments on mixed-mode and indirect solar dryers have been performed for forced air circulation under indoor controlled conditions. Dryers are tested for a wide range of operating conditions of absorbed thermal energy (300800W/m) and air mass flow rate (0.009-0.026 kg/s). Based on comparison results of computed values of e for both of these dryer, it is found that there is significant performance improvement of 48% in case of mixed-mode in contrast to indirect dryer. The study further reveals that for both dryers there is sharp rise in e values when air mass flow rate is increased from 0.009 to 0.017 kg/s and thereafter a marginal increase can be noticed when air mass flow rate is enhanced to 0.026 kg/s. Another important finding of present study relates to invariable e values obtained for a wide range of absorbed energy and ambient air temperature data irrespective of air circulation mode adopted for a dryer. Keywordsmixed-mode dryer; indirect dryer; noload indoor test; forced convection; dryer effectiveness

어류군집 특성과 하안형태복잡도와의 관계

Numerous studies suggested that fish assemblage structure reflects the status of stream ecosystems. The status of streams integrity, including various trophic levels, water quality and habitat degradation, can be assessed by fish assemblages. In this study, we investigated the relationships between fish assemblages and streamline geometry of streams. Previous studies suggested that geomorphologic parameter can be a critical factor of permeability between adjacent two systems. From a landscape ecological perspective, edges may partially control the flow rate of energy between two adjacent systems. Thus, the Streamline geometry can be a geomorphologic parameter that exhibits the integrity of stream. We selected the Nakdong river for study areas, which is one of major rivers and the longest (525 km) River in South Korea. We used the revised IBI representing overall ecological characteristics of Korean fish assemblages and eight sub-assessment criteria of IBI, collected from 82 sampling sites in the Nakdong River. For calculating the Streamline geometry, we measured fractal dimension index that generally used in biology, ecology and landscape ecology. We used the digital land-use/land-cover map and generated a 1-km buffer for each sampling site and refined the shape of the Streamlines. Pearson correlation analyses were performed between Streamline geometry and IBI and sub-assessment criteria of IBI. The results show that IBI and eight sub-assessments of fish are significantly correlated with geometry of Streamline. The fractal dimension of Streamline geometry were related with IBI (r = 0.48) and six sub-assessments of IBI, including total number of native fish and native species, the number of riffle benthic species, sensitive species, tolerant species and native insectivore. Especially, the number of tolerant species(r = -0.52) and native insectivore(r = 0.52) show strong correlation with geometry of Streamline. These results indicate that lower Streamline geometry can result in poor fish assemblages, while higher geometry of Streamline can enhance fish assemblages by potentially supplying insects and better habitat conditions. We expect the results of our study to be useful for stream restoration and management. However, we see the necessity of study investigating the mechanisms how Streamline geometry affect fish assemblages.

Performance of a hydroxygen-blended gasoline engine at different hydrogen volume fractions in the hydroxygen

The gasoline engines always encounter the deteriorated thermal efficiency and increased toxic emissions at part load conditions. This paper investigated the effect of hydrogen/oxygen blends (hydroxygen) addition on the performance of a gasoline engine at different hydrogen volume fractions in the hydroxygen. The experiment was conducted on a 1.6 L gasoline engine equipped with a hydrogen and oxygen port injection system. A hybrid electronic control unit was adopted to control the spark timing and the injection timings and durations of hydrogen, oxygen and gasoline. The test was performed at a typical city driving speed of 1400 rpm, a manifolds absolute pressure of 61.5 kPa and two excess oxygen ratios of 1.00 and 1.20. The overall volume fraction of the hydroxygen in the total intake gas was fixed at 3%. The hydrogen volume fraction in the hydroxygen was raised from 0% to 100% by changing the injection durations of hydrogen and oxygen. The test results demonstrated that the engine thermal efficiency was obviously increased with the increase of hydrogen volume fraction in the hydroxygen. The fuel energy flow rate of the 3% hydroxygen-blended gasoline engine was lower than that of the original engine when the hydrogen volume fraction in the hydroxygen exceeded 70%. Both the flame development and propagation periods were shortened after the hydroxygen addition. HC, CO and NOx emissions were decreased with the increase of hydrogen volume fraction in the hydroxygen. But NOx emissions of the hydroxygen-blended engine were higher than those of the original engine for all hydrogen volume fractions in the hydroxygen. Moreover, at an excess oxygen ratio of 1.00, CO from the 3% hydroxygen-blended gasoline engine was also higher than that from the original engine. The reduced particulate emissions can be obtained only at relatively high hydrogen volume fractions in the hydroxygen.

Energy Recovery in Passenger Cars

The turbocharged direct injection stoichiometric spark ignition gasoline engine has less than diesel full load brake engine thermal efficiencies and much larger than diesel penalties in brake engine thermal efficiencies reducing the load. This engine has, however, a much better power density, and therefore may operate at much higher brake mean effective pressure (BMEP) values over driving cycles thus reducing the fuel economy penalty of the vehicle. This engine also has the advantage of the very well developed three way catalytic (TWC) converter after treatment to meet future emission regulations. Replacement of fossil gasoline with renewable gasoline-like fuels has major advantages. Ethanol and methanol have larger than gasoline resistance to knock and heat of vaporization, and this ultimately translates in larger than gasoline compression ratio and boost pressure and spark advances closer to maximum brake torque producing better efficiencies both full and part load. For the specific of these novel turbocharged direct injection stoichiometric spark ignition renewable gasoline-like engines coupled to a hybrid-electric power train, the paper considers the option to boost the total fuel conversion efficiency generating both mechanical and electric energy. When the internal combustion engine operates, significant fuel energy is lost in both the exhaust and the coolant. Part of this energy is recovered here by using organic Rankine cycle (ORC) systems fitted to both the exhaust and the coolant, with their expanders driving generators charging the battery of the car. The exhaust and the coolant organic Rankine cycle are effective in increasing the amount of fuel energy converted in usable power over the full range of loads and speeds. The organic Rankine cycle system fitted on the exhaust permits to increase the usable power versus the fuel energy flow rate of a 3.4% on average, with top improvements up to 6.4%. The system is effective particularly at high speeds and loads. The organic Rankine cycle system fitted on the coolant permits to increase the usable power versus the fuel energy flow rate of a 1.7% on average, with top improvements up to 2.8%. The system is effective particularly at low speeds and loads. The two combined organic Rankine cycle systems permit to increase the usable power versus the fuel energy flow rate of a 5.1% on average, with top improvements up to 8.2%.

Non-equilibrium Landauer transport model for Hawking radiation from a black hole

We propose that the Hawking radiation energy and entropy flow rates from a black hole can be viewed as a one-dimensional (1D), non-equilibrium Landauer transport process. Support for this viewpoint comes from previous calculations invoking conformal symmetry in the near-horizon region, which give radiation rates that are identical to those of a single 1D quantum channel connected to a thermal reservoir at the Hawking temperature. The Landauer approach shows in a direct way the particle statistics independence of the energy and entropy fluxes of a black hole radiating into vacuum, as well as one near thermal equilibrium with its environment. As an application of the Landauer approach, we show that Hawking radiation gives a net entropy production that is 50% larger than that obtained assuming standard 3D emission into vacuum.

Измерения и анализ локальной церебральной гемодинамики у больных с сосудистыми мальформациями головного мозга

Hemodynamic parameters of the blood flow in human cerebral vessels up to the 4th branch levels were measured. A framework based on "Pressure - Velocity" and "Discharge - Energy flow rate" regimen was designed and implemented. This framework makes it possible to detect brain vascular anomalies like arteriovenous malformations and arterial aneurysms depending on hemodynamic parameters, and to monitor the efficiency of the operation. Modification in the low-frequency spectrum of the cerebral blood flow following the operation was detected by the wavelet analysis of the hemodynamic parameters. The results obtained give qualitative and quantitative characteristics of the presence of cerebral blood vessels anomalies and makes it possible to estimate the efficiency of their embolization at operation.

Temperature Dependence of the Heat Diffusivity of Proteins

In a combined experimental-theoretical study, we investigated the transport of vibrational energy from the surrounding solvent into the interior of a heme protein, the sperm whale myoglobin double mutant L29W-S108L, and its dependence on temperature from 20 to 70 K. The hindered libration of a CO molecule that is not covalently bound to any part of the protein but is trapped in one of its binding pockets (the Xe4 pocket) was used as the local thermometer. Energy was deposited into the solvent by IR excitation. Experimentally, the energy transfer rate increased from (30 ps)(-1) at 20 K to (8 ps)(-1) at 70 K. This temperature trend is opposite to what is expected, assuming that the mechanism of heat transport is similar to that in glasses. In order to elucidate the mechanism and its temperature dependence, nonequilibrium molecular dynamics (MD) simulations were performed, which, however, predicted an essentially temperature-independent rate of vibrational energy flow. We tentatively conclude that the MD potentials overestimate the coupling between the protein and the CO molecule, which appears to be the rate-limiting step in the real system at low temperatures. Assuming that this coupling is anharmonic in nature, the observed temperature trend can readily be explained.

Poiseuille flow of moderately rarefied gases in annular channels

In this study, rarefaction effects in pressure-driven gas flows in annular micro-channels are investigated. The influence of gas rarefaction, aspect ratio of the annulus, and surface accommodation coefficient on wall friction, mass flow rate, and thermal energy flow rate is studied. For this, the linearized Navier–Stokes–Fourier (NSF) and regularized 13-moment (R13) equations are solved analytically. The results are compared to available solutions of the Boltzmann equation to highlight the advantages of the R13 over the NSF equations in describing rarefaction effects in the process. Moreover, a second-order slip boundary condition is proposed to improve the accuracy of the classical NSF equations.