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Micro bubble formation and bubble dissolution in domestic wet central heating systems  [cached]
Fsadni Andrew M.,Ge Yunting
EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20122501016
Abstract: 16 % of the carbon dioxide emissions in the UK are known to originate from wet domestic central heating systems. Contemporary systems make use of very efficient boilers known as condensing boilers that could result in efficiencies in the 90-100% range. However, research and development into the phenomenon of micro bubbles in such systems has been practically non-existent. In fact, such systems normally incorporate a passive deaerator that is installed as a ‘default’ feature with no real knowledge as to the micro bubble characteristics and their effect on such systems. High saturation ratios are known to occur due to the widespread use of untreated tap water in such systems and due to the inevitable leakage of air into the closed loop circulation system during the daily thermal cycling. The high temperatures at the boiler wall result in super saturation conditions which consequently lead to micro bubble nucleation and detachment, leading to bubbly two phase flow. Experiments have been done on a test rig incorporating a typical 19 kW domestic gas fired boiler to determine the expected saturation ratios and bubble production and dissolution rates in such systems.
Effects of outlet positions and plant species on rural domestic sewage purification in engineered vertical flow wetland

LIU Fen-Fen,WANG De-Jian,

中国生态农业学报 , 2011,
Abstract: In this study,four different types of engineered vertical flow constructed wetland(VF-CW)-Canna indica Linn wet-land(M),Pennisetum alopecuroides(Linn.) Spreng wetland(L),Sorghum sudanense(Piper) Stapf wetland(S) and control wetland without plant(CK)-were used to determine the effects of outlet positions(high,middle and low position) and plant species on pollutant removal efficiency in rural domestic sewages.Domestic sewages from anaerobic tanks in the Changshu Agro-ecological Experimental Station were inter...
Hydraulic Domestic Heating by Throttling  [PDF]
Mohammad A. K. Alia, Tariq Younes, Hussein Sarhan
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.26060
Abstract: In this work an experimental investigation was carried out in order to explore the possibility of realizing a domestic heating system by throttling hydraulic oil. Considering the continuous increasing price of diesel oil, this work gains unique importance. Generating heat directly by throttling is realized using a simple environment friendly system which does not require oil transportation and storage, and eliminates the need for chimneys and annual preventive maintenance, as it is the case with heating by utilizing oil burners, which is prevailing in Jordan. Experimental results show that it is possible to raise the room temperature up to 70?C during 15 minutes which is not a limit value. Experimental results show that temperature rate could be increased by selecting the appropriate pump power and by connecting a number of throttles in parallel.
Magnetohydrodynamic (MHD) Free Convective Flow past an Infinite Vertical Porous Plate with Joule Heating  [PDF]
Sigey K. Johana, Okelo A. Jeconia, Gatheri K. Francis, Ngesa O. Joel
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.45113

This work addresses the problem of Magnetohydrodynamic laminar unsteady flow of an incompressible electrically conducting fluid past an infinite vertical porous plate. It investigates how joule heating affects the velocity and temperature profiles of the fluid flow subjected to transverse magnetic field. The research examines specific equations of MHD flow which are solved numerically by finite difference approximations, using computer programme. The numerical results of this study reveal that an increase in joules heating parameter causes an increase in the velocity and temperature profiles uniformly near the plate but remain constantly distributed away from the plate, implying that the flow field of the MHD free convective flow is influenced substantially by the strength of Joules heating near the wall of the plate and at the mainstream.

Physical Modeling And Simulation Of Thermal Heating In Vertical Integrated Circuits  [PDF]
Abderrazzak El Boukili
Physics , 2013,
Abstract: Interconnect is one of the main performance determinant of modern integrated circuits (ICs). The new technology of vertical ICs places circuit blocks in the vertical dimension in addition to the conventional horizontal plane. Compared to the planar ICs, vertical ICs have shorter latencies as well as lower power consumption due to shorter wires. This also increases speed, improves performances and adds to ICs density. The benefits of vertical ICs increase as we stack more dies, due to successive reductions in wire lengths. However, as we stack more dies, the lattice self-heating becomes a challenging and critical issue due to the difficulty in cooling down the layers away from the heat sink. In this paper, we provide a quantitative electro-thermal analysis of the temperature rise due to stacking. Mathematical models based on steady state non-isothermal drift-diffusion transport equations coupled to heat flow equation are used. These physically based models and the different heat sources in semiconductor devices will be presented and discussed. Three dimensional numerical results did show that, compared to the planar ICs, the vertical ICs with 2-die technology increase the maximum temperature by 17 Kelvin in the die away from the heat sink. These numerical results will also be presented and analyzed for a typical 2-die structure of complementary metal oxide semiconductor (CMOS) transistors.
Simulation of kinematics and the separation of polydisperse drip flow in the vertical cyclones having a side inlet wet steam or air
Lagereva E.A.
Nauchno-tekhnicheskiy vestnik Bryanskogo gosudarstvennogo universiteta , 2016, DOI: 10.22281/2413-9920-2016-02-04-99-109
Abstract: The presented method of calculation of the separation of polydisperse condensed moisture from a flow of wet steam or air in a vertical cyclone with tangential inlet side of the flow of the working fluid, and histograms of the size distribution is not deposited drops and diagrams of the distribution on the inner wall surface of the cyclone mass flow of the precipitated liquid. It includes gas-dynamic model of the motion of the gas and liquid phases of the working fluid inside the cyclone and the approach implements the idea of spatial and fractional discretization of the separation process. On the basis of calculations of the kinematics of condensed moisture specific cyclones have shown the feasibility of improving the accepted system of dehumidification that is associated with the implementation of intermediate wicking devices, their rational placement on the surface of the shell and setting the optimum constructive sizes.
Effects of Thermal Radiation and Radiation Absorption on Flow Past an Impulsively Started Infinite Vertical Plate with Newtonian Heating and Chemical Reaction  [PDF]
Swetha Ravi, Jagdish Prakash, Viswanatha Reddy Gottam, Vijaya Kumar Varma Sibyala
Open Journal of Fluid Dynamics (OJFD) , 2015, DOI: 10.4236/ojfd.2015.54036
Abstract: A perfect solution to the present natural convective flow problem of a vertical transfinite plate owing to the impulsive motion in the ubiety of first ordered chemical reaction, radiation absorption, radiation, Newtonian heating and species concentration in its plane is evolved by applying the method of Laplace transforms in closed form at the plate. Exact results for velocity, temperature, concentration fields are prevailed and expressions for heat and mass transfer rates are also found. The effects are analyzed for the respective invariables for both ammonia and water vapor.
Mechanisms of the Vertical Secular Heating of a Stellar Disk  [PDF]
N. Ya. Sotnikova,S. A. Rodionov
Physics , 2003, DOI: 10.1134/1.1573281
Abstract: We investigate the nonlinear growth stages of bending instability in stellar disks with exponential radial density profiles.We found that the unstable modes are global (the wavelengths are larger than the disk scale lengths) and that the instability saturation level is much higher than that following from a linear criterion. The instability saturation time scales are of the order of one billion years or more. For this reason, the bending instability can play an important role in the secular heating of a stellar disk in the $z$ direction. In an extensive series of numerical $N$-body simulations with a high spatial resolution, we were able to scan in detail the space of key parameters (the initial disk thickness $z_0$, the Toomre parameter $Q$, and the ratio of dark halo mass to disk mass $M_{\rm h} / M_{\rm d}$). We revealed three distinct mechanisms of disk heating in the $z$ direction: bending instability of the entire disk, bending instability of the bar, and heating on vertical inhomogeneities in the distribution of stellar matter.
The effect of bars and transient spirals on the vertical heating in disk galaxies  [PDF]
Kanak Saha,Yao Huan Tseng,Ronald E. Taam
Physics , 2010, DOI: 10.1088/0004-637X/721/2/1878
Abstract: The nature of vertical heating of disk stars in the inner as well as the outer region of disk galaxies is studied. The galactic bar (which is the strongest non-axisymmetric pattern in the disk) is shown to be a potential source of vertical heating of the disk stars in the inner region. Using a nearly self-consistent high-resolution N-body simulation of disk galaxies, the growth rate of the bar potential is found to be positively correlated with the vertical heating exponent in the inner region of galaxies. We also characterize the vertical heating in the outer region where the disk dynamics is often dominated by the presence of transient spiral waves and mild bending waves. Our simulation results suggest that the non-axisymmetric structures are capable of producing the anisotropic heating of the disk stars.
International Journal of Engineering Science and Technology , 2012,
Abstract: The unsteady free convective flow past a vertical porous plate with Newtonian heating has been studied. The governing equations have been solved numerically by Crank-Nicolson implicit finite-difference scheme. The variations of velocity and fluid temperature are presented graphically. It is found that the fluid velocity decreases with an increase in Prandtl number. Both the fluid velocity and the fluid temperature increase with an increase in suction parameter. An increase in Grashof number leads to rise in the fluid velocity. Further, it is observed that the shear stress and the rate of heat transfer at the plate increase with an increase in either Prandtlnumber or suction parameter or time.
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