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This study investigates spray characteristics, flashing and non-flashing, of unsaturated neem biodiesel (BD), biodiesel-ethanol (BDE50) blend, and diesel for application in advanced combustion engines. Fuel properties, injection pressure, nozzle geometry, and the surrounding ambient gas conditions govern the spray breakup and air-fuel mixing. The spray characteristics of fuel is studied at various injection pressure and ambient gas densities using the high-speed shadowgraphy technique. BDE50 shows improved spray dispersion with distinct tree-shaped spray morphology at ambient density of 1.14 kg/m3 and injection pressure of 50 MPa. Theoretical analysis confirms occurrence of cavitation due to high volatile component (ethanol) in biofuel mixture and throttling conditions. At high ambient gas density and injection pressure, diesel and BDE50 exhibit high spray cone angle. Neem biodiesel maintains high tip penetration and low cone angle due to poor atomization. The study recommends use of BDE50 blend for achieving improved mixture formation in engines.

The rotating flash flow has rarely been studied, although its characteristics affect significantly the performance of the two-phase flow turbine. In this paper, through analyzing the flashing flow obtained by CFD methods, which is validated with the experimental data, the relationships of average flow parameters under various rotational speeds were studied theoretically and numerically using the flow equations established on the Frenet coordinate system. The ratio of the mass flow rate under various rotational speeds was formalized and found to be dependent on the rotational speed and thermophysical properties. The generation and development of vapour were revealed and correlated to the geometry of the channel. The secondary flow in the flashing rotating channel was discussed and found to rotate in opposite directions upstream/downstream of the throat. The flashing induced near the throat had the effect on flow homogenizing in the normal direction of the cross-section. The analysis could be further applied to the analogy of the secondary flow between the rotating single-phase flow and the rotating flashing flow.

In this chapter, we are going to explain how to numerically model the geothermal flash cycles including single- and double-flash cycles based on thermodynamic equations and using actual wellhead data. Furthermore, the exergy costing method is explained to calculate the energy production cost as well as the total cost of the power plant. In this chapter, the readers will learn how to model and evaluate the performance of the cycles in terms of thermodynamics and economics using EES (Engineering Equation Solver) software. This model optimizes the cycles for the highest net power as objective functions obtaining the best-operating conditions such as flash pressure, turbine back pressure, etc. Furthermore, the distribution of exergy destruction, which is known as the Grassman graph, is presented graphically for the cycles to observe how the secondary flashing process affects the systems’ exergy destruction.

Geothermal-based flash steam power plants are promising systems for clean power generation. A comprehensive thermodynamic analysis through energy and exergy approaches is presented here to investigate the optimum flashing pressures for multistep plants, including single-, double-, triple-, and quadruple-flash systems with reinjection. A new methodology is presented to investigate the optimum pressure levels for the flashing process, which can be considered as a suitable range of operation in power-generating geothermal plants. The present methodology is combined with a family of curves representing power output vs flashing pressure to determine the maximum available power for the system. The performances of the proposed systems are evaluated from both energy and exergy perspectives. It is shown that an energy efficiency analysis alone is insufficient to differentiate between the systems. The results of the exergy approach indicate a significant improvement in terms of efficiency as the quantity of flashing steps has risen. The potential performance enhancement in terms of power output becomes smaller as the quantity of flashing steps becomes four or more.

In this chapter, information about the binary cycle in geothermal power plants (GPPs) is given. Binary GPPs are thermodynamically closest to a fossil-sourced thermal power plant or nuclear power plant. In the binary GPP, the geothermal fluid works on the principle of transferring its energy to a second fluid (n-pentane, isopentane, isobutane) with a low boiling point temperature without flashing. The geothermal fluid, whose temperature is reduced by heat transfer, is sent underground by reinjection. The cycle of the second fluid takes place as an ORC. The second fluid that takes its heat from the geothermal fluid evaporates. It is passed through the turbine and then sent to the condenser. The second fluid is condensed in the condenser and the cycle is continued with the pump. As a result, it is important to determine and explain the amount, location, and causes of equipment’s energy losses in such complex plants.

As the periodic emission of light pulses by light emitting diodes (LEDs) is known to stimulate growth or induce high value biocompounds in microalgae, this flashing light regime was tested on growth and biochemical composition of the microalgae Nannochloropsis gaditana, Koliella antarctica and Tetraselmis chui. At low flashing light frequencies (e.g., 5 and 50 Hz, Duty cycle = 0.05), a strain-dependent growth inhibition and an accumulation of protein, polyunsaturated fatty acids, chlorophyll or carotenoids (lutein, β-carotene, violaxanthin and neoxanthin) was observed. In addition, a 4-day application of low-frequency flashing light to concentrated cultures increased productivities of eicosapentaenoic acid (EPA) and specific carotenoids up to three-fold compared to continuous or high frequency flashing light (500 Hz, Duty cycle = 0.05). Therefore, applying low-frequency flashing light as finishing step in industrial production can increase protein, polyunsaturated fatty acids or pigment contents in biomass, leading to high-value algal products.

The physics of the atomisation of flash boiling jets is known to be extremely complex with interactions of different mechanisms at microscopic and macroscopic level. Early studies describe both the mechanical and thermodynamic effects focusing on the influence of the initial pressure and temperature on the spray characteristics. The resulting flashing jet usually emerges to the low-pressure region with a high velocity and fragments to large blobs and ligaments which break up to droplets due to both mechanical and thermodynamic effects. This present study describes a numerical approach for simulating the atomisation of flashing liquids suitable for both primary atomisation and secondary break-up using the Eulerian-Lagrangian-Spray-Atomisation model coupled with a pressure equation for the metastable jet. The proposed approach aims at describing the atomisation of superheated jets and the impact of bubble nucleation at different stages and regimes inside the channel the liquid emerges from. The changes in the regime outside the nozzle are discussed for various cases of flashing liquids providing insights for the interactions of the mechanisms that contribute to the liquid fragmentation and the spray characteristics such as the droplet size and velocity and the spray angle.

In this paper we present a set of experimental data acquired on a CO2 flashing ejector designed for expansion loss recovery applications. Experimental results are compared with CFD simulations obtained using a Homogeneous Equilibrium Model (HEM) and a recently developed mixture model that treats both the liquid and vapour phases as compressible and metastable materials. The models are implemented within a commercial CFD software via user defined subroutines. Pro and cons of each of the two approaches are critically discussed in order to understand the relative performances in terms of numerical stability and accuracy. From this comparison, it can be shown that while the HEM is faster and intrinsically stable, the mixture model has the potential to better reproduce the experimental data, especially in terms of mass-flow rates predictions.

Nowadays, desalination of salt water is considered as an important industrial process. In many regions of the world, the multi-stage flash (MSF) water desalination technique has an essential contribution in the production of freshwater. In this study, a (MSF) model is used to design a MSF desalination system and, the feasibility of using the MSF desalination process in proximity of a 650 MW power plant is investigated. This power plant can provide 385.03 kg/s superheated steam from low pressure (LP) section of heat recovery steam generator (HRSG) for thermal desalting system. Three modules were tested with different numbers of heat rejection sections. The optimum design was 25 stages in the heat recovery section and 3 stages in heat rejection section. The designed MSF system with gained output ratio (GOR) of 8.76 has 28 flashing stages and can produce 2229 kg/s of freshwater. The expected performance characteristics of the designed MSF desalination plant are determined.

Evaporation is an essential process in alumina refineries both to produce water for such applications as residue washing processes, and reconcentrating process liquor back to the main process circuit for further digestion. This chapter introduces the application of two novel low grade heat-driven reconcentration processes. The first one consists of both flashing and falling film techniques, and is meant to couple to one of the available waste streams in the evaporation unit as a heat source thereby reconcentrating the process liquor. The heat source has been identified as the process condensate stream. The condenser of the reconcentration process is cooled by barometric water from the recovery lake. The generated freshwater is either discharged or sent to the freshwater lake so as to manage the water balance of a refinery. For 200 m 3 /hr process condensate simulated at two fixed temperatures of 75°C and 85°C, the novel process generates up to 36% more reconcentrated process liquor with the same specific capital cost compared to the conventional multi-effect falling film evaporation system. This technology is also applicable to other mineral refineries in general that involve reconcentrating liquor and water balance management. The second one is a novel flash-boosted evaporation process that utilizes the available waste heat sources of the evaporation units to reduce live steam consumption for evaporation purpose in alumina refineries. The results reveal a significant reduction in the live steam consumption of the evaporation plant in one of the major alumina refineries in Western Australia. This system can be attached to the main evaporation process without any process interruption. In this case, the available waste stream is utilized to recover the duty of one of the selected evaporation units, and it shows that the selected unit can be completely turned off, resulting in 82% of its relevant live steam consumption being saved. A detailed capital cost analysis and pumping power consumption evaluation is presented as well. Both technologies are also applicable to other mineral refineries in general that involve reconcentrating liquor and water balance management.

This paper introduces a new optimization model for the single and multiple-effect evaporation (SEE/MEE) systems design, including vapor recompression cycle and thermal integration. The SEE/MEE model is specially developed for shale gas flowback water desalination. A superstructure is proposed to solve the problem, comprising several evaporation effects coupled with intermediate flashing tanks that are used to enhance thermal integration by recovering condensate vapor. Multistage equipment with intercooling is used to compress the vapor formed by flashing and evaporation. The compression cycle is driven by electricity to operate on the vapor originating from the SEE/MEE system, providing all the energy needed in the process. The mathematical model is formulated as a nonlinear programming (NLP) problem optimized under GAMS software by minimizing the total annualized cost. The SEE/MEE system application for zero liquid discharge (ZLD) is investigated by allowing brine salinity discharge near to salt saturation conditions. Additionally, sensitivity analysis is carried out to evaluate the optimal process configuration and performance under distinct feed water salinity conditions. The results highlight the potential of the proposed model to cost-effectively optimize SEE/MEE systems by producing fresh water and reducing brine discharges and associated environmental impacts. This project has received funding from the European Union's Horizon 2020 Research and Innovation Programme under grant agreement No. 640979. The financial support provided by the National Council for Scientific and Technological Development of Brazil (CNPq), under process No. 233953/2014-0 is also gratefully acknowledged.

This chapter includes a detailed explanation about mathematical simulation methods of all the relevant multi-effect distillation (MED) processes—the conventional MED, preheated MED, boosted MED, and flash-boosted MED. Mass and energy balances for each section of these configurations (such as the evaporators, condensers, flashing chambers, heat exchangers, deaerators, etc.) have been clearly delineated. The general temperature–energy plots have been introduced for the evaporators, condensers, and heat exchangers, and the UA-value equations, being the most important factor in heat transfer devices, have been prominently described for each section. The solving procedure and validation of the simulation method has been explained in detail. Finally, all the assumptions and boundary conditions, including the solving flowchart and relevant results, have been described.

The geothermal reservoir and its producing well form a serially connected synergetic flow system. There is a radially-inward Darcy flow toward the well in the reservoir, and a turbulent upflow through the tubing. The pressure losses of the two flows are added. The pressure energy of the undisturbed reservoir actuates this motion, providing the required energy against the pressure losses and for lifting the fluid to the surface. The so-called thermal lift together with the lifting force of the dissolved gases maintains the operation of the free flowing well. Two-phase flow develops in the upper section of the well. Several forms of vertical two-phase flows are studied. Ros’ method is applied to determine the two-phase pressure losses. Flashing produces similar lifting effects if the temperature of the produced hot water is sufficiently high.

Multistage Flash (MSF) desalination is a highly complex process; however, its non-linearity is represented in some operation conditions such as limitation on the top brine temperature (TBT) at the brine-heater outlet. Furthermore, the need for continuous monitoring of liquid levels in the flashing chambers is necessary to avoid loss of efficiency due to blow-through or loss of boiling due to flooding in the flash chambers. This study focuses on an advanced control system such as hybrid Fuzzy Logic controller (FLC) and Generic Model Controller (GMC) which is used successfully to control MSF desalination plant over four distinct seasons (winter to summer). Two single loops of controller are working simultaneously in gPROMS to control the TBT and the brine level (BL) of the last stage. The MSF plant control system is operated at optimal conditions based on the seawater intake temperature. In this study, the set-point tracking performance has been investigated whereby, the controller will track the optimum set points variation for TBT and BL. The controller performance of disturbance rejection has been studied by changing the recycle flow rate suddenly by + 10%. The capability and efficiency of the propose controller has been compared with the conventional PID controller and Generic Model Controller. As result reveals, the proposed Hybrid Fuzzy-GMC is highly recommended to be implemented in MSF plant.

Arapucandere is one of a number of similar Cu–Zn–Pb ± Au–Ag epithermal deposits in the Biga Peninsula, which are mineralogically and tectonically similar. Fluid inclusions have very low salinities between 1.7 and 0 wt.% NaCl and a wide range of temperatures from ~ 360 to 160 °C. There was extensive boiling and “flashing” of the hydrothermal fluids which initiated mineral deposition. The range of temperatures is consistent with emplacement of the veins at ~ 700 m depth, with the pressure decreasing from near lithostatic to near hydrostatic and a decrease in temperature to ~ 250 °C due to adiabatic expansion of the fluids. There is evidence of a limited amount of boiling, but the temperature and pressure decrease was close to the liquid–vapour curve. Flashing of the fluids was caused by sudden drops to sub-hydrostatic pressures and even lower temperatures. Mineralization was caused by these pressure related temperature decreases as there is no evidence of cooling and dilution of the ore-fluids. δ 34 S values of sulphides indicate a magmatic source but the more negative than usual values also suggest boiling affected isotopes. δD and δ 18 O of the fluids indicate a mixing between meteoric waters and magmatic fluids, with the large range of δD due to boiling. LA-ICP-MS analyses of fluid inclusions reveal high Cu–Zn–Pb concentrations in the fluids, despite their low salinity, transported as chloride complexes. Exceptional pressure and temperature decrease causing the fluids to “flash” was likely to have been in response to earthquakes.

The ultimate objective of redraw rod rolling is progressively lengthening the rod and reducing the cross-sectional area to a dimension that permits drawing. This is not a simple objective, as rolling from a round to a round in a single pass cannot happen because of side spread. It is necessary to roll a sequence of alternate cross-section shapes, such as round-to-oval-to-round, and so forth. Rolling pass schedules leading to round stock generally employ sequences of ovals and rounds. The alternating geometry ensures that the width of the entering rod section is less than the width of the emerging rod section, which is necessary for roll entry. As a practical matter, actual rod cross sections may be “out of round” and not rigorous ovals. Nevertheless literal oval and round geometry is employed in analysis. Numerous sequences of geometry exist in rod, including diamond/ diamond, diamond/square, round-cornered-square, and square/oval. This chapter outlines a methodology using which all of these symmetrical shape sequences can be analyzed. When spread is not accommodated by pass geometry, metal is squeezed between the rolls, producing “fins” or “flash.” For research and development evaluations, wear may be of little concern, and trial roll passes may even be undertaken on rolls that are not fully hardened. However, roll pass design pertinent to commercial production should anticipate roll wear. It can even be argued that, ideally, roll pass design geometry should reflect a mid-life state of wear.

Demisters are used to remove entrained brine droplets from flashed off vapor within the flashing stages of the multi stage flash desalination process (MSF). This is necessary to prevent accumulation of brine droplets on the outside surface of the condenser tubes and contamination of the desalinated water. The aim of this work is to design a new demister with lower pressure drop and unaffected separation efficiency which can be later installed in the flashing stages of the MSF plant and causes reduction in the required heat transfer area. In this work the demister performance is predicted as a function of design (wire diameter), and operating parameters (stage temperature). This objective was pursued through the use of commercial computational fluid dynamics (CFD) software. The wire mesh demister was modeled as a tube bank. The model was time dependent and was validated against experimental and field data obtained from large scale MSF units. This manuscript includes model development and computer solution using the FLUENT code. The model predictions for both experimental and large scale units show good agreement of measured pressure drop and separation efficiency against data from existing MSF plants.

The aim of the present work is to get an insight of the phenomena behind the low-pressure low-power transients that occur during startup of a natural circulation boiling system. A RELAP5 model developed for a test facility and its prototype is used to record additional system parameters that were not included in the data obtained from experiments. The flow oscillations observed during experimental and numerical studies are analyzed and classified. It is inferred that the low amplitude oscillations are not condensation induced geysering instabilities, but a density wave instability supported by flashing. The similarity between the nature of startup transients observed in the test facility and the prototype is also examined. The effect of flashing is more pronounced in the prototype due to the strong variation of saturation temperature as the length scale is 4 times that of the model. The time series data obtained from experimental observations and numerical simulations are analyzed to identify the structural nature of flow oscillations. The power spectral density estimated using fast Fourier transform (FFT) algorithm illustrates the chaotic nature of the signals. The nonlinear time series analysis (TISEAN) package has been used for the estimation of Lyapunov exponent and the Poincaré section. The Poincaré section and the Lyapunov exponent confirm the chaotic nature of the flow oscillations., by S.P. Lakshmanan and Manmohan Pandey

Publisher Summary This chapter defines the control valve sizing formulas, which involve liquid formulas, gas and vapors, and special conditions. Special conditions in this chapter explains that equations are given to correct for flashing, cavitation, high-viscosity fluids, and mixed phase flow, where the simplified equations may lead to inaccurate sizing. These additional expressions, together with the FCI equations, provide satisfactory solutions for most control valve sizing applications. The simplified equation for gases and vapors agrees favorably with experimental data when used for conventional globe valves, but agreement with experimental data is poor when used with high recovery valves. The chapter also explores that a control valve may be thought of as a section of pipe with a variable resistance. Control valves are typically used to match pumps to the pipeline system characteristics.

In this paper, desalination systems integrating thermal and membrane processes are investigated. Specifically, a hybrid desalination plant integrating reverse osmosis (RO) and multi stage flash (MSF) systems is mathematically modeled. The non linear programming problem is developed in order to optimize the configuration and operating conditions in order to satisfy fresh water demands at minimum costs. Both implementations, with one and two reverse osmosis stages are considered at the particular framework RO-MSF adopted. The system is modeled in such a way that the RO unit receives brine feed from the MSF. In addition, partial extractions of flashing brine stream from flash chambers of MSF can be performed in order to feed the RO system. In fact, the flow-patterns and flow-rates of the brine streams of MSF are optimization variables. Heat transfer areas of pre-heaters and the geometric design of stages are design variables to be optimized. The optimization procedure will also decide between one and two RO stages and the number of modules operating in parallel at each stage. Moreover, all the operative conditions will be optimized. Different case studies considering various seawater conditions were successfully solved without convergence difficulties. It can be concluded that the optimal arrangement of hybrid system depends strongly on the seawater conditions (salinity and temperature) and the fresh water demand as well.

Publisher Summary This chapter reviews basic principles involved in stabilization, the various process schemes used to stabilize a liquid hydrocarbon stream, and the equipment used in the stabilization process. In almost all cases the molecules have a higher value as liquid than as a gas. Crude oil streams typically contain a low percentage of intermediate components. Thus, it is not normally economically attractive to consider other alternatives to multistage separation to stabilize the crude. In addition, the requirement to treat the oil at high temperature is more important than stabilizing the liquid and may require the flashing of both intermediate and heavy components to the gas stream. Gas condensate, on the other hand, may contain a relatively high percentage of intermediate components. Thus, some sort of condensate stabilization should be considered for each gas well production facility. The most common method used to remove the light components from hydrocarbon liquids before the liquid enters a stock tank or a pipeline is stage separation. In addition, separation followed by weathering in a stock tank is the simplest method of stabilization, but it is often the most efficient method. A stabilizer can achieve a stable specification product with a higher liquid recovery, but this usually results in higher capital expenditures (CAPEX) and operating expenses (OPEX). The addition of a stabilizer requires additional space, which is normally not a factor for onshore applications but may be a major consideration for an offshore installation.

This chapter provides an overview of the thermodynamic process, energy conversion system, and designing of the single flash steam power plants. The terminology single-flash system indicates that the geofluid has undergone a single flashing process—occurred at a number of places. These are the first power plant installed at a newly-developed liquid-dominated geothermal field accounting about 29% of all geothermal plants. The geothermal wells produce a mixture of steam and liquid, the single flash plant is a simple way to convert the geothermal energy into electricity. The various processes involved in the setup and designing of the power plants such as flashing process, piping layouts, separation process are discussed with the examples. Two-phase pipelines can be designed as elements of a geothermal gathering system but proper account must be taken of the pressure drop because it can be larger than that in single-phase steam lines. The relative size of the cooling systems for flash-steam plants is the same as for a binary plant as they are larger than cooling systems at conventional plants of the same power rating. The performance of the entire plant can be assessed using the second law of thermodynamics by comparing the actual power output to the maximum theoretical power produced from the given geothermal fluid.

This chapter analyzes the characteristics of major associated processes in thermal desalination, which includes: venting, steam Jet Ejectors, demisters, and MSF Weirs. Venting in the thermal desalination is driven by steam ejectors for removal of the non-condensable gases during startup and operation. During maintenance and other shut down procedures, the flashing chambers in MSF or the evaporation effects in MEE are opened to ambient air. Therefore, air removal is one of the main activities in the startup procedure. The startup ejectors have higher capacity and are capable of processing large air volumes over a short period of time. Conventional jet ejector has three main parts: the nozzle, the suction or mixing chamber, and the diffuser. The nozzle and the diffuser have the geometry of converging/diverging venturi. The diameters and lengths of various parts forming the nozzle, the diffuser, and the suction chamber together with the stream flow rate and properties define the ejector capacity and performance. The ejector capacity is defined in terms of the flow rates of the motive fluid and the entrained stream. Their sum gives the mass flow rate of the compressed gases. Further, wire mesh mist eliminator or demisters is a simple porous blanket of metal or plastic wire that retains liquid droplets entrained by the gas phase. Demisters are used in distillation or fractionation, gas scrubbing, evaporative cooling, evaporation and boiling, and trickle filters. Today, the wire mesh mist eliminator is widely used in thermal desalination plants. The main features of wire mesh mist eliminators are low-pressure drop, high separation efficiency, reasonable capital cost, minimum tendency for flooding, high capacity, and small size. The performance of wire mesh eliminators depends on many design variables such as supporting grids, vapor velocity, wire diameter, packing density, pad thickness, and material of construction.

Publisher Summary Compressed gases are more dangerous than chemicals in liquid or solid form because of the potential source of high energy, low boiling-point of some liquid contents resulting in the potential for flashing, ease of diffusion of escaping gas, low flashpoint of some highly flammable liquids, and the absence of visual and/or odor detection of some leaking materials. Compressed gases present a unique hazard from their potential physical and chemical dangers. Unless cylinders are secured, they may topple over, cause injury to operators, or become damaged themselves and cause contents to leak. If the regulator shears off, the cylinder may rocket like a projectile, or torpedo, dangerously around the workplace. Other physical hazards stem from the high pressure of a cylinder's contents, for example, accidental exposure of a compressed gas/air hose or jet to eyes or to an open cut or wound, whereby the gas can enter the tissue or bloodstream, is particularly dangerous.

This chapter analyzes and evaluates the performance of the multistage flash desalination (MSF) system. This is made through a discussion of the process developments of MSF; standard features of the brine circulation MSF process; modeling and analysis of the single stage flashing system, the once through multistage system, and the brine circulation multistage system; and features and performance of novel configurations, which include MSF with brine mixing and MSF with thermal vapor compression. The MSF process is an innovative concept, where vapor formation takes place within the liquid bulk instead of the surface of hot tubes. The chapter also presents a novel system for the multi-stage flash desalination. The system is based on the conventional MSF configuration. It includes two of its basic elements; the brine heater and the heat recovery section. The cooling water stream, typical of the MSF system, is also eliminated. The new system adopts a direct brine recycle stream from the brine stream leaving the last flashing stage. This stream is mixed with the intake seawater stream in an insulated and vented tank. Accordingly, the temperature of the feed stream is adjusted to meet summer and winter operating conditions.

Publisher Summary The liquid mass flow entrained with the gas as an aerosol is often assumed to have the same value as the vapor mass flow obtained from a flash calculation. This can lead to a severe prediction error. This chapter presents an experimental data base to examine the validity of the assumptions in some existing models. In the experiment, water flashing jets from a pilot scale set-up are generated. The jet is a superheated liquid cylinder all along its trajectory .There is almost no fragmentation, no dispersion of the je, except when a small obstacle is put on the trajectory of the jet, which causes violent fragmentation. The temperature decrease between the reservoir and end of jet is quite low (25 to 50 K) because heat transfer area is low. New experimental data demonstrates that different types of jets have to be considered and that some models for rain-out give reasonable predictions. Improvement of these models as well as the extension of their applicability to jets issued from long cylindrical ducts is required.

A tribological analysis of the extraordinarily low coefficient of friction (μ) of diamond/Ag/Si (μ: 0.003) was carried out in an ultra-high vacuum (UHV), in terms of the effect of gas molecules adsorbed on the surfaces. To discuss the sliding mechanism of the thin Ag film, adsorption experiments of 0.1–100 L of N 2 and O 2 and sliding tests were conducted under UHV conditions. In preparing the Ag film on Si (111) substrates, the surface was cleaned by flashing at 1200°C prior to Ag deposition to desorb the adsorbed hydrocarbons and the oxidized layer of Si. After cleaning the Si surface by flashing, the Ag monolayer on the Si functioned as a lubricant, reducing the μ as low as the detection limit. On the other hand, when an Ag monolayer was deposited on an oxidized Si wafer without flashing, sliding tests proved that the coefficient of friction did not decrease below 0.3. The surface cleaning process is a necessary requirement for sliding with very low friction. N 2 was adsorbed on the Ag layer deposited on a cleaned Si surface, and a sliding test was conducted. The coefficient of friction did not increase over a minor level with exposure of 0.1 to 100 L. However, with O 2 adsorption to Ag on cleaned Si (111), a very low μ was still observed. These results suggest that these adsorbed gas molecules do not have a fatal effect on a low friction force sliding, within the limit of the cycles tested. A plausible model for the extraordinarily low friction in the diamond/Ag/Si system is presented to explain the observed results.

This chapter describes a number of incidents involving liquefied flammable gases (LFG) that could have occurred only with these materials (or other flashing flammable liquids). It also discusses recommendations made many years ago that are not always followed. The property of LFG that makes it so hazardous is that it is usually stored and handled under pressure at temperatures above normal boiling points. Any leak thus flashes, much of it turning to vapor and spray. This can spread for hundreds of meters before it reaches a source of ignition. Any flammable liquid under pressure above its normal boiling point will behave like LFG. Liquefied flammable gases are merely the most common example of a flashing liquid. The term liquefied petroleum gas (LPG) is often used to describe those liquefied flammable gases that are derived from petroleum. The term LFG is preferred when the discussion applies to all liquefied flammable gases. It includes materials such as ethylene oxide, vinyl chloride, and methylamines, which behave similarly so far as their flashing and flammable properties are concerned. LFGs stored at atmospheric pressure and low temperature behave differently from those stored under pressure at atmospheric temperature. This chapter highlights certain incidents of major and minor leaks and provides recommendations that have been outlined to prevent them.

Publisher Summary This chapter provides an overview of boiler-feed pumps. For feed temperatures of the order of 230–260°C, it is essential to provide booster feed pumps which receive water at, for example, 4 bar 130°C from the deaerator and increase its pressure to 45–65 bar so as to ensure that when passing through the feed-water heater, it can be raised to 230–260°C without flashing into steam. The feed pump then raises the water pressure from 45–65 bar to 200 bar or more in super-critical steam stations. Booster pumps and feed pumps for feed-water temperatures up to about 150°C are generally of the throughbolt sectional stage type. The pumps for feed water at 150–260°C (or higher) have a barrel enclosing the pump proper to minimize thermal stresses and to ensure uniform water flow and, in consequence, uniform heat flow and expansion about the shaft axis during rapid temperature changes.

This chapter will introduce the first concepts of nonequilibrium with emphasis on nucleation and flashing in nozzles, and subsequent void development. Both number and size of bubbles must be accurately determined for initial calculation of flashing void development downstream of restrictions. Void development upstream of a restriction is negligible if the inlet is subcooled. A new method is presented of accurately determining number of nuclei and their size, and shows this results in accurate calculation of downstream void development. The activation criterion developed for site nucleation, different from that developed for subcooled boiling, is one sided due to the uniform superheat. A priactical method of utilizing the activation criterion is then identified. A defined figure-of-merit for the particular fluid solid combination yields minimum nucleation surface energy per site, and allows characteristic site nucleation frequencies, and number densities of nucleation sites of given sizes to be obtained from data. A bubble transport equation is used to predict the number density and size of bubbles at the throat. Throat superheats are calculated with a standard deviation of 1.9K for throat superheats up to ˜100K and expansion rates between 0.2 bar/s to over 1 Mbars, extending previous correlations by more than three orders of magnitude. Throat void fractions for all data found in the literature are less than 1% confirming earlier assumptions and allowing nozzle critical flow rates to be calculated with an accuracy of ˜3%. Accurate calculation of throat superheats allows for correct calculation of throat pressures up to ˜70 bars below saturation, a critical factor in calculating choked flows. A quasi-one-dimensional, five-equation model, developed on a microcomputer, was used to calculate the behavior of flowing, initially subcooled, flashing liquids. Equations for mixture and vapor mass conservation, mixture momentum conservation, liquid energy conservation, and bubble transport were discretized and linearized semi-implicitly, and solved using a successive iteration Newton method. Closure was obtained through simple constitutive equations for friction and spherical bubble growth, and a new nucleation model for wall nucleation in small nozzles combined with an existing model for bulk nucleation in large geometries. Good qualitative and quantitative agreement with experiment confirms the adequacy of the nucleation models in determining both initial size and number density of nuclei. It is shown that bulk nucleation becomes important as the volume-to-surface ratio of the geometry is increased.

This chapter discusses the design and circuitry in X-ray flashing and application of short bursts of high energy X-ray flashes. In X-ray flashes, the radiation is emitted from tubes in which strong discharges of flashlike duration occur. M. Steenbeck has reported a discharge tube and a method for producing intense X-ray light flashes. The gas-filled X-ray flash tube with mercury anode and striction capillary disclosed by Steenbeck has been further developed by J. Miihlenpfordt with more favorable arrangement of the construction elements. From his first tube, he developed a series of other types on which he made observations which led him finally to complete abandonment of the capillary and to the development of the high-vacuum X-ray flash tubes. X-ray flash arrangements utilizing capacitor discharges can be used in single flash operation and in periodic operation. The application possibilities of X-ray flash tubes, as visualized early by Miihlenpfordt, include structural investigations of rapidly moving dynamically loaded machine elements, particularly wear and fracture occurrences in highly loaded gear drives, deformation and loosening of blades in high-speed turbines (machines), and explosion of windings in electrical machines. Often it is necessary to obtain a long burst of periodic X-ray flashes. Such cases are the observation of optical screened periodically moved subjects. A subject of a paper by Frungel is a method for operating X-ray apparatus and X-ray tubes in the form of electric impulses with the result of higher efficiency in the tube and higher yield in X-radiation.

This chapter discusses the measurement of nonelectrical quantities. The measurement of the degree of acidity or alkalinity of a solution is a matter of some importance to a wide variety of industries. In general, the effective acidity or alkalinity of a solution is not directly dependent upon the total quantity of acid or base present, although sometimes this relation may be important, in which case it can be measured by chemical titration. The effective acidity or alkalinity of a solution does, however, bear a direct relationship to the concentration of hydrogen ions in the solution. Computers are rapidly coming into use for use in measurements, either for the control of electronic measuring apparatus or for analysis of the data obtained in the measurements themselves. An investigation of the exact nature of high-speed movements is often important, and for this purpose, investigation under the illumination from a flashing source of light—so controlled that the repetition rate is very nearly equal to the speed of rotation or the rate at which some particular part of the operation repeats—enables a high-speed phenomenon to be examined as though it were moving quite slowly.

As results of measuring the rate of sublimation or evaporation of simple metal getters (i.e. Ba, Mg, or Al), the values obtained by experiments accord with the values induced by calculation in the high temperature region, but in the lower temperature region the former is very small. This is due to the stable thin film existing on the metal surface that prevents the sublimation of metal. It is possible to remove the film beforehand by mechanical or chemical polishing. Soon after the metal covered with a film boils in a vacuum up to above its melting point, the film splits and then from the splits the fresh metal flashes suddenly. Many intermetallic compounds are used generally as alloy getters, because of their stable character in the atmosphere. The melting point of intermetallic compound (e.g. BaAl4) is higher than that of each component, so flashing temperature will increase over its melting point of alloy. It seems to be at the flashing that the alloy becomes liquid perfectly, and the active metal atoms diffuse out easily to the surface and evaporate immediately. The vapor pressure of metal component in the alloy decreases more than that of simple metal in accordance with the quantity of the other component, and the reasonable value is gained by employing Raoult's equation. Notwithstanding that the addition of the third metal to the alloy decreases the melting point of the alloy, if the vapor pressure of the active metal component is maintained considerably, the new alloy will serve as a flash getter that forms the active deposit having an amorphous construction. Because its flashing temperature is a little lower, the deposit metal has a little kinetic energy, and the wall is not heated by the radiation from the getter source.

This chapter focuses on the multi-input panel light flasher. The multi-input panel light flasher flashes a fairly high-intensity master panel light on and off when one or more of the low-intensity fault lamps is illuminated, and at the same time emits a series of audible clicks. Thus, when a fault occurs the driver's attention is immediately attracted by the flashing and clicking of the master lamp circuit, and he can then look at the bank of fault lamps to locate the precise cause of the trouble, that is, overheat, ice warning, and low fuel. The full circuit of the negative ground version of the multi-input panel light flasher is shown diagrammativally in the chapter. Circuit operation is quite simple. As the input voltages of the unit are obtained from the warning lamps of other units, and these lamps are either full on or full off, the unit's input voltages are at either 0 V or 12V positive.