Hot Water Jet Research Articles

Apparatus for Use in Evaluating Protection from Low Pressure Hot Water Jets

Abstract Use of hot water has become extensive, especially in bitumen extraction from oil sands and in the production of heavy oil. The hot water is often under pressure and is 80–90°C, which is well above temperatures that result in immediate, potentially severe burn injuries. The ASTM F2701-08 apparatus consists of a funnel through which hot liquid is hand-poured to produce a 10 s exposure. Two 40 mm diameter copper calorimeters, mounted in an insulating sheet are positioned beneath the funnel outlet and are intended to measure the energy transfer through the fabric from the hot liquid. For this research, changes were made to the apparatus and procedures to more closely simulate low pressure hot water streams found in the oil industry and to improve reproducibility. The funnel producing the liquid splash was replaced with a small pipe directly fed by a circulating hot water bath via a small pump, through a hose and valve system, allowing for consistent application of a given quantity of water at a consistent temperature and flow rate. Water temperature, flow rate, and pressure can be altered as desired. A series of fabrics varying systematically on several parameters were tested with the modified equipment. Resulting heat transfer data suggest the system differentiates well among both semi-permeable and impermeable fabrics. Specifications for hot water protection are proposed.

Penetration length studies of supercritical water jets submerged in a subcritical water environment using a novel optical Schlieren method

In hydrothermal spallation deep drilling a high-velocity, hot, supercritical water jet is directed towards the rock to induce fragmentation. One major challenge in the realization of this novel technique is the entrainment of comparatively cool, aqueous drilling fluid by the hot water jet, which can lead to significant heat losses before the hot jet's energy can be transferred to the rock. The present work quantifies such entrainment effects by determining penetration lengths of supercritical water jets injected into a cool, subcritical environment using a novel optical Schlieren method. Penetration lengths of supercritical jets were found to be equal to the injector's nozzle diameter and almost independent of the jet's temperature at the nozzle exit and the jet's mass flow under almost all experimental conditions investigated. A semi-empirical model adapted from steam jet studies confirmed these findings and indicates that heat and mass transfer are primarily controlled by turbulent mixing.

Vertical buoyancy preserving and non-preserving fountains, in a homogeneous calm ambient

Experiments were conducted on the maximum and terminal penetration depths of fountains of light fluid, issuing vertically downwards into quiescent denser fluid. Fresh water jets into saltwater, and hot water jets into fresh cold water were investigated. The source Richardson numbers extended from 0.01 (jets) to 1 (plumes). Circular and three other different shape nozzles have been employed. The normalized penetration depth is constant for jets, while it decays exponentially in plumes. Numerical evaluation of the penetration depth has indicated the need for reevaluation of the entrainment coefficient, in negatively buoyant jets.

Bubble departure in the direct-contact boiling field with a continuous liquid–liquid interface

Behavior of vapor bubbles was experimentally investigated in the boiling field where a volatile liquid layer of per-fluorocarbon PF5050 (boiling point 306 K) was directly in contact with an immiscible hot liquid layer of water above it. Heat was supplied to the continuous liquid–liquid interface by the impingement of the downward hot water jet. Vapor bubbles were generated not only from this continuous interface but from a large number of PF5050 droplets floating on it. According to precise observation, incipience of boiling did not occur at the liquid–liquid interface but in the PF5050 liquid close to the interface in both cases of continuous and dispersed interfaces. As a result, the bubbles broke up the thin PF5050 liquid film above them and rose up into the water layer. This bubble departure phenomenon, which does not occur in the ordinary pool boiling field on the solid heating wall, is very important to evaluate the heat transfer performance in the present direct-contact boiling system. For modeling this behavior, sizes of the bubbles were measured at the moment just after they were released into the water pool. Volumes of the bubbles were larger in the case of departing from the continuous liquid–liquid interface than from the droplets. This tendency could be explained by taking into account the buoyancy force acting on unit area of the thin PF5050 liquid film above the bubble before departure, which was one of the most important parameters for the liquid film breakdown.

Direct-Contact Evaporation Rate on Individual Bubbles in the Heat Transfer Field with a Continuous Liquid-Liquid Interface

Heat transfer characteristics were experimentally examined in the field where a volatile liquid pool of per-fluorocarbon PF5050 (boiling point 306 K) was directly in contact with an immiscible hot water pool. Heat was supplied to a horizontal continuous liquid-liquid (LL) interface by downward hot water jet flow. Bubble incipience occurred with a thin PF5050 liquid film atop growing bubbles. Characteristics of bubble departure from the droplets were discussed based on comparison with Mersmann's formula. On heat transfer, curvature of the liquid-liquid interface controlling the bubble departure sizes had a predominant effect in both droplet and LL cases. Heat transfer characteristics could be explained based on this result, by using Weber number and buoyancy-interfacial tension ratio.

941 コバルト基合金のエロージョン特性

The cobalt alloys "Stellite No6,No21 and Alloy No.25" have excellent properties to resist corrosion and erosion. On this account these alloys are applied to the valves and many other machinery parts. However, these alloys show unexpected erosion damages under a certain kind of fluid conditions. This study is carried out to clarify the cobalt alloys erosion properties by the room and hot water jet impact tests. Test results suggest that the good erosion properties of cobalt alloys may be attributed to the features of the ε phase transformations. On the contrary, these alloys show greater erosion damages comparing with other alloys under the slight or no ε phase transformed fluid conditions.

Possibilities for the rehabilitation of settlements affected by large scale radioactive contamination

With the support of the IAEA, a decontaminatio n exercise was conducted in the highly contaminated area of Masany, Belarus. The aim of the work was to determine the effectiveness of decontamination methods. On the roof two different methods were used: a special roof-cleaning trolley, that can safely decontaminate asbestos type roofs, and a high pressure hot water jet, using either clean water or water with a detergent added. The decontamination factors, DF's were of the order of 0,2-0,3 for both methods. The walls were decontaminated by high-pressure hot water jet, planing of wooden walls, and industrial vacuum cleaning resulting in DF's 0,1-0,5. The upper layer of the surrounding soil areas was removed to a depth of about 10-cm, giving dose rate reduction factors, DRF's of 0,1-0,3. Inside the house, vacuum cleaning was performed with very little effect. In the kitchen garden three different methods were used: removal of the upper 10-cm soil layer QORF of 0,25), triple digging 0ORF of 0,3), and normal digging (DRF of 0,5). In conclusion, it was demonstrated that it is still possible, more than a decade after the Chernobyl accident, to substantially reduce the external dose rate in and outside a dwelling by forced clean up.

Hot Water Jet Erosion Characteristics of Ti-Ni Shape Memory Alloys

The Co-free materials with high erosion resistance are anticipated for parts of equipment in nuclear power plants. The erosion resistance of Ti–Ni shape memory alloys (SMAs) against the impact of hot water jet onto the specimen surface was investigated experimentally and by finite element method (FEM). The results are compared with that of an existing Co-based alloy (Stellite). Both of the erosion damaged cross-sectional area and the maximum damaged depth increased linearly with the elongated exposure time. The damaged areas of SMAs were extremely small compared to those of Stellite. However, no significant difference in the maximum damaged depth was found between the two materials. From the FEM results, larger values of the maximum shear stress and the mean stress were found to distribute in the specimens in testing. It is estimated that the essential erosion damage mechanism of Ti–Ni SMAs is cavitation. In Stellite a combination of the shear stress and the cavitation controls erosion. The erosion resistance of the Ti–Ni SMAs is superior to that of Stellite. It is suggested that the Ti–Ni SMAs will be one of the promising alternative materials for Stellite.

Chromatic parameters as performance indicators for stone cleaning techniques

To determine the degree of soiling of urban buildings subject to environmental pollution and, at a later stage, to assess the effectiveness of cleaning techniques on the types of stone used in the construction of these buildings, it is very useful to define the chromatic parameters (L*,a*, b*,C*,WI, and YI) before and after treatment. A comparative study of these parameters and the original color of the stone is carried out. The best cleaning performance is achieved using a hot water jet at a temperature of 90°C and a pressure of 120 bars. In areas with significant black encrusted gypsum and calcite layers, these cannot be removed completely with water. Thus, chemicals must be applied, the most appropriate being sodium hydroxide-based products. Using these cleaning techniques, it is possible to obtain chromatic parameters that come close to those of the stone in its original state, allowing for an increase in yellow hues resulting from the preservation of the patina inherent to the natural aging process that stone surfaces undergo. © 2000 John Wiley & Sons, Inc. Col Res Appl, 25, 442–446, 2000

A hot-water ice-coring drill

AbstractA new method of ice-core drilling uses an annulus of hot-water jets to melt out a cylindrical ice core. This lightweight device used in combination with a fast hot-water drill can quickly obtain ice cores from any depth.

Digital interferometry of phase objects

A novel interferometric technique for the measurement of a phase object is presented. It compares favourably with other optical measurement procedures such as holographic interferometry, speckle photography and ESPI. Although the method is based on the same equations as those used in the latter and on a somewhat similar experimental set-up, it does not use the speckle effect as an information carrier. As a result, although our system shares with ESPI the advantage of rapid digital fringe visualization, larger angles of refraction are admissible. The method is demonstrated by measuring the temperature field produced by an axisymmetrical hot water jet discharged from below into a tank containing colder water. An uncertainty analysis shows that the method is reasonably accurate for this application.

Hyperthermic seizures: an animal model for hot-water epilepsy

Freely ambulant wistar adult rats of both sexes when exposed to a hot water jet on the head (50 degrees C - 55 degrees C) for a period of 8-10 minutes, manifested seizure activity similar to the ones noted in 'hot-water epilepsy' (HWE) in humans. Depth electrode recording from the hippocampus revealed seizure discharges during the ictus lasting from 34 seconds to three minutes, followed by low voltage indeterminate activity and a quiescent resting phase. Seizure initiation was noted to be critically dependent on the rectal temperature of 41.5 degrees C and regional hippocampal temperature of 37 degrees C. There appeared to be no clear evidence for kindling phenomenon. Intervention of hyperthermia by cooling the body after the ictus prevented subsequent occurrence of spontaneous seizures. Pathological study of the brain revealed ischaemic changes in specific topographic areas like Sommer's sector in hippocampus, layer 4 and 5 neurons of the cerebral cortex and reticular neurons in the brain stem- a pathological feature reminiscent of the human epileptic brain. Seizure initiation by hyperthermic stimulation with hot water poured over the head, the progression and the EEG recording the seizure activity in these rats appears to resemble the HWE in human subjects and could thus serve as the first animal model for this form of "reflex' epilepsy. This has given new insight into the understanding of human HWE. Our preliminary observations in humans has suggested that HWE is a type of hyperthermic seizure similar to febrile convulsion but differs from it with respect to stimulus and rate of rise in temperature in a susceptible individual.

Measurement of an axisymmetric temperature field by speckle photography methods

Two alternative procedures to measure the temperature distribution in an axisymmetric hot water jet using the principle of speckle photography are reported. The two methods differ in the position of the speckle generator with respect to the jet and light source. They produce comparable results, but the uncertainties associated with them are different owing to dissimilar fringe visibilities.

Reconstruction of an axisymmetric refractive index distribution with non-negligible refraction

Various algorithms for the exact reconstruction of an axisymmetric refractive index field are available. The first part of this paper demonstrates that these algorithms are equivalent to one another and shows that they reduce to conventional straight-line Abel inversion when refraction is negligible. In the second part, the application of one of these reconstruction methods is illustrated with an analytical refractive index distribution and with experimental holographic interferometry data involving a thin laminar hot water jet.

Experimental investigation into a turbulent jet with negative buoyancy

An experimental investigation of a steady-state negatively buoyant jet has been performed using a hot water jet projected vertically downwards from a 7.5 mm radius inlet pipe into a cold ambient. The Richardson number was 0.1 based on inlet pipe radius and the Reynolds number was 5000. Mean and fluctuating velocities and temperatures, triple velocity correlations and velocity–temperature correlations were measured for the jet in a constant temperature ambient. Correlations between orthogonal velocity components were also measured. Velocity measurements were performed using laser Doppler anemometry (LDA), and errors associated with beam movement (due to refractive index fluctuations) were experimentally quantified. Temperatures were measured with fast response thermocouples. The two techniques were used in conjunction to provide velocity–temperature correlations. The intermittency factors around the edge of the flow were measured optically, employing refractive index as a tracer. The normal stresses were found to be high in the shear region at the jet-flow/reverse-flow interface and in the region of large-scale fluid reversal. The contribution from the intermittency at the boundary of the flow was evident in the velocity and temperature fluctuations. The triple velocity products were interpreted as fluxes of the Reynolds stresses and in general exhibited net fluxes away from the regions of high stress intensity. Balances of the terms in the axial momentum and turbulent kinetic energy equations showed that the main contribution from buoyancy was in the mean motion, with very little direct input to the turbulence field.

Comparison of measurements and integral model predictions of hot water plume behaviour in a crossflow

Measurements of the trajectory and dilution rate of a hot water jet entering vertically into a crossflow have been made in a water flume. Under various source conditions, thermistor probes at selected downstream locations were used to map out the cross-sectional extent of the plume, and thus to establish mean plume altitude and cross-sectional area as functions of distance from the source. These measurements were compared against the predictions of a simple integral model, similar to well-established models in the literature but modified for use in the flume study by the inclusion of an equation of state for water and an empirical correlation for the length of the potential core. An approximate analytical solution of the integral conservation equations, valid for both gaseous and water plumes, is presented. With entrainment and added mass constants very close to those previously estimated for gaseous plumes, good agreement between measured and predicted plume trajectory and dilution rate was found over the range of source conditions tested.

Test drilling with hot water jet at the Inland Ice margin, Pâkitsoq, central West Greenland

A new hot water jet driII was tested on the Inland Ice margin north-east of Jakobshavn. A total of 2436 m was driIled and data on drilling performance is presented together with the prelimiriary interpretation of borehole logging.

Wall conditioning in JT-60

The vacuum vessel of JT-60 has a volume of 160 m 3 and a vacuum side surface of 2750 m 2 containing the surfaces of the first wall and many types of ports. The first wall is made of 20 μm TiC coated molybdenum and Inconel 625, bolted to the inner surface of the vacuum vessel. The vacuum vessel is evacuated with four identical pumping systems with a total pumping speed of 29 m 3/s for hydrogen. The wall conditioning procedure consisted of two wipes with special cloths wetted by freon after hot water and freon jet cleaning, and three bakeouts were carried out before the first plasma production. An ultimate pressure of 7.4 × 10 −7 Pa and an outgassing rate of 6.8 × 10 −10 Pa m 3/s m 2 were obtained. Low current pulse discharge cleaning (TDC) was carried out for two weeks at a vacuum vessel temperature of 200°C. The TDC is performed typically with a plasma current of 30 kA, a pulse duration of 40 ms, a repetition period in the range from 0.3 s to 1.2 s, a hydrogen pressure of 5.0 × 10 −3 Pa, and a toroidal field of 0.45 T. The TDC conditioning for 50 h removed a quantity of water vapor corresponding to approximately 0.3 g. The main residual gases consisting of hydrocarbons, were monitored in addition to hydrogen and carbon monoxide.

Waterways, Ice Permeability at Depth, and Water Pressures at Glacier D’Argentière, French Alps

AbstractTo clear up the changes which had happened at the subglacial catchment of glacier d’Argentière, an extensive study, with 31 borings and a coring down to the bottom (240 m) was performed in 1979/80, just upstream from the catchment, in an overdeepened area. The behaviour of the water level during boring with a hot water jet, and just after, was different from one bore hole to another, mainly because transient leaks appeared in the walls of bore holes. Next, the water level fluctuated slowly, in the same way in most of the deep bore holes, showing that glacier ice below about 100 m deep is slightly pervious. What is so measured is the pore pressure of water in deep ice. The piezometric gradient between bore holes, and the time lag between fluctuations of water level, which increases with distance from the right bank, shows that there is no waterway at the bottom of the overdeepened area, save at its up-stream end. Most of the melt water must flow between ice and rock along the right bank, its free surface rising by about 150 m during the increased discharge in June. No clear-cut correlation between the bottom pore pressure and the air temperature or the discharge at the subglacial catchment down-stream was found.

Waterways, Ice Permeability at Depth, and Water Pressures at Glacier D’Argentière, French Alps

AbstractTo clear up the changes which had happened at the subglacial catchment of glacier d’Argentière, an extensive study, with 31 borings and a coring down to the bottom (240 m) was performed in 1979/80, just upstream from the catchment, in an overdeepened area. The behaviour of the water level during boring with a hot water jet, and just after, was different from one bore hole to another, mainly because transient leaks appeared in the walls of bore holes. Next, the water level fluctuated slowly, in the same way in most of the deep bore holes, showing that glacier ice below about 100 m deep is slightly pervious. What is so measured is the pore pressure of water in deep ice. The piezometric gradient between bore holes, and the time lag between fluctuations of water level, which increases with distance from the right bank, shows that there is no waterway at the bottom of the overdeepened area, save at its up-stream end. Most of the melt water must flow between ice and rock along the right bank, its free surface rising by about 150 m during the increased discharge in June. No clear-cut correlation between the bottom pore pressure and the air temperature or the discharge at the subglacial catchment down-stream was found.