Transient contact pressure

In BWRs, all stresses (pressure difference, hydraulic vibrations, contact pressure of spacers, etc.) are first evaluated and categorized into primary membrane stress, primary bending stress, and secondary stress. The maximum allowable stresses are set for each of these categorized stresses at both normal and abnormal transients. The maximum allowable stresses in the Super LWR fuel rod design are determined similarly. 

For the standby pump start test, which is an important test to ensure the pumps transfer without large pressure swings, a check should be made to see if the relief valves lift or the pressure falls to a pressure one half the difference between the standby pump start pressure and the compressor trip pressure. The transient pressure is best measured with a multipen chart recorder. The chart speed must be high enough to fully display the pressure variation. While not as good as the chart recorder, a simple shop-made test setup can be substituted. A spare switch is temporarily connected to the same location as the other switches. This switch is calibrated to close at the threshold acceptance pressure. The contacts are wired to a test light through a seal relay. The purpose of the relay is to maintain the cir-... 

Anderson and Armstrong (1977) summarize a number of other studies carried out at the Argonne National Laboratory and elsewhere in which there was contact between R-22 and water (or R-22 and mineral oil) (see Henry et ai, 1974, 1976 Board et al., 1974). In these studies, pressure transients were measured. Anderson and Armstrong have summarized these data in Fig. 11. Note that for water temperatures below about 350 K, the pressure rise upon contact is small. Above a water temperature of about 350 K, which corresponds to a calculated interface temperature of... 

Tolerance to CS may develop from repeated exposures at low concent rations,20 but it is reduced by hyperventilation, as well as by increased environmental temperature and humidity.2 Whole-body exposure to CS solutions may result in a transient increase in blood pressure, but not to the extent observed with CR.3 20 CS is a hapten and may cause allergic contact dermatitis, with erythema, edema, and vesication, which is less severe than the effects of CN. ... 

Two-phase flow is always involved in the cooldown of a transfer line. Since this process is a transient one, several different types of two-phase flow will exist simultaneously along the inlet of the transfer line. Severe pressure and flow oscillations occur as the cold liquid comes in contact with successive warm sections of the line. Such instability continues until the entire transfer line is cooled down and filled with liquid cryogen. 

Stolk and Syverson (1978) described an absorber-reactor that is capable of carrying out transient studies at millisecond rates. They presented a high-temperature, high-speed constant volume adsorber reactor that is capable of measuring adsorption rate in the presence of a chemical reaction. The reactor provides rapid gas-solid contact in a constant-volume cell with transient rates for temperature and pressure measurements in the millisecond region. Using... 

Fig. 3 Spotting tools for non-contact printing a Bubble ink-jet A heating coil locally heats the loaded sample, resulting in a changed viscosity and expansion of fluids. The generated droplet can be easily expelled from delivery nozzles, b Microsolenoid A microsolenoid valve, fitted with the ink-jet nozzle is actuated by an electric pulse transiently opening the channel and dispenses a defined volume of the pressurized sample, c Piezo ink-jet A piezoelectric transducer that is fitted around a flexible capillary confers the piezoelectric effect based on deformation of a ceramic crystal by an electric pulse. An electric pulse to the transducer generates a transient pressure wave inside the capillary, resulting in expulsion of a small volume of sample...

The first method, shown in Figure 3.12(A), places a valve in the condensate hne and directly backs up the liquid into the condenser as needed. The second method places a control valve in a vapor hne, added to bypass the condenser and go directly into the accumulation tank (see Figure 3.12(B)). Although somewhat counterintuitive, the vapor bypass valve must open as pressure drops, in order to raise the pressure at the accumulation tank and force hquid condensate back into the condenser to restore the energy balance. Care must be taken that the surface of the liquid in the tank is not disturbed, as undesirable pressure transients can develop with the hot vapor in contact with the sub-cooled liquid. Another concern with both of these condensate methods is the venting of process inerts as they build up over time. Valve position is the best indication of this pending problem. 

However, eventually 5jR > 1 for a dissolving bubble, so that the steady-state solution prevails. For gas bubbles dissolving in water at atmospheric pressure with i (0) <0.2 mm, Houghton, Ritchie, and Thomson (H8) find that the transient term becomes negligible after about 100 sec. After this time the result reduces to the quasi-steady solution, governed by the Laplace equation, whose solutions have been extensively studied. For a bubble attached to a wall with zero contact angle, Liebermann (L6) thus shows that the rate of solution is reduced by a factor of In 2, leading to the result... 

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