Steady-state flow system, pressure

Ns P P number of adsorption sites per unit area of surface, total pressure. steady state pressure in a flow system when atomisation is taking place. 

Po steady state pressure in a flow system in the absence of atomisation. 

In a closed system, a steady state is established only when the rate of evaporation of the adsorbed layer becomes comparable with the rate of adsorption on the sample. In a flow system, the steady state pressure achieved with the sample adsorbing can be adjusted by altering the flow of gas into the cell. Once a new steady state is reached, VdNj dt = 0. The net rate of adsorption is just equal to the net flow into the cell, and is therefore immediately known, provided the exit speed SE has been previously determined. 

The autoregulating Windkessel was found to accurately reproduce the experimental flow step response of both vascular beds and the systemic circulation. The model further provided the steady-state pressure-flow autoregulation curve, in Hnearized form. The impedance spectrum was predicted to differ from that of the three element Windkessel for frequencies below the heart rate. For frequencies near zero, the impedance approached the slope of the pressure-flow autoregulation curve, as opposed to peripheral... 

Van Huis, G.A., Sipkema, R, and Westerhof, N. 1985. Instantaneous and steady-state pressure-flow relations of the coronary system in the canine beating heart. Card. Res. 19 121—131. 

An extraction plant should operate at steady state in accordance with the flow-sheet design for the process. However, fluctuation in feed streams can cause changes in product quaUty unless a sophisticated system of feed-forward control is used (103). Upsets of operation caused by flooding in the column always force shutdowns. Therefore, interface control could be of utmost importance. The plant design should be based on (/) process control (qv) decisions made by trained technical personnel, (2) off-line analysis or limited on-line automatic analysis, and (J) control panels equipped with manual and automatic control for motor speed, flow, interface level, pressure, temperature, etc. 

Consider a eonstant pressure, steady-state flow proeess with an inflow of reaetant in seetion (1) and die outflow of die produet in seetion (2) leaving die system boundary (i.e., a ehemieal reaetor). 

A steady-state process is one in wliich there is no change in conditions (temperature, pressure, etc.) or rates of flow with time at any given point in die system. The accumulation term in Eq. (4.5.1) is dien zero. If diere is no cheniieid reaetion, the generation tenn is also zero. All other processes are unsteady state. 

A capillary system is said to be in a steady-state equilibrium position when the capillary forces are equal to the hydrostatic pressure force (Levich 1962). The heating of the capillary walls leads to a disturbance of the equilibrium and to a displacement of the meniscus, causing the liquid-vapor interface location to change as compared to an unheated wall. This process causes pressure differences due to capillarity and the hydrostatic pressures exiting the flow, which in turn causes the meniscus to return to the initial position. In order to realize the above-mentioned process in a continuous manner it is necessary to carry out continual heat transfer from the capillary walls to the liquid. In this case the position of the interface surface is invariable and the fluid flow is stationary. From the thermodynamical point of view the process in a heated capillary is similar to a process in a heat engine, which transforms heat into mechanical energy. 

Assuming steady state in Eqs. (10.8-10.10) and (10.18-10.20), we obtain the system of equations, which determines steady regimes of the flow in the heated miero-channel. We introduce values of density p = pp.o, velocity , length = L, temperature r = Ti 0, pressure AP = Pl,o - Pg,oo and enthalpy /Jlg as characteristic scales. The dimensionless variables are defined as follows ... 

Measurements Using Liquid-Phase Reactions. Liquid-phase reactions, and the oxidation of sodium sulfite to sodium sulfate in particular, are sometimes used to determine kiAi. As for the transient method, the system is batch with respect to the liquid phase. Pure oxygen is sparged into the vessel. A pseudo-steady-state results. There is no gas outlet, and the inlet flow rate is adjusted so that the vessel pressure remains constant. Under these circumstances, the inlet flow rate equals the mass transfer rate. Equations (11.5) and (11.12) are combined to give a particularly simple result ... 

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