Unsteady state condensible

Large condensing loads, if handled on a steady state basis, result in appreciable cooling water and blowdown drum capacity requirements. These loads may be reduced, however, by the use of unsteady state condensing, e.g., by a worm cooler. 

In some cases where condensing loads are high, or where it is required to recover condensed liquid blowdown material for pollution, toxicity or economic reasons, an unsteady state condensing system may be appropriate. Examples or such applications are as rollows ... 

Another example of an unsteady state condensible blowdown system is the design for a phenol condensible blowdown tank. A blowdown tank is used in phenol treating plants to handle streams containing phenol and heavy hydrocarbons (lubricating oil stocks). The blowdown tank is illustrated in Figure 4. The design basis is as rollows ... 

Ravindranath and Mashelkar 121 Unsteady state Solid-state poly condensation Particle... 

When an agitated batch containing M of fluid with specific heat c and initial temperature t is heated using an isothermal condensing heating medium Tt, the batch temperature t2 at any time 0 can be derived by the differential heat balance. For an unsteady state operation as shown in Figure 7-27, the total number of heat transferred is q, and per unit time 0 is ... 

This problem can be treated as a steady state problem without reaction, or as an unsteady state problem. We will carry out the solution as a steady state problem. Recall that the water vapor condenses on compression so that the compressed gas is still saturated. 

TRANSIENT HEATING OR COOLING IN AGITATED VESSELS. Consider a well-agitated vessel containing m kilograms or pounds of liquid of specific heat Cp. It contains a heat-transfer surface of area A heated by a constant-temperature medium such as condensing steam at temperature 7. If the initial temperature of the liquid is T , its temperature at any time tr can be found as follows. The basic relation for unsteady-state heat transfer is... 

The absorption of a gas during condensation of water vapor on a cold water droplet Is a complex process characterized by unsteady state mass and heat transfer [6]. In the classical development of absorption of a gas In a liquids three theoretical models have ensued The film theory, the penetration theory, and the boundary layer theory. Each model Invokes different assumptions which result in different conclusions. 

Angelo [7] has shown that during periods of continual surface renewal, the actual mass transfer coefficient may be fifteen times as large as that predicted by boundary layer theory. Thus, the unsteady state absorption during surface renewal is a more complex situation not covered by these theories. In order to describe a fog or mist formation>it is necessary to study droplet growth by condensation with no Internal turbulence. Bogaevskii [2] reported water droplets growing by water vapor condensation in a mine shaft to absorb about six times more sulfur dioxide than that predicted by steady state absorption. 

In analyzing the self-similar solution of an unsteady rarefaction wave in a gas-vapour mixture with condensation, we will first discuss the situation where the onset of condensation occurs at a saturation ratio of unity. Then, the change in the state of the mixture is continuous. The solution is fully isentropic and follows from the characteristic form of the Euler equations, which for a left running wave is ... 

The foregoing results showing an unsteady shock wave profile apply to the thermal equilibration in the shock profile in condensed systems. If structural relaxation also occurs behind the shock front (as in cases A, B, C in Fig. 5, and in Ref. [33]) and if the relaxation process is slow compared with the propagation of the shock wave, then we would expect to observe additional energy exchange processes accompanied by further thermal relaxation in the shock profile. Even in a dense Lennard-Jones liquid, we found that the liquid structure did not relax quickly to a hydrostatic state under shock compression, and we observed thermal relaxation similar to that displayed in Fig. 6, but with a smaller overshoot in the kinetic energy after the shock front [30]. 

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