Exchanger flooding

Vapor Lock and Exchanger Flooding in Steam Systems... 

Flooded refrigeration systems are a version of the closed-cycle design that may reduce operating problems in some appHcations. In flooded systems, the refrigerant is circulated to heat exchangers or evaporators by a pump. Figure 11 shows the flooded cycle, which can employ any of the simple or compound closed-refrigeration cycles. 

B = direct expansion coils, C = flooded evaporators, and D = special heat-exchanger designs. 

Equipment Constraints These are the physical constraints for individual pieces of eqiiipment within a unit. Examples of these are flooding and weeping limits in distillation towers, specific pump curves, neat exchanger areas and configurations, and reactor volume limits. Equipment constraints may be imposed when the operation of two pieces of equipment within the unit work together to maintain safety, efficiency, or quahty. An example of this is the temperature constraint imposed on reactors beyond which heat removal is less than heat generation, leading to the potential of a runaway. While this temperature could be interpreted as a process constraint, it is due to the equipment limitations that the temperature is set. 

This matrix will contain information regarding loading characteristics such as flooding hmits, exchanger areas, pump curves, reactor volumes, and the like. While this matrix may be adjusted during the course of model development, it is a boundary on any possible interpretation of the measurements. For example, distillation-column performance markedly deteriorates as flood is approached. Flooding represents a boundary. These boundaries and nonlinearities in equipment performance must be accounted for. 

Thermal shock In biphase systems, steam bubbles may become trapped in pools of condensate in a flooded main, branch, or tracer line, as well as in heat exchanger tubing and pumped condensate lines. Since condensate temperature is almost always below saturation, the steam will immediately collapse. 

The amount of particulate matter varies from very high values in silt carrying rivers (the Mississippi River carries an average of 2600 mg/liter at flood time) to practically zero (0.05 mg/liter ref. 17) in the ocean. A typical value may be 1-10 mg/liter. The mineral particles often consist of clay with ion exchange properties. 

Photosynthesis and gas exchange of leaves are affected by many stresses including drought, flooding, salinity, chilling, high temperature, soil compaction and inadequate nutrition. Many, but not all, of these stresses have symptoms in common. For example, stomatal conductance and the rate of assimilation of CO2 per unit leaf area often decrease when stress occurs. Further, it is possible that several of the stresses may exert their effects, in part, by increasing the levels of the hormone abscisic acid (ABA) in the leaf epidermis. This hormone is known to close stomata when applied to leaves. 

Formation damage caused by clay migration may be observed when the injected brine replaces the connate water during operations such as water-flooding, chemical flooding including alkaline, and surfactant and polymer processes. These effects can be predicted by a physicochemical flow model based on cationic exchange reactions when the salinity decreases [1665]. Other models have also been presented [345,1245]. 

Level, e.g. Overfilling Leakage from a dump valve Flooding of condensers (heat exchangers) ... 

Experimental flooding data for the ion-exchange resin (d = 190 pm, ps = 1, 250 kg/m3) in the low-g rotor with backflow of the solids discharge1-20-1... 

In addition to Nafion-based catalyst layers, additional types have been developed, including CLs with different ion exchange capacities (lECs) [57,58] or with other hydrocarbon-type ionomers such as sulfonated poly(ether ether ketone) [58-60], sulfonated polysulfone [61,62], sulfonated polyether ionomers [63], and borosiloxane electrolytes [64], as well as sulfonated polyimide [65]. These nonfluorinated polymer materials have been targeted to reduce cost and/or increase operating temperature. Unfortunately, such CLs still encounter problems with low Pt utilization, flooding, and inferior performance compared wifh convenfional Nafion-based CLs. 

S. W. Cha, R. O Hayre, Y. I. Park, and E. B. Prinz. Electrochemical impedance investigation of flooding in micro flow channels for proton exchange membrane fuel cells. Journal of Power Sources 161 (2006) 138-142. 

W. He, G. Lin, and T. V. Nguyen. Diagnostic tool to detect electrode flooding in proton-exchange-membrane fuel cells. AIChE Journal 49 (2003) 3221-3228. 

X. Liu, H. Guo, and C. Ma. Water flooding and two-phase flow in cathode channels of proton exchange membrane fuel cells. Journal of Power Sources 156 (2006) 267-280. 

F. B. Weng, A. Su, C. Y. ITsu, and C. Y. Lee. Study of water-flooding behavior in cathode channel of a transparent proton-exchange membrane fuel cell. Journal of Power Sources 157 (2006) 674—680. 

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