Flood cycles

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. 

A full range of sedimentary environments equivalent to the more commonly described clastic deposits is also occupied by evaporite facies where climate and hydrology permit. Indeed, small changes in these parameters commonly lead to fresher water clastic and carbonate sediments interbedded with evaporites, such as in Great Salt Lake, Utah (Spencer et al., 1985). In other cases (e.g. Lake Eyre) irregular flood cycles are recorded as multiple silt-mud-gypsum triplets, because clastic bedload material is first deposited followed by evaporation of the lake water and precipitation of the dissolved load. 

The downcomer in Fig. 4.12a is likely to lose its seal whenever its liquid height drops below tray level. When the seal is lost, vapor fium the tray ascends the downcomer, which may cause flooding, cycling, and/or poor separation. Downcomer unsealing by this mechanism is most likely to occur when the liquid drawn constitutes a laige portion of the downcomer liquid flow, when the quantity drawn tends to fluctuate, and/or when excessive leakage takes place due to tray weeping or draw pan leaks. 

Water can cause severe operational problems in services which are not meant to handle it. One refiner (296) stated that 99 percent of his fractionator upsets are due to water other refiners (296) agreed with this evaluation. Most problems occur when the column separates water-insoluble materials such as hydrocarbons. The main adverse effects of water in such services are pressure surges, flooding, cycling, corrosion, hydrates, and off-spec products. Typical sources of water in this t5q>e of services are... 

Entry of a slug or pocket of water into a column containing hot (usually >200°F) water-insoluble materials can cause pressure surges. Pressure surges are most damaging and hazardous, and are discussed in Sec. 13.5. Other adverse effects of water are flooding, cycling, severe corrosion, and off-spec products, caused by accumulation of small quantities of water in the column at close to ambient temperatures (usually 0 to 250°F). These are discussed in Sec. 13.7. Accumulation of small quantities of water under cold (less than about 30 to 50°F) conditions may cause hydrates. These are discussed in Sec. 13.10. 

Draining and flooding cycles influence N2O emissions (Figure 16.8). Draining the floodwater from salt marsh cores resulted in increased N2O emissions. However, the emission of NjO decreased when the sediment was reflooded. Results demonstrate that the N2O emission from natural wetlands... 

There are several other advantages to HVOF over VPS. VPS must be run in a vacuum, but HVOF can be run at atmospheric conditions. This avoids costly and time-consuming evacuation and flooding cycles inherent to vacuum chambers. Also, a real-time control feature such as particle or substrate pyrometry is not available or very difficult to implement in vacuum situations but is easily adaptable to HVOF [3,49]. In terms of control, the particle velocity is more sensitive to changing parameters than particle temperature. It is important to control both, because using greater velocity... 

Ancient Egypt s social structure developed around the exploitation of the Nile s flood cycle, and agriculture required large-scale organisation to exploit the annual renewal. Out of the abundance came a centralised economy, with population concentrated in the river valley, and from this conformity an army could be drawn to defend and... 

Fig. 5. Equipment foi surface treating plastic components. Parts ate loaded into one of the two lower chambers which is then evacuated to remove most of the air. This chamber is then flooded with a dilute mixture of fluorine and nitrogen which is made and stored in the upper chamber. After the treatment is completed, the fluorine mixture is pumped back up to the upper chamber for storage and the lower chamber repeatedly flooded with air and evacuated to remove any traces of fluorine gas. Two treatment chambers are cycled between the loading/unloading operation and the treatment step to increase equipment output. The fluorine—nitrogen blend may be used several times before by-products from the treatment process begin to interfere. AH waste...

The injection of large volumes of steam, steam flooding, is used to mobilize oil which is produced at offset production wells. Smaller volumes of steam are injected in the cycHc steam stimulation or huff n puff process (Eig. 2). Many wells are placed on several cycles of steam stimulation and then used as injection or production wells in steam flood projects. 

This formulation applies both to the use of a semi-continuous cycle with an expansion valve and to a discontinuous cycle (such as that in the solar refrigerator) using a flooded evaporator in which the warm condensate must first cool itself before it can cool the load. 

Image erasure. The potential differences due to latent image formation are removed by flooding the photoreceptors with a sufficiently intense light source to drive the surface potential to some uniformly low value (typically I00V corresponding to fields of 10 Vcni ) the photoreceptor is then ready for another print cycle. 

Fig. 4.5.1 Life cycle of the scyphozoan jellyfish Periphylla periphylla, counterclockwise from egg (white, about 1 mm diameter) to mature adult (orange-red, about 15 cm diameter, 400 g weight). This illustration is a gift from Dr. Per Flood.

Figure 1. Generalized nutrient balance of ecosystems in the intervals between disturbance events. Natural disturbances such as wildfires, hurricanes, and floods as well as anthropogenic disturbances such as deforestation and biomass burning can dramatically influence nutrient inputs, internal cycles, and ecosystem outputs (losses).

Mercury in soil is not only likely to have a different potential for evasion and methylation than Hg in runoff, but soil Hg may be perturbed by land disturbance. Land disturbances that are particularly relevant to Hg cycling include the formation of wetlands and flooding of reservoirs (Rudd 1995 see Chapter 3). Disturbances such as clear-cutting can also result in marked increases in the release of THg and MeHg from soils (Munthe and Hultbeig 2003 Porvari et al. 2003). Fire can result in large Hg losses by volatilization (Grigal 2002). 

Miscible water-alternating-gas (WAG) process. Injection alternates between gas (usually natural gas or C02) and water the miscible gas and oil form one phase. The WAG cycles improve sweep efficiency by increasing viscosity of the combined flood front (Figure 12). 

The possible explanation of these results is related to the construction of dikes in this area a few years prior to the experiment. This changed the biogeochemical cycles of many nutrients in natural ecosystems too. Furthermore, the input of nutrients with flooded waters was not taken into account. 

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