Aaberg exterior hoods

Mechanical thermocompression may employ reciprocating, rotary positive-displacement, centrifugal, or axial-flow compressors. Positive-displacement compressors are impractical for all but the smallest capacities, such as portable seawater evaporators. Axial-flow compressors can be built for capacities of more than 472 mVs (1 X 10 ftVmin). Centrifugal compressors are usually cheapest for the intermediate-capacity ranges that are normally encountered. In all cases, great care must be taken to keep entrainment at a minimum, since the vapor becomes superheated on compression and any liquid present will evaporate, leaving the dissolved solids behind. In some cases a vapor-scrubbing tower may be installed to protect the compressor. A mechanical recompression evaporator usually requires more heat than is available from the compressed vapor. Some of this extra heat can be obtained by preheating the feed with the condensate and, if possible, with the product. Rather extensive heat-exchange systems with close approach temperatures are usually justified, especially if the evaporator is operated at high temperature to reduce the volume of vapor to be compressed. When the product is a sohd, an elutriation leg such as that shown in Fig. 11-1225 is advantageous, since it cools the product almost to feed temperature. The remaining heat needed to maintain the evaporator in operation must be obtained from outside sources.  [c.1143]

Overdesign. Overdesign has a great impact on the cost of heat exchange and sometimes is confused with energy conservation, through lower AT and AP. The best approach is to define clearly what the objective of overdesign is and then to specify it expHcitly. If the main concern is a match to other units in the system, a multiplier is appHed to flows. If the concern is with the heat balance or transfer correlation, the multiplier is appHed to area. If the concern is fouling, a fouling factor is called for. If low AT or AP is the principal concern, however, that should be specified. Adding extra surface saves energy only if the surface is configured to do so. Doubling the area may do nothing more than double the AP, unless it is configured properly.  [c.87]

Module Eactor Estimates. AH equipment of a given type can be lumped together into a module, such as a heat-exchanger module. Eactors are given (9) to relate the various capital cost categories for each module type to the total purchased equipment cost of the module. The capital cost categories are then summed over aH module types. This approach offers the advantage that the cost of commodity materials and labor are usuaHy available in module categories to maintain accurate up-to-date module factors. Although the method requires a larger database, it appears to offer greater potential accuracy than overaH or category factor methods.  [c.443]

The refrigerant-recirculating pump pressurizes the refrigerant Hquid and moves it to one or more evaporators or heat exchangers that may be remote from the receiver. The low pressure refrigerant may be used as a single-phase heat-transfer fluid as in A of Figure 11, which eliminates the extra heat-exchange step and increased temperature difference encountered in a conventional system that uses a secondary refrigerant or brine. This approach may simplify the design of process heat exchangers where large specific volumes of evaporating refrigerant vapor would be troublesome. Alternatively, the pumped refrigerant in the flooded system may be routed through conventional evaporators as in B and C, or special heat exchangers as in D. The flooded refrigeration system is helpfljl when special heat exchangers are necessary for process reasons, or where multiple or remote exchangers are required.  [c.67]

Chemical Designations - Synonyms Epoxidized tall oil, octyl ester Chemical Formula Mixture. Observable Characteristics - Physical State (as shipped) Liquid Color. Pale yellow Odor Mild. Physical and Chemical Properties - Physical State at IS X and 1 atm. Liquid Molecular Weight 420 (approx.) Boiling Point at 1 atm. Not pertinent Freezing Point Not pertinent Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity (est.) 1.002 at 20 °C (liquid) Vcpor (Gas) Specific Gravity Not pertinent Ratio of Specific Heats of Vcpor (Gas) Not pertinent Latent Heat of Vaporization Not pertinent Heat of Combustion Data not available Heat of Decomposition Not pertinent.  [c.278]

See pages that mention the term Aaberg exterior hoods : [c.354]   
Industrial ventilation design guidebook (2001) -- [ c.818 , c.819 , c.820 , c.821 , c.822 , c.823 , c.824 , c.825 , c.826 , c.827 , c.828 , c.829 , c.830 , c.831 , c.832 , c.833 , c.834 , c.835 , c.836 , c.837 , c.838 , c.839 , c.840 , c.841 , c.842 , c.843 , c.844 , c.845 , c.846 , c.847 , c.848 , c.849 , c.850 , c.851 , c.852 , c.853 , c.854 , c.855 , c.856 , c.857 , c.858 , c.859 , c.860 , c.861 , c.862 , c.863 , c.864 , c.865 , c.866 , c.867 ]