Heat generation natural convection with

The first section presents some fundamental ideas that are frequently referred to in the remainder of the chapter. The next three sections deal with the major topics in natural convection. The first of these addresses problems of heat exchange between a body and an extensive quiescent ambient fluid, such as that depicted in Fig. 4.1a. Open cavity problems, such as natural convection in fin arrays or through cooling slots (Fig. 4.1fe), are considered next. The last major section deals with natural convection in enclosures, such as in the annulus between cylinders (Fig. 4.1c). The remaining sections present results for special topics including transient convection, natural convection with internal heat generation, mixed convection, and natural convection in porous media. 

Free or natural convection occurs when fluid motion is generated predominantly by body forces caused by density variations, under the earth s gravitational field. In the absence of the gravitational field, body forces may be caused by surface tension. The subject material here is focussed on heat transfer with motion produced by buoyancy forces. 

Other factors that need to be considered in any natural convection calculation include the geometry of the container (if any), flows generated from (or limited by) other surfaces in the vicinity, the interaction with forced flows, and possible radiative heat-transfer interactions. Because natural... 

Background. Natural convection driven by internal heat sources is of interest in geophysics, and the heat transfer associated with such motion is important in the design of tanks in which fermentation or other chemical reactions occur and in the safety analysis of nuclear reactors where a core meltdown is postulated. The last of these applications has led to the intensive study of internally generating horizontal fluid layers. 

The vertical arrangement of the steam generator above the core level permits natural circulation of the coolant through the core and a primary circuit thermalhydraulic design with low flow resistance. Also, any nucleate boiling in the core creates a pronounced buoyancy-induced enhancement of this natural convection flow. Consequently, reactor shutdown decay heat can be passively removed from the core through the steam generators entirely by natural circulation. 

The fuel is composed of 1500 cylindrical rods made with zircaloy containing pellets of UO2 with enrichment variable from 1.8 to 3.4%. The length of the rods is 1050 mm and the diameter 9 mm. Water is used as moderator and reflector. Natural convection of the water is used to remove the heat generated in the core. Control rods, containing an alloy of Ag-In-Cd, are used to regulate the reactor power and to shut down the reactor. Due to the versatility of the reactor, which allows realization of many academic experiments, the facility is used mainly for training purposes in the field of power reactor engineering, and for determination of nuclear parameters of the CAREM LWR power reactor. 

The primary system is cooled by heat exchangers located within the heat exchanger-pump modules. The venturi with a bypass provides natural convection in primary system irrespective of steam generator and pump states. 

Qian, L., Qiu, S., Zhang, D., Su, G.H., Tian, W., 2010. Numerical research on natural convection in molten salt reactor with non-uniformly distributed volumetric heat generation. Nuclear Engineering and Design 4. 

The dishes were 5, 7, and 10 cm in diameter (Thibodeaux et al., 1980). Using heat transfer data for a cold plate facing upward. Equation 2.34 in Table 2.3 can be applied to assess natural convection as well. In the above cases, the correlations relate chemical dissolution at the sediment-water interface, which forms a boundary layer with fluid density slightly greater than that of pure water. This particular mass transfer process is very slow since a high-density fluid accumulates on the bottom surface and forms a stable layer, which resist the generation of BL turbulence. The resulting estimated MTCs should be the lowest for the water-side bed sediment surfaces, and appropriate for waterbodies in the absence of bottom of currents. 

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