Conductive heat loads

To reduce the conducted heat load, the mechanical supports are made as small as possible, and special materials are used. Handle the dewars gently they are often fragile. 

Power dissipation in the leads is a source of heat that should be considered larger diameter leads reduce the power dissipation but increase the conducted heat load. The optimization problem is discussed by McFee (1959) and Walmsley et al. (1972). Subsequent authors in the journal containing the Walmsley article consider the cooling effect of evaporated gas on the optimization problem. 

Trays may be square or rectangular, with 0.5 to I m" per tray, and may be fabricated from any material compatible with corrosion and temperature conditions. When the trays are stacked in the truck, there should be a clearance of not less than 4 cm between the material in one tray and the bottom of the tray immediately above. When material characteristics and handling permit, the trays should have screen bottoms for additional diying area. Metal trays are preferable to nonmetalhc trays, since they conduct heat more readily. Tray loadings range usually from I to 10 cm deep. 

Next generation machines will impose inereasingly greater thermal loads on their PFCs. High thermal conductivity CFC materials may offer a solution to the high-heat loads, but further research is needed to overeome the problems noted above and to assure the place of earbon materials in future fusion power reaetors. 

Studies of nonisothermal mam stream and horizontal directing jet mterac-non were conducted to evaluate the maximum heat load that can be eltectively supplied by such HVAC systems. To summarize experimental data both in free and confined conditions, it was suggested that the above limiting condition is achieved when the current Archimedes number Ar ratio of rhe buoyancy forces over ineiTia forces along the resulting jet axis) does not exceed s[Pg.502]

A liquid-phase reaction A B is to be conducted in a CSTR at steady-state at 163°C. The temperature of the feed is 20°C, and 90% conversion of A is required. Determine the volume of a CSTR to produce 130 kg B h 1, and calculate the heat load (Q) for the process. Does this represent addition or removal of heat from the system ... 

Load cool points are dependent on load conhgurations and the types of items that comprise the load (liquid-hlled containers, process equipment, etc.). Prior to conducting heat penetration studies, maximum and minimum load conhgurations must be established. The penetration thermocouples are positioned within liquid-hlled containers at the cool point previously determined by container mapping studies. The probed containers should be distributed uniformly throughout the load. When the load consists of multiple layers or pallets, a sufficient number of thermo-couple-probed containers should be employed to provide an equal representation among layers. 

For the TFTR heat load structures, more than twenty different materials were surveyed for thermal conductivity and thermal shock resistance (64) a result of these tests several grades of... 

Starting pressure. In principle, a cryopump could be started at atmospheric pressure. However, a thick layer of condensate of gases, easily removed by pre-evacuation, would be formed, restricting the capacity of the cryopump in its working phase. Further, at p > l(T3mbar, the thermal conductivity of the gas would present a high heat load to the cryo surface. 

The thermocouple gauge is more straightforward than the Pirani gauge and less complicated electronically. The thermocouple gauge has a thermocouple attached to a filament under constant electrical load, and it measures the temperature at all times. If the filament becomes hotter, it means that there is less air/gas available to conduct heat away from the wire, and therefore there is greater vacuum within the system. 

Fig. 3.25. Heat flux histories following an ELM of 1MJ/m2 with a power flux triangular waveform (curve 1) with ramp-up and ramp-down phases lasting 300 ds each on a 10mm thick W target under an inter-ELM power flux of 10MWm 2. Curves. (1) incident heat flux load (2) conducted heat flux into the material (3) heat flux spent in melting of the material (the evaporation and black-body radiation heat fluxes are comparatively small and not shown). Curve (4) shows the surface target temperature and (5) shows the temperature of the melt layer. Curve (6) shows the vaporized thickness (amplified of a factor of 1000) and (7) the melt layer assuming that no losses of molten material occur during the ELM [3]...

D. From C we know that conductive/convective heat loss is 189 W m2, and we also know that the total heat load from net radiation is 300 W m 2. Therefore, the amount of energy that must be dissipated as latent heat through transpiration is... 

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