Local cooling

Mold Coolers for Plastic Injection Molding. Heat pipes are used for local temperature control in the injection molding of plastics (see Polymerprocessing). A heat pipe is often used to force local cooling within a mold to speed operation, control viscosity, retention of material in a difficult mold area, or to reduce thermal stresses on cooling. 

Local air motion is another thermal nonuniformity that can cause a local cooling of the skin and the feeling of a draft. Draft discomfort from local air motion increases as the air temperature decreases below skin temperature. Fluctuations in the local air motion increase the perception of drafts and should be avoided. The unsteadiness of air motion is often described in terms of its turbulence intensity (Tu) ... 

TABLE 6.10 Proposed Physiological Criteria for Determination of OLE, and Local Cooling (ISO 7R 11079)... 

Local cooling The cooling of a given area in a space by means of chilled air jets or chilled water panels. 

U = overall heat transfer coefficient, from equation 12.1, using h cg, Tv = local vapour (gas) temperature, tc = local cooling medium temperature. 

The POA also contains cold-sensitive neurons (CSNs), cells activated by local cooling and inhibited by local warming. Most CSNs are wake-active thus, like arousal-related neurons in PLH, PH, DRN and basal forebrain, they exhibit... 

Why does the evaporation of an alcohol achieve a cooling effect Evaporation is a process that requires heat (an endothermic process). The skin in the area of application provides the necessary amount of heat needed to evaporate the alcohol, leading to the localized cooling sensation. 

For organic solvent processes, the humidity of the air can also play a role in the product quality. One particular problem which can arise is that of condensation of water in the bed. In the vicinity of the nozzle, local cooling may be experienced due to solvent evaporation (Smith and Nienow, 1982), as discussed in Sec. 2.3. Asa consequence of this local cooling, the temperature... 

The rate of absorption from an SC injection site may be retarded by immobilization of the limb, local cooling to cause vasoconstriction, or application of a tourniquet proximal to the injection site to block the superficial venous drainage and lymphatic flow. In small amounts, adrenergic stimulants, such as epinephrine, will constrict the local blood vessels and, therefore, slow systemic absorption. Conversely, cholinergic stimulants (such as methacholine) will induce very rapid systemic absorption subcutaneously. Other agents may also alter their own rate of absorption by affecting local blood supply or capillary permeability. 

The dissolved substances (especially if the solution is very concentrated) often crystallises in the funnel on account of local cooling and in this way filtration is hindered. This trouble can be partially met by using a funnel (Fig. 3) with the delivery tube cut short (0 5-l-0 cm.). But it is much more satisfactory to use a so-called hot water funnel (Fig. 4) in which the filtering surface of the funnel is heated with boiling water in a metal jacket. When inflammable solvents are used, the flame must be extinguished before filtration. 

Local cooling of the polymer melt by the addition of water can be determined using the enthalpy of vaporization as follows ... 

The acid is sprayed into the furnace at two to six locations. This multi spray arrangement avoids localized cooling that occurs when all the acid is sprayed in at one location. 

Figure 22.9. Comparison of model (thin line) and experimental (thick line) temperatures for the cooling of tempered chocolate at a nominal rate of 2 C/min. The model uses apparent specific heat capacity data obtained by first calculating the local cooling rate and temperature (Tewkesbur>, Stapley and Fryer 2000).

Ty = local vapour (gas) temperature, tc = local cooling medium temperature. 

There are several possible ways of accomplishing this. These include localized cooling at the joining area, mechanical seal (such as Swagelok), ceramic-to-ceramic, ceramic-to-metal seals (cermets), gland packing, and special types of seals. 

Two other cases of oxaliplatin extravasation have been reported (233). Both occurred when the intraport needle disconnected. The initial symptoms were swelling and tenderness at the port site. The patients developed severe inflammation after 3 days. Treatment included local cool packs, diclofenac ointment, and oral indometacin, morphine, or dexamethasone. The authors avoided saline instillation because sodium chloride and oxaliplatin may be incompatible in combination (119). Both patients recovered without any sign of local necrosis and longterm sequelae (233)... 

Among several antidotes for the treatment of vinca alkaloid extravasation, hyaluronidase is the most effective (79). Seven patients with extravasation of vincristine, vinblastine, or vinorelbine received hyaluronidase 250 units diluted in 6 ml of 0.9% saline, through the indwelling needle or, when the needle had been already removed, as six subcutaneous injections around the extravasation site. None developed skin necrosis. Local mild skin warming in order to produce local vasodilatation may have an additional beneficial effect, but should be avoided when simultaneous extravasation of a vinca alkaloid and an anthra-cycline is suspected, because local warming can worsen the anthracycline-associated local reaction, whereas local cooling, which is generally beneficial in anthracycline-related extravasation alone, can worsen skin necrosis due to vinca alkaloids (76). 

Substantial localized cooling was required to control the bed temperature at normal fluorination rates. 

Evaporation is accompanied by local cooling and condensation by local warming. The addition of mas s to droplets and the conduction of latent heat away from the surface of the droplet or particle are, as has been pointed out by Pritchard (1987), the determining processes of particle growth. Under conditions of turbulent airflow, conduction of heat away from the surface of droplets or particles is enhanced and hygroscopic growth rates exceed those found under still conditions or under conditions of laminar airflow. The implications of this will be considered later. 

The difficulties of the old type apparatus were in both the inability to remove large quantities of heat at a high temperature level and in the uneven temperatures both along and across the reactor. The injection of air or other cooling gas or vapor near the reaction zone resulted in both undesirable dilution, and too rapid and localized cooling. 

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