Heat-conducting tip

The next type of nozzle is one with a heat-conducting tip (Figure 4.20b), also called a mini-torpedo, located inside the central channel. The tip is heated by the heat of the nozzle casing and the molten material. The insulating chamber is basically the termination of the channel and the melt does not get left behind in it. Colour can be changed rapidly. 

Nozzles with heat-conducting tip. Depending on their casing design, these nozzles feature various possibilities for attachment of the tip. The designs most commonly used are ... 

One major rationalisation that reduces this detrimental fall in power is use of a housing with a flat copper bottom that transfers and conducts heat well. Heating elements of this sort are used in, for example, torpedoes with a heat-conducting tip. 

FIGURE 1.40 Heat conductive tip with multi-hole FIGURE 1.41 Minimized ante-... 

The first approach developed by Hsu (1962) is widely used to determine ONE in conventional size channels and in micro-channels (Sato and Matsumura 1964 Davis and Anderson 1966 Celata et al. 1997 Qu and Mudawar 2002 Ghiaasiaan and Chedester 2002 Li and Cheng 2004 Liu et al. 2005). These models consider the behavior of a single bubble by solving the one-dimensional heat conduction equation with constant wall temperature as a boundary condition. The temperature distribution inside the surrounding liquid is the same as in the undisturbed near-wall flow, and the temperature of the embryo tip corresponds to the saturation temperature in the bubble 7s,b- The vapor temperature in the bubble can be determined from the Young-Laplace equation and the Clausius-Clapeyron equation (assuming a spherical bubble) ... 

Tip assemblies used for work at helium temperatures may be modified as shown in Fig. 12. The inclusion of the nichrome sections is necessary if temperature control is desired. Since both the heat capacity and the electrical resistivity of tungsten at helium temperatures are extremely low and its heat conductivity is very high, a rise in temperature from I K to about 1000°K corresponds to changes of a few milliamperes in the heating current if all-tungsten assemblies are used. The nichrome sections act as thermal barriers, since alloys do not lose their high-temperature thermal properties at 4°K, and permit fine control of temperature. For... 

Figure 1. The MHHP modular sorber diagram 1 - tubular case of the hydride module 2 -corrugated heat-conducting insert 3 - hydrogen ceramic collector-filter 4 - metal hydride 5 - tip of a metal hydride bed 6 - hydrogen manifold 7 - spacer plate 8 - heat exchanger shroud 9 - union 10 - flange-cover of a heat exchanger. Heat exchanger thermal insulation is not shown conditionally.

In principle, the heat conduction can occur via near-field radiation, the gas molecules of the surrounding atmosphere, the liquid film covering tip and sample surfaces and forming a liquid bridge, or the mechanical tip-sample contact. By means of surface roughness, the effective contact area is presumed to be much smaller than the apparent (i.e. the geometric) one (Fig. 20). 

Consider steady one-dimensional heat conduction in a pin fin of constant diajneter D with constant thermal conductivity. The fm is losing heal by conveclion to the ambient air at T with a heat transfer coefficient of A. The nodal network of the fm consists of nodes 0 (at Ihe base), 1 (in the middle), and 2 (at the fin tip) with a uniform nodal spacing of Ax. Using the energy balance approach, obtain the finite difference formulation of (his problem to determine T, and T2 for Ihe case of specified temperature at the fin base and negligible heat transfer at the fin tip. All temperatures are in C. 

Fin length for heat conduction from primary surface to either fin tip or midpoint... 

By and large, the repair and/or rework of through-hole solder joints stiU uses hand-soldering procedures (see Fig.40.30). In the case of a repair procedure, the first step is to add flux and solder to the joint. Then the soldering iron is contacted to the lead, thereby allowing the solder to reflow. The tip should be removed from the joint as soon as possible to prevent excessive heat conduction up the lead and into the component, where it may damage the active (Si chip) device(s), glass-to-metal seals, etc. 

Some companies put a pressed copper plate in the bottom of the heater hole to improve heat conduction to the end of the torpedo tip (see Figure 5.7). 

The difficulties with color change restrict the field of application of internally heated systems. The following combination can be found more often Externally heated manifold and internal heating in the nozzle area, equivalent to the design of the gate elements as a torpedo or as a thermal conductive tip. 

Heat losses by heat conduction into the mold can be minimized by supporting elements made from titanium. Even in mini systems, heating, thermocouples, and tips are interchangeable. 

Using laser and/or electron beam welding, components can be produced that combine the (targeted) properties of material (e.g., a mold steel and a highly heat conductive copper base) where needed. This allows many previously structurally desirable but not technically feasible applications of copper-steel composite components. Figure 3.17 shows an injection molding nozzle on which the highly stressed tip and the thread were manufactured from a Co-base alloy. 

Heat production is correlated with the intensity and duration of the RF energy deposited. On the other hand, heat conduction or diffusion is usually explained as a factor of heat loss in regard to the electrode tip. Heat is lost mainly through convection by means of blood circulation (Patterson et al. 1998). 

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