Thermal link

Eurther research on convective transport under low Reynolds number, quasicontinuum conditions is needed before the optimal design of such a micro heat exchanger is possible. The cooling heat exchanger is usually thermally linked to a relatively massive substrate. The effects of this linkage need to be explored and accurate methods of predicting the heat-transfer and pressure-drop performance need to be developed. 

The purpose of this experiment was to select the best thermal link to cool down sensitive masses of the order of 100-1000 kg for the detection of rare decays [24] and gravitational waves [25],... 

In the heat pulse method, the sample of heat capacity C is thermally linked to the thermal bath (at temperature rB) by a conductance G. 

Let us examine in Fig. 12.1 a schematics of a set up for heat capacity measurement a support (Sp) of heat capacity CSp is thermally linked to the thermal bath through a thermal resistance RG = l/G. 

In a classical low-temperature measurement of heat capacity, the sample is placed (usually glued) onto a low heat capacity support which is thermally linked to the thermal bath by a thermal conductance (see Fig. 12.1). 

The HEM is a thermal model which represents a doped semiconductor thermistor (e.g. Ge NTD) as made up of two subsystems carriers (electrons or holes) and phonons. Each subsystem has its own heat capacity and is thermally linked to the other one through a thermal conductance which takes into account for the electron-phonon decoupling (see Fig. 15.2). 

An extremely simplified scheme of a calorimeter (composite thermal detector) is shown in Fig. 15.6. The temperature of an absorber A (TA) is measured by a thermometer T. A thermal conductance G forms a thermal link with the heat sink B at the temperature Ts. In the ideal adiabatic situation (G = 0), an absorption of an energy AE produces an absorber temperature increase ... 

This new mechanical (and thermal) configuration has overcome the vibration problems at the expense of a longer cold down time due to smaller thermal conductance of the thermal link. It has also pointed out phenomena not observed in the initial configuration. 

J.A. Caballero I.E. Grossmann, 2001, Generalized disjunctive programming model for the optimal synthesis of thermally linked distillation columns,, Industrial Engineering Chemistry Research 40 (10) 2260-2274... 

Figure 2.38 Schematic of the suspended-tube reactor (left and middle) and SEM (right) showing four suspended SiNx tubes connected to the Si reaction zone, Si slabs thermally linking the four tubes and a meandering Ti/Pt resistive heater/temperature sensor [72] (by courtesy of L. R. Arana).

Figure 9.17. A cartoon representation of a bolometer a small thermometer at the focus of a beam of radiation, thermally linked to a bath.

The reboiler is the thermal link between the HP column and the LP column. It provides vapor boil-up for the LP column and reflux for the HP column. The reboiler functions by condensing a nitrogen stream and boiling an oxygen stream. Based upon the boiling points presented in Table 3.3, this would not seem feasible. However, as demonstrated in Figure 3.18, as the pressure increases, the boiling point... 

In thermal detectors and especially in bolometers, the energy exchange between the sensing element and the heat sink through a thermal link of conductance G results in a thermal noise known as phonon noise. The NEP associated with this phonon noise, which is a white (frequency-independent) noise, is given by ... 

Suppose that we are going to measure the T of the system by measuring the magnetization recovery after saturation (say by a comb as described in III.D.2.). Then immediately after the comb (t=0), the spin temperature Tg is infinite throughout the sample. The lattice temperature T, however, is much colder, say, equal to room temperature, and for all practical purposes we can take it to be zero for this discussion. The paramagnetic impurity provides the thermal link between the hot spins and the cold lattice. 

Structural adhesives must have a glass transition temperature higher than the operating temperature to avoid a cohesively weak bond and possible creep problems. Modem engineering plastics, such as polyimide or polyphenylene sulfides, have very high glass transition temperatures. Most common adhesives have a relatively low glass transition temperature so that the weakest thermal link in the joint may often be the adhesive. 

---