Carrier temperatures

If we also consider that the reactor is heated to a constant heat carrier temperature (Tc), the heat balance in Equation 9.2 becomes... 

The thermal time constant is only one aspect of reactor dynamics. In practice, the heat carrier temperature cannot be adjusted instantaneously at industrial scale, as it has its own dynamics, depending on the equipment and the temperature control algorithm. These aspects of the dynamics of the heat exchange and temperature control systems are considered in the next sections. 

Figure 9.13 Heating curve of a reactor heated with a constant heat carrier temperature of 100°C.

This expresses that the reactor contents temperature approaches the heat carrier temperature asymptotically, following an exponential law (Figure 9.13). 

Required heat carrier temperature (Tc) to reach the temperature (T), starting from (T0) within a given time (t) ... 

The set point of the heat carrier temperature is calculated proportionally to the deviation of the reactor temperature from its set point ... 

In such a case, it is recommended to limit the heat carrier temperature and to install a trip between pressure (vacuum) and the heating system. 

The self-consistent theoretical models based on the Boltzmann transport theory are used to characterize the microscale heat transfer mechanism by explaining mutual interactions among lattice temperature, and number density and temperature of carriers [12]. Especially, a new parameter related with non-equilibrium durability is introduced and its characteristics for various laser pulses and fluences are discussed. This study also investigates the temporal characteristics of carrier temperature distribution, such as the one- and two-peak structures, according to laser pulses and fluences, and establishes a regime criterion between one-peak and two-peak sttuctures for picosecond laser pulses. 

As for the carrier temperature much higher than the lattice temperatiu e owing to the ultt a-short pulse laser heating, especially, a consistent theoretical model should be developed to be able to mimic the non-equilibrium between carriers and lattice. In the case that photons incident on semiconductor have energy greater than the band gap energy of the material, the main heat carrier is an electi-on-hole pair, whereas it is the free electron for metals [11, 17, 18]. 

The influence of laser fluence and pulse duration time on microscale heat tiansfer mechanisms are investigated by using one-dimensional said transient equations of eerier and lattice temperatures. The scale difference between energy relaxation and laser pulse duration times results in file fiiermal non-equilibriimi state fiiat can be controlled by laser fluence as well as pulse dmation time. In the case fiiat a few picosecond pulse laser is irradiated over file semiconductor surface with relatively hi fluence, a two-peak structme in file carrier temperature variation can be observed. As pulse dmation increases, file m imiun eerier temperature and file number density decrease, whereas file lattice temperature is nearly of constant values. Meanwhile, the two-peak structme due to Auger heating disappears and converts into the one-peak stinctme as file laser fluence decreases. 

STABILITY POISONS When water vapor is present in the sulfur dioxide-air mixture supplied to a platinum-alumina catalyst, a decrease in oxidation activity occurs. This type of poisoning is due to the effect of water on the structure of the alumina carrier. Temperature has a pronounced ejffect on... 

General advantages of facilitated transport membranes are improved selectivity, increased flux and, especially if compared with membrane contactors, the possibility to use expensive carriers. The specific prerequisites, advantages and disadvantages connected the mobile carriers, are reported in Table 7.1. So far, mainly conventional liquid membranes have been loaded with different mobile carrier systems to obtain facilitated transport properties [3]. Problems encountered are (evaporative) loss of solvent and carrier, temperature limitations, a too large membrane thickness and therefore too low permeabilities as weU as a limited solubility of the carrier in the liquid medium. The low fluxes achieved have, untU now, limited their application... 

Xi Y., Xi J.-Q., Gessmann Th., Shah J. M., Kim J. K., Schubert E. F., Fisher A. J., Crawford M. H., Bogart K. H.A, Allerman A. A. Junction and carrier temperature measurements in deep ultraviolet light-emitting diodes using three different methods Appl. Phys. Lett. 86, 031907... 

Substance Energy Gap, E, in E/2 kT) eV Room Temperature Electrical Resistivity, ohm cm Mobility, E) cmVV-s Sign of Majority Carriers Temperature Range, "C Ref. 

Poor resolution] carrier concentration incorrect/wrong carrier/temperature too high/flow rate too fast. 

Nonequilibrium suppression of generation-recombination occiu only in a relatively narrow range of carrier energies. If carrier temperature is equal to the lattice temperature Tj or close to it, the nonequilibrium is insufficient to cause significant suppression. If opposite is the case, hot carrier effects (e.g., impact ionization) may obliterate any benefits stemming from the nonequilibrium transport. 

We will assume that the temperature in the expressions for Auger generation and recombination (as given in Sects. 1.4.2 and 1.4.6) actually represents carrier temperature. The increase of external fields above the hmit of hot carrier effects means an increase of Auger generation. At the same time expressions for it as quoted in Sect. 1.4 cease to be valid. 

One of the approaches to estimate the effects of scattering mechanisms is to consider carrier temperature increase due to a particular mechanism [340]. In narrow-bandgap materials for a temperature range between 200 K and room temperature the prevaihng mechanism is polar optical phonon scattering [13]. The increase of carrier temperature due to this mechanism is [341]... 

Cleaning of sample carrier Temperature rise time Inlet temperature Ionization... 

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