Adiabatic control

Adiabatic. Control gas flow and/or solids feed rate so that the heat of reaction is removed as sensible heat in off gases and solids or heat supphed by gases or solids. 

For our estimations and the adiabatic control volume in Figure 4.10, 7b should be the adiabatic flame temperature. Consider a fuel-lean case in which no excess fuel leaves the control volume. All the fuel is burned. Then by the conservation of species,... 

Adiabatic control of bond distance in selective non Franck-Condon transitions... 

Consider, to be specific, a molecule like Na2. In Fig. 1(a) we show some singlet electronic potential curves. A selective transition between the initial state (x) and the ground state of the excited potential Vn3(a ), o(x), is highly non Franck-Condon and thus involves a large displacement of the molecular bond. If the transition between these states can be adiabatically controlled, then it will be in principle possible to follow or control the bond length as the transition proceeds. The first problem involves the smallness of... 

Adiabatic control of bond distance in selective non Franc K-Cond on transitions I. -Ft. Solo. B.-Y. Chang. V.-S. Malinovsky and. San la maria 127... 

It is obvious that adiabatic control is not appropriate for every reaction the adiabatic temperature rise must be limited to moderate values in order to avoid too high a final temperature. Thus, only moderately exothermal reactions can be performed under adiabatic conditions. 

It fill is section we show how strong fields can be used to adiabatically control... 

The self-heating process, of 2 cm of a chemical of the TD type charged in the open-eup cell, or confined in the closed ceil, in accordance with the self-heating property of the chemical, and subjected to the adiabatic self-healing test started from a 7[, recorded for the time, A t, required for the temperature of the chemical to increase by the definite value of T of 1.25 K from the F,., is shown in Fig, 15. The adiabatic control and the record of the self-heating process, in the early stages, of 2 cm of the chemical are started at the point of time s in Fig. 15, respectively. The higher the 7, the shorter becomes the time... 

The PID-SCR temperature control technique is adopted for the adiabatic control. Besides, other devices are also adopted to attain as complete an adiabatic control as possible. To cite an instance, a pre-amplifier is incorporated before the PID controller to amplify the A i.e., the temperature difference between the temperature of 2 cm of a chemical of the TD type, including every gas-penneable oxidatively-heating substance, and the T),. A zero suppression circuit is composed of this amplifier to cancel the slight stray-, or pseudo-, Ihermoelcctromotive force of the differential thermocouple. Such a pscudo-ihcmioclcctromolivc force of a differential thermocouple may still appear even if the temperature of 2 cm of the chemical and the r , . are physically the same, and even if the two thermocouples to make up the differential thermocouple are... 

The adiabatic control is performed between the temperature of 2 cm of the chemical and the Tam, not between the temperature of 2 cm of the chemical and that of the inside wall of the adiabatic jacket, in order to hold the chemical under true adiabatic conditions. 

On the other hand, it is apparent to us in Fig. 22 that, as the temperature of the composite rises away from the 7, at each rate of electric heat generation, the adiabatic control becomes gradually broken. As stated in Subsection 4.4.6, die glass closed cell used in the recorder is not perfcclly explosion-proof besides. Therefore, the adiabatic self-healing process recorder is not appropriate for the record of the whole self-heating process up to the thermal explosion of 2 cm of... 

It is, however, evident that this recorder requires still considerable improvements, in particular, regarding the performance of the adiabatic control. 

Once the indicator of the analog D.C. microvoltmeter reaches the graduation line of zero at the center of the scale span of the meter, the adiabatic control by means of the adiabatic self-heating process recorder and the record of the selfheating process, in the early stages, of 2 cm of the chemical confined in the... 

Record of the self-heating process, in the early stages, of 2 cm of a chemical of the TD type confined in the closed cell and inserted into the adiabatic jacket kept always at the very slowly increasing temperature of the chemical itself by the adiabatic control... 

After the start of the adiabatic control, the Tam is raised automatically by the adiabatic control in order that the condition, A Tsjf = T - Ta, , = 0, may always hold, with the result that the heat generated in the self-heating chemical is all accumulated in it, and, it continues to self-heat at a very slow, but virtually constant, rate depending on the value of T/, in the meantime, the temperature of the space in the air bath, except that in the adiabatic jacket, is maintained at the Ts of the run throughout every run. 

In the meantime, the A Tdijf pen runs almost parallel with the time axis on the strip chart of the two-pen strip-chart recorder after the start of the adiabatic control. This denotes that the state, A - T - Tqiiii 0, IS rcslizcd. in 8.nd around 2 cm of the chemical confined in the closed cell and subjected to the adiabatic self-heating test. The A Tdiff pen, however, comes to drift toward the plus side on the strip chart in the course of time. This denotes that the state, 7 > Tam, comes to occur in and around 2 cm of the chemical confined in the closed cell, in spite of the adiabatic control, because the rate of increase in temperature, i.e., the rate of the exothermic decomposition reaction, of 2 cm of the chemical confined in the closed cell and subjected to the adiabatic self-heating test... 

Effect of the range of the pre-amplifier on the precision of the adiabatic control... 

It has been ascertained, in result, that the rate of increase in temperature of the mixture decreases gradually at ranges above 100 yV, but the rate is kept almost constant at ranges below 50 iN (Fig. 40). Therefore, 50 /iV has been chosen as the standard range of the pre-amplifier of the recorder in the two kinds of adiabatic tests, considering Ihe stability of the adiabatic control as well. 

The self-heating process, in the early stages, of 1.2 g of AIBN confined in the closed cell and inserted into the adiabatic jacket kept always at the very slowly increasing temperature of AIBN itself by the adiabatic control is recorded in the digital representation as the variation of the value, with time, of the thermoelectromotive force of the thermocouple to measure the temperature of AIBN to put it concretely, the numerical value of the thermoelectromotive force of the thermocouple is printed out every minute by means of the digital D.C. millivolt recorder, in such a manner as exemplified in Table 5 presented in Section 4.7, in order to utilize the record for the calculation of the values of the... 

The heater is able to heat the atmosphere in the jacket at the maximum heating rate of 20 K/min in order that, even if some oxidizing gas is supplied into the jacket at the maximum flow rate of 20 cm /min, the condition, A Tjijf= T - Tam = 0, may hold while the adiabatic control is performed for the oxidatively-heating process, in the early stages, of the substance. The other points are the same as those described in Subsection 4.2.2. 

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