Primary temperature

For the same polymer this parameter has values of 4.47 X 10" and 5.01 X 10 " kg sec" at 298 and 398 K, respectively. Since density is far less sensitive to temperature, these results show that the primary temperature dependence of viscosity is described by the temperature dependence of f. 

The reactor coolant pH is controlled using lithium-7 hydroxide [72255-97-17, LiOH. Reactor coolant pH at 300°C, as a function of boric acid and lithium hydroxide concentrations, is shown in Figure 3 (4). A pure boric acid solution is only slightly more acidic than pure water, 5.6 at 300°C, because of the relatively low ionisation of boric acid at operating primary temperatures (see Boron COMPOUNDS). Thus the presence of lithium hydroxide, which has a much higher ionisation, increases the pH ca 1—2 units above that of pure water at operating temperatures. This leads to a reduction in corrosion rates of system materials (see Hydrogen-ION activity). 

Determination of T y. In the formulation of the phase equilibrium problem presented earlier, component chemical potentials were separated into three terms (1) 0, which expresses the primary temperature dependence, (2) solution mole fractions, which represent the primary composition dependence (ideal entropic contribution), and (3) 1, which accounts for relative mixture nonidealities. Because little data about the experimental properties of solutions exist, Tg is usually evaluated by imposing a model to describe the behavior of the liquid and solid mixtures and estimating model parameters by semiempirical methods or fitting limited segments of the phase diagram. Various solution models used to describe the liquid and solid mixtures are discussed in the following sections, and the behavior of T % is presented. 

Primary Temperature Points Defined by the International Practical Temperature Scale (IPTS-90)... 

However, in addition to these primary reference points, a secondary series of reference points was established by the IPTS-68 (see Table 2.30). These secondary points can more easily be used (than the primary temperature points) for testing temperature equipment such as liquid-in-glass thermometers. They are useful because they require less equipment and are therefore easier to obtain. Remember that these points are secondary standards and should not be considered primary standards. 

In the SUPRAYIELD process, the delayed decompression is a degenerated flash process slowed down to such an extent that the period of time for going from a high primary pressure to a lower secondary pressure corresponds to the reaction time needed for the desired conversion of pentosan to furfural. To make this a practical proposition, the primary temperature must be high, say 240 °C, and the secondary temperature should not be below 180 °C as in this range the reaction rate would be too slow. 

As after heating the reactor to the primary temperature the pressure in the vessel is high, the delayed decompression can be readily effected and controlled by a simple leak valve. In special cases, when the primary temperature is limited by the available steam pres-... 

Losses can occur only during the short heating period when the reaction medium is not yet boiling. For this reason, the heating to the primary temperature should be an inverse flash , as fast as possible. 

Depending on the primary temperature, the process can be run with or without a foreign acid. The higher the primary temperature, the smaller is the need for a foreign acid. 

The two primary temperature-sensing devices used in the CPI are thermocouples (TCs) and resistance thermometer detectors (RTDs). Thermocouples are less expensive and more rugged than RTDs but are an order of magnitude less precise than RTDs. Typically, RTDs should be used for important temperature control points, such as on reactors and distillation columns. 

The small reactor is designed with low pressure and low primary coolant temperature in comparison with standard 900 MW(e) reactors. It was pointed out that lower primary temperature leads to ... 

When NSSS is in operation, temperature in the central cavity of the pressurizer is settled at 120° C, i.e. these are conditions of minimum nitrogen solubility in water. Besides, sequential connection of the reactor annulus and peripheral and central cavities allows to operate the pressurizer as hydraulic siphon gas being accumulated in the upper part of the reactor or in peripheral cavity of the pressurizer will flow under fluctuation of the primary temperature to the central cavity and adds to total mass of gas. 

Structural mechanics analysis indicates that the acceptable temperature difference between the primary temperatures from IHX outlets is about 40 K. Thermal hydraulics analysis indicates that with one module isolated in one loop, the temperature difference is 10 K at 90 % power. With 2 modules isolated, this temperature difference is 24 K at 67 % power. To achieve this, it is necessary to reduce the core flow (to 67 %) in proportion to the power as well as the sodium flow in the unaffected loop (50 %) as in the affected loop (50 %) The... 

The method of differential scanning calorimetry (DSC) was used to delme temperature transitions and evaluate the phase state of blocks in PC PTMO. Investigations of PC and PC PTMO block copolymer resins were carried out with the help of seaiming ealorimeter DSK-2 ( by the firm Perkin-Almer ) in the temperature interval from 173 to 523 K at the heating speed 40° a minute. The measurement accuracy was 1-2 degrees. After the first scanning the specimen was quenched up to the primary temperature and the hardened specimen was scanned again. 

Most of the tests [2] consist of an initial self-steady state in which a pulse-wise perturbation induces a transient. In this case the perturbation is a thermal unbalance as severe as possible, e.g. thermal power increase by 12 kW (about 5% of the full power) during 150 seconds. Primary pressure and circulating flow evolve mildly, with increases below 2 and 3% respectively, and primary temperatures hardly notice the perturbation. Therefore steam generation remains quite stable during the whole transient, a remarkable feature of the Steam Supply System (Fig. 2). 

The cooling system will dissipate 1.0 MW year round with primary temperatures approximately as indicated in Figure 16. The system components have enough capacity to enable dissipation of at least 2 MW for wet bulb temperatures less than 75°F. 

The third environmental stimulus that has been used with polyelectrolytes and zwitterionic polymer systems is temperature. As with pH and salt, the primary temperature-induced response is a change in the conformational state of the polymer structure. The conformational state change is caused by one or more of the monomers passing through its lower critical solution temperature (LCST). This has been demonstrated in polyelectrolytes and zwitterionic polymers, where the charged monomers are responsible for the change, and in systems in which an additional temperature-sensitive monomer is included as a copolymer. 

Fully integrated primary pumps Confirmation of the possibility to build such pumps for operation at primary temperature conditions... 

When the vessel is opened, especially during refuelling, decay heat is removed by the twelve RRPa cooled by chilled water to obtain a very low primary temperature compatible with the conditions of maintenance. The primary circuit operates in a natural convection mode and the RRPa loops operate with a forced circulation. 

The question to be answered is what can be adjusted, other than tenderature, that will affect the reaction rate and/or the conversion. In the reaction rate expression, the primary temperature effect is in the Arrhenius expression. For gas-phase reactions, assuming ideal gas behavior, the concentrations c,- = P/i r. The increase in tenperature discussed in Exanple 19.1 will actually reduce the concentrations however, the exponential increase in the reaction rate constant is the primary effect. It is also observed that increasing the pressure increases the concentration, thereby increasing the reaction rate. There is an additional effect. This can be seen from the equation of a plug flow reactor. 

Pig. 4.33. Growth of a lamella in-between two tilted crystallites. At the primary temperature To growth stops at first and then proceeds continuously upon cooling to Ti and T2, accompanied by a crystallite thinning... 

A 1.1 Principle—This section of the Annex deals with the basic calibration of the vapor temperature sensor against primary temperature standards as recommended by the National Institute for Science and Technology (NIST) in order to avoid the problems associated with the use of secondary temperature references. It can also be used for the calibration of other temperature sensors. 

A2.4.1 A suitable apparatus for primary temperature reference is shown in Fig. A2.1. For the freezing point of... 

Cooke, el al. Review of Scientific Instrument, Vol 32, 1961, p. 780. TABLE A2.1 Primary Temperature Standards (Melting Points)... 

A2.S.2.1 This practice is not regarded as primary temperature reference but is acceptable for routine laboratory use. 

Primary temperature increasing due to reduced coolant mass flow rate though the core... 

For the single-phase case, the natural circulation flowrate is found by integration of the loop momentum equation and coupling this to the energy equation. Thus, the primary temperature increase is given by the standard result. 

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