Heating and cooling curves

These relays also possess characteristics similar to those of a bimetallic relay and closely match the motor heating and cooling curves. They are basically made of a low-melting eutectic alloy which has defined melting properties. The alloy, with specific proportions of constituent metals such as tin, nickel and silver, can be made for different but specific melting temperatures. This property of the alloy is used in detecting the motor s operating conditions. 

Figure 12.31 Heating and cooling curves of an intermittent duty motor...

In Figure 8.5, w is the distance between the heating and cooling curves at the point where a = 0.5 is called the hysteresis width. This temperature may be quite small, or it may amount to several degrees depending on the nature of the phase transition and the heating rate. Many substances exhibit this type of behavior as a result of a phase change. 

FIG. 1.— Comparison of the Variation of Optical Rotation with Temperature for Native K-Carrageenan (—) and Segmented K-Carrageenan (—). [Heating and cooling curves are distinguished by the arrows. Measurements were made at 546 nm with 3% (w/v) solutions. The gel point (G) and liquefaction point (L) are shown.]... 

An unusual state of matter An unusual change of state Heating and cooling curves... 

From the simple model [Eq. (XIV.3.1)] it is possible to solve for the mean temperature of the reacting mixture at the stationary state Ts and also for the ignition temperature T. These two temperatures are determined by the two points of intersection of the heating and cooling curves (Fig. XIV. 1). By rewriting Eq. (XIV.3.1) these temperatures are given by the two lowest roots of the transcendental equation... 

Figure 4.6 Heating and cooling curves for a heat exchanger.

Other experimental factors that can influence the quality of the DSC measurement and the information that can be extracted from it are sample mass, particle size, the presence of impurities, the shape of the crystalline particles and the presence of nuclei or seeds of various polymorphs. For the investigation of solvates (pseudopolymorphism), the sample pan type also plays an important role (Giron 1995). Threlfall (1995) recommends routinely running both heating and cooling curves, while Perrenot and Widmann (1994) demonstrated the additional information that can be obtained by carrying out multiple heating runs on a particular sample. 

Fig. 21. Composite heating and cooling curves for alternative solutions.

Transition temperatures and heats were obtained from differential heating and cooling curves both at atmospheric and higher pressures by Goranson and Kracek (7). Existence of three phases is confirmed by the earlier birefringence studies of Boeke (8 ). 

The adopted melting data were measured by the differential heating and cooling curve method by Goranson and Kracek (7). Riccardi and Sinistri ( ) found the melting point at 971 K with - 7.52 kcal mol by differential thermal analysis. 

Figure 4. Heating and cooling curve of PSPCHOL I with a heating- (cooling-) rate of 20 C/min. (Reproduced with permission from reference 8. Copyright 1989 Huthig and Wepf Verlag, Basel.)...

Figure 10. Heating and cooling curves for a cluster of (TeFeig crossed circles are on the heating curve, and crosses are on the cooling curve.

Describe how the molecular motion changed during each segment of the heating and cooling curves. 

FIGURE 4.1 Differential scanning calorimetry heating and cooling curves of glyceryl tri-palmitate (Dyn 116) bulk material, with microparticles prepared by solvent evaporation and microparticles prepared by melt dispersion 1 d after the preparation. The plots are displaced vertically for better visualization. (Adapted from [13] with permission from Elsevier.)... 

Calorimetric measurements at a salt concentration of 0.8 M (NaCl) were carried out with a differential scanning microcalorimeter microDSC III (Setaram, Caluire, France). The melting of naphthalene was used to calibrate the apparatus. The sample cell was filled with 850 mg carrageenan solution (0.2% w/w in 0.8M NaCl) and the reference cell with exactly the same amount of NaCl solution. Heating and cooling curves were recorded in the temperature range from 10 to 120°C at a rate of 1.0°C min-1. 

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