Caloric Effect

A to B, while a temperature drop, ATad, is observed during the adiabatic process A C. The maximum magnetic entropy for a system with a spin s, ftln(2s+ 1), reached at infinite temperatures, is indicated as a grey broken line. 

A significant increase in the specific maximum entropic change was achieved by substituting the fumaric acid with the much smaller formic acid, as reported in Table 4.1 where data for a selection of networks based on gadolinium 

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The useful portion of the magneto-caloric effect is typically about 25°C on either side of the material s Curie temperature. Therefore, in order to span over a wide temperature range, a refrigerator must contain several different coolants arranged according to their differing ordering temperatures. 

Magnetic refrigeration offers high thermodynamic efficiencies due to the reversibility of the magneto-caloric effect. For active magnetic regeneration... 

It is natural that pectin, a normal constituent of fruits and berries, should be used with these foods when thickening and gelation are required. Although pectin does give nearly the same caloric effect upon digestion as does sucrose, it imparts a desirable body and viscosity to fruit juices at a much lower concentration than does sucrose. Knowledge of this fact is used in many canned fruits and berries prepared especially for dietetic purposes. 

Similar to the conclusions drawn from Table 2 (vide supra) with respect to the caloric effects, we now find in view of Table 4 that the good agreement between the diffusivities obtained for benzene in MFI structures through... 

Let us try to examine these phenomena from the angle of causality principle. Taking the example of thermo-osmosis (Chapter 3), temperature difference is the starting cause, the effect of which is thermo-osmotic fluid flow, which in turn generates another cause, viz. pressure difference under specific circumstances (e.g. experimental set-up), the effect of which is hydrodynamic fluid flow in the reverse direction. Normally, both these causes and effects operate simultaneously. However, when two opposing flows are balanced, a steady state is reached. Similar type of situation occurs in other steady-state phenomena discussed in Chapters 4-6 including mechano-caloric effect. 

Simultaneous thermal analysis (STA) refers to the simultaneous application of two or more thermoan-alytical methods on one sample at the same time, such as DTA and thermoconductivity. In practice, however, this term is mostly used for simultaneous measurement of the mass changes and caloric effects on a sample under thermal treatment. The benefits are (i) information on transformation energetics and mass change in one run, under identical conditions (ii) time saving and (Hi) no differences in sample composition for the various thermal measurements - important for non-homogeneous sample materials. Although TG-DSC and TG-DTA are the most widely used of the simultaneous techniques due to... 

The transition in several polymers and />-alkanes has been identified by DSC measurements performed by Boyer and co-workers. - Generally, an endothermic change of slope is observed at However the caloric effect is quite weak and difficulties may arise from oxidation effects. Other authors could not confirm the findings of Boyer for n-tetracosane2S.28 even though running very sensitive calorimeters, too. Thus, the possible caloric effects of the transition seem to be not as easily detectable as the other physical effects already reported. 

Two years later came the very important paper On the Caloric Effects of Magneto-Electricity, and on the Mechanical Value of Heat. In this paper he demonstrated that the heat caused by the passage of an electric current is not transferred from another part of the circuit, which is correspondingly cooled,... but is actually generated. In his own words, he showed that ... 

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