critical temperature


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Related to critical temperature: critical volume, triple point

critical temperature

[′krid·ə·kəl ′tem·prə·chər]
(agriculture)
The temperature below which a plant cannot grow.
(physical chemistry)
The temperature of the liquid-vapor critical point, that is, the temperature above which the substance has no liquid-vapor transition. Symbolized Tc.

Critical Temperature

 

(1) The temperature of a substance in its critical state. For single substances the critical temperature is defined as the temperature at which the physical properties of the liquid and the vapor in equilibrium become identical. At the critical temperature the density of the saturated vapor and the liquid become identical, the interface between them disappears, and the heat of vaporization becomes zero. The critical temperature is one of the constants of a substance. (For the value of the critical temperature Tc for some substances, see.)

In binary systems (for example, propane-isopentane) the fluid-vapor equilibrium has no single critical temperature but rather a spatial critical curve for which the terminal points are the critical temperatures of the pure components.

(2) The temperature in fluid mixtures having components of limited solubility at which the mutual solubility becomes unlimited; it is called the critical solution temperature.

(3) The transition temperature of a number of conductors into the superconducting state. It has been measured for a large number of metals, alloys, and chemical compounds. In pure metals the lowest critical temperature occurs in titanium (0.37°K) and the highest in technetium (11.2°K). A very high value has been found in the compound Nb3Ge (Tc ≈ 23°K).

critical temperature

1. The temperature at which a steel structure cannot carry the service load for which it was designed because of softening of the steel that occurs when it is heated significantly.

critical temperature

i. The temperature inside the cylinder of a reciprocating engine that will cause the fuel to explode rather than burn evenly when it is ignited.
ii. The temperature at which the internal structure of a metal takes on a crystalline form.
References in periodicals archive ?
From (14), (15) and the equation of parameter a for alloy [Cu.sub.3]Au in [10], we find the dependence of the critical temperature [T.sub.c] on pressure.
Because material was by then in short supply, critical temperatures were not determined by the multi-specimen procedure specified in ISO 13477.
Caption: FIGURE 3 GWP of fluids versus critical temperature and flammability.
Caption: FIGURE 8: Critical temperatures of the beam with different geometric parameters of cracks.
For the other fuels, the rail pressure drop during the warm-up phase was expected to occur at higher fuel temperatures according to their components and their critical temperatures. The results of all investigated warm-up phases are summarized in Figure 3 in terms of the estimated fuel temperature inside the HPP to the time, when the first rail pressure drop was observed during the measurement.
Variations of critical temperature and natural frequency with the linear temperature change for initially stressed laminate plates are shown in Tables 8-9.
There is a critical temperature [T.sub.u] at which the emission rate of ultrafine particles increases stepwise by 4 to 6 orders of magnitude.
Ground taxi with light braking does not appreciably heat up the wheels or brakes, and the thermal fuse-plugs do not reach the critical temperature during routine ground taxi operations.
With these components, formulators can determine the critical temperature before lyophilization begins, saving time and money associated with trial and error freeze dry attempts.
These periodic fluctuations in the distribution of the electrical charges are what destabilize the superconducting state above the critical temperature.
Binders used in Europe with an upper PG of 82 typically exhibit critical temperature of -6[degrees]C to -12[degrees]C.
Critical temperature predicted the temperature (reported in K) above which the gas form of the structure cannot be liquefied, no matter the applied pressure.

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