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The term subcooling (also called undercooling) refers to the intentional process of cooling a liquid below its normal boiling point. For example, water boils at 373 K; at room temperature (293 K) liquid water is termed "subcooled". Subcooling is a common stage in refrigeration cycles and steam turbine cycles.
It is possible, at a given pressure, to superheat a liquid above its boiling point without it becoming gaseous. Supercooling should not be confused with freezing-point depression. Supercooling is the cooling of a liquid below its freezing point without it becoming solid.
Superheating can occur when an undisturbed container of water is heated in a microwave oven.At the time the container is removed, the lack of nucleation sites prevents boiling, leaving the surface calm.
The incorporation of a subcooling stage after the receiver reduces even more the chances to observe flash gas. [5] This subcooling may be done in a reserved portion of the main condenser, or separately with a heat exchanger. Some receivers may incorporate an internal heat exchanger that draws heat form the subcooled liquid to superheat the gas ...
A realistic indication of energy efficiency over an entire year can be achieved by using seasonal COP or seasonal coefficient of performance (SCOP) for heat. Seasonal energy efficiency ratio (SEER) is mostly used for air conditioning. SCOP is a new methodology that gives a better indication of expected real-life performance, using COP can be ...
The energy required to heat water is significantly lower than that needed to vaporize it, for example for steam distillation [10] and the energy is easier to recycle using heat exchangers. The energy requirements can be calculated from steam tables. For example, to heat water from 25 °C to steam at 250 °C at 1 atm requires 2869 kJ/kg.
Non-resting energy expenditure, or NREE, is all the energy your body uses outside of rest. It’s a broad category that includes a few key components : Thermic effect of food (TEF).
By the principle of minimum energy, there are a number of other state functions which may be defined which have the dimensions of energy and which are minimized according to the second law under certain conditions other than constant entropy. These are called thermodynamic potentials. For each such potential, the relevant fundamental equation ...