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A cooling curve of naphthalene from liquid to solid. A cooling curve is a line graph that represents the change of phase of matter, typically from a gas to a solid or a liquid to a solid. The independent variable (X-axis) is time and the dependent variable (Y-axis) is temperature. [1] Below is an example of a cooling curve used in castings.
The law holds well for forced air and pumped liquid cooling, where the fluid velocity does not rise with increasing temperature difference. Newton's law is most closely obeyed in purely conduction-type cooling. However, the heat transfer coefficient is a function of the temperature difference in natural convective (buoyancy driven) heat transfer.
The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work (energy) required. [1] [2] Higher COPs equate to higher efficiency, lower energy (power) consumption and thus lower operating costs. The COP is used in thermodynamics.
There is also the peritectoid, a point where two solid phases combine into one solid phase during cooling. The inverse of this, when one solid phase transforms into two solid phases during cooling, is called the eutectoid. A complex phase diagram of great technological importance is that of the iron–carbon system for less than 7% carbon (see ...
The critical heat flux is an important point on the boiling curve and it may be desirable to operate a boiling process near this point. However, one could become cautious of dissipating heat in excess of this amount. Zuber, [6] through a hydrodynamic stability analysis of the problem has developed an expression to approximate this point.
The cooling produced in the Joule–Thomson expansion makes it a valuable tool in refrigeration. [8] [20] The effect is applied in the Linde technique as a standard process in the petrochemical industry, where the cooling effect is used to liquefy gases, and in many cryogenic applications (e.g. for the production of liquid oxygen, nitrogen, and ...
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Lumped system analysis often reduces the complexity of the equations to one first-order linear differential equation, in which case heating and cooling are described by a simple exponential solution, often referred to as Newton's law of cooling. System analysis by the lumped capacitance model is a common approximation in transient conduction ...