Search results
Results From The WOW.Com Content Network
The higher temperature object has molecules with more kinetic energy; collisions between molecules distributes this kinetic energy until an object has the same kinetic energy throughout. Thermal conductivity , frequently represented by k , is a property that relates the rate of heat loss per unit area of a material to its rate of change of ...
Solutions of the heat equation are characterized by a gradual smoothing of the initial temperature distribution by the flow of heat from warmer to colder areas of an object. Generally, many different states and starting conditions will tend toward the same stable equilibrium. As a consequence, to reverse the solution and conclude something ...
Simple solutions for transient cooling of an object may be obtained when the internal thermal resistance within the object is small in comparison to the resistance to heat transfer away from the object's surface (by external conduction or convection), which is the condition for which the Biot number is less than about 0.1.
The third chart in each set was supplemented by Gröber in 1961, and this particular one shows the dimensionless heat transferred from the wall as a function of a dimensionless time variable. The vertical axis is a plot of Q / Q o , the ratio of actual heat transfer to the amount of total possible heat transfer before T = T ∞ .
That is, the method assumes that the temperature within the object is completely uniform, although its value may change over time. In this method, the ratio of the conductive heat resistance within the object to the convective heat transfer resistance across the object's boundary, known as the Biot number, is calculated.
The SI unit for heat capacity of an object is joule per kelvin (J/K or J⋅K −1). Since an increment of temperature of one degree Celsius is the same as an increment of one kelvin, that is the same unit as J/°C. The heat capacity of an object is an amount of energy divided by a temperature change, which has the dimension L 2 ⋅M⋅T −2 ...
The rate of heat flow is the amount of heat that is transferred per unit of time in some material, usually measured in watts (joules per second). Heat is the flow of thermal energy driven by thermal non-equilibrium, so the term 'heat flow' is a redundancy (i.e. a pleonasm).
Another way of stating this, is that the volume-specific heat capacity (volumetric heat capacity) of solid elements is roughly a constant. The molar volume of solid elements is very roughly constant, and (even more reliably) so also is the molar heat capacity for most solid substances. These two factors determine the volumetric heat capacity ...