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14.4 Heat Transfer Methods
The reverse process releases energy, so that dry ice is an effective coolant.
The amount of energy required is the same as for other transitions.
The material presented in this section and the preceding section can be used to calculate any number of effects related to temperature and phase change.
To apply the appropriate equation, it is necessary to identify which temperature and phase changes are taking place.
Both temperature and phase changes can be caused by heat transfer and work.
Determine if there is a change in the temperature or phase by examining the situation.
When the presence or absence of a phase change is not obvious, you may want to look at the temperature change obtained and see if there were no phase changes.
If you can take you past a boiling or melting point, then you should do the problem in steps.
List all objects that change temperature and phase.
Identifying the unknowns will help determine exactly what needs to be determined in the problem.
A written list can be useful.
Make a list of what is given and what can be inferred from the problem.
The unknown is the appropriate equation for the quantity to be determined.
If there is a temperature change, the transfer of heat depends on the specific heat and the transfer of heat depends on the latent heat.
Get numerical solutions complete with units by substituting the knowns along with their units into the equation.
If there is more than one stage to the process, you will need to do this in steps.
The temperature change does not cause a phase change that you have not taken into account.
Solid phase of water is formed from ice crystals.
It takes a certain amount of time for enormous heat to be accumulated from the air, even if the air is above.
The warmer the air is, the quicker the snow will melt.
The methods by which heat transfer occurs are equally fascinating.
heat transfer occurs when there is a temperature difference.
The walls of a picnic ice chest can be used to transfer heat.
We can control rates of heat transfer by choosing materials, such as thick wool clothing for the winter, controlling air movement, or using a white roof to reflect summer sunlight.
It is hard to imagine a situation in which no heat transfer occurs.
Every process involving heat transfer takes three methods.
The heat from the electric burner of the stove is transferred to the bottom of the pan.
In weather systems, this type of transfer takes place in a forced-air furnace.
Warming of the Earth by the Sun is an example.
There is thermal radiation from the human body.
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