what really happens in refrigeration cycle.
2007-03-17 03:52:56 · 5 answers · asked by RAJ K 1 in Science & Mathematics ➔ Engineering
what is the condition for evaporation and boiling.what happens in refrigeration cycle.
2007-03-17 04:04:32 · update #1
When something evaporates it is due to its vapor pressure. If water is in a room with no humidity, the water will evaporate because there is a pressure gradient between the vapor pressure of the water and the pressure of the humidity in the room. However, if the humidity in the room is the same as the vapor pressure of the water it will not evaporate.
When something boils, its vapor pressure is at atmospheric pressure that is 14.7 psia. Water boils at 212F at atmospheric pressure. Now if you pull a vacuum on the water it will boil at a lower temperature. This is refereed to as lowering the bubble point. Liquids with high vapor pressures actually have very low boiling points. For instance, butane actually boils at 31F. Cool huh?
Refrigeration is caused when you compress and expand a vapor. The compressed vapor will increase in temperature. The compressed vapor is then passed thru a condenser where it is cooled to near ambient temperature. The vapor is then expanded. When the vapor is expanded it undergoes what is called a Joule Thomson effect. That is the vapor will cool to a lower temp than ambient. That is refrigeration.
This is just a little tidbit Hydrogen does not cool when it is expanded. It actually heats up.
2007-03-17 07:19:55 · answer #1 · answered by Scott S 4 · 0⤊ 0⤋
Boiling occurs at a fixed temperature only. Like, water boils only at 100 degrees.
Evaporation on the other hand can occur at any temperature. Water can evaporate even at room temperature.
Basically both are the same processes, liquids turning into gases.
2007-03-17 05:07:09 · answer #2 · answered by nayanmange 4 · 0⤊ 0⤋
Essentially, what happens for both occurence is that water molecules gain enough energy to 'escape'.
The main difference is that evaporation occurs at surface level while boiling is the whole mass of water.
2007-03-17 04:21:17 · answer #3 · answered by ? 2 · 0⤊ 0⤋
evaporation is a natural process while boiling is a man made process .
evaporation takes place from the surface while boiling starts from the bottom.
2007-03-17 04:07:45 · answer #4 · answered by sth 2 · 1⤊ 0⤋
boiling causes evaporation. u kno.. as the sun heats up the ocean it boils and the water evaporates...
2007-03-17 03:58:06 · answer #5 · answered by BlueSmiley 3 · 0⤊ 0⤋