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| Subject: | | Re: Which way does the refridgerant flow? |
| Date: | | June 03, 2003 at 23:58:04 |
| Posted by: | | The Prof on via: or 130.13.145.66 |
| In Reply to: | | The message posted by Richard on June 03, 2003 at 23:09:20: |
Richard, happy to help you out. lets take it in steps starting at the compressor since its a loop and we could start anywhere. (1)Compressor draws LOW PRESSURE HOT VAPOR refrigerant from the evaporator (suction port - large line), and compresses the vapor.
(2) HIGH PRESSURE HOT VAPOR from the compressor goes into the condensor. The vapor gives up its latent heat to the cooler outside air through the condensor and changes back to LIQUID (like steam back to water). Now its a HIGH PRESSURE LIQUID.
(3)The HIGH PRESSURE LIQUID now encounters an orifice (small opening) either an orifice tube or expansion valve. When the liquid squirts through this opening, its pressure is reduced and it gets very cold.
(4) The now LOW PRESSURE COLD LIQUID absorbs heat from the cab through the evaporator and the liquid inside turns into vapor (boils) (like water absorbing heat and turning to steam)except refrigerants boil at veeery low temperatures.
(4a) Note: If the orifice is an O-tube, under some conditions too much refrigerant might get into the evaporator and not all boil. An accumulator is hooked on the evaporator output to "accumulate" this excess liquid and prevent the liquid from reaching the compressor.
(5) This LOW PRESSURE HOT VAPOR from the evaporator is now drawn into the compressor. Back to step 1.
It may seems backwards that boiling causes cold but its a case of where does the HEAT go. When you boil water, it ABSORBS heat from someplace. That someplace had to give up that heat. That place then will be colder than it was. Consider when you place a piece of hot metal in water. If the metal is hot enough, it will boil the water. In the meantime, the metal gets colder. Neat huh?
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