Why cant it be used in a closed loop system.
2007-10-16 13:56:04 · 6 answers · asked by theroadwetake 3 in Science & Mathematics ➔ Engineering
http://www.youtube.com/watch?v=yh_-DUKQ4Uw
2007-10-16 14:05:48 · update #1
The heat balance for a heat pump is:
energy in in compressor + heat in in evaporator = heat out in condenser
Typically the energy required to run the compressor may (depending on the temperature difference between evaporator and condenser) be one third of the energy (heat) given out in the condenser. The circuit is in effect 'pumping' heat. I am not sure what you are getting at with the reference to a closed loop system.
2007-10-16 14:40:47 · answer #1 · answered by Robert A 5 · 0⤊ 0⤋
No device or machine has an efficiency of 100% or more. Do not confuse mechanical efficiency of the refrigeration motor/compressor with Coefficient of Performance of the whole system of devices which are involved. This overall performance is calculated differently. This applies to both air conditioners and heat pumps (reverse-cycle air conditioners). Actually, both are classified as "heat pumps".
The refrigerant is already in a closed loop system. The compressor is only part of the energy transfers which are occurring.
Energy is not being produced - as would be the implication when a supposed efficiency of over 100% is stated.
The Coefficient shows the energy consumed versus the net heat transfer accomplished. For most "heat pumps" when cooling or heating, this will often be over 1.0 . Depending on the outside temperature a heating heat pump can have a Coefficient of 3 - 4 at around 40-30 deg F. It will diminish as the outside temperature drops and will be less than 1.0 at very cold temperatures. All the while, the motor/compressor efficiency will remain about the same.
2007-10-17 01:33:44 · answer #2 · answered by Bomba 7 · 1⤊ 0⤋
The statement that a heat pump is more than 100% efficient is not quite true. It is delivering more work than it uses in electricity, but it is drawing from or giving energy to the environment. Actually there are losses in the heat pump system, but their effect is more than made up by the ability to receive from and give energy to the air or ground.
2007-10-17 00:55:23 · answer #3 · answered by Ed 6 · 0⤊ 0⤋
Efficiency is defined mathematically as a ratio of output (quantity) divided by input (quantity).
In a heat pump, the only energy you are purchasing or putting to work directly is the energy required to power an electric motor.
The heat energy you are tapping into and exchanging is provided free by the sun, the earth, a lake, the atmosphere.
So even though it seems illogical, by the mathematical understanding of efficiency, yes a heat pump exceeds 100%.
It may seem like "cheating" but who would argue the value of a heat pump!
2007-10-16 21:37:00 · answer #4 · answered by Anonymous · 0⤊ 1⤋
No machine has even 100% efficiency. There are always some losses like friction and heat which will drop the efficiency.
2007-10-16 21:00:38 · answer #5 · answered by Norrie 7 · 0⤊ 1⤋
Yes.Up to 400%.It takes energy from the out side
2007-10-16 21:03:56 · answer #6 · answered by JAMES 4 · 0⤊ 2⤋