# COP Heat Pumps

N

#### News

Jan 1, 1970
0
Does anyone know how COP relates to temperature rise. That is, if the
ground is 10C and a heat pumps is rated at COP 4, what temperature would the
heat pump recover? What would COP 3 produce at 10C?

S

#### [email protected]

Jan 1, 1970
0
Does anyone know how COP relates to temperature rise.

COP is coefficient of performance, it's a dimensionless number but
will be dependent on temperature rise, so if the heat pump is capable
of moving heat from the low temperature reservoir to the higher
temperature dump then the COP for that temperature difference tells
you how much heat will be put in the dump for every unit of energy
used in the pump.

That is, if the
ground is 10C and a heat pumps is rated at COP 4, what temperature would the
heat pump recover? What would COP 3 produce at 10C?

You need to specify both the low temperature reservoir and the heat
dump temperatures.

So if the pump is rated at a COP of 3 with the lower reservoir at 10C
and a dump at 21C then for every kWhr of electricity put into the
device it will release 3 kWhrs into the higher temperature.

As the delta t between cold and hot increases the COP will fall,
ultimately to the point that the difference is to great fro the
refrigerant to work at.

I'd quite like to know the COP of a natural gas liquifying unit.

AJH

L

#### ledbalon

Jan 1, 1970
0
News said:
Does anyone know how COP relates to temperature rise. That is, if the
ground is 10C and a heat pumps is rated at COP 4, what temperature would the
heat pump recover? What would COP 3 produce at 10C?
Cop is just a factor of how much energy one can remove compaired to how
much energy is put in. So a COP of 1 means 100% in 100% out

COP 3 means 100% in and you can extract 300% work out.

The increase is due to latent energy that is in the ground or water
(lake) So you are not getting over unity.. you are just pulling the
energy from a different source.

So.. if you had a compressor 1 ton its abilty to move temp would be 3
times the input ... not the same as a 3 ton compressor.

or three tons is an equivilant in the energy to pull the same temp.

so .. what the heck does this mean? Say it costs $100 a month to run the compressor. A COP of 3 would mean you would get the same out put but would cost you$33 a month to run. Hope this does not confuse.

SteveP

N

#### [email protected]

Jan 1, 1970
0
ledbalon said:
The increase is due to latent energy that is in the ground or water

"Latent" means phase change, eg freezing or condensing.

Nick

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