Continuing from
http://www.ata.org.au/forums/topic/4384#post-31362
the COP values for a heat pump that uses CO2 for its refrigerant is included as the purple-coloured line with asterisk-markers in Chart 1(5) below
.

.
Domestic hot water is heated to 60degC to kill micro-organsims.
The performance of a non-CO2 heat pump (e.g. Siddons) when it delivers heat at 60degC is shown by the line "Output Heat at 60degC". The line gives the COP value (Y-axis) for each input temperature (X-axis).
The performance of a CO2 heat pump (e.g. Sanden) when it delivers heat at 60degC is shown by the line "CO2 Output Heat at 60degC".
For heat pumps that are delivering heat at 60degC, the Chart shows that if the heat is collected at zero degC (e.g. from outside-air, at night in winter) this CO2 heat pump has COP=3.5 compared with COP=2.4 on the line for this non-CO2 heat pump.
The different COP values mean that the number of kWh of electricity (and the annual running cost $) used by the non-CO2 heat pump will be
100 x 2.4 / 3.5 is 69%
of the kWh (and $) used by the CO2 heat pump.
The Chart shows that if the heat is collected from warmer-outside-air at 10degC this CO2 heat pump has COP=4.2 compared with COP=2.8 for this non-CO2 heat pump.
A COP of 4.2 means that the use of one kWh of electricity delivers 4.2kWh of heat.
The Chart at
http://www.ata.org.au/forums/topic/4384#post-31076
shows that the Danfoss SC21G heat pump has lower COP values e.g. COP=1.8 when it collects heat at zero degC and COP=2.2 when it collects heat at 10degC.
Posted Sunday 17 Mar 2013 @ 9:09:51 pm from IP
#