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Posted by Robert Scott on June 9, 2008, 3:41 pm
The COP of a geothermal heat pump is given for inlet water temperatures in the
range of 30-50F as being from near 1.5 to about 3.0. Does anyone have any data
on what the COP would be if the inlet temperature were raised to about 75F by
low-grade solar heat?
I currently have a "Water Furnace" brand heat pump with a closed-loop feed
system. I am trying to decide if I should add solar heat using an independent
system, or if I should use the solar heat just to boost the efficiency of my
heat pump, One of the advantages of the second approach is that I can make use
of lower temperature storage of solar heat, as opposed to the direct method.
But the second approach won't do me much good unless it significant raises the
COP of the heat pump.
Robert Scott
Ypsilanti, Michigan
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Posted by on June 9, 2008, 3:54 pm
On Mon, 09 Jun 2008 19:41:23 GMT, ---@---.--- (Robert Scott) wrote:
>The COP of a geothermal heat pump is given for inlet water temperatures in the
>range of 30-50F as being from near 1.5 to about 3.0. Does anyone have any data
>on what the COP would be if the inlet temperature were raised to about 75F by
>low-grade solar heat?
Your COP of the HP would go down slightly ( lower delta to
work with ), but your *system* efficiency / cost effectiveness would
go up a LOT. IOW, you're picking up some free heat. Free is good.
>
>I currently have a "Water Furnace" brand heat pump with a closed-loop feed
>system. I am trying to decide if I should add solar heat using an independent
>system, or if I should use the solar heat just to boost the efficiency of my
>heat pump, One of the advantages of the second approach is that I can make use
>of lower temperature storage of solar heat, as opposed to the direct method.
>But the second approach won't do me much good unless it significant raises the
>COP of the heat pump.
You can no longer look at just the HP / COP, when you're
adding in another system that doesn't change it ( much ). You have to
look at your TOTAL SYSTEM.
BTW - we're STILL not going to let you have full votes in
Denver !!!!! BWahahahahahaha !! :-)
>
>
>Robert Scott
>Ypsilanti, Michigan
--
Click here every day to feed an animal that needs you today !!!
www.theanimalrescuesite.com/
Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
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Posted by Mark on June 9, 2008, 10:36 pm
> =A0 =A0 =A0 =A0 Your COP of the HP would go down slightly ( lower delta to=
> work with ), but your *system* efficiency / cost effectiveness would
> go up a LOT. =A0IOW, you're picking up some free heat. =A0Free is good.
>
I believe the COP goes up as the delta T goes down.. If he warms the
evaporator with solar heat, the COP of the HP will improve.
To the OP, perhaps you can measure the COP on a summer day when the
air temp is around 75.
Mark
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Posted by on June 10, 2008, 1:24 am
wrote:
>
>> Your COP of the HP would go down slightly ( lower delta to
>> work with ), but your *system* efficiency / cost effectiveness would
>> go up a LOT. IOW, you're picking up some free heat. Free is good.
>>
>
>I believe the COP goes up as the delta T goes down.. If he warms the
>evaporator with solar heat, the COP of the HP will improve.
Could be, on second thought. Probably is, in fact. My main
point was that he needs to look not just at that, but at the gain ( in
absolute terms ) from the solar, and see that regardless of COP, the
system *as a whole* is improved by it.
>To the OP, perhaps you can measure the COP on a summer day when the
>air temp is around 75.
>
>Mark
--
Click here every day to feed an animal that needs you today !!!
www.theanimalrescuesite.com/
Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
HVAC/R program for Palm PDA's
Free demo online at www.pmilligan.net/palm/
Free 'People finder' program now at www.pmilligan.net/finder.htm
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Posted by Robert Scott on June 10, 2008, 9:30 am
On Mon, 09 Jun 2008 15:54:25 -0400, .p.jm@see_my_sig_for_address.com wrote:
> Your COP of the HP would go down slightly ( lower delta to
>work with ), but your *system* efficiency / cost effectiveness would
>go up a LOT.
Well, if you define COP as the ratio of heat produced divided by the electrical
power consumed (including the fan, not just the compressor), then COP is
equivalent to system efficiency. Of course if I add solar pre-heating to the
inlet water, I will have to add in whatever electrical power it takes to run the
solar heating system, which could be substantial.
>
> BTW - we're STILL not going to let you have full votes in
>Denver !!!!! BWahahahahahaha !! :-)
That's good. I'm for Obama anyway.
Robert Scott
Ypsilanti, Michigan
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