Re: [EnergyPlus_Support] Re: Unitary Air conditioners

[Marcus <jones.0bj3@xxxxxxxxx>]

JijuKin, this is how I understand it;

The COP is the output cooling thermal power divided by the input electrical power for a single fixed operating condition in i.e. kW/kW. So the output would be measured by, for example, the enthalpy change of air or water through the cooling coil (evaporator). And the input power would be, at a minimum, the electrical power to the motor of the compressor, this would be for a central water chiller for example. However some packaged units also include in the COP the input power of the fan on the condenser coil, so be careful! And also check that the rating conditions for your unit COP match the rating conditions that EnergyPlus expects, for example, from the manual for packaged DX;

"""
Rated conditions are air entering the cooling coil at the maximum supply air flow rate at 26.7°C drybulb/19.4°C wetbulb with air entering the outdoor condenser coil at 35°C drybulb. The input power includes electric power for the compressor and condenser fan but does not include the power consumption of the supply air fan.
"""

The SCOP is the integrated COP over the entire season, in i.e. kWh/kWh. So you would theoretically integrate the cooling power and the electrical power over the entire season and divide them at the end. I beleive the SCOP is calculated on a test bed by using i.e. 4 rated COP's and taking a weighted average. I have also heard that rated SCOP is higher than rated COP by around 10%, so there should be a way to estimate rated COP from SCOP. Let's see, anyone have a nice reference to convert SCOP to COP? 

Cheers,

Marcus
-- 
Marcus Jones,  M.Sc., LEED®AP BD+C
Freelance energy consultant
Vienna, Austria

On Fri, Sep 30, 2011 at 1:31 AM, Linda Lawrie <linda@xxxxxxxxxxxxxx> wrote:

 

I'd assume he meant page 12 of the same document the original poster
said had
Table 6.8.1A (ASHRAE 90.1 2007)

On Thu, 29 Sep 2011 23:26:54 -0000, ooikoonbeng2004 wrote:
> Richard, May we know pg 12 of which document? A search using 'SCOP'
> and 'Coefficient of Performance' in index of the E+Documentation did
> not reveal anything you stated. Thanks. ooi
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad
> <RRaustad@...> wrote:
>>
>> Look at the definition for seasonal coefficient of performance -
>> heating
>> (SCOPh) on pg 12.
>>
>> The SCOP and COP do not mean the same thing. You need to use the
>> rated
>> COP and capacity of the equipment in your simulation.
>>
>> On 9/28/2011 11:42 AM, Jiju Kin wrote:
>> >
>> > Hi,
>> >
>> > I am doing simulation for LEED certification and not understand
>> how if
>> > determines the SCOP in Table 6.8.1A (ASHRAE 90.1 2007), is the
>> same as
>> > COP? the simulation options exists only the COP as a parameter to
>> be
>> > used.
>> >
>> > JijuKin
>> >
>>
>> --
>> Richard A. Raustad
>> Senior Research Engineer
>> Florida Solar Energy Center
>> University of Central Florida
>> 1679 Clearlake Road
>> Cocoa, FL 32922-5703
>> Phone: (321) 638-1454
>> Fax: (321) 638-1439 or 1010
>> Visit our web site at: http://www.fsec.ucf.edu
>>
>> UCF - From Promise to Prominence: Celebrating 40 Years
>>
>
>
>
>

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