Re: [EnergyPlus_Support] HVAC systems

["Michael J. Witte" <mjwitte@xxxxxxxx>]

> But why should I add the DX Cooling Electric Consumption in case A,
> Electric Consumption affect the Heat rejection??

If you draw a boundary volume around the DX system, heat enters the 
cooling coil, electric power enters the compressor, and heat leaves 
through the condenser coil.  All of the power added to the system by 
the compressor is ultimately rejected as heat from the condenser 
coil.  There is a small amount of heat which may be lost from the 
compressor directly to the outside air, but this is neglected in the 
simulation.

> and What's the difference between Tower Heat Transfer and Chiller 
Cond
> Heat Trans?
> Doesn't all the heat rejection from chiller remove by Cooling
> Tower?(water cooled case)
> How about air-cooled case?

Chiller Cond Heat Trans is the heat rejected from a single chiller.  
Tower Heat Transfer is the heat rejected by a single tower.  In a 
system with only one chiller and one tower, these values should be 
equal.  For an air-cooled chiller, Tower Heat Transfer does not apply.

Mike Witte



On 8 Aug 2002, at 2:05, rmp4aup6 wrote:

> Thank you very much.
> I spend some time to study basic knowledge of HVAC system.
> But there are some points unclear to me. So, please........Thank you
> very much.
> 
> Basically, we have two types of HVAC:
> A. Package-system(Window-type and seperate-type): most of them are
> air-cooled
> B. Central-system: air-cooled and water-cooled
> I hope it is not wrong in my understanding.
> 
> Now, I want to simulate these two types seperately:
> (1)case A(package system):
> The total heat rejection should be "DX Coil Total Energy" + "DX
> Cooling Coil Electric Consumption",
> (2)case B-1 (central system with air-cooled)
> the same as case A, I think!!
> (3)case B-2 (central systems with water-cooled)
> the total heat rejection should be "Tower Heat Transfer"
> 
> But why should I add the DX Cooling Electric Consumption in case A,
> Electric Consumption affect the Heat rejection??
> and What's the difference between Tower Heat Transfer and Chiller Cond
> Heat Trans?
> Doesn't all the heat rejection from chiller remove by Cooling
> Tower?(water cooled case)
> How about air-cooled case?
> 
> I am very sorry to ask so many questions.
> 
> HSIEH Chun-Ming 
> 
> 
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