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[EnergyPlus_Support] energy balance equation
Hello everybody,
I'm trying to understand from EnergyPlus Engineering Document which is
the energy balance equation used by the software.
In particular, I'd like to know at which time step each term in the
balance is evaluated.
In the Engineering Doc there are many equations that are not consistent:
(1.8), (1.11) or (1.29)?
My guess would be:
- heating/cooling load at time step t is calculated on the basis
of set point temperature at time step t and heat transfer
(internal surfaces, air mixing with other zones, infiltration from
outside, internal convective gains etc..) at time step (t-dt)
- if the system is able to provide such load (as by definition for a
Purchased Air system) the zone temperature at time t matches
exactly the set point scheduled for time t
- if the system is not able to provide all the required load (as for a
real system), zone temperature is updated on the basis of the difference
between the cooling/heating load calculated at time step (t-dt)
and the system power at time t
Is it right?
My interest is in the meaning of "Zone/Sys Sensible Cooling
(Heating) Rate" output at time t for a Purchased Air
system.
Is it the cooling (heating) load calculated at time t or (t-dt) or what
is the time shift?
I would appreciate your help.
Thank you
Adriana Angelotti
Adriana Angelotti
PhD student
eErg end-use Efficiency Research Group
Politecnico di Milano, Dipartimento di Energetica
Piazza Leonardo da Vinci 32
20133 Milano
Italy
ph +39.02.2399.3859
fax +39.02.2399.3940
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