[Bldg-sim] Fancoils and Chiller DOE-2 Simulation

[Paloma Rocío Cubillas Fernández]

I will be very gratefully for any help.

 

I´m a researcher in the University of Cadiz (Spain). We´re studying how
DOE-2 carry out the simulation for Fancoils and Chillers systems. We need to
know the relation between the capacities and the air entering temperatures
(wet bulb and dry bulb), and water entering temperatures. The simulations
proceed of cases that have a Chiller enough powerful to attend the fancoils
demand has been concluded. The conclusions have been reached with different
simulations and tests. All these cases, show that, curiosity, fancoils´
total and sensible capacities  are not depended of water entering
temperatures. In all these cases is easy to calculate the capacities (they
are the product between nominal capacities and air entering temperatures
functions). The fancoil power, logically, is the same that the product of
the capacity and the PLR. The outside temperatures of air and water, are
calculated with this power, and the power that the chiller gives is a bit
bigger that the fancoil power needed, and is the same that  the Net hourly
loop load (including thermal losses). Every equation looks closed and
logical (except the fact that the capacity calculation, in those cases, is
not function of water entering temperatures, but the calculations and tests
confirm that).

 

Our problems merge when chiller is not enough big to attend the fancoils
demand, then some calculation relations change. Now the fancoil power is not
the logical product between the capacity and the PLR, and the capacity is
not the product of the nominal value and the air entering temperatures
function. Maybe now, in this cases, the water entering temperatures will be
considered in the fancoil capacities calculation in some way, but we haven´t
found any logical relation to explain how it´s working.  DOE-2 have a
function that modifies the capacities in function of water entering
temperature and air wet bulb temperatures. We are trying to find a relation
between this function and the capacities calculation in this cases, but we
haven´t found anything at the moment. In addition, for Fancoil PLR minor
that 1 the fancoil power continues coinciding with the load on loop, and the
chiller power is a bit bigger that this, being the same that the Net Hourly
loop load. However, for fancoil PLR equals to 1, not even these relations
are correct.

 

Someone could give some information about the way in that eQuest works when
the chiller is not enough big to attend the fancoils demand?

Any help will be very useful.

 

Thank you very much in advance to everybody.

 

 

 

 

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Paloma Rocío Cubillas Fernández

Personal Docente e Investigador

Universidad de Cádiz

Dpto. Máquinas y Motores Térmicos

Escuela Politécnica Superior de Algeciras

Avda/Ramón Puyol, s/n. CP. 11202. Algeciras.

Teléfono: 956-028030

Fax: 956-028001

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