Re: [TRNSYS-users] cooling coil

[David Bradley <bradley@tess-inc.com>]

Ming,
  There are three cooling coil models available in the TESS HVAC
Library. 

Type508 models a cooling coil using one of four control modes. The
cooling coil is modeled using a bypass approach in which the user
specifies a fraction of the air stream that bypasses the coil. The
remainder of the air stream is assumed to exit the coil at the average
temperature of the fluid in the coil and at saturated conditions. The two
air streams are remixed after the coil. In its unrestrained
(uncontrolled) mode of operation, the coil cools and dehumidifies the air
stream as much as possible given the inlet conditions of both the air and
the fluid streams. The model is alternatively able to internally bypass
fluid around the coil so as to maintain the outlet air dry bulb
temperature above a user specified minimum, to maintain the air outlet
absolute humidity ratio above a user specified minimum or to maintain the
fluid outlet temperature below some user specified maximum.

Type752 component models a simple cooling coil where the air is cooled as
it passes across a coil containing a cooler fluid (typically water or a
refrigerant). This model uses the bypass fraction approach for cooling
coils to solve for the outlet air conditions. The bypass factor approach
assumes that a portion of the air stream comes to temperature equilibrium
with the coil fluid and the other portion of the air stream (the bypass
fraction) is thermally unaffected by the coil in the air stream. These
two flows then mix to produce the outlet air condition. This coil may
operate in 1 of 4 control modes:
1 - The outlet air temperature is controlled to be at a user-specified
temperature
2 - The outlet air temperature and outlet air humidity ratio are
controlled to be at user-specified conditions
3 - The outlet air temperature and outlet relative humidity are
controlled to be at user-specified conditions
4 - The outlet air humidity ratio is controlled to be at a user-specified
condition
The big difference between Type508 and Type752 is that Type508 fully
solves both the outlet air stream and outlet liquid stream conditions
while Type752 solves for onlyt the air stream outlet conditions and
reports the load on the liquid stream.

Type697 models a cooling coil where the air is cooled as it passes across
a coil containing a cooler fluid (typically water). This model relies on
user-provided external data files which contain the performance of the
coil as a function of the entering air and fluid conditions. Sample data
files accompany to show the format of these external files.

Kind regards,
 David


At 21:03 9/17/2006, Liu, Ming - liumy008 wrote:

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Hello everyone,
 
I need a component ?Cooling Coil? to setup my model. One side is the secondary coolant; its inlet temperature is about -29C. The other side is air; its inlet temperature is about -22C. However, in the Cooling Coil (Type32 & Type52) in TRNSYS, air is assumed to exchange heat with water. I can not set the inlet water temperature to a minus value.
 
Is there anyone know what component I can use instead of Type 32 and Type 52?
 
Thanks in advance!
 
Ming
 
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