Re: [TRNSYS-users] questions about ground source heat pump system using type668

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

Dear Jiang Shuang

> (1)I use type515 and type14 combined
> with an equation to control the water-to-water heat pump. When the
> heating signal is 1, it works under heating mode, and when the cooling
> signal is 1, it works under cooling mode. However, I find that when both
> heating signal and cooling signal change to 0, the heat pump stop
> working, but it still has a power output! I have used the control part to
> a water-source heat pump, and all components work well.

unless I am mistaken, this was a bug in the initial release of the TESS
Libraries 2.0.00. It was fixed in the release of 2.0.01. You should
contact your distributor to get the latest version of the appropriate
DLL.

> (2)I find the example about type668
> given in trnsys is about hot water producing and more examples in the
> internet are also about heating. But in my country, it is common that
> ground source heat pump is used to produce chilled water and hot water to
> air conditioners in a building, in which they exchange heat with the
> outdoor air. Then the airs are distributed to rooms. My question is that
> if type668 can be used for the above purpose. If not, which type should I
> choose? 

yes, certainly. Type668 simply models a  water to water heat pump.
The control signals can be set up to take energy from the ground and use
it to heat load side water (heating mode) or to reject energy to the
ground and cool load side water (cooling mode). 

> (3) The vertical u-tubes (type557)
> has a parameter: number of boreholes in series, what does it mean? If
> there are many series parallel loops (It is common in practice), what
> should I do?

Type557 parameter 4 asks you to specify the total number of boreholes in
the entire storage volume of earth. Parameter 6 asks you to specify the
number of boreholes in series per parallel loop. Based on these two
values, Type557 internally calculated how many parallel loops there are
in your field.

Kind regards,
  David

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Thermal Energy System Specialists (TESS), LLC
David BRADLEY                           2916 Marketplace Drive - Suite 104
Partner                                        Madison, WI 53719
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E-mail: bradley@tess-inc.com
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