Re: [TRNSYS-users] concrete core cooling modelled with active layer

["Arie Kalkman" <a.kalkman@chri.nl>]

Dear Oliver,

 

The cooling power also depends on the room temperature. The quoted 40-60 W/m2 is usually specified at peak cooling demand, usually at a roomtemperature of 25 or 26 C. If the room doesn’t get that hot, the supplied cooling power is less. Usually, the aim of the concrete cooling system is to condition the room (which is quite succesfull when 21 C room temperature is achieved) and not to deliver a large cooling power. However, when a comparison with other cooling systems is made, the maximum cooling power is sometimes used. In my opinion, your modeling results show that for the specific project you don’t need these large cooling powers.

 

Regards, Arie

 

 

 

 

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Van: trnsys-users-bounces@engr.wisc.edu [mailto:trnsys-users-bounces@engr.wisc.edu] Namens Pol Olivier
Verzonden: dinsdag 6 februari 2007 15:44
Aan: trnsys-users@engr.wisc.edu
Onderwerp: [TRNSYS-users] concrete core cooling modelled with active layer

 

Dear TRNSYS users,

I am modelling a concrete core cooling (activation of storage mass of slabs) with an active layer (with TRNSYS 16.01).

Relevant data are:

-          distance to edge of the slab: 12cm

-          pipe spacing: 20cm

-          flow mass: 12kg/h.m²

-          Temperature of supply air into the rooms: 19°C

According to the definition of outputs for a surface, the energy abstracted from the room into the slab should be QCOMI and QCOMO (considering both l-wave radiation and convection).

My results are:

-          inlet temperature 19°C, QCOMImax=15W/m²

-          inlet temperature 17°C, QCOMImax=20W/m² (average air temperature in summer: 21°C)

-          inlet temperature 17°C, without cooling of supply air, COMImax=25W/m² (average air temperature in summer: 22°C)

The values I obtain for QCOMI and QCOMO are much lower than the ones obtained in the practice (usually between 40 and 60W/m²).

I tried different variations (simulation time step, distance to the edge of the slab, flow mass and auto-segmentation, internal calculation of convective heat transfer coefficient, number of loops) without success…

Are QCOMI and QCOMO the right outputs?

Thank you for your suggestions,

Olivier Pol.

 

 

 

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