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Re: [EnergyPlus_Support] Re: Total or sensible heat
You are correct that EnergyPlus bases the ZONE SIZING supply air flow rate
calculations on sensible load. For heating, this carries through to the
capacity of the heating coil or furnace which is a sensible device. For
cooling, however, the capacity includes both sensible and latent and the
nominal SHR of the cooling system may change due to the level of latent loads
in the zone. So for heating, sensible only. For cooling, primarily sensible
but latent also.
By the way, a simple way to experimentally produce the sensible gain from
people is to use incandescent light bulbs. Some experimenters mount the light
bulbs inside a black metal can to better simulate the radiant heat emission.
Mike
On 14 Jul 2006 at 8:50, eric_zhou1223 wrote:
> Hi,Mike,
>
> Sorry for the question making you a little puzzled.
>
> In fact, I will make a test to simulate Human's emitting heat, using
> some electric heaters (and some humidifiers for human emitting
> vapor).
> I need to purchase the heaters with suitalble heating capcity
> first. So I checked the handbook for the human's emitting heat:
> sensible heat will be 65W, while the latent heat 69W where a male
> has light working at 25C. Assuming 9 persons in each test cab.
> Should I chose the capacity of electric heater for each room using
> 9*65W or 9*(65+69)W ?
>
> I am not sure if my discription is clear this time..
>
> Besides, the variable "Zone,Sum,Zone Total Internal Total Heat Gain
> [J]" can also be splitted to two parts: sensible and latent. As I
> know , the internal heat gain will bear (or "cancel"?) a part of
> heating load in winter. When I consider the internal gain's impact
> on the capacity of HVAC equipments, should I focus on the sensible
> part or latent part of the internal gain, or both?
>
>
> The two questions may be from the same blur conceptual source in my
> knowledge. I thought the HVAC equipment is sized based on the
> sensible heat always and the latent is just floating
> (uncontrollable) ...
>
> Would you give me some lights on this. Thanks in advance.
>
> Eric
>
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte"
> <mjwitte@...> wrote:
> >
> > I am sorry, but I do not understand the question about the
> electric heater.
> > Are you planning to do a physical (real life) experiment?
> >
> > The internal heat gain variables are defined in the Input Output
> Reference (see
> > p. 195, pdf p. 232). These do not include any heating added by
> the HVAC
> > system.
> >
> > Mike
> >
> >
> > On 9 Jul 2006 at 12:52, eric_zhou1223 wrote:
> >
> > > Hi all,
> > >
> > > I am studying the internal gains 's impact on humen comfort by a
> > > small test..
> > > The sensible heat and the latent heat emitted by humans can be
> > > evaluated through some empirical values in handbooks.
> > > Now I need to decide the size of the electric heater in my
> test.
> > > Should I choose the Total heat value emitted by humans or the
> > > Sensible heat only to make the sizing decision?
> > >
> > > It seems I should use Sensible heat to size my electric heater.
> Am I
> > > right?
> > >
> > > SOunds like a conceptual issue..
> > >
> > > Besides, among "Zone,Sum,Zone Total Internal Total Heat Gain
> > > [J]","Zone,Sum,Zone Total Internal Convective Heat Gain
> > > [J]", "Zone,Sum,Zone Total Internal Radiant Heat Gain [J]" and
> the
> > > summation of the latter two variables, which one can account for
> the
> > > supplementary heating in winter seasons?
> > >
> > > I still think the "sensibe" part should be considered as a part
> of
> > > heating ammount,working along with the HVAC equipments, whilst
> > > the "latent" part be ignored since it could not be controlled..
> > >
> > > I would appreciate any instructions and help.
> > >
> > > Eric
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > The primary EnergyPlus web site is found at:
> > > http://www.energyplus.gov
> > >
> > > The group web site is:
> > > http://groups.yahoo.com/group/EnergyPlus_Support/
> > >
> > > Attachments are not allowed -- please post any files to the
> appropriate folder
> > > in the Files area of the Support Web Site.
> > >
> > > EnergyPlus Documentation is searchable. Open EPlusMainMenu.idf
> and press the
> > > "search" button.
> > >
> > > Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> > ========================================================
> > Michael J. Witte, GARD Analytics, Inc.
> > EnergyPlus Testing and Support
> > EnergyPlus-Support@...
> >
>
>
>
>
>
>
>
>
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
>
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
>
> Attachments are not allowed -- please post any files to the appropriate folder
> in the Files area of the Support Web Site.
>
> EnergyPlus Documentation is searchable. Open EPlusMainMenu.idf and press the
> "search" button.
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support
EnergyPlus-Support@xxxxxxxx
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