[Equest-users] Coil Flow and Pressure Drop

[Darryl Kasun via Equest-users]

Hi Sharad,

Makes sense that eQUEST takes into account heat losses through piping and
I'm assuming also eQUEST takes into account losses across any heat
exchanger via coils.

I am also curious how eQUEST calculates the PD across coils at different
flow rates - any insight would be appreciated.

Thanks
Darryl

On Tuesday, 30 August 2016, Sharad Kumar via Equest-users <
equest-users at lists.onebuilding.org> wrote:

> Hi Darryl,
>
> It seems that the 25 degree F and delta T 10 degree F are seeming to be
> correct.
> But as far as i know the AHU part has lesser load and capacity as there
> can be some transmission or heat losses as far as my knowledge.
>
> The chiller piping has lesser heat losses through the circulation loop.
> The  delta T on room side can vary and match to optimum.
> Always i have found that chiller has higher load as compared to air side.
> One can measure the pressure differential with the help of venturimeter ,
> manometer or pitot tube or differential pressure measurement meter.
>
> Thanks,
> Sharad.Kumar
>
>
>
> Today's Topics:
>
>    1. Coil Flow and Pressure Drop (Darryl Kasun via Equest-users)
>
>
> ---------- Forwarded message ----------
> From: Darryl Kasun via Equest-users <equest-users at lists.onebuilding.org>
> To: equest <equest-users at lists.onebuilding.org>
> Cc:
> Date: Tue, 30 Aug 2016 11:28:22 -0700
> Subject: [Equest-users] Coil Flow and Pressure Drop
> Hi everyone,
>
> I am looking for confirmation I understand what eQUEST is doing with
> inputs for VAV boxes with HW reheat coils.
>
> On the water side for each. reheat coil, I know design flow, design delta
> T, design heat gain and design pressure drop.
>
> Based on the below inputs, I am assuming eQUEST will calculate the design
> flow ~ 1.9 GPM;  [9,625 Btu/hr / 500 / 10 degF = 1.9 GPM].
>
> [image: Inline image 5]
>
> On the air side, I also know the design flow and delta T.  For this
> example, it is 270 CFM and 25 degF:
>
> [image: Inline image 4]
>
> Will eQUEST use the max airflow (270 CFM) and subsequently calculate the
> max heat gain across the coil (~7,290 Btu/hr); [1.08 * 270 CFM * 25 degF =
> 7,290 Btu/hr].
>
> If so, does eQUEST adjust the HW flow rate through coil to match this heat
> gain (~1.46 GPM); [7,290 Btu/hr / 500 / 10 degF = 1.46 GPM]
>
> Am I correct in how eQUEST is using these inputs?
>
> Also. how does eQUEST calculate the PD through the coils, both on the
> water-side and air-side?
>
> Thanks
> Darryl
>
> _______________________________________________
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> Equest-users at lists.onebuilding.org
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>
>
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