[Bldg-sim] Heat Recovery Chillers and Lab Outdoor Air

[Sam Mason]

Thanks in advance for any help.

1. I am trying to model a York heat recovery chiller for a lab facility
and one of the options on the table is adding a second injection rig to
boost the heat recovery capacity of the chiller. When I set the controls
and temperatures for a single rig, it operates closely to what my hand
calcs show for three months of operation in heat recovery mode. However,
I don't know how to boost the heating capacity in heating mode to
simulate the second rig. The heating capacity seems to be limited by the
cooling capacity. Do I need to do hand calcs and provide an exceptional
calculation which accounts for the derated chiller performance and
recovered heat? Any thoughts?

2. For the same lab, the baseline and proposed systems are 100% OA VAV
reheat. After all efficiency measures are included, the total system CFM
for the proposed model is 50,000 CFM less than the proposed, and because
it is a 100% OA system, the baseline system is providing an additional
50,000 CFM of outdoor air. Per ASHRAE G.3.1.2.5, the minimum ventilation
rates shall be the same, but changing the baseline model fundamentally
changes the way a 100% OA lab system is designed to work. If 100% OA is
not provided, then some amount of recirculation is assumed, and for labs
handling sensitive testing and materials, recirculation is not allowed
under any circumstance. Is there a CIR or addenda regarding this issue
in lab modeling? Any thoughts or experience are greatly appreciated.

Sam

--
Sam Mason
Environmental Designer

Atelier Ten
Consulting Environmental Designers
45 East 20th Street, 4th Floor
New York, NY  10003
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sam.mason at atelierten.com
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