[Equest-users] Cogen heat recovery for dhw

Edward Allen eallen at long.com
Tue Jul 3 21:27:17 PDT 2012


Do you have a seperate DHW loop set up?  If so, this is your problem.  Heat recovery from either jacket or exhaust can only go to a single loop each.  If you are proposing to implement cogen then you want to put DHW loads on the heating loop as a process load with and appropriate schedule.  This way you can assign the heat recovery to a single loop for simple modeling.

Good Luck,

Edward M. Allen, P.E. CEM
Senior Energy Engineer
Investive Building Projects
(formerly LONG Energy Solutions)

----- Reply message -----
From: "Kimberly Wiebe" <Kimberly.Wiebe at BuroHappold.com>
To: "equest-users at lists.onebuilding.org" <equest-users at lists.onebuilding.org>
Subject: [Equest-users] Cogen heat recovery for dhw
Date: Tue, Jul 3, 2012 4:13 pm


I am working on a project in which the heat recovered from the CHP equipment (1,416 kBtu/h) is able to meet the entire service water loop load (1,384.7 kBtu/h). Both the DHW and CHP run 24 hours a day. The building is both residential and commercial.

Net hourly loop load, including thermal losses and pump heat = Recovered heat or free cooling heat applied to this loop ... this is true for all hours in the hourly report.

However, there is still a consistent small natural gas load for the domestic hot water. It is flat for all hours of the day. What is this energy use going to? Standby losses?

I am thinking that it is a minimum energy use of the equipment if the equipment is operating. What is the minimum part load ratio for a gas fired storage service water heater? Where can I find the inputs/ outputs to confirm this?



Kim Wiebe
Direct: +1 310 945 4813
kimberly.wiebe at burohappold.com<mailto:kimberly.wiebe at burohappold.com>

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