Best way to model dumping heat

asked 2015-03-11 14:35:21 -0500

Jamie Bull

flag of United Kingdom of Great Britain and Northern Ireland

5072 ●6 ●27 http://oco-carbon.com/

updated 2015-04-13 18:13:23 -0500

Neal Kruis

4675 ●9 ●17 http://bigladdersoftware.com/

My model includes the SOFC fuel cell from the Microcogeneration.idf example file, in which the generator runs as Baseload so runs constantly, generating both heat and power). My problem is that I'm getting plant loop overheating warnings as the heat demand is too low, if not outright failures due to a runaway plant temperature error.

So there are two main problems to be dealt with:

1) There is a lot of heat building up in the zone where the CHP is located leading to very high air temperatures
2) The CHP is generating more heat than is needed in the building leading to runaway plant temperatures

The solution to both of these seems to be to dump the excess heat (leaving aside changing the operation to FollowThermal for now). I assume adding extract ventilation would be the best option for problem 1, but what would be my best option for dumping heat to solve problem 2?

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answered 2015-03-11 18:53:51 -0500

Ivan Korolija

911 ●3 ●7

Does it need to be realistic or it can be unrealistic solution as well. If unrealistic solution is acceptable you can add mock thermal zone with radiator heating branch and hight temp. setpoint. More realistic solution would be to add some thermal storage, or attach absorption chiller (if temperature is hight enough) if you have cooling requirements as well.

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No need to be realistic in this case, and no cooling load either. Some of my cases will have storage which will help to alleviate the problem, but others won't so I need another option that's something like a radiator on the roof. The mock zone you suggest can represent outdoors so it should work here. Rather than (or as well as) having a high setpoint, it needs to only request heat when the system is overheating. Link to an EMS program to control the heat dump.

Jamie Bull ( 2015-03-12 07:50:50 -0500 )edit

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answered 2015-03-12 08:58:29 -0500

Archmage

7185 ●3 ●11

You could add a FluidCooler:SingleSpeed to the hot water plant loop. Place it downstream of the CHP device and use component setpoint based operation to limit the loop to 80C.