Add additional inputs for chilled and hot water tank auto-sizing

Issue overview

The current chilled water storage tank sizing limits the cold water temperature to be lower than 8C ( or around 46 F). If the chilled water plant exit temperature is greater than 8C, a severe error warning will be thrown—"Autosizing of Source side chilled water tank design flow rate requires Sizing:Plant object to have an exit temperature <= 8C". That limit seems to be ok for regular chilled water applications, where the chiller water temperature is around 42F (or ~6C). However, for some applications, such as process cooling, and/or low-lift chillers, and/or radiant cooling, a higher chilled water temperature (e.g. 60+F or ~16+C) is need. The auto-sizing will then be prohibited by the program due to the 8C limit on chilled water temperature. The issue requests to add additional inputs to deal with the chilled water temperature limits in order to allow auto-sizing for the above-mentioned applications. In addition, similar limitations may also exist for a few other plant sizing scenarios. This might also be attributed to the different engineering standards at different parts of the world. For example, according to an example reported in Helpdesk ticket number 15550, a district heating plant sizing limit which limits the water temperature to be 125C, while in Berlin Germany region, the district heating plants can have 135C/85C supply/return temperatures.

Details

Some additional details for this issue (if relevant):

Platform (Operating system, version)
Version of EnergyPlus (if using an intermediate build, include SHA)
Ref to Helpdesk ticket number 15550

Checklist

Add to this list or remove from it as applicable. This is a simple templated set of guidelines.

[ ] Defect file added (list location of defect file here)
[ ] Ticket added to Pivotal for defect (development team task)
[ ] Pull request created (the pull request will have additional tasks related to reviewing changes that fix this defect)

This limit (and a similar one for hot water storage) is driven by these stated sizing assumptions that are used for autosizing the Source Side Design Flow Rate

  N17, \field Tank Recovery Time
       \type real
       \default 4.0
       \note Parameter for autosizing design flow rates for indirectly cooled water tanks
       \note time required to lower temperature of entire tank from 14.4C to 9.0C
       \units hr

The sizing method takes the design supply temperature from the plan sizing object and applies it to the above temperatures to determine the required flow rate. So, to provide more flexibility, it seems that the storage objects need 2 additional inputs for the Design Tank Setpoint Temperature (9.0C) and the Design Tank Maximum Temperature (14.4C) or some other names that reflect common terms used in storage design.

For hot water tanks the default temperatures are 14.44 to 57.22 C.

NREL / EnergyPlus