Dear All,
I’m modelling a water centrifugal chiller in System 8 of ASHRAE 90.1 (Appendix G), using HAP by Carrier.
I have to need how calculate the minimum entering condenser water temperature (ECWT) for a water-cooled chiller and the part-load ratio below which cycled operation occurs. This cycling point is defined as a percentage of full load capacity. How I could calculate these data? Should I consider 21 °C as minimum temperature?
About Cooling Control I understand that 2 chiller equally sized have to be equally unloading. Am I right?
No instructions are given for Cooling Tower: Full Load Fan kW, fan electrical Efficiency and % Airflow at Low fan Speed. Where can I get these data?
Then I have to model the Primary/Secondary Systems with variable-speed. In my case the building has a floor area more than 20,000 m2.
I have to put in the software the “Mechanical and Electrical efficiency” and the “W/L/s” for both pumps in Primary Loop and in Secondary Loop.
How could I calculate the data for the two loops?
The ASHRAE in the Section G3.1.3.10 gives me only 349 kW/1000 L/s but not the other data.
Moreover I have to put in these data for the secondary loop: Control Head (kPa) and Minimum Pump Flow (%).
Thanks.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5868 thumbs up
March 16, 2015 - 1:21 pm
HAP will automatically calculate many of these variable once you select the basic system type. Sounds like you need some help from someone who knows HAP better than I. Contact HAP technical support or you could try the HAP Users group at onebuilding.org.
The only item on your list that is defined by 90.1 is the cooling tower fan power which is 38.2 GPM/HP in my IP version from Table 6.8.1G. The new Section 1.4 spreadsheets may help you with modeling the Baseline systems.
Giuseppina Amorusi
Artelia Italia2 thumbs up
March 18, 2015 - 3:58 am
Thank you so much for your suggestion. I'll follow that.