Can We add Two diff. zones with diff SHR
Can We add Two diff. zones with diff SHR
(OP)
Hi Friends
I am reviewing load calcutions submitted by a vendor
Application is comfort HVAC for Living Quarter on an offshore Rig.
There are about 90 small rooms being served by a large common AHU
Vendor has divided the load for rooms into two groups
In group 1, about 40 rooms and in group 2 about 50 rooms are considered. Then psychrometric analysis is performed for each group using air flows and average SHR for each group. Once the psychrometric is done, vendor has added the flow and capacity to arrive at the total capacity of one AHU serving all the 90 rooms
My question is that
-Is the right way to do?
-Can we add the capacities or psychromteric analysis should be done for the one single AHU which will serve all the rooms
-I know SHR plays an important roll in equipment selection. When calculations are done for two groups, the RSHR for group -1 is 0.85 and for group-2 is 0.9. But when we consider all the 90 rooms as one system then the RSHR is about 0.879
If this is acceptable then it is OK, If not then What should be my comment on the vendor calculations?
Can we add SHR
I am reviewing load calcutions submitted by a vendor
Application is comfort HVAC for Living Quarter on an offshore Rig.
There are about 90 small rooms being served by a large common AHU
Vendor has divided the load for rooms into two groups
In group 1, about 40 rooms and in group 2 about 50 rooms are considered. Then psychrometric analysis is performed for each group using air flows and average SHR for each group. Once the psychrometric is done, vendor has added the flow and capacity to arrive at the total capacity of one AHU serving all the 90 rooms
My question is that
-Is the right way to do?
-Can we add the capacities or psychromteric analysis should be done for the one single AHU which will serve all the rooms
-I know SHR plays an important roll in equipment selection. When calculations are done for two groups, the RSHR for group -1 is 0.85 and for group-2 is 0.9. But when we consider all the 90 rooms as one system then the RSHR is about 0.879
If this is acceptable then it is OK, If not then What should be my comment on the vendor calculations?
Can we add SHR





RE: Can We add Two diff. zones with diff SHR
RE: Can We add Two diff. zones with diff SHR
RE: Can We add Two diff. zones with diff SHR
Offshorehvac,
imok2 hit the nail on the head regarding redundancy in the design. Somewhere or the other, we have to take chances. For example, you are adding the loads of first forty rooms and calculating the SHR.When you check individual room sensible and latent loads, you may get as many as 40 ratios. Likewise, it is same for the second group of 50 rooms.
There is always a question about what can be the correct SHR and accordingly what is the correct ADP. You can answer this question, indirectly, by specifying a range for DBT and RH for individual rooms. The somewhat incorrect ADP specification will be offset by the range.
If you want to play a safe hand, go with Chris's suggestion. Chose coil ADP corresponding to the lower SHR vaule and go for zone reheating.
RE: Can We add Two diff. zones with diff SHR
it probably peaks in the late afternoon, so even the guys on the midnight shift are up and about and most likely not in their rooms
sounds like not much of a challenge with humidity, what is the load like when it's cloudy out and the surrounding air has the same dewpoint as the surface of the sea
Take the "V" out of HVAC and you are left with a HAC(k) job.
RE: Can We add Two diff. zones with diff SHR
Take the "V" out of HVAC and you are left with a HAC(k) job.
RE: Can We add Two diff. zones with diff SHR
Take the "V" out of HVAC and you are left with a HAC(k) job.