Recent content by tankanghan

What is typically (or best) to use for water pipe 4", annealed temper or hard drawn temper????

Is there a code requirement for minimum outdoor air for data center(mostly unoccupied)?

Thanks Goober Dave. I appreciate the input. The Cv vs valve position is exactly what im looking for. The only thing i can find is wide open Cv. The Ashrae characteristic curve show the % flow vs valve travel. But no Cv...i wonder if that %flow on the y-axis is also the %Cv???

Can anyone tell me a simple way to figure out how fast the space temperature will rise based solely on a given constant heat source in the space, ignoring other contributors such as walls.....

I have been looking at these sites you receommnded, but i have not found a Cv vs %valve open , or "pressure drop vs valve open"??? for a typical 3/4" to 1/1/4" globe control valve.... are there any more site you can recommend for this??? i did found the formula for the %flow vs %valve travel for...

Thanks to all. It is basically transformers. CFM = (42KW x 3412)btuH / (1.08 x 10 delta T F) = ~13,300 cfm at peak so It will cycle at say 10F ambient, right? so instead of that, with VFD at 10F outside i just need 1,560 cfm air not the full 13,300 with 95F inside. .... Does this argument...

There is no chiller in this scheme. Basically just cooling tower.

Thanks to all who comment...it appear the vfd is better approach and maybe less expensive...so the fan will basicallyt ramp down to what the cfmm is needed to maintain 90 or 95F in the room and the above the 95F then it will run full speed....Thanks again

Here in our site, we have man made pond system where we reject heat into...but the pond circulate to another pond using spray and pump system to have better heat transfer...and i think its roughyl the same depth.....there is actually a pond design manual generated by one of our engineers here...

HAs anyone experience any water system delta T as high as 50F delta??? Typical one i see is about 15F to 20F at most....The driving force for the delta T, of course, is the load,....i was told that in Europe they have systems that goes as high as 50F delta T.... By process water, i meant the...

Thanks for the responses.

Thanks again, i appreciate the comment. The space is sandwich between two airconditioned space....i assumed that the room load is very small compared to the 42 kw equipment heat

Thanks for the response....is there a site somewhere where i can see the Cv at different valve opening for a generic globe valve 1-1/4" and below??? I spent some time but couldnt find any...not even from valve manufacturer... I appreciate any response...

Does the control valve CV change when the valve throttle ?? or is it the same Cv ?

Thanks again, i appreciate the comment. the desired is so as not to use as much airflow during the colder ambient. If i just have one speed 13,000 cfm fan, at low outdoor air, the space will be colder and the fan might just cycle on space temperature. Maybe ths is not the proper way?? So for...