Are you a fan of fans? Centrifugal (I prefer to call Centripetal but that’s a tale for another day), Axial, Cross flow, whichever you like, fans can prove to be a challenging topic. A recent series in the Ashrae Journal discusses industrial fans, but what got me thinking about the topic of fans was a much smaller situation. PC computer fans.
Your standard 120 mm PC fan is a fairly homogenous product, but there also exist other fans in the same frame size with considerably higher energy use, cfm, and static pressure capability. These fans can be used to cool equipment, like say a bitcoin miner or a 4U server, sometimes coupled with a direct chip to water to air setup (something like this).
So which use of fans is best? 1 really impressive fan (like this) or 2 run of the mill fans stacked or 2 run of the mill fans next to each other (like these). The single fan consumes 30 watts, while the 2 fans consume 4 watts each. The 30 watt fan moves 240 cfm, while the cheapo fan moves 70 cfm. How much air do you need, and how much static pressure do you need? These fans get slapped in an application but they won’t move that same air volume with any resistance. That’s where the fan curves come into play.
For those of you that don’t know I started in the industry as a facilities technician, then within three months became a site lead mechanical engineer. One thing that always perplexed me was the persistence of the 15-ton (or any nominal sized refrigeration component) compressor. Even today, working as a regional engineer over 3000 miles of data center footprint, I still deal with this from people who should know better.
I just received the check from our major project at the CH2 data center in downtown Chicago. A $544,000 rebate for validating our energy savings is a pretty impressive feat. The projects included VFDs on DX Cracs, modifying the BMS and economizer, installing hot aisle containment, installing lighting occupancy sensors, and upgrading the cooling towers with new fans and new evaporative media. They tell me this is the biggest check they have ever issued and we are doing a big presentation ceremony in a few days to celebrate this projects successes. Big congratulations to the team I worked with that made this all a reality, Dan Fargano, Travis Nelson, and Jason Brick.
Do you want to have the impact of an air side economizer without the negative side effects on air quality while avoiding the humidity lock out hours? Well there is a new product on the market that might have just what you need. The Pumped Refrigerant Economizer is a clever way to economize without using water or fresh air introduction. So what does this Pumped Refrigerant Economizer do? Continue reading Another Tool in the Toolkit – Pumped Refrigerant Economizers→
Happy Earth Day! I just wanted to take some time to acknowledge this occasion and what I think it means to data center operators.
Earth Day started around 1970 and when it gained traction, the idea was to educate and inform while celebrating our planet. Well in that vein, I did some reading today on energy efficiency and conservation. Where else, besides in heavy industry, do we have the opportunities to save millions of kWh a year? Lots of different estimates of energy consumption exist, but roughly 1.5-2% of all energy is spent in data centers in the United States (good luck finding a solid source for that number). And as IT becomes a bigger sector of the economy, so too has the consumption of data centers increased. These old centers give us so many opportunities.
Do you have a chiller plant? Is your air handling equipment operating at some level below 100%? You can probably benefit greatly from a chill water reset, especially if you operate with a largely sensible load (like a data center!). Even if you have latent cooling, the latent capacity is not impacted as much as you think by higher chill water temperatures. The coils leaving air temperature is what determines how well the air handler removes humidity as that air is typically at saturation. So as long as you are meeting your air temperatures set point, latent capacity is not impacted.
So what of the chill water reset? Well, ASHRAE recommends, in a series of articles co- authored with Taylor Engineering, the use of a chill water temperature reset followed by a chill water d/p reset. Continue reading Chill water resets→
For all those looking for some easy peasy NPV calculations I put together a spreadsheet. Please note, I am always open to improvement so if you see something that can make it better please let me know.
Just fill in the yellow boxes (I have locked down discount rate at 10% and inflation at 3%, if you know enough to want to play with that let me know and I will give you the unlock password). Select 10 or 15 year project life, and the spreadsheet will auto manipulate. This is focused around energy savings projects but you can use anything with a cash flow that will accelerate with inflation.
From time to time I have heard a lot of heated discussions on which aisle containment solution is better. No doubt aisle containment is an effective way to improve airflow management and enhance efficiency. From cold aisle to hot aisle, full to partial containment, passive or active hot chimney, each camp has its own supporters and opponents. With every operating data center having its own constraints, the key is to adopt an approach that find a balance between effectiveness, cost and what can realistically be done in that data center. Here I outline some common containment strategies for a typical data center white space with raised floor, using downflow air supply, top return with perimeter CRAC/CRAH units. Continue reading Chill Out – Battle of Aisle Containment→