Designing a Data Center Cooling Unit When we design a data center cooling system, we usually concentrate on its capacity and redundancy. The air management is, most of the time, ignored which is why many data centers have hot spots, problems with cooling and very high PUE. To design a good air management system in a data center, we need to take the following into consideration: Keys to designing an efficient air system Delta T or CFM/kW: this is the design engineers’ most underused parameter. In order to decide on a good CFM/kW, the server air flow requirements must be thoroughly checked prior to installation. For example, if we design a data center with 100CFM/kW, but the server fans draw 130CFM/kW at maximum speed, we will create an imbalance in pressure between the cold aisle, hot aisle and the outside. This means that we will have air infiltrating to the cold aisle from the hot side or from the outside, which would therefore create hot spots. Decreasing the CFM/kW requirement, and increasing the delta T between the cold aisle and the hot aisle, can help with increasing efficiency and capacity of a cooling unit, but it will create a big imbalance in the room which will cause hot spots. Designing with the inappropriate parameter tends to create complications in the future. A safe number, based on our experience, is 160CFM/kW or delta T of 20F. Containment: there is a flawed impression with designers that a containment in the hot or cold side is required for efficiency purposes only; however, selecting a cooling unit, or designing a cooling system for a data center, with or without good containment can make a significant difference. For example, if 80F is required in the cold aisle, and your containment is not efficient, then your cooling units need to be oversized in order to compensate the infiltration of hot air between the hot and cold aisles. Designing a perfect containment system is key in any [...]
Data centers typically are high-density enclosed spaces that produce and distribute a significant amount of heat in a small area. This is due to the fact that the power they require to operate is dissipated into the air as heat. This heat needs to be removed or the temperature within the data center will rise, and if the temperature rises enough, the equipment can be seriously impacted. Long-term results end in equipment failure. Traditional comfort cooling systems often cannot remove enough heat and there is a critical need to house dedicated units with precision cooling capabilities. But not just any cooling system will do the trick. There are many things to consider when designing an HVAC system for a data center that ensures it maintains a regulated temperature, is sustainable, and continues to help the data center perform its functions optimally. The HVAC system is managed by the air conditioning system, which is influenced by 5 main factors: Type of IT equipment IT equipment configuration Service levels Costs and budget Energy efficiency and green standards IT Equipment The type of IT equipment has a huge bearing on the choice of cooling infrastructure. There are two types of common servers used: 1.) rack-mount servers, and 2.) blade servers. Both have their benefits and limitations. Rack-Mounted Servers Rack-mounted servers are contained in a horizontal case “1U to 5U” in height. ‘U’ is a measurement of rack height that equals 1.75” (44.45 mm). Offers an efficient use of floor space Easier management of cables and servers Flexibility to use servers from different manufacturers Hold more memory, more CPUs and more input/ output (I/O) Limitations: Communications have to travel to the top of rack or edge network device before it can travel back. Blade Servers Blade servers are plug-and-play processing units with shared power feeds, power supplies, fans, cabling and storage. Use less space, so multiple servers can be located in the same area Servers sharing the same space and resources means utilizing [...]
Over the last decade, the legalization of cannabis has managed to break most of the stereotypes and stigmas as ever more growing number of studies discover new medical qualities of the plant’s secondary compounds. A former domain of drug dealers and enthusiasts, cannabis plants have become the darling of the pharmaceutical industry. Quality cannabis cultivation and cannabinoid compound extraction require high standards of Controlled Environment Agriculture (CEA) with new opportunities for many ancillary businesses, predominately the HVAC sector. Traditional comfort cooling AC systems have proven to be ineffective and inefficient to address the environmental challenges of commercial indoor cannabis cultivation and many HVAC professionals embarked on a quest to develop superior commercial cannabis cooling systems. However, the majority of HVAC engineers lack the knowledge of biophysics and biochemistry in order to properly evaluate the dynamically changing environment of cultivation, while the majority of cultivators are incapable of relaying this knowledge to the engineers in technical terms. This disconnect still persists in the industry and HVAC professionals must understand the specifics of CEA in order to successfully design the systems. The State of the Cannabis Industry Currently, thirty states have some form of legal medical marijuana program and in nine states and in nine states it enjoys a recreational status. The cannabis industry in these nine states alone is worth over $9 billion; a surprising number given legalization was only enacted in 2014. It is expected that several more states will legalize recreational marijuana in the next several years. The industry is expected to be worth over $21 billion in 2021 as the beverage, food, cosmetics, Big Pharma and many other businesses are aggressively introducing cannabinoid compounds in their products worldwide. 3 Critical Requirements for Healthy Marijuana Plants Though cannabis is a resilient plant with a broad variety of habitat, only specific environmental conditions allow for expressing full genotype potential of each cultivar. Every single factor of climate control is essential and an inadequately designed climate control system can inhibit [...]
It's an unwritten rule that the difference between the supply air temperature and the return (room air temperature) should be 20°F. For example, if the room temperature is 75°F the supply air temperature must be 55°F.Where did this rule come from?As we attempted to track the origin of this (or myth as some may call it), we do have some hypotheses as to why it might have happened.The 1st hypothesis - The inability of a direct expansion system or chilled water system of achieving more than 20°FThe refrigerant boiling pointWe selected the refrigerant based on its boiling point at a manageable pressure. What do we mean by a manageable pressure? A pressure that we can work with that isn’t as high and not in a vacuum.For example, the boiling point of R502 (or its HFC counterpart R404A) at 35 PSI is 2°F. And because the Delta T across most coils is 10°f, the air leaving will be 12°F which will make it ideal for low temperature applications (freezers).On the other hand, R12 (or its 134A counterpart) has a boiling point of 35°F at the same PSI that will make it ideal for medium temperature applications (i.e. refrigerators).Lastly, R22 (or its R407C counterpart) has a boiling point of 45°F at 70 PSI which makes it ideal for high temperature applications (i.e. conventional commercial air conditioning).With commercial air conditioning, a supply air of anything below 55°F will be too cold and uncomfortable. The comfort point is 75°F (middle of the ASHRAE comfort zone) thus the 20°F split was created.The water freezing point As we all know that the water freezing point is 32°F, therefore the coldest water that a chiller can produce without the risk of freezing is around 45° F. It will create air around 55°F and the comfort point is 75°F, thus once again the 20°F split was created.The 2nd hypothesis - The comfort point (middle of the ASHRAE comfort zone)The comfort point is 75°F and 50% RH, which has [...]
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