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What is a Hot/Cold Aisle in CRAC?

Computer Room Air Conditioning: Chapter 2


Hot and Cold Aisles


In this module, we will look into hot and cold aisles in computer room air conditioning. We’ll also learn about hot and cold aisle contaminants. Skip to quiz!


Hot and Cold Aisles


Hot and cold aisles are a design layout for data centers where servers and computers are kept and data is stored. The purpose of hot and cold aisles is to manage airflow in data centers to lower energy consumption and increase efficiency.


Rows of server racks are oriented in a way that the front of servers face each other and the back of servers also face each other. Let’s watch a video to learn more about hot and cold aisles.


We can arrange CRAC systems in different ways. Cooling air circulated through an elevated floor has been successful in CRAC systems.


Cold air is circulated through perforated floor tiles between the racks forming cold aisles. This cold air flows through the racks, where it picks up heat before exiting from the back of the racks. Warm exit air forms hot aisles behind the racks, and it returns to the CRAC system below the floor.



Aisle Containment


However, the ‘hot and cold aisles’ method is not perfect. There can be some mixing of hot and cold air. Gaps in the floor result in air leaks. This means cold air can directly mix with hot air.


A data center should be designed with aisle containment to improve efficiency further. The mixing of hot and cold aisles can be eliminated by installing a physical barrier between hot and cold aisles. Aisle containment lowers energy costs by managing airflow.


Cold aisle containment is a popular choice for existing data centers. This is because it’s easy and cheap to install compared to hot aisle containment.


Hot aisle containment costs more to install. This containment requires more height, so it’s best suited for a new building. Old buildings may not have sufficient height to install. Hot aisle containment provides superior performance.


The main components of a CRAC system are:

  • Cooling coil,

  • Air filter,

  • EC blower,

  • Humidifier, and

  • Electric heaters.

Cooling air circulated through an elevated floor has been successful with computer room cooling systems.


Cold air is circulated through the perforated floor tiles between the racks forming cold aisles. Cold aisle containment is a popular choice for existing data centers because it is easy and cheap to install. Hot aisle containment provides superior performance, but requires more height and is costly to install.




 

Question #1: Hot and cold aisles is a design layout for _________.

  1. Supermarket

  2. Shopping mall

  3. Data center

  4. Hospital

Scroll down for the answer...












Answer: Data center

Hot and cold aisles is a design layout for the data centers where servers and computers are kept, and data is stored.


Question #2: Cooling air circulated through an __________has been successful in CRAC systems.

  1. Windows

  2. Elevated floor

  3. Ceiling

  4. Opened doors

Scroll down for the answer...













Answer: Elevated floor

Cooling air circulated through an elevated floor has been successful in a CRAC systems.


Question #3: Which of the following is comparatively cheaper to install?

  1. Cold aisle containment

  2. Hot aisle containment

Scroll down for the answer...









Answer: Cold aisle containment

Cold aisle containment is easy and cheap to install compared to hot aisle containment.


Question #4: ____________ provides superior performance.

  1. Cold aisle containment

  2. Hot aisle containment

Scroll down for the answer...









Answer: Hot aisle containment

Hot aisle containment provides superior performance but requires more height and is costly to install.


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