How to Calculate Cooling Capacity For Outdoor Telecom Cabinet
Richard Wang May/6/2024
Reference Video:
1. Background of Outdoor Telecom Cabinet Security
Outdoor Telecom Cabinet is an important device for carrying core telecom equipment in outdoors, and its heat dissipation capacity is a basic condition for the smooth operation of the entire system. However, during the long-term operation of this kind of projects, we found that the cooling capacity calculation for outdoor telecom cabinets was wrong, resulting in heat dissipation problems at telecom carries‘ outdoor sites. We believe that the issue of how much cooling capacity an outdoor telecom cabinet should be equipped with air conditioners is very clear to many manufacturers and telecom operator. However, problems often arise not because of theoretical calculations, but because of neglect of the actual deployment environment. and a series of problems caused by negligence in expansion management. This article will try to start from the perspective of cooling capacity calculation for outdoor telecom cabinet, focusing on issues that are easily overlooked during actual deployment, so as to help operator customers better understand How to Calculate Cooling Capacity for Outdoor Telecom Cabinet.
2.Understand Cooling Capacity of Air Conditioner on Outdoor Telecom Cabinet
2.1 What is Cooling Capacity and Its Key Assumption
Typical 300W Cooling Capacity Air Conditioner
The picture above is a typical 300W Air Conditioner. There are also larger cooling capacities such as 600W, 1200W, 1500, 3000W, etc. This article will take this 300W Air Conditioner as an example to illustrate.
300W Cooling Capacity Air Conditioner Specifications
The table above is an example of the Cooling Capacity of this 300W Air Conditioner. You can find a row of parameters saying Cooling Capacity@L35/L35. From here we can draw two important messages:
(1) Max Cooling Capacity 300W
This specification means that this air conditioner can take 300W of equivalent heat from the outdoor telecom cabinet out of the cabinet. (Although this statement is not particularly accurate, it is easy for everyone to understand and apply)
(2) @L35/L35
The first L35 refers to when the temperature inside the cabinet is 35℃, and the second L35 refers to when the ambient temperature is 35℃. It can be seen that the 300W cooling capacity is based on this assumption. This assumption is crucial, and problems occur in many projects because this assumption is not carefully considered.
Cooling Capacity 300W@L35/L35
Ti is temperature inside the outdoor telecom cabinet.
Ta is the external ambient Temperature.
2.2 Cooling Capacity with Different In Cabinet and External Ambient Temperature
Cooling Capacity 300W with Different Temperature
If we look more deeply at the cooling capacity table above, we can find that the cooling capacity can actually reach 300W cooling capacity at different equivalent temperatures. For example, what we marked in the picture above:
(1) 300W@L25/L25
We can know from the figure that when the in cabinet temperature is 25℃ and the external ambient temperature is 25℃, the system can reach 300W.
(2) 300W@L35/L35
We can know from the figure that when the in cabinet temperature is 35℃ and the external ambient temperature is 35℃, the system can reach 300W.
(3) 300W@L40/L40
We can know from the figure that when the in cabinet temperature is 35℃ and the external ambient temperature is 35℃, the system can reach 300W.
We can find that when the in cabinet temperature and external ambient temperature are required to be consistent, the expected cooling capacity of 300W can be achieved.(Of course there are some additional costs, the power they consume is different, this will be discussed in detail in other articles)
However, we need to know that the above assumptions are very idealistic. In actual scenarios, the external ambient temperature will change with the environment. Then our previous idealized assumptions are no longer valid. This is often a scenario faced in actual deployment.
2.3 Equivalent Cooling Capacity Varies Due to Different Geographical Locations
Source: https://climateknowledgeportal.worldbank.org/country/colombia/climate-data-historical
Temperature in Different Region in Colombia
In actual deployment scenarios, the external ambient temperature will not be as ideal as imagined, and often varies depending on the site deployment location, thus affecting the equivalent cooling capacity of the air conditioner. Taking the country of Colombia as an example, we can find that different regions have different maximum temperatures in summer, which causes the equivalent cooling capacity of the same air conditioner to be different in different regions. As shown in the picture above, we have two sites, Site1 and Site2. It can be seen that the maximum temperature of Site1 is 32℃, and the maximum temperature of Site2 is about 20℃. Assume we use the same air conditioner used in the previous example, and assume the in cabinet temperature we set is 25℃. Then we can see the location of the equivalent cooling capacity from the figure below:
Equivalent Cooling Capacity for Site1 and Site2
According to the figure above, we can see that air conditioners with the same cooling capacity have different equivalent cooling capacities because different regions have different maximum ambient temperatures. Based on our example, we can find:
Site1 equivalent cooling capacity = 250W
Site2 equivalent cooling capacity = 325W
It can be found that the gap is not small. Therefore, we can draw an important conclusion. Air conditioners with the same capacity have different equivalent cooling capabilities because the maximum ambient temperature in the deployment area is different.
However, most suppliers and Carrier customers do not perform equivalent calculations on outdoor telecom cabinet cooling capacity due to differences in site location. In many cases, the configured air conditioner is only calculated based on the approximate heat dissipation of the equipment configured in the outdoor telecom cabinet. So suppose we have a DWDM project with the same configuration for each site, but the geographical location covers different areas of Colombia. Assuming we use the same air conditioning configuration, it may cause problems because the equivalent cooling capacity is different in different areas.