Calculation method for selection of cabinet air conditioning

Fans are suitable for cabinet temperatures that are higher than the ambient temperature, but when the ambient temperature is higher than the cabinet temperature or the required temperature inside the cabinet (usually 35 ℃), industrial air conditioners should be considered. When the air circulation inside and outside the cabinet requires isolation, industrial air conditioners should also be considered.

The air conditioner adopts the principle of compressor refrigeration for strong cooling, achieving constant temperature control of the internal temperature of the electrical control cabinet. Due to the mutual isolation of air circulation inside and outside the cabinet, it can effectively prevent harmful and humid gases and dust from entering the cabinet.

According to their installation methods, air conditioners can generally be divided into wall mounted (side mounted, embedded, and cabinet mounted) and top mounted.

The selection of air conditioning is also based on the difference between the temperature inside the cabinet and the ambient temperature, as well as the heat loss inside the cabinet, in order to determine the required cooling capacity of the air conditioning. Nowadays, it is generally selected according to the empirical formula provided by Pfannenberg in Germany. The calculation is as follows:

QE=QV-KXAXΔT

In the formula: QE - total cooling capacity (W);

QV - total heat loss of components in the cabinet (W);

K - Thermal conductivity coefficient (W/m2K), which varies depending on the material of the cabinet. Generally, steel plate is 5.5, aluminum plate is 11, and plastic is 0.3;

A - The actual heat dissipation area of the cabinet (m2), and the installation method of the cabinet has a significant impact on the heat dissipation of the cabinet. Pfannenberg in Germany provides the calculation of the heat dissipation area for the following typical installation methods:

(Width=cabinet width, height=cabinet height, depth=cabinet depth)

1. A single cabinet with space around: A=1.8X height X (width+depth)+1.4X width X depth

2. Single cabinet for wall mounting: A=1.4X width X (height+depth)+1.8X depth X height

3. Starting or terminal cabinet, with space around: A=1.4X width X (height+depth)+1.8X width X height

4. Starting or terminal cabinet for wall mounting: A=1.4X height X (width+depth)+1.4X width X depth

5. The cabinet located in the middle has space around it: A=1.8X width X height+1.4X width X depth+depth X height

6. Cabinet located in the middle, for wall mounting: A=1.4X width X (height+depth)+depth X height

7. The cabinet located in the middle is used for wall installation, with a top cover of A=1.4X width X height+0.7X width X depth+depth X height

Δ T - the temperature difference between the inside and outside of the cabinet, the temperature inside the cabinet (usually 35 ℃) minus the temperature outside the cabinet (i.e. the ambient temperature at the work site).