How to ensure that the reserved space does not affect the heat dissipation performance of the distribution box?

 

When designing theenclosure of the distribution box, our design team needs to consider several factors to ensure that the reserved space does not affect heat dissipation.

 

We carefully plan the location of the reserved space to keep it away from heat-generating components and consistent with the established heat dissipation channels. Second, we optimize the heat dissipation design by adding additional heat dissipation channels to the reserved space and implementing intelligent thermal control systems. Third, we select suitable materials, use heat-resistant materials for insulation, and select enclosure materials with good heat dissipation performance. Finally, we perform thermal simulations and actual tests to verify and optimize the design to ensure that the reserved space does not compromise the overall heat dissipation performance of the distribution box.

 

Table of contents

1. Reasonable planning of reserved space

2. Optimization of heat dissipation design

3. Material selection and heat insulation treatment

4. Simulation and testing

 

 

 

1. Reasonable planning of the reserved space location

Keep away from the concentrated heat source area:

The heat generation of different electrical components in thedistribution box varies greatly. Components such as high-power transformers, rectifiers, and high-power resistors will generate a lot of heat when working and are the main heat sources. When planning the reserved space, it is necessary to accurately measure the heat dissipation range of these heat source components, and obtain their thermal field distribution under different loads through equipment such as thermal imagers. For example, in a typical industrial distribution box, when the high-power transformer is in operation, the temperature within 15-20 cm around it rises significantly. Therefore, the reserved space should be set at the edge or corner position at least 20 cm away from these heat sources to avoid excessive local temperature due to proximity to the heat source, affecting the possibility of future use of the reserved space, and also preventing obstacles to the heat dissipation of other normally operating components.

In addition, the heat dissipation direction of the heat source components must also be considered. Some components may dissipate heat upward, while others may dissipate heat laterally. For example, some vertically mounted power modules mainly dissipate heat upward. In this case, the reserved space should not only be away from the heat source in the horizontal direction, but also maintain a certain distance in the vertical direction to prevent the hot air flow from directly impacting the reserved space.

Combined with the layout of the heat dissipation channel:
It is key to have a deep understanding of the established heat dissipation channel principle and airflow direction of the distribution box. If the distribution box adopts the natural convection heat dissipation method of bottom air intake and top air outlet, this is based on the principle of hot air rising and cold air replenishment. At this time, the reserved space must not be set on the straight channel of the air inlet and outlet, so as not to block the air flow like a "roadblock". For example, in a small distribution box, the air inlet is located on the left side of the bottom and the air outlet is located on the right side of the top, and the air flow rises in a diagonal direction. The reserved space can be set in a position parallel to the heat dissipation channel but does not hinder the airflow, such as the right edge of the distribution box, to ensure that the air can flow smoothly in the distribution box and take away the heat.

For distribution boxes that use forced ventilation to dissipate heat, that is, accelerate the air flow through fans and other equipment, the reserved space should also be planned according to the air supply direction and airflow organization of the fan. For example, axial fans usually blow air from one end to the other, and the reserved space should avoid the fan's direct blowing path and main air flow channel to avoid interfering with the uniform distribution of airflow and heat dissipation efficiency.

 

2. Optimize heat dissipation design
Add heat dissipation channels:

For the reserved space, it is very necessary to design additional heat dissipation channels. For example, a guide plate is set between the reserved space and the heating element. The guide plate can be made of thin aluminum plate or plastic material. Its shape and angle should be precisely designed according to the air flow direction in the distribution box and the position of the reserved space. Through CFD (computational fluid dynamics) simulation software, the optimal shape and installation angle of the guide plate can be determined to guide the hot air to flow quickly to the air outlet and avoid the accumulation of hot air near the reserved space. For example, the guide plate is designed to be inclined at a 45-degree angle, which can effectively guide the hot air emitted from the heating element to the direction of the air outlet without forming vortices around the reserved space.
In addition to the guide plate, small vents can be opened on the side wall or bottom of the reserved space. The size, number and location of these vents need to be determined by calculation and experiment. If the vent is too small, the air circulation is not smooth and the heat cannot be effectively removed; if the vent is too large, it may affect the protection level of the distribution box. Generally speaking, the total area of ​​the vents should be determined based on the volume of the reserved space and the expected heat output. For reference, a vent area of ​​5-10 square centimeters can be set for every cubic meter of reserved space. At the same time, dust screens should be installed at the vents to prevent dust and other foreign objects from entering the distribution box and affecting the performance of electrical components.

Adopt intelligent heat dissipation control:
Installing intelligent heat dissipation equipment, such as intelligent temperature-controlled fans, is an effective means to achieve precise heat dissipation. The intelligent temperature control system consists of temperature sensors, controllers, and fans. Temperature sensors should be distributed at various key locations in the distribution box, especially near the reserved space, to monitor temperature changes in real time. When the temperature in the distribution box rises, the sensor transmits the temperature signal to the controller, which automatically adjusts the fan speed according to the preset temperature to enhance heat dissipation. For example, when the temperature near the reserved space reaches 40℃, the controller increases the fan speed from 1000 rpm to 1500 rpm to ensure that the temperature in this area does not continue to rise.
In addition, variable frequency fans can also be used to adjust the fan speed steplessly according to temperature changes to achieve more refined heat dissipation control. At the same time, the intelligent temperature control system is integrated with the monitoring system of the distribution box, and the temperature conditions and fan operating status in the distribution box are remotely monitored through the network, so as to timely discover potential heat dissipation problems and make adjustments.

 

3. Material selection and thermal insulation treatment

Use thermal insulation materials:

Insulating materials are installed between the reserved space and the heating element to effectively block heat transfer to the reserved space, reduce the thermal impact on the reserved space, and do not affect the overall heat dissipation performance of the distribution box. For example, ceramic fiber insulation board has good thermal insulation performance, and its thermal conductivity is as low as 0.05 - 0.15W/(m・K), which can effectively block heat transfer. Install the ceramic fiber insulation board between the reserved space and the heating element to form a thermal barrier. During installation, ensure that the insulation board is in close contact with the heating element and the reserved space to avoid gaps that cause heat leakage.

Aerogel insulation felt is also an excellent thermal insulation material with extremely low thermal conductivity and good flexibility. Aerogel insulation felt can be wrapped around the heating element or covered on the inner wall of the reserved space to further enhance the thermal insulation effect. When selecting insulation materials, factors such as fire resistance, corrosion resistance and service life should also be considered to ensure that the insulation materials can continue to play a role during the long-term operation of the distribution box.

Shell materials with good heat dissipation performance:
Choose a distribution box shell material with good heat dissipation performance, such as aluminum alloy. Aluminum alloy has a high thermal conductivity, generally between 180-230W/(m・K), which can quickly transfer the heat inside the distribution box to the surface of the shell and dissipate it. Compared with traditional steel shells, the heat dissipation efficiency of aluminum alloy shells can be increased by 30%-50%. Even if there is reserved space, good shell heat dissipation performance can help maintain a lower temperature inside the box and ensure the overall heat dissipation effect.

When selecting aluminum alloy materials, choose the appropriate aluminum alloy model according to the use environment and budget of the distribution box. For example, 6061 aluminum alloy has good comprehensive performance, high strength, good corrosion resistance, and is suitable for most industrial and civil distribution boxes; for some distribution boxes used in harsh environments, such as seaside or chemical sites, 5052 aluminum alloy can be selected, which has better corrosion resistance. At the same time, the aluminum alloy shell can also be subjected to surface treatment, such as anodizing treatment, which can not only improve the corrosion resistance of the shell, but also increase its heat dissipation area, further improving the heat dissipation performance.

 

4. Simulation and testing

Thermal simulation analysis:

During the design stage, it is essential to use professional thermal simulation software to conduct thermal analysis on the distribution box. Currently, commonly used thermal simulation software includes ANSYS Fluent, FloTHERM, etc. By establishing a three-dimensional model of the distribution box, inputting parameters such as the heating power, heat dissipation method, and material properties of electrical components, the influence of reserved space on heat dissipation performance under different working conditions is simulated. For example, during the simulation process, different load conditions can be set to simulate the heating of electrical components under full load, half load, etc., and observe the temperature distribution.

By adjusting the position, size, and heat dissipation design parameters of the reserved space, such as changing the shape of the guide plate, the position and size of the vents, etc., multiple simulation analyses are performed to find the optimal design solution. During the simulation process, temperature cloud maps and airflow streamlines can be generated to intuitively display the temperature distribution and airflow flow in the distribution box, helping designers to accurately judge the influence of reserved space on heat dissipation performance and perform targeted optimization. For example, through the temperature cloud map, it is found that the temperature in a corner of the reserved space is too high, which can be solved by adjusting the position of the vents or adding insulation materials.

Actual test verification:
Making a distribution box prototype and testing the heat dissipation performance under actual operating conditions are key steps in verifying the design. Simulate various possible heating conditions of electrical components, such as simulating the heating of electrical components of different powers by adjusting the load resistance, and measure the temperature of each area in the distribution box including the reserved space. Use high-precision temperature sensors to evenly arrange multiple measurement points in the distribution box to ensure that temperature data can be accurately obtained.

According to the test results, optimize the design. If it is found that the temperature of the reserved space is too high, the heat dissipation channel can be further improved, such as increasing the size of the vents, adjusting the angle of the guide plate, etc.; or adjusting the position of the insulation material to enhance the insulation effect. At the same time, the heat dissipation performance of the distribution box under different ambient temperatures can also be tested to ensure that the reserved space will not affect the heat dissipation performance of the distribution box in various actual use environments. Through actual test verification, the design plan is continuously optimized to ensure that the heat dissipation performance of the formal product is not negatively affected by the reserved space.