Students who have seen our PC power supply product reviews should have found that in addition to a very small number of Fanless products, PC power supply is basically indispensable to the cooling fan, and the cooling fan on the PC power supply will mostly have a more special posture, to not say that the fan itself is different, generally speaking, it is still those standard specifications of the product, but they tend to install a plastic sheet on the position of the air outlet, it looks like it is deliberately intercepting a part of the airflow, What's more, it is directly to the power supply to make a fan with its own wind baffle, which also limits the area of the air outlet.
According to the general cognition, such a practice is really puzzling, the power supply configuration fan is for heat dissipation, adding such a piece of plastic on the fan, is not equivalent to adding an obstacle to the fan, reducing the heat dissipation efficiency of the fan? Therefore, some students do not hesitate to risk losing the power supply warranty or even damaging the power supply, they have to disassemble the power supply and remove the plastic sheet on the fan, thinking that this is "unsealing" and maximizing the heat dissipation efficiency of the power supply. But is this really necessary? In fact, it is really not necessary.
What exactly is the use of plastic sheets on power supply fans?
In fact, if you think about it a little, you will find that this piece of plastic sheet is definitely not to "reduce the heat dissipation efficiency", this kind of thing that increases the additional cost in exchange for a negative experience, normal manufacturers will certainly not do it, not to mention that the practice of "adding plastic sheets to the power supply fan" does not only exist in individual manufacturers, but is a very common practice, but what is not done is a minority. In fact, the role of this plastic sheet is exactly the opposite of what everyone thinks, it is designed to optimize the internal heat dissipation of the power supply, and its real role is the deflector plate of the cooling fan, which can make the heat dissipation gas flow inside the power supply have a higher flow rate, and at the same time have a more clear heat dissipation path.
The role of the installed deflector, in addition to guiding the fan air flow direction, there is also a role is to increase the gas flow rate, which is the principle and the orifice plate flowmeter work mode is the same, after the installation of the deflector, equivalent to the fan before and after the emergence of a different aperture, according to the Venturi effect, the air flow will form a local contraction in the position of the deflector plate, so that the average flow rate increases, generally speaking, the same heat dissipation area, the faster the average flow rate, the better the heat dissipation efficiency, so after installing the deflector, Components exposed to the cooling airflow will achieve better heat dissipation efficiency.
Of course, it is undeniable that after the installation of the deflector, the airflow resistance of the fan has indeed increased, that is, the requirements for wind pressure will become higher, which means that the actual air volume will decrease. Take the Kyushu Fengshen PQ1000M power supply standard fan Honghua HA1225H12F-Z as an example, this fan in the case of no air deflector, the measured maximum air volume is 67.3CFM, and after the installation of the standard deflector, the measured maximum air volume dropped to 48.1CFM, and if you change to a larger area of plastic sheets, the actual air volume of the fan will further decline, so the area of the deflector plate should not be too large, generally speaking, it will not exceed one-third of the fan outlet.
After installing the deflector, can the actual air volume of the fan still meet the heat dissipation needs? At this point, we can according to the "Super Classroom (298): How much fan is needed to dissipate heat for the CPU with 200W power consumption? The formula mentioned in the formula is calculated, according to the Kyushu fan PQ1000M power supply at full load, the conversion efficiency is 93% of the calculation, its heat generation is mainly derived from the power dissipated, that is, equivalent to 70W power, if the power supply is allowed to heat up to 10 degrees, then the calculation of the fan is only needed to provide 12.6CFM air volume, after adding a deflector fan air volume is more than enough.
Where is the air deflector of the fan to be installed?
On this issue, we may wish to first take a look at how the heat generated inside the power supply is, students who are interested in learning more can go to see our previous class article "Super Energy Classroom (286) :P How high is the heat energy of the C power supply? Here we will briefly talk about it. The following figure is a power supply with the cooling fan removed, rated at 850W, and passed the 80Plus Gold certification. This power supply in the case of full load, the heat of various internal positions, you can see the main voltage of the power supply and the position of the secondary side of the temperature is significantly higher than other positions, when other positions are still maintained at a temperature of about 60 ° C, the temperature of this part has exceeded 100 ° C, it is clear that if you want to optimize the heat dissipation inside the power supply, this part is the position that needs to be focused on.
In fact, the internal layout of this power supply is also the current mainstream design, the left side is the AC input end, but also the outlet of the power supply, generally called the outside; the right side is the module interface of the power supply, which is also known as the inside of the power supply; the fan is blowing the air flow from top to bottom to the PCB, and after turning 90 ° left, it is discharged from the air outlet of the power supply to the outside.
At present, the mainstream design, located near the power supply outlet EMI circuit and PFC circuit, that is, we often say that the high voltage side of the power supply or the primary side, this position is high voltage and low current, the loss is relatively small, the heat dissipation pressure is relatively low; compared to the low voltage side near the inner position of the power supply, that is, the secondary side is low voltage and high current, and the main transformer is mostly closer to the secondary side, which means that the heat dissipation pressure of this part will be greater, so the current ideal heat dissipation design on the mainstream power supply, It is to let the air flow go from the inside to the outside, that is, from right to left in the above figure, the deflector on the cooling fan, which achieves such a thing.
So remove this deflector, will it cause heat dissipation problems in the power supply? There is indeed such a possibility, after removing the deflector, it seems that all the components of the power supply have been dissipated by the airflow, but in fact, the airflow interference inside the power supply is greater, the heat dissipation efficiency will actually be reduced, the temperature inside the power supply will rise, in order to control the heating, the speed of the power supply fan will increase, resulting in running noise will become larger, so removing the deflector may bring about a negative impact on the use experience.
Of course, many components inside the power supply are actually components that can continue to work stably at relatively high temperatures, so the deflector on the fan is more of an optimized means than a necessary configuration, and there has never been a mandatory specification that instructs the manufacturer to configure the deflector for the cooling fan. But removing the deflector will not bring better heat dissipation performance to the power supply, and the player disassembles the power supply by himself there is also a risk of damaging the product, at least the warranty service of the power supply is lost, so such a "damage to others and not to themselves" thing, everyone does not need to do it.