我们热衷于强制对流技术
In the thermal management industry, we are highly concerned with the convection type. Is it natural or is it forced convection? The answer to that question makes a big difference when it comes to designing a cooling solution. With natural convection, we use buoyancy to do the lifting. Forced convection solutions get outside help to move fluid through a system. Many applications need to make the switch from a natural convection solution to a forced convection one when more heat transfer is required and adding surface area isn’t an option. Adding more surface area can add more weight to a cooling solution or the extra surface area might choke flow produced from natural convection.
最多使用自己的设备
For air cooling, fan and blowers mechanically force air through a cooling solution like a heat sink, thus increasing the amount of heat transfer with a given amount of surface area. All of these devices come in different sizes, performances, and other options. In this post, we’ll focus on air forced convection and the devices that create those air flows.
空气强制对流：风扇和鼓风机
风扇和鼓风机有什么区别？
Both a fan and a blower have a motor with engineered blades that produce a pressure differential when spun. The pressure differential is what drives the air flow through the device. The difference between the fan or blower is the direction the air is expelled from the blade.
Axial fans pull air from one end of its axis of rotation, then force the air out along the other direction along that same axis.
Blowers, also known as centrifugal fans, pull air from the axis of rotation. It can either be one side or both sides of the axis. So instead of pushing out along the axis, the air is directed outward, generally guided by a housing or case that points the air flow perpendicular to the axis of rotation.
使用风扇或鼓风机时要考虑的事项
性能
PQ曲线，也称为压力流量曲线，表征风扇或鼓风机的性能。驱动风扇的电机具有一定的速度和扭矩可以处理。电机只有这么多的魅力来推动空气通过叶轮叶片。风扇或鼓风机的PQ曲线中描述了它在特定速度下可以移动多少空气的关系。如果您尝试超过此曲线，电机将熄火，然后您的应用将没有任何流量。这会导致过热和潜在的产品故障。
您不仅需要考虑风扇和鼓风机的机械流动性能，还需要检查如何为风扇供电。不幸的是，风扇和鼓风机不能神奇地为自己供电，因此我们需要设计一个板或电源来提供风扇推动空气所需的电压和电流。虽然风扇使用的电压可以保持一致，但它消耗的电流可能因制造商而异。确保为风扇提供正确的电压和电流，同时在电流消耗时仍保持显着的安全系数。你不想要任何烧坏的董事会和不满意的客户，因为你对你的粉丝不好。
风扇和鼓风机的防护等级 （IP）
由于热管理应用中使用的大多数风扇都是电风扇，因此在挑选风扇时，环境因素是一个重要的考虑因素。确定风扇可以处理哪种环境的常用方法是通过入口防护等级或 IP 等级。IP等级的第一个数字是指固体颗粒进入以及设备保护的颗粒大小。第二个数字是指设备具有的液体保护量，从小液滴到将设备浸入液体中。
用户将使您的产品经历各种折磨。除非您的产品在洁净室中度过难关，否则您的设备和风扇或鼓风机将受到灰尘的影响。消费电子产品经历了各种各样的灰尘源，从人类和宠物脱落到衣服和家具上的杂散纤维。此外，这些消费者很容易将他们的饮料（无论是热的还是冷的）洒在您的设备上。制造车间的产品不仅会看到这些颗粒，还可能看到机器上的油脂和污垢。关键是您的设备，因此您的风扇和鼓风机，必须设计和制造以处理用户将要扔给它的任何东西。在开始挑选风扇或鼓风机之前，花一些时间考虑一下用户对您的产品的滥用程度。
风扇和鼓风机可靠性
您的产品的使用寿命有多长？如果您的产品需要主动冷却，则需要在产品的整个生命周期内使用强大的风扇或鼓风机。指定一个在产品预期使用寿命之前会磨损的风扇将缩短产品的可用性窗口，并且您可能会从不满意的客户那里得到一些简短的回复作为回报。否则，您可能需要计划中期维护，需要更换风扇以延长产品的使用寿命。在某些情况下，这对最终用户来说是困难且不切实际的。
Fan and blower reliability and lifetime is heavily dependent on what type of bearings the fan or blower uses. Less expensive fans typically use sleeve bearings to support the fan impeller within the fan frame. Fans using ball bearings will wear more slowly over time, giving those fans a longer lifetime. Other fans have been known to use rifle bearings, fluid bearings, or even maglev bearings, all of which have the aim to increase the overall lifespan of the fan. Be careful in selecting what sort of bearing your fan or blower uses and how that affects your overall product lifespan.
