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Q&A about AC Fan, DC Fan and EC Fan:
1. How do AC Fan/DC Fan/EC Fan/Blower work to dissipate heat?
Ans

AC Fan/DC Fan/EC Fan/Blower could be thought of air pump that utilize power from a motor to output a volumetric flow of air at a given pressure. AC Fan/DC Fan/EC Fan/Blower are moving sufficient air to convert the heat energy to the ambience.

2. AC Fan/DC Fan/EC Fan/Blower Definitions:
Ans

2-1. AC Fan & DC Fan: The most obvious difference between AC Fan and DC fan is the type of electricity that they use. DC Fan use direct current(DC) electrical flows which could only move in one direction. AC Fan use alternating current(AC) charges that can change direction quickly.

 

2-2. EC Fan: EC stands for “Electronically Commutated”. EC Fan combines AC Fan and DC Fans’ voltages bringing the best of both worlds. The motors runs on a DC voltage, but with a single phase 230V AC or three phase 400V AC supply. The non-rotating part of the motor(stator) is extended to make room for an electronic PCB board which includes power transformation AC to DC, as well as the controls.

 

2-3. Blower: A centrifugal fan with a high pressure ratio(output pressure/input pressure) is known as a blower. Blowers deliver a high volume transfer rate with a relatively greater pressure ratio. The pressure ratio of a fan is below 1.1 while blowers have a pressure ration of 1.1 to 1.2.

3. What is the difference between Fan(AC Fan/DC Fan/EC Fan) & Blower :
Ans

Fan(AC Fan/DC Fan/EC Fan) produce a gas flow with less pressure and larger gas volume, while blowers produce a relateively higher pressure ratio with larger gas volume flow.

4. What is the Air Flow of AC Fan/DC Fan/EC Fan/Blower in specification?
Ans

The Air Flow of AC Fan/DC Fan/EC Fan/ Blower correspond to the volume of air moved through the fan in a set interval. Thus, it is a very important parameter for us. In most data sheets, the typical parameter is CFM(cubic feet per minute) or m³/h (cubic meters per hour). Be careful while compare AC Fan/DC Fan/EC Fan & Blower’s specifiation.

5. What is the Air Pressure of AC Fan/DC Fan/EC Fan/Blower in specification?
Ans

In essence, the Air Pressure of AC Fan/DC Fan/EC Fan/Blower in a point in the ventilation system is the atmospheric pressure inside the duct on the exhaust side, and as air moves from high to low pressure, air is expelled from the duct. This results in a reduction of pressure in the duct on the other side of the AC Fan/DC Fan/EC Fan/Blower so that it is lower than atmospheric pressure, causing air to flow into the system. Known as static pressure, refers to the AC Fan/DC Fan/EC Fan/Blower on the intake side and the pressure difference between the air outlet end, usually in millimeters water column (mmH2O) or inches water column(inchH2O)

6. What is the Noise Level of AC Fan/DC Fan/EC Fan/Blower in specification?
Ans

For many users, the drawback of merely looking at a specified acoustic specification of AC Fan/DC Fan/EC Fan & Blower is that it is hard to image how unbearable that number is in the real world. Typically, the Noise Level unit of AC Fan/DC Fan/EC Fan & Blower is either specified in dB(decibel) or dB(A). Where is the Noise Level of AC Fan/DC Fan/ EC Fan & Blower comes out? Mostly, it was affected by motor, bearing, wind sound and etc.

7. Fan Bearing System of AC Fan/DC Fan/EC Fan and Blower:
Ans

There are 2 main types of AC Fan/DC Fan/EC Fan and Blower bearings that are ball & sleeve bearings. Before selecting the bearing, we must consider the fan life span, operation temperature, lubrication & cost. Since AC Fan/DC Fan/EC Fan and Blower stability is the most critical factor in fan performance, it is important that a fan run consistently for a number of years. Sleeve bearing is around 30000 hrs at 40℃ shorter than ball bearing is around 50000 hrs at 40℃.

8. What is PQ curve of AC Fan/DC Fan/EC Fan and Blower :
Ans

From the fan spec, you will find a PQ curve on drawing. P stands for Pressure, Q is CFM of its AC Fan/DC Fan/ EC Fan and Blower. The PQ curves predict the pressure-flow rate performance of each AC Fan/DC Fan/ EC Fan and Blower. Choose a fan that has its peak efficiency at or near your operating point.

9. How to select a AC Fan/DC Fan/EC Fan/Blower?
Ans

9-1. Caculate the watts consumption you would need to dissipate?


9-2. Confirm the environmental temperature and target temperature.


9-3.What is the acoustic noise of AC Fan/DC Fan/EC Fan/ Blower you need?


9-4.Confirm the AC Fan/DC Fan/EC Fan/Blower dimensions.



Q& A of Heatsink/Thermal Module solution(Skived Heatsink/Extrusion Heatsink/Heatpipe)
1. Methods of heat transfer:
Ans

1-1. Heat Sink conduction through Aluminum & Copper(Skived/Extrusion/Heatpipe Assembly/Thermal module…etc.) The thermal conductivity of the heatsink(Skived/Extrusion/Heatpipe Assembly/Thermal Module) material has a major impact on cooling performance. Heatsink thermal conductivity is measured in W/mK; higher values mean better conductivity.

 

1-2. Heat convection through AC Fan/DC Fan/EC Fan/ Blower.Forced convection is a type of heat transfer in which an external sourceb (AC Fan/DC Fan/EC Fan/Blower) is used to generate fluid motion and increase the heat transfer. The most common perception is that higher the flow, higher the forced convection, as the result, higher the cooling.

 

1-3. Heat Radiation

2. What is a heatink(Skived Heatsink/Extrusion Heatsink/Heatpipe Assembly/Thermal Module)?
Ans

A Heatsink(Skived Heatsink/Extrusion Heatsink/Heatpipe Assembly/Thermal Module) is an object that transfers and dissipates heat. Heatsink(Skived Heatsink/Extrusion Heatsink/Heatpipe Assembly/Thermal Module) are used in a wide range of applications, ex.-information equipment, manufacturing equipment, appliance apparatus, lighting equipment, medical equipment, telecommunication equipment and network equipment, and etc.

3. How do Heatsinks(Skived Heatsink/Extrusion Heatsink/Heatpipe Assembly/Thermal Module) performed?
Ans

The performance specification for any Heatsink(Skived Heatsink/Extrusion Heatsink/Heatpipe Assembly/Thermal Module) would be thermal resistance or thermal sensitivity, which is typically express in C° / W as the temperature increase per watt of heat.

4. Heatsink materials in Common:
Ans

4-1. Alloy Heatsinks (Skived Heatsink/Extrusion Heatsink/Heatpipe Assembly/ Thermal Module) have lower thermal conductivity than pure metals, but may have better mechanical or chemical (corrosion) properties.

 

4-2. Aluminum Heatsink(Skived Heatsink/Extrusion Heatsink/Heatpipe Assembly/Thermal Module) – The thermal conductivity is 205W/mK, the aluminum heatsink(Skived Heatsink/Extrusion Heatsink/Heatpipe Assembly/ Thermal Module) is inexpensive compared with Copper, due to its softness, it could be milled quickly, also the weight is light, thus the Aluminum Heatsink(Skived Heatsink/Extrusion Heatsink/Heatpipe Assembly/Thermal Module) will put less wight on its mounting.

 

4-3. Copper Heatsink(Skived Heatsink/Extrusion Heatsink/Heatpipe Assembly/Thermal Module) – Copper thermal conductivity is about twice as high as Aluminum(400W/mK), hence the Copper Heatsink(Skived Heatsink/Heatpipe Thermal Module) is an excellent thermal conductive material for heatsinks.(Skived Heatsink/Heatpipe Assembly/Thermal Module). The disadvantages are heavy & high price.

5. Manufacturing process of Heatsink:
Ans

5-1. Extrusion Heatsink: The Extrusion Heatsink are most common solution in market so far. The Extrusion Heatsink may be cut, machined, CNC and options added. There are limits for Extrusion Heatsink, such as high-to-gap ratio and fin thickness.

 

5-2. Stamped Heatsink: The maching process for skived fin heatsink uses cutting tools and a controlled slicing technique to manufacture heatsink from a solid block of aluminum or copper. The benefits are thinner blades, bigger heat dissipate area than extrusion heatsink.

 

5-3. Stamped Heatsink: The Stamped Heatsink are manufactured by the application of extreme pressure to a piece of aluminum or copper to produce fins of the desired height, thickness and shape, which are then bonded to the heatsink metal base.

 

5-4. Die-Cast Heatsink: The Die-Cast heatsink are manufactured by forcing liquid aluminum under high pressure into re-usable steel molds. This is an ideal solution when you require a more complex design in high volumn and with lower thermal conductitivy.

 

5-5. Precision Machine/CNC process: Through the Precision Maching/CNC process utilizes the latest multi-axis CNC center, lathe, EDM and grinding machine to provide you compelex and high precision heatsink to a high tolerace. Most precision machine/CNC process will have no problem holding a tolerance of 0.002” or 0.005MM.

 

5-6. Heatpipe Assembly: Heatpipe are usually sintered or powered copper, and could be manufacturered under any type of orientation including horizontal, gravity aded or against gravity.The Heatpipe Assembly allows for great potential to increase your thermal performance .



Types of Heatsinks
Heat sinks can be classified in terms of manufacturing methods and their final form shapes.The most common types of air-cooled heat sinks include:

 

 

Stampings Copper or aluminium sheet metals are stamped into desired shapes. They are used in traditional air cooling of electronic components and offer a low cost solution to low density thermal problems. They are suitable for high volume production, because advanced tooling with high speed stamping lowers costs. Additional labour-saving options such as clips and dry interface materials can be factory applied to help to reduce the board assembly costs.

 

Extrusions These are by far the most common for power amplifiers, and allow the formation of elaborate two-dimensional shapes capable of dissipating large heat loads. They may be cut, machined, and options added. Cross-cutting will produce omni-directional, rectangular pin fin heat sinks, and incorporating serrated fins improves the performance by approximately 10 to 20%. Extrusion limits, such as the fin height-to-gap ratio and fin thickness, usually dictate the flexibility in design options. Typical fin height-to-gap aspect ratio of up to 6:1 and a minimum fin thickness of about 1.3mm are attainable with standard extrusion processes.

 

Bonded / Fabricated Fins Most air cooled heat sinks are convection limited, and the overall thermal performance of an air cooled heat sink can often be improved significantly if more surface area can be exposed to the air stream. Such high performance heat sinks utilise thermally conductive aluminium-filled epoxy to bond planar fins onto a grooved extrusion base plate. This process allows for a much greater fin height-to-gap aspect ratio of 20 to 40, with the intent of greatly increasing the cooling capacity without increasing volume requirements. Very tall fins don't always work.

 

Castings Sand, lost core and die casting processes are available with or without vacuum assistance, in aluminium or (less frequently for audio applications) copper/bronze. This technology is used in high density pin fin heat sinks which provide maximum performance when using forced air cooling.

 

Folded Fins Corrugated sheet metal - either aluminium or copper, increases surface area and, hence the volumetric performance. The heat sink is then attached to either a base plate or directly to the heating surface via epoxying or brazing. It is not suitable for high profile heat sinks, but it allows high performance heat sinks to be fabricated for specific applications.

5. What are the parameters affect the thermal conduction & thermal convection of Heatsink(Skived Heatsink/Extrusion Heatsink/Heatpipe/ Thermal Module)?
Ans

5-1. Determine which Meterials of Heatsink(Skived Heatsink/Extrusion Heatsink/Heatpipe/Thermal Module) to go.

 

5-2. Choose the right Fan(AC Fan/DC Fan/EC Fan/Blower)

 

5-3. Heatsink(Skived Heatsink/Extrusion Heatink/Heatpipe/Thermal Module) thermal resistance.

 

5-4. Die-Cast Heatsink: The Die-Cast heatsink are manufactured by forcing liquid aluminum under high pressure into re-usable steel molds. This is an ideal solution when you require a more complex design in high volumn and with lower thermal conductitivy.

 

5-5. Determine the fan(AC Fan/DC Fan/EC Fan/Blower) specification While checking a heatsink(Skived Heatsink/Extrusion Heatsink/Heatpipe/Thermal Module), it is also important to determine the rate of fan(AC Fan/DC Fan/EC Fan/Blower). High air flow & air pressure are not definitely better performance, all the mechanical design/air convection & air conduction shall be considered.