Innovations in Thermal Control

by Mary Angelie M. Alagao

From the appliances and gadgets we use at home to the rockets we send to outer space, electronics is the key in making these things work. Advancement in technology translates to an increase in know-how and understanding which leads to further development of sub-branches including electronics. But what is the consequence of its continuous upgrade? More power consumed. As more power is used up, our electronic devices get hotter. And as they get hotter, there is a great possibility of reaching past its limits, to a point where overheating occurs. What happens next? Damage. 

Of course, this isn’t what we would want to happen. We want to use electronics that would be able to last for years, especially if it is to be used in space flights and satellites. Here are two new technologies which are designed to help solve the issue of thermal control in electronics. 

Satellites used for communications, global positioning systems and civil defense purposes have heat pipes that regulate temperature and keep the overall system working. A heat pipe efficiently transfers heat from a hot location to a cold one without the use of a mechanical pump. This is sealed in a tube in which air is removed. When the liquid in the heat pipe comes in contact with a hot surface, vapour is produced due to its absorption of heat from that surface. This vapour condenses once it touches a cold surface. A process called capillary action occurs when the individual liquid molecules interact and attract to the surface of the container, thus, causing the liquid to be drawn back to the hot surface. And the cycle continues.

Heat pipes are thought to solve thermal control issues in electronics placed in microgravity since natural convection does not occur in space.

Scientists introduced the Constrained Vapor Bubble (CVB), which uses a cuvette pipe filled with pentane. This pipe is a rectangular-shaped glass tube made of quartz. With this design, temperature along the CVB can be measured with great accuracy. It is also possible to measure the size and shape of its meniscus since the tube is transparent. This experiment was launched at the International Space Station. The CVB also contains a Light Microscopy Module or LMM, an automated optical microscope controlled from Earth, allows scientists to record changes taking place inside the CVB. 

Aside from CVB, another technology promises an easier and more efficient heat removal in space, this is called the Electrohydrodynamic (EHD)-based thermal control. This technology, like the heat pipe, does not use a mechanical pump. It uses electricity to move the coolants toward tiny ducts inside a thermal cold plate; the heat waste is then pumped into a radiator and is dispersed far-from circuits that are heat-sensitive. The EHD consumes roughly half a watt, which means the electronics is safe from overheating.

Both technologies are lightweight, making them both suitable for space-manned missions. If both these technologies successfully live up to its promise, more advanced electronics can be made, more successful space missions can be achieved, and more questions about our universe could be answered.