On Peltier Elements

10/19/17

“How can we completely rethink cooling systems?”

              Engineers often run into a very peculiar problem. Machines and devices can create large amounts of heat during operation as a result of their high energy use. A common remedy for this conundrum is to implement a thermal cooling system. Examples of these systems include heat sinks (a special form of heat exchanger built for electronics that uses a working fluid to transfer heat away from the device to another location), air conditioning (machines that use a fluid refrigerant operating at a cycle to take heat from one area and transfer it into another).

But even with these current processes, there is a new, most intriguing technology that holds much promise. Consider this. When a current is drawn between two conductive objects, heat may be either added or removed at the junction, making one side hot and another side cold. The hot side will then be attached to a heat sink while the other side will go below room temperature.  This device has been termed by engineers a Peltier Element.

One can construct a Peltier Material as follows. First, take two semiconductors, one a p-type and the other an n-type, and place them in parallel thermally and in series electrically together. Then join them together using a thermally conductive plate. If one were to apply a D.C voltage between the free ends of these two semiconductors then a temperature potential difference will merge. The side with the cooling plate will absorb the heat, which is later transferred to the opposing side that contains the heat sink. The more Peltier Elements within a given space the more efficient that the system will operate at.

Peltier element devices have numerous advantages. First, they have they do not have any moving parts, so much less maintenance is required and less brake-down will occur. No Chlorofluorocarbons (elements commonly found in traditional HVAC systems that induce ozone depletion) are used in their operating process so these machines will be much less damaging to the environment. Furthermore, the control of temperature with these units is so granular that it can even go to the fractional level, much better than older systems. In addition, these systems are made to have a very flexible shape than older, more rigid cooling systems so they can be placed in much more convenient locations. Building on top of this more flexible geometry is their greater temperature bandwidth, meaning that they can perform in conditions not before seen in HVAC systems. This leads to a longer lifespan so Peltier elements can give an individual “more bang for their buck”. Finally, these systems are easily controllable due to their voltage input system.

We can accomplish many feats with Peltier element technology. Their small and modular geometry allows them to be placed in a variety of locations such as in camping equipment and portable coolers. The granular control on Peltier elements make them a strong contender for use in scientific equipment, making them effective in assisting with sunlight temperature irregularities on satellites and military technology.

This is not to say that Peltier Elements have no downsides. One of the biggest hindrances to further adoption is their low efficiencies. Specifically, Peltier Elements require a large amount of electricity to function properly. This also only make Peltier elements very expensive to maintain, as power costs money. Their small form factor also makes it difficult to use in larger scale applications such as industrial operations (Lorenzo, Sarah 2016).

In summation, Peltier elements are a novel technology that holds much promise. Their operating process, the Peltier effect, is a wonderful facet of the physical universe that grants it many useful properties, such as a smaller form factor, a modular geometry, and a longer lifespan. This also allows Peltier elements to be more useful for applications such as satellites and military equipment where flexibility and longevity are needed. However, many of these same advantages can also bring detriment to it, with Peltier elements being to electrically consumptive and too small for large industrial applications. Perhaps with enough time and investment into research, Peltier elements will be able to solve these problems and replace traditional cooling methods.

References

Lorenzo, Sarah. What is a Peltier Cooler? 6 June 2015, http://www.tech-faq.com/peltier-cooler.html. Accessed 18 Oct. 2017.

Centrifugal Fan

09/25/17

“How can we use a fan to control gases?”

Most HVAC systems by moving around gases. However, materials at this phase can be quite difficult to control, so how can we use our engineering mindset to create such a mechanism? Well, we know that blades on a turbine react when a fluid passes through it, and through symmetry we can assume that a fluid will react to motor movement. So what if we were to construct something similar (like a motor) that would take in the gas, impart kinetic energy through its centripetal acceleration, and then change its direction by 90 degrees? Well, this is the fundamental idea behind a centrifugal fan and is one of the most fundamental components of modern HVAC systems.