by Breana Cronk, IQS Editor
In 1821, Thomas Johann Seebeck discovered thermo-electricity and developed the preliminary design for thermocouples. At this time, the idea of electricity in every home was a stretch and the NASA space program was a complete work of fiction. Nearly two hundred years later, thermocouples can be found in virtually every industrial, commercial and residential building. Simple in design, thermocouples are constructed of two distinct metal wires joined together. If the temperatures changes, the voltage readout also changes and alerts users to the difference. In some ways these devices are like common thermostats, but for electronics rather than room temperature. They have become such an integral element of temperature sensory that researchers at the NASA Glenn Research Center continue to expand upon Seebeck’s original idea for both space and earthbound applications. Research conducted there and independently by manufacturers allows for innovative thermocouple technology that can be applied in the home, in the workplace and in outer space.
Photos courtesy of Thermal Devices.
The basic phenomenon behind thermocouple technology, first noticed back in 1821, is that of thermo-electricity. Seebeck found that when two dissimilar metals at differing temperatures met at a junction, the generation of electricity resulted. The basic idea led to the basic thermocouple design mentioned earlier. The simplicity of thermocouple instruments allows their use in both small and large scale operations. Thermocouples are found in the furnaces, water heaters and even the fireplaces of most modern homes as well as most diesel engines. Industrial sized thermocouples are just as common and used to monitor a number of metallurgical processes and appliances such as hot isostatic pressure vessels.
While alternative temperature sensors abound, the popularity of Seeback’s thermocouples has scarcely wavered in their two hundred years of existence. This is because the thermocouple is an extremely versatile and reliable apparatus. Thermocouple types cover the alphabet from B to N and offer consistent temperature calibrations for temperatures as low as -450 degrees F to 4000 degrees F. While home applications use only a small portion of this scale, the range allows for heat treating industries to monitor expensive equipment and processes. Likewise, NASA uses low temperature probes to safely explore the outer parameters of our solar system while at the same time employing devices that can withstand extreme heat in order to learn about the sun.
With so many possibilities and capabilities available, it is no wonder that thermocouples have become a central topic for engineers at NASA and within the development and research departments of manufactures from a broad array of industries. Recent advancements in the field of thermocouple technology include the use of thin-films which allow the temperature changes to occur even faster as well as providing significant spatial savings. The exploration of ceramic components in place of metal wiring is another technological breakthrough that offers ceramic improved stability and durability with significant cost reductions. Developments continue to reach back to Seebeck’s 1821 principals and pull them forward into the 21st Century. Thanks to Seebeck’s original design and the continued strides made be scientists and engineers alike, thermocouples provide smaller, faster and more precise temperature controls than ever before.
Photo courtesy of Thermal Devices.