VALJAKKA, Jukka, VIERINEN, Kari, PITKANEN, Jaakko & VAITTINEN, Martti
Department of Physics, Espoo-Vantaa Institute of Technology,Vanha maantie 6, FIN-02600 Espoo, Finland. Jukka.Valjakka@Evitech.fi, Kari.Vierinen@Evitech.fi, Jaakko.Pitkanen@Evitech.fi, Martti.Vaittinen@Evitech.fi
Abstract: Modern high technology infrared camera has been used in engineering project studies. In these projects students learn physics and engineering at the same time. In physics they learn electromagnetic radiation, its emission and absorption, black body radiation, thermodynamics, etc. There have been various engineering applications. In civil engineering students have studied thermal leaks in buildings and pipelines. They have also studied electrical systems of buildings. In mechanics students have searched faults in mechanical systems, such as printing machines, bearings, etc. In electronics the heating of components is easy way to see if circuits are working properly.
The uses of modern technology in physics teaching and integration of engineering subjects to physics measurements have increased students’ motivation to learn physics. They have also possibility to study engineering problems in the beginning of their studies, which gives them the feeling of real work.
Keywords: Infrared camera, projects, physics, engineering
Engineering is based on laws of physics and mathematics. But in the engineering education there is problems in motivation of students to study physics and mathematics, especially if they are taught traditionally. Most of the students are motivated to study engineering, but the gap between pure physics and mathematics and engineering is too large for the students.
One way to solve these motivation problems is to integrate physics, mathematics and engineering subjects more closely together. This can be done by co-operaration of teacher of the different subjects. But it can also be done by smaller or larger projects, which include both engineering and physics and mathematics. In those projects students have to learn mathematics, physics and in order to get the project done. Also most of the engineering students are interested in modern technology. So, it will be good if the projects include the use of modern pieces of equipment like high technology sensors and computers.
In this case, we will report some projects, where we have used modern high technology infra-red camera in solving engineering problems and at the same time students have learned physics, mathematics and engineering.
We have used modern IR-camera, which is based on modern platinum silicide focal plane array detector operating at cryogenic temperatures (77 K) [1]. FPA technology requires no mechanical scanning. Instead, a mosaic of 65,536 discrete platinum silicide detectors, arranged in a pattern of 256 by 256 elements, is used. The PtSi detector works like a photodiode, that is when infrared light of the proper wavelength (3.4 to 5 m m) strikes each individual detector, the detector will change its resistance to a bias current imposed on it and allow an increase in current flow. The amount of current is proportional to the amount of infrared energy striking the detector. The camera has changeable lens of 16 degrees viewing angle.
The detector is cooled by small microcooler [1], a tiny helium pump working according to Stirling process. Microcooler can work over 2000 hours without any maintenance.
The camera is portable like modern videocamera, only a bit heavier and it uses normal videocamera batteries. With normal battery it can work about 1-2 hours.
The camera can be connected to normal videorecorder and the images can be stored on videotape for later inspection. The camera has also place for memory flascards where still images can be stored. These images can be moved to computer using special software, Thermalite[1]. In this program images can be studied more detailed than with camera and the images can be attached to documents.
There have been a number of projects where students have studied heat leaks in buildings. Most of these projects have been ordered by outside customers. When the building is studied wintertime during cold weather, faults and mistakes in insulation can be detected. In Finland where winters can be very cold, the insulation of houses has also a great economic importance.
With IR camera also the heating systems can be studied. There have been some cases where the floor heating systems has worked improperly. In the floor heating system the electrical heating resistors or in distirct heating systems the heating pipes where the warm water flows are mounted under the final surface of the floor. With IR camera it is usually possible to locate the faults in leads or pipes.
Elecronic circuits and electric power systems can very effectively be studied by IR camera. In figure 1 there is an IR image of grouding cable of a power center. Because the cable is on a little higher temperature than the surroudings there is some current in the groud lead. Usually there should be no current in this cable, so the system is not working properly.
Figure 1. Grouding of a power center.
In many industrial applications bearings and other parts of machinery are regularly inspected using infrared camera fo maintenance purposes. From IR images very small changes in temperature can be seen and the parts that do not work properly can be changed before they cause major faults. That saves time and money.
With our civil engineering students we have studied the air-conditioning system of our institute, motors, fans and bearings in those systems in order to see if there is any faults. With media engineering students we have studied printing machines in our printing laboratory.
The use of modern technology in physics teaching motivates students to study physics. When they solve real life problems in their physics courses they will understand that engineering is based on physics laws. In order to become as a good engineer it is important to learn to understand these laws. IR camera can be used in many fields of engineering and it is important tool for many engineers working in industry or research applications. Our projecs have shown that students can solve engineering problems during their first study years and in working with the project they can learn the physics and mathematics they need for solving the task. If the project is for customer outside, there is usually more fixed deadlines and students learn how to work with proper timing.