A temperature sensor is a device that gathers data
concerning the temperature from a source and converts it to a form that can be
understood either by an observer or another device. These sensors come in many different forms
and are used for a wide variety of purposes, from simple home use to extremely
accurate and precise scientific use.
They play a very important role almost everywhere that they are applied. Knowing the temperature helps people to pick
their clothing before a walk outside just as it helps chemists to understand
the data collected from a complex chemical reaction (“What Is a Temperature Sensor”). Temperature control in buildings is very
important because occupant comfort is key to a building’s success. If the occupants in a building are
uncomfortable, not only will it be inconvenient for them, but it also may cause
their work to suffer or even cause illness over time. Temperature sensors can be used in buildings
to monitor the current temperature of the room and then adjust it according to
the data that it records.
Temperature sensors don’t directly measure the
temperature. They actually infer the
temperature by sensing some change in a physical characteristic. Some common types of temperature sensors are:
Thermocouples, resistive temperature devices (RTDs or thermistors), infrared
temperature measurement devices and liquid expansion devices (Mathas).
Thermocouples consist of two strips of wire made of different metals and
joined at one end. Changes in
temperature at the juncture induce a change in electromotive force between the
other ends. As the temperature goes up,
this output emf of the thermocouple rises.
RTD’s rely on the resistance change in a metal, with the resistance
rising linearly with temperature.
Infrared devices infer temperature by measuring the thermal radiation
emitted by a material. Fluid expansion
devices (the household thermometer is the most common example) measure the
temperature by measuring the displacement of fluid expansion. These are the least accurate of the
temperature measuring types (“Temperature Measurement”).
An example of temperature sensors being used is in a common
closed-loop air conditioning system. The
system is set at a certain temperature, then the sensor measures the actual
temperature of the room and turns the air on/off according to what it
reads. This allows the system to save
energy; instead of running at a constant temperature all day, the system only
turns on when the room is too cold, and it shuts off when the room is too hot.
Comments:
Comments:
Bruder: It was very interesting to learn how movement
sensors and temperature sensors have to work together in order to detect human beings. Also, it was very cool to learn about how
ultrasonic motion sensors work and how they can work through walls and
obstructions.
Kilgallon:
Before reading this post, I had very little knowledge of pressure
sensors and how they worked. It was very
interesting to learn how theses sensors can be used in a piping system to
detect changes and ultimately prevent system failures. Even though it is just a small part of a
bigger system, it seems like a very important piece of the puzzle.
References:
Mathas, Carolyn.
"Temperature Sensors; The Basics." Digi-Key Article Library. Hearst Electronic Products, n.d. Web.
"Temperature
Measurement." Temperature Measurement. N.p., n.d. Web. 17 Feb. 2014.
"What Is a
Temperature Sensor?" WiseGEEK.
N.p., n.d. Web. 17 Feb. 2014.
I found it interesting that temperature sensors do not actual measure the temperature directly. I also didn't know that there were so many types of temperature sensors. I enjoyed reading your blog post.
ReplyDeleteI wanted to read your post because it is closely related to my post, which is about humidity sensors. Both temperature sensors and humidity sensors are incredibly important in HVAC design, and humidity is dependent on temperature. Both are important for health and comfort in a building. As you mentioned, closed-loop A/C systems can be optimized by turning off the system once a space has reached the desired temperature. Keeping humidity at a desired level will also aid in energy optimization, as the temperature is more likely to remain constant when the moisture content remains steady as well.
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