Thermal Resistor definition of Thermal Resistor in the Free Online Encyclopedia.

thermal resistor [′thər·məl ri′zis·tər]

(electricity)

A resistor designed so its resistance varies in a known manner with changes in ambient temperature.

Thermal Resistor

a semiconductor resistor that has the property of significantly changing its electrical resistance upon a change in temperature. It is one of the simplest semiconductor devices. The main parameters of a thermal resistor are the operating temperature range and the temperature coefficient of resistance, which is defined as the relative percentage increase in the resistance upon a temperature change of 1°K.

A distinction is made between thermistors, which have a negative temperature coefficient of resistance (the resistance decreases with increasing temperature), and posistors, which have a positive coefficient (the resistance increases with increasing temperature). Graphs of the coefficients of both types are shown in Figure 1. Thermal resistors are made of mixtures of oxides of transition metals (for example, Mn, Co, Ni, and Cu), Ge and Si alloyed with various additives, silicon carbide (SiC), semiconductors of the A^IIIB^V type, synthetic diamond, or organic semiconductors. The operating temperature range of most thermistors is in the interval from 170°–210°K to 370°–570°K, with the temperature coefficient of resistance at room temperature ranging from – 2.4 to – 8.4%/°K. Other types of thermistors include high-temperature thermistors, operating in the range from 900° to 1300°K, and low-temperature thermistors, which operate in the range from 4.2° to 77°K and have temperature coefficients of resistance of at least –15 to –20%/°K.

The most important of the posistors are those made of solid solutions based on barium titanate, BaTiO₃, alloyed with lanthanum, cerium, bismuth, or other metals. In the temperature region close to the ferroelectric phase transition (seeFERROELECTRIC), the resistance of such thermal resistors increases by several orders of magnitude upon an increase in temperature, and in a short temperature interval (about 5°K), their temperature coefficient of resistance may reach 50%/°K or more. A change in the composition of the solid solution may shift the region of the phase transition in a temperature interval from ~200°K up to ~500°K. Posistors are also made of Si alloyed with B.

Figure 1. Typical dependence of the electrical resistance on temperature for (1) thermistors and (2) posistors

Thermal resistors are produced in the form of rods, tubes, disks, plates, and beads. Their size ranges from several micrometers to several centimeters. They are used in systems and devices for remote and centralized temperature measurement and control, for fire alarms and heat control, for balancing the temperatures of various components of electrical circuits, and for the measurement of vacuum and the speed of liquid and gaseous flows. They are also used in power meters.

REFERENCES

Shashkov, A. G. Termorezistory i ikh primenenie. Moscow, 1967.
Sheftel’, I. T. Termorezistory. Moscow, 1973.

I. T. SHEFTEL’

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No references found	The thermal resistor is the one that makes the work possible. How An Inkjet Printer Works by Melanie Smith / Computers and Internet community The longwave radiant exchange is modeled using thermal resistors instead of the customary net radiation approach so that the jump resistors can be individually identified and assigned values. Calculating center-glass performance indices of glazing systems with ... by Wright, John L. / ASHRAE Transactions A thermal resistor must be inserted to connect the layers on either side of it. Calculating center-glass performance indices of windows with a ... by Collins, Michael R.; Wright, John L. / ASHRAE Transactions	thermal photography thermal pollution thermal polymerization thermal potential difference Thermal Power Engineering thermal power plant thermal printer thermal probe thermal process Thermal Protection thermal protector thermal pulse thermal pulse method thermal quality of snow thermal radiation Thermal Reactor thermal recalibration Thermal Recovery Thermal Reduction thermal reforming thermal regenerative cell thermal relay thermal relief Thermal Resistance thermal resistivity Thermal Resistor thermal Rossby number thermal runaway thermal scattering thermal sensor thermal shield Thermal Shielding Thermal Shock thermal soakback thermal spraying thermal spring Thermal Stability of a Building Thermal Steam-Turbine Power Plant thermal steering thermal storage thermal storage roof thermal storage wall thermal stratification Thermal Stress thermal stress cracking thermal structure thermal switch thermal telephone receiver thermal tide thermal time scale thermal titration	Thermal Radiator Rotary Joint Thermal Radiator Rotation thermal reactor thermal reactor thermal reactors thermal reactors thermal recalibration Thermal Receiving Unit thermal receptor thermal receptor thermal receptor thermal receptor Thermal Recovery Thermal Reduction Thermal Reduction Batch Processor Thermal Reflector System thermal reforming thermal regenerative cell Thermal regulation Thermal regulation Thermal regulation thermal relay thermal relief Thermal Residue Stress Thermal resistance Thermal resistance Thermal resistance coefficent Thermal resistance coefficent Thermal resistivity Thermal resistivity Thermal Resistor Thermal Response Index Thermal Response Parameter thermal Rossby number Thermal runaway Thermal Scale Model Thermal scanners Thermal scanners Thermal scanners thermal scattering Thermal seafloor vent Thermal seafloor vent Thermal seeker thermal sensation thermal sensation thermal sensation Thermal Sensing Circuit Interrupter thermal sensitivity thermal sensor thermal sensor thermal shadow thermal shield Thermal Shield Antenna Thermal Shielding Thermal shock Thermal shock Thermal Shock Rig Thermal Shock Testing Thermal sight Thermal sight Thermal sight

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No references found

The thermal resistor is the one that makes the work possible.

How An Inkjet Printer Works by Melanie Smith / Computers and Internet community

The longwave radiant exchange is modeled using thermal resistors instead of the customary net radiation approach so that the jump resistors can be individually identified and assigned values.

Calculating center-glass performance indices of glazing systems with ... by Wright, John L. / ASHRAE Transactions

A thermal resistor must be inserted to connect the layers on either side of it.

Calculating center-glass performance indices of windows with a ... by Collins, Michael R.; Wright, John L. / ASHRAE Transactions

thermal photography

thermal pollution

thermal polymerization

thermal potential difference

Thermal Power Engineering