Kosketuslämpömittauksessa

Kosketuslämpömittauksessa, known in English as contact thermometry, is a fundamental method for determining temperature through direct physical contact between a temperature-sensing element and the object or medium being measured. This technique relies on the principle that when two objects at different temperatures are brought into contact, heat energy will transfer between them until they reach thermal equilibrium. The temperature sensor, designed to react predictably to these heat transfers, records the resulting temperature.

Various types of sensors are employed in contact thermometry. Thermocouples are widely used, consisting of two dissimilar metal wires joined at one end. A voltage is generated at this junction that is proportional to the temperature difference. Resistance thermometers, such as resistance temperature detectors (RTDs) and thermistors, utilize the change in electrical resistance of a material with temperature. Bimetallic strips, where two metals with different coefficients of thermal expansion are bonded together, bend in response to temperature changes, making them suitable for mechanical thermometers. Liquid-in-glass thermometers, a traditional method, rely on the thermal expansion of a liquid (like mercury or alcohol) within a calibrated glass tube.

The accuracy of contact thermometry depends on factors such as the sensor's calibration, the quality of thermal contact, and the time allowed for thermal equilibrium. Proper insulation of the sensor and consideration of heat conduction along the sensor itself are crucial to minimize errors. Despite the advent of non-contact methods like infrared thermometry, contact thermometry remains a reliable and widely used technique in numerous applications, including industrial processes, scientific research, and everyday temperature measurement.