Influence of air Gap Between the Transformer of Resistance and Object of Monitoring on Temperature Measurement Error

In operation the description of the developed heattransfer model in thermotransformers of resistance (RTD) in the conditions of air gap between surfaces of the sensor and object of measurement is provided. Research of influence of thickness of air gap on the relative error of temperature measurement by platinum, copper and nickel thermotransformers of resistance in the ranges of temperatures corresponding to each type is executed. Dependences of minimum necessary duration of heating up of sensors on the taken temperatures are received

Influence of air Gap Between the Transformer of Resistance and Object of Monitoring on Temperature Measurement Error

In operation the description of the developed heattransfer model in thermotransformers of resistance (RTD) in the conditions of air gap between surfaces of the sensor and object of measurement is provided. Research of influence of thickness of air gap on the relative error of temperature measurement by platinum, copper and nickel thermotransformers of resistance in the ranges of temperatures corresponding to each type is executed. Dependences of minimum necessary duration of heating up of sensors on the taken temperatures are received

Numerical evaluation of the measurement error of temperature by surface thermocouples in the conditions of incomplete thermal contact with object of measurement

One-dimensional and two-dimensional models of heat transfer are given in operation for research of the main characteristics of process of temperature measurement by means of surface thermocouples. Results of numerical evaluations of the relative error of the measurement arising owing to existence of air gap between a sensitive element of the thermocouple and object of measurement are provided. It is revealed that the measurement error in case of observance of necessary time of heating up (set minimum required time of measurement) can be lowered to level of an allowed error

Process Simulating of Heat Transfer in High-temperature Thermocouples

Numerical research of integral characteristics of process of heattransfer in sensitive elements of R, A and B types thermocouples in case of measurement of high temperatures (more than 900 K) is executed. Theoretical dependences of minimum necessary duration of heating up of the thermocouple on value of temperature on boundary of a sensitive element are received. It is shown the thermocouple of R type requires bigger time of heating for obtaining satisfactory accuracy of measurements. Temperature fields in sensitive elements of the specified thermocouples are received. It is shown that distribution of temperature on the thermocouple not linearly and has similar character for the researched thermocouples

Influence of Conditions of Heating up on Integral Characteristics of Heattransfer in the Sensitive Element of the Thermoconjugate Sensor

Heattransfer models in a sensitive element of the thermoconjugate temperature sensor in different conditions of heating up of the thermocouple are developed. Tasks of heat conduction for cases when on outline borders of the thermocouple conditions of I, II and III kinds are set are considered. Dependences of necessary duration of heating up of the thermocouple for different values of a heat flux to outline borders of a sensitive element for thermocouples of types K, L and E, distribution of temperature in the thermocouple in different conditions of heating up are received

About Influence of Operational Temperatures on Reliability of Operation of the Equipment of Thermal Power Plants

The description of degree model of reliability of the heat power equipment in which as a factor of loading the working temperature of the equipment is used is provided, interval estimates of constant values of model are given. For a row of elements of constructions of boilers dependences of the relative increase in failure density are given by operation in the conditions of the increased temperatures for a long time

Numerical Research of the Measurement Error of Temperature Thermocouples with the Isolated Seal

Mathematical models of heattransfer are developed for an assessment of measurement errors of temperature by thermocouples with an isolated and uninsulated seal. Dependences of necessary time of heating (for authentic measurement) for the thermocouples with an isolated seal manufactured of different materials are set. It is shown that for thermocouples with isolated seal minimum necessary duration of heating up slightly exceeds this index for thermocouples with an uninsulated seal

Determination of necessary time of measurements of surface thermocouples depending on conditions of technological processes

Researches of nonstationary processes of heating up of sensitive elements of thermocouples by means of one-dimensional and two-dimensional mathematical models of heat transfer are conducted. By the created models are defined duration of heating up of the sensitive elements necessary for achievement of the temperature of the thermocouple within a permissible deviation from rated direct current characteristic for three types of thermocouples – K, L and S. Distinctions in the results received by means of one-dimensional and two-dimensional models of heat transfer are shown and justified. For surface thermo-electric transformers, temperature measurement conditions are simulated in case of different value of air gap between the heater and thermocouple surface. It is shown that the value of a gap has an essential impact on minimum necessary time of measurement. Change of duration of heating up of thermocouple from heatphysical characteristics of the typical materials which are used in the case of manufacture of sensing elements is probed

Numerical Research of the Measurement Error of Temperature Thermocouples with the Isolated Seal

Mathematical models of heattransfer are developed for an assessment of measurement errors of temperature by thermocouples with an isolated and uninsulated seal. Dependences of necessary time of heating (for authentic measurement) for the thermocouples with an isolated seal manufactured of different materials are set. It is shown that for thermocouples with isolated seal minimum necessary duration of heating up slightly exceeds this index for thermocouples with an uninsulated seal

Influence of Radiation and Convective Types of Heat Exchange on the Necessary Duration of Temperature Measurement by Thermocouples

Results of research of influence of radiation heat exchange on duration of execution of measurement high темератур are given by thermocouples, influence of the free convection on results of temperature measurement is also considered by the thermocouples set in protective sleeves with a gap. Researches showed that radiation heat exchange leads to lowering of duration of heating of the thermocouple to 30% whereas the free convection in a protective sleeve practically doesn’t exert impact on process of heating up of the sensor