Measurement of Zone Temperature Profile of a Resistive Heating Furnace Through RVM Model
ABSTRACT
In this paper, a system for measuring the zone temperature profile of a horizontal tube furnace is proposed. This system consists of an ultrasonic transducer, quartz tube, resistive horizontal tube furnace, Arduino micro-controller and relevance vector machine (RVM)-based regression model. The ultrasonic transducer is placed in such a way that the acoustic wave is transmitted and then reflected back from the resistive horizontal tube furnace. The variations in the temperature values inside the tube furnace may affect the receiving voltage of the ultrasonic transducer. The RVM model is employed to predict the temperature using the inputs as the ultrasonic transducer voltage and the distance of the propagating path of the ultrasonic wave. The experimental results demonstrate that the proposed system is effective to measure the temperature inside a horizontal furnace and it shows a correlation coefficient value of 0.9695 with the K-type thermocouple readings. Such a system can be employed in an industrial furnace to measure the temperature with a higher accuracy.
EXISTING SYSTEM:
The horizontal furnace is commonly used for calcinations and annealing of the synthesized material at a predefined temperature. The material properties and the crystal growth are affected based on the variations in the temperature values inside the tube furnace. The accurate measurement of the temperature inside the horizontal tube furnace is an important task for material synthesis process . In literature, the contact and the non-contact based methods have been used for measuring the temperature. The contact based measuring techniques use various temperature sensors namely, the mercury thermometer, the thermocouple and the thermistor . The pyrometer , the laser , the infra-red sensor the ultrasonic and the fibre optics based techniques have been used as non-contact temperature sensors. The thermocouple, the radiation pyrometer, and other conventional instruments fail to measure the continuous variations in the temperature values. The thermocouple has been used to measure temperature with a range of 1800°C, provided this sensor should be appropriately positioned with the measurable device. However, the pyrometer can measure any temperature range above 700°C with a higher accuracy but for the dusty environment, it may fail to predict the accurate reading. Sometimes, the reading of the pyrometer may lapse by hundreds of degree. Have used a pyroelectric material such as the lithium niobate (LiNbO3) to measure the temperature inside a tube furnace. At there, authors have generated current based on the heating and cooling of the tube furnace. The temperatures at different zones of the tube furnace have been evaluated using the current values. However, it has been reported that the pyroelectric material inside the tube furnace is able to measure the temperature up to 450°C. Thus, to avoid improper positioning of the sensor inside the tube furnace and the dusty environment condition, an accurate and non-contact based temperature measuring device is required.
.PROPOSED SYSTEM :
The experimental set-up or the schematic diagram of the proposed system is depicted in Fig 1.
Fig. 1. Schematic diagram of the proposed system for temperature measurement.
The components of this set-up are the horizontal furnace, quartz tube, ultrasonic transducer (LV-MaxSonar-EZ ), K-type thermocouple (accuracy ±0.2°C , Arduino microcontroller kit, temperature controller unit and RVM model. In this work, a horizontal tube furnace of radius 2.5 cm and length 16.51 cm is considered. This horizontal tube furnace is segmented into three zones namely, zone-1, zone-2, and zone-3, respectively. The zone- 1 is considered as the region from the starting point of the tube furnace to a distance of 3 cm along the horizontal direction. Similarly, the zone-2 corresponds to the region from the end point of zone-1 (3cm) to a distance of 6 cm. Likewise, the zone-3 refers to the region at a distance of 6 cm from the end of the zone-2. The quartz tube of radius 2.4 cm and length 50.80 cm is placed inside the tube furnace. The quartz tube is used for efficient transmission and reception of the ultrasonic wave.
The ultrasonic transducer is fixed at one end of the quartz tube. A hardware-software interface based on the Arduino micro-controller and a laptop computer is used to generate a 42 KHz continuous ultrasonic wave. This wave is transmitted inside the quartz tube and its touches to the flat surface of the glass rod. The glass rod is considered as the object from which the ultrasonic wave is reflected back to the transducer. A variac is used to energize the tube furnace at different voltages which ranges from 0 to 240 V.
The ultrasonic transducer produces the voltage and the distance from the object to the transducer. Based on the distance values, the zone voltages at different heating and cooling conditions are evaluated. The readings have been taken by varying the spotting position of the K-type thermocouple. The thermocouple readings are used to compare the temperature values obtained using ultrasonic principle. Here, from the ultrasonic transducer, we have evaluated the distance from the object to transducer and the voltage. To convert the voltage to temperature, the RVM based regression model is used.
CONCLUSION :
The ultrasonic transducer produces the voltage and the distance from the object to the transducer. Based on the distance values, the zone voltages at different heating and cooling conditions are evaluated. The readings have been taken by varying the spotting position of the K-type thermocouple. The thermocouple readings are used to compare the temperature values obtained using ultrasonic principle. Here, from the ultrasonic transducer, we have evaluated the distance from the object to transducer and the voltage. To convert the voltage to temperature, the RVM based regression model is used. The proposed system is simple and has low-cost for measuring temperature inside a furnace. This system can be used in industrial applications for measuring high temperature.