Name: RENAN COSTA LAZARO
Publication date: 25/05/2021
Advisor:
Name |
Role |
|---|---|
| ARNALDO GOMES LEAL JÚNIOR | Advisor * |
| CARLOS EDUARDO SCHMIDT CASTELLANI | Co-advisor * |
Examining board:
| Name |
Role |
|---|---|
| ANSELMO FRIZERA NETO | Internal Examiner * |
| ARNALDO GOMES LEAL JÚNIOR | Advisor * |
| CARLOS EDUARDO SCHMIDT CASTELLANI | Co advisor * |
Summary: The monitoring of thermal properties in liquids is an important and complex task, widely applied in industrial processes. In crude oil processing operations, for example, an inefficient thermal monitoring can result in financial and environmental losses, once parameters such as temperature, viscosity and thermal conductivity directly impact volumetric oil efficiency. In these operations, electronic sensors are often used due to their low cost and commercial availability. Nevertheless, this type of sensor associated with flammable oils operations can expose the workspace to risks of explosion. Optical solutions, such as fiber sensors, have been widely developed due to its intrinsic operation, in addition to characteristics such as: immunity to electromagnetic interference, compactness, multiplexing capacity and chemical stability. In thermal measurements, stationary and transient methods are
mostly designed for components powered by electrical current. Despite this, some of these methods, such as modified transient plane source (MTPS), allow physical modifications in their design, such as the exchange of non-optical sensors for optical sensors. Among the various types of thermal optical sensors, fiber Bragg gratings (FBG) stand out, due to its simple manufacturing and linear temperature response. Thus, this work presents an optical system for measuring density, specific heat and thermal conductivity in liquids, based on MTPS and FBG. For the task, we developed a methodology which automatizes the data collection, admitting also characterization of multiple FBGs simultaneously. Thereafter, an optical diaphragm-based system is proposed for the task of measuring density. The sensor (with sensitivity of 0.025 nm/kPa) is constructed with two FBGs, in which one is embedded between the diaphragms and the other is used to compensate the liquid temperature variation. In addition, the diaphragm material (nitrile rubber) is corrosion resistant and chemically stable, which enables operations in liquids
such as crude oil. For the estimation of specific heat and thermal conductivity, an FBG (with sensitivity of 11.5 pm/oC and determination coefficient R2 = 0.9999) is applied in three experiments, named tank, beaker and test tube. The results show the repeatability and reproducibility of the system, in addition to the possibility of accuracy adjustments through a calibration constant. Finally, an analysis of thermal power and flexibility of the methodology are performed, describing the heat distribution in the setup and the possibility of constructing a liquid detection system.
Keywords: Density. Thermal conductivity. Specific heat. Optical sensors. Fiber Bragg gratings.
