FBG-Based Sensor for the Assessment of Heat Transfer Rate of Liquids in a Forced Convective Environment

Abstract

The assessment of heat transfer is a complex task, especially for operations in the oil and gas industry, due to the harsh and flammable workspace. In light of the limitations of conventional sensors in harsh environments, this paper presents a fiber Bragg grating (FBG)-based sensor for the assessment of the heat transfer rate (HTR) in different liquids. To better understand the phenomenon of heat distribution, a preliminary analysis is performed by constructing two similar scenarios: those with and without the thermal insulation of a styrofoam box. The results indicate the need for a minimum of thermal power to balance the generated heat with the thermal losses of the setup. In this minimum heat, the behavior of the thermal distribution changes from quadratic to linear. To assess such features, the estimation of the specific heat capacity and the thermal conductivity of water are performed from 3 W to 12 W, in 3 W steps, resulting in a specific heat of 1.144 cal/g °C and thermal conductivity of 0.5682 W/m °C. The calibration and validation of the HTR sensor is performed in a thermostatic bath. The method, based on the temperature slope relative to the time curve, allowed for the measurement of HTR in water and Kryo 51 oil, for different heat insertion configurations. For water, the HTR estimation was 308.782 W, which means an uncertainty of 2.8% with the reference value of the cooling power (300 W). In Kryo 51 oil, the estimated heat absorbed by the oil was 4.38 kW in heating and 718.14 kW in cooling.

Heterogeneous Optical Fiber Sensor System for Temperature and Turbidity Assessment in Wide Range

“…As FBGs are well-known for their temperature sensitivity, the temperature sensor was based on the direct application of the optical fiber (with inscribed FBGs) in the liquid sample. Thus, the temperature was directly evaluated through the heat transfer from the liquid to the FBG [ 31 ]. Furthermore, since the turbidity directly affects the liquid thermal properties, it is possible to estimate the turbidity from the thermal dynamics in the liquid.…”

A Low-Frequency Magnetic Field Sensor Based on Fiber Bragg Gratings

“…Recently, fiber Bragg grating (FBG)-based sensors stand out as a promising sensors among the aforementioned optical magnetic sensors [13][14][15][16]. As FBG is designed to reflect light in a narrow band of wavelengths, the composition of FBGs could encode optical pulse signals in both the time and frequency domain, and hence is more suitable to achieve wavelength division multiplex (WDM).…”