Development of fibre bragg grating (FBG) based pressure transducer with temperature compensation

In this work, an aluminium diaphragm fibre Bragg grating (FBG) pressure transducer with temperature compensation is been presented. FBG based sensors good for some applications such as pressure vessel, biomedical and combustion chamber. One of the greatest challenges for an FBG based transducer is the inconsistency in output wavelength due to temperature variations. This lead to huge variation pressure readings. In this study, two FBG are bonded on the diaphragm and base surface of the pressure transducer, respectively. The inconsistency of wavelength was eliminated by applying the temperature compensation technique. The result shows that this FBG pressure transducer has a sensitivity of 2.849 nm/MPa and a linear fitting coefficient of 99.97% in a pressure range from 0 to 0.2 MPa. This FBG pressure transducer is proven to be suitable for pressure measurement of gas or liquid with an average error of 1.97%

A highly sensitive multiplexed FBG pressure transducer based on natural rubber diaphragm and ultrathin aluminium sheet

Pressure measurement with a good sensitivity has always been a concern in most of the engineering applications and biomedical field. In this paper, a multiplexed FBG bonded on an ultrathin aluminium sheet which act as a cantilever deflected due to a deformation from a natural rubber based diaphragm has been proposed and studied. By using two gratings inscribed on a single optical fibre which senses the positive and negative strain has enhanced the sensitivity of the pressure transducer recorded at 329.56 pm/kPa or corresponding to 10.7893 kPa−1 across the range of 0 to 10 kPa with a good linearity of 99.76%. Furthermore, the thermal cross-sensitivity is compensated

Investigation of pipe materials and thermal conductivity of soil on the performance of ground heat exchanger operating under Malaysia climate

In nature, renewable energy is inherently free and must be implemented. The use of air conditioning and refrigerants that affect global warming is a serious issue. In building applications, renewable energy from the geothermal source, namely ground heat exchanger (GHE), has great potential. The main concept of GHE is utilizing the ground as an infinite thermal reservoir for cooling and heating to the fluid medium. In the GHE system, the air is used as a fluid medium of work. Because of the temperature difference between the air and underground temperature, the air cools in summer and gets heated in winter. In this present work, a study has been conducted to investigate the effect of pipe materials and thermal conductivity of soil on the performance of the GHE. The study acknowledges that the pipe materials do not give a significant effect on the performance of the GHE. Therefore, the lower thermal conductivity of pipe materials with low cost can be used in GHE implementation. The study also revealed that the range of thermal conductivity of soil which gives good ground heat exchanger performance is between 1.5 to 5 W/m·K. Besides, the length of the pipe was reduced from 25 to 10 meters

Soil characteristic study to improve heat conductivity capability in ground heat exchanger

The use of vapor compression air conditioning has contributed to the global warming effect by increasing greenhouse gas emissions. Renewable energy from geothermal sources, specifically ground heat exchangers (GHE), has great potential in building applications. The underlying concept of pipe called GHE utilises the ground as an unlimited thermal reservoir for cooling and heating purposes. Because of the temperature differences between underground and surrounding air, the air in the underground cools in the summer and warms in the winter. Thermal conductivity of the ground or soil is among a parameter that contribute to the GHE’s performance. Therefore, the purpose of this research is to investigate the effect of hybrid soils without moisture on the performance of the GHE system. The hybrid soils consist of two elements, which are native soil with three grain sizes and bentonite. The native soil grain sizes are 0.154–0355 mm, 0.355–0.6 mm, and 0.6–1 mm. Bentonite has been introduced into all native soil grain sizes, which ranges from 0 to 100%. The native soil and bentonite were mixed consistently, and the thermal conductivity was measured by using a thermal property analyzer device. The study shows that the grain size 0.6–1 mm of native soil has the highest thermal conductivity at 20% bentonite, which is 0.269 W/m K compared to other grain sizes. The performance of the GHE system was evaluated based on simulation of mathematical model which shows that pipe length of 16 m gives significant effect of temperature reduction. In short, the performance of GHE has increased once the thermal conductivity of hybrid soil increased

High-Resolution Fibre Bragg Grating (FBG) Pressure Transducer for Low-Pressure Detection

Fibre Bragg grating (FBG) pressure sensor has shown great potential in replacing the conventional electrical pressure sensor due to its adaptability to the harsh environment. However, increasing its resolution for low-pressure measurement is still a challenge. In this work, the bonding of FBG to a rubber-based diaphragm pressure transducer was proposed. The proposed pressure transducer had enhanced the sensitivity to 117.7 pm/kPa across the range of 40 kPa, which corresponded to the pressure resolution of 0.008 kPa. Furthermore, the proposed pressure transducer possessed a reference FBG for temperature compensation, where the overall temperature effect was less than 1%

Simulation of the ground heat exchanger under malaysian environment based on different thermal conductivity of soil and pipe materials

Energy is a major global issue that is essential to the advancement of technology and humanity. Renewable energy is becoming increasingly important as primary energy consumption rises year after year. Renewable energy from geothermal sources, namely ground heat exchangers (GHE), has a lot of potential for use in building applications. Over the past few decades, extensive research has been conducted and GHE technology is well known. The main idea behind GHE is to use the ground as an endless thermal reservoir for fluid medium cooling and heating. Air is used as a fluid medium of work in the GHE system. The air cools in the summer and heats in the winter due to the temperature differential between the air and the ground. In this study, a simulation was conducted to examine the effects of pipe materials and soil thermal conductivity on the performance of the GHE. According to the findings of the study, the materials of the pipe does not have a significant impact on the overall performance of the GHE. As a result, low-cost pipe materials with low thermal conductivity can be used in GHE configurations. The study also showed that the thermal conductivity of soil should be between 1.5 and 10W/m.K for optimal ground heat exchanger performance. In addition, the length of the pipe was reduced from 25 to 14m, thereby decreasing the land area

A natural rubber diaphragm based transducer for simultaneous pressure and temperature measurement by using a single FBG

A natural rubber diaphragm bonded with a single FBG is demonstrated to measure the pressure and temperature simultaneously. Half of the grating is bonded to the rubber diaphragm while the other half is bonded to the aluminium sheet. Under varying pressure at constant temperature, the sensitivity is recorded at 0.1007 nm/kPa with coefficient of 6.49 × 10−5 kPa−1. The temperature sensitivities at constant pressure is recorded at 0.0797 nm/°C and 0.0326 nm/°C, respectively. The experimentally obtained different sensitivities of the sensor in matrix equation approach capable to interpret the Bragg wavelength shifts into pressure and temperature information simultaneously

Modal properties investigation of car body-in-white with attached windscreen and rear screen

Vibration analysis of car body in white (BIW) is crucial during design stage. Car BIW holds all the essential components; therefore, analysing its dynamic behaviour is necessary to understand how vibrations are transferred to the end rows from any vibration sources. This paper presents the modal properties of car BIW with attached windscreen and rear screen calculated by means of finite element analysis (FEA) and experimental modal analysis (EMA). The aim for the analysis is to observe the effect of windscreen and rear screen to the dynamic properties of car BIW. Detailed CAD models of BIW for both schemes were used for normal modes calculation in FEA, therefore providing the finest prediction of its modal properties. Actual car BIW was hanged on a metal frame to imitate free-free boundary condition as in FEA; prior to EMA. The EMA was done for both schemes, whereby the results for FEA were confirmed with EMA, at least for the first five modes with errors below 15%. It can be concluded from the analysis that the attached windscreen and rear screen is significantly affects the first five modes of the BIW. However, other higher frequencies remain unchanged

Temperature-insensitive pressure transducer based on reflected broadened spectrum with enhanced sensitivity

Pasting of half the grating of an FBG sensor on a natural rubber diaphragm was used to sense the pressure measurement. The pressure-induced strain on half of the grating resulted in bandwidth broadening. From the pressure range of 0 kPa to 20 kPa, the pressure sensitivity at 15 dB bandwidth changed was obtained at 77.7 pm/kPa with 99.94% of linearity. Through total reflected power monitoring via photodetector, the pressure transducer retrieved a sensitivity of 0.1686 dB m/kPa and evaded a complex demodulation technique. As a result of the temperature-independent bandwidth change, the pressure transducer was totally temperature insensitive

The use of an improved technique to reduce the variability of output voltage in real-time Fibre Bragg Grating based monitoring system

Fibre Bragg Grating (FBG) sensors have been widely utilized in the structural health monitoring (SHM) of structures. However, one of the main challenges of FBGs is the existence of inconsistency in output voltage during wavelength intensity demodulation utilizing photodetector (PD) to convert the light signal into digital voltage readings. Thus, the designation of this experimental work is to develop a robust FBG real-time monitoring system with the benefit of MATLAB graphical user interface (GUI) and voltage normalization algorithm to scale down the voltage inconsistency. Low-cost edge filter interrogation system has been practiced in the experimentation and splitter optical component is make use to reduce the intensity of the high power light source that leads to the formation of noise due to unwanted reflected wavelengths. The results revealed that with the advancement of the proposed monitoring system, the sensitivity of the FBG has been increased from 2.4 mV/N to 3.8 mV/N across the range of 50 N. The redundancy in output voltage variation data points has been reduced from 26 data/minute to 17 data/minute. The accuracy of the FBG in detecting the load induced falls in the acceptable range of total average error which is 1.38 %