Temperature Measurement Technique Research Articles

Influence of Injection Parameters and Operating Conditions on Ignition and Combustion in Dual-Fuel Engines

Dual-fuel (DF) engines offer great fuel flexibility since they can either run on gaseous or liquid fuels. In the case of diesel pilot-ignited DF engines, the main source of energy is provided by gaseous fuel, whereas the diesel fuel acts only as an ignition source. Therefore, a proper auto-ignition of the pilot fuel is of utmost importance for combustion in DF engines. However, auto-ignition of the pilot fuel suffers from lower compression temperatures of Miller or Atkinson valve timings. These valve timings are applied to increase efficiency and lower nitrogen oxide (NOx) engine emissions. In order to improve the ignition, it is necessary to understand which parameters influence the ignition in DF engines. For this purpose, experiments were conducted and the influence of parameters, such as injection pressure, pilot fuel quantity, compression temperature, and air–fuel (A/F) equivalence ratio of the homogenous natural gas–air mixture were investigated. The experiments were performed on a periodically chargeable combustion cell using optical high-speed recordings and thermodynamic measurement techniques for pressure and temperature. The study reveals that the quality of the diesel pilot ignition in terms of short ignition delay and a high number of ignited sprays significantly depends on the injection parameters and operating conditions. In most cases, the pilot fuel suffers from too high dilution due to its small quantity and long ignition delays. This results in a small number of ignited sprays and consequently leads to longer combustion durations. Furthermore, the experiments confirm that the natural gas of the background mixture influences the auto-ignition of the diesel pilot oil.

Precise temperature sensing with nanoscale thermal sensors based on diamond NV centers

Sensing temperature with high precision and high spatial resolution is challenging and requires novel temperature measurement techniques. Recently, an atomic-scale thermal sensor based on a defect center in diamond, i.e., a nitrogen-vacancy (NV) center, has been developed, and successfully demonstrated temperature sensing at the mK level and a few tens of nanometers. Here we discuss a temperature sensing mechanism based on the NV center in both experimental and theoretical aspects. At room temperature, we show temperature sensing over a wide-range of temperatures ∼90 K with a precision of 0.2 K. We also map temperature gradients in a bridge-like device a few hundreds of micrometers long. In addition, we theoretically compare three sensing protocols and analyze temperature sensitivity to find optimal measurement time and NV concentration for the ensemble measurement.

SEMTherm 2017: International Conference on Microtechnology & Thermal Problems in Electronics (MICROTHERM2017) and International Conference Smart Engineering of New Materials (SENM2017)

PREFACEThe issue covers selected papers presented during SEMTherm 2017 - the Joint Event of two International Cyclic Conferences: MicroTherm – Microtechnology and Thermal Problems in Electronics and SENM – Smart Engineering of New Materials. The Duoconference was held in Lodz, Poland on 26-29 June 2017. It gathered about 150 participants from 16 countries in Lodz – beautiful, post-industrial city located in the centre of Poland.MicroTherm is an International Conference on Microtechnology and Thermal Problems in Electronics being organised every two years, since 1996. The success of the first seminar devoted to thermal management aspects, and the successive conferences has led us to the twelve edition. Since the first meeting, the scope of the Conference has expanded, following the electronics progress. Now, it covers the subjects connected with extreme temperature electronics, sensors and measurement techniques, modelling, simulation, wide band-gap materials, packaging and reliability, renewable energy sources and photonics with special emphasis on microelectronic technologies. Traditionally, the programme of MicroTherm 2017, despite of invited talks and regular sessions in a form of planar discussions and poster presentations, included also Students’ Session. The latter gave an opportunity for students and young researchers to present their first achievements in the field of science.The tradition of SENM dates back to 1985 when the First International Conference on Diamond Crystallization under Reduced Pressure was held in Jabłonna in Poland. Since then, the Conference has been organised regularly every five years, and from 2015, it is the biennial event. From the early beginning, the main aim of this conference has been the creation of the international forum of scientists for the presentation of the newest achievements and investigation results in vacuum and plasma techniques, synthesis, characterisation and application of diamond, its derivatives and other wide bandgap materials. Over time, the scope of the conference has expanded to include nanomaterials, biomaterials and new functional materials, in the range of production, design and optimisation of the synthesis and modification technologies.Owing to the overlapping scopes of MicroTherm and SENM conferences, organisation of the Joint Event SEMTherm has been widely appreciated. Details about the forthcoming event will be available at the duoconference website soon.Ewa Raj and Katarzyna ZnajdekEditors

Near-Infrared Temperature Measurement Technique for Water Surrounding an Induction-heated Small Magnetic Sphere.

A technique to measure the temperature of water and non-turbid aqueous media surrounding an induction-heated small magnetic sphere is presented. This technique utilizes wavelengths of 1150 and 1412 nm, at which the absorption coefficient of water is dependent on temperature. Water or a non-turbid aqueous gel containing a 2.0-mm- or 0.5-mm-diameter magnetic sphere is irradiated with 1150 nm or 1412 nm incident light, as selected using a narrow bandpass filter; additionally, two-dimensional absorbance images, which are the transverse projections of the absorption coefficient, are acquired via a near-infrared camera. When the three-dimensional distributions of temperature can be assumed to be spherically symmetric, they are estimated by applying inverse Abel transforms to the absorbance profiles. The temperatures were observed to consistently change according to time and the induction heating power.

Near-Infrared Temperature Measurement Technique for Water Surrounding an Induction-heated Small Magnetic Sphere

Near-Infrared Temperature Measurement Technique for Water Surrounding an Induction-heated Small Magnetic Sphere

Accelerated thermal profiling of gas turbine components using luminescent thermal history paints

Abstract Environmental requirements to reduce CO2 emissions and the drive towards higher efficiencies have resulted in increased operating temperatures in gas turbines. Subsequently, Original Equipment Manufacturer (OEMs) require improved component design and material selection to withstand the harsher conditions. This demands rapid evaluation of new components and their surface temperature to accelerate their market entry. Accurate temperature information proves key in the design of more efficient, longer-lasting machinery and in monitoring thermal damage. A number of traditional temperature measurement techniques are available, but can incur a number of limitations. Online temperature measurements, such as pyrometry or phosphor thermography, often require optical access to the component during operation and are therefore not suitable for inaccessible components. Other options including thermocouples can only provide point measurements and cannot deliver profiles across the surface. Offline techniques store temperature information that can be measured and analysed following operation. Several of these, however, are of destructive nature, can affect local thermal gradients and only provide point measurements. This article discusses an innovative offline measurement technique: luminescent Thermal History Paints (THPs). THPs are comprised of ceramic pigments in a binder matrix that can be applied to any hot component as a thin coating. These pigments are doped with optically active ions, which will phosphoresce when excited with a light source. The coating material experiences irreversible structural changes depending on the temperature it is exposed to. Changes in the material structure are reflected in its phosphorescent properties, which are measured with standard optical instrumentation at any surface location. Since the changes are permanent, the temperature information is stored in the coating and can be extracted after operation. Following calibration, it is therefore possible to relate phosphorescent behaviour to the past maximum temperature experienced at each location. This is done with Sensor Coating Systems Ltd. (SCS)’s portable instrumentation, which can provide rapid, automated and objective measurements across a component surface. Unlike the more traditional thermal paints, THPs are non-toxic, and provide a continuous measurement capability across the range 150°C–900°C with significantly improved durability. This article describes the underlying principles behind this novel technology and the advantages it provides over existing state-of-the-art methods. The benefits will be demonstrated through measurements on nozzle guide vanes (NGVs), with the view to compare and validate them against thermocouple measurements. The results show that the THP extends the limited information from thermocouples to provide a more complete view of the thermal processes on the component.

Experimental Aspects of Measuring the Vial Heat Transfer Coefficient in Pharmaceutical Freeze-Drying

One of the current methods for cycle optimization in primary drying to is develop a graphical design space based on quality by design (QbD). In order to construct the design space, the vial heat transfer coefficient (Kv) is needed. This paper investigated experimental factors that can affect the Kv result, examined the relationship between the batch average Kv and Kv values for individual vials, and recommended best practices for measuring Kv. Factors investigated included the technique for measuring ice temperature, shelf temperature, the use of a radiation shield on the door of the freeze-dry chamber, and shelf spacing. All experiments reported here used a chamber pressure of 100mTorr. The most important factor was the technique for ice temperature measurement, where it is important to assure that any restrictions to vapor flow at the top of the vial are the same between monitored and non-monitored vials. Another factor that was found to play a role was the shelf temperature whereby the lower the shelf temperature, the larger the "edge effect," and the larger the average Kv. Factors that were found to not have a significant effect were the use of a radiation shield inside the chamber door and the shelf spacing. Being aware of these factors and knowing best practices when determining the vial heat coefficient will lead to more accurate design spaces and better cycle optimization.

Brain-core temperature of patients before and after orthotopic liver transplantation assessed by DWI thermometry.

To assess brain-core temperature of end-stage liver disease patients undergoing orthotopic liver transplantation (OLT) using a temperature measurement technique based on the apparent diffusion coefficient of the cerebrospinal fluid in the lateral ventricles. The study group was composed of 19 patients with a model for end-stage liver disease (MELD) score of 23.7 who underwent MR imaging before and after OLT. MR imaging studies were performed with a 1.5T MR scanner. Brain-core temperature (T: °C) was calculated using the following equation from the apparent diffusion coefficient (D) of the cerebrospinal fluid in the lateral ventricles: [Formula: see text] measured with a DWI sequence (b value 1000s/mm2). We compared brain-core temperature of all patients before and after OLT. Brain-core temperature measurements were successfully taken in all patients before and after OLT. The measured brain-core temperature mean ± standard deviation was 38.67 ± 1.76°C before OLT and 38.60 ± 0.99°C after OLT, showing no significant difference (P=0.643). Brain-core temperature was stable in patients undergoing OLT. DWI thermometry may provide a supplementary brain biomarker to confirm that cerebral blood flow and metabolism are stable in patients undergoing OLT.

On-Line Temperature Estimation for Noisy Thermal Sensors Using a Smoothing Filter-Based Kalman Predictor.

Dynamic thermal management (DTM) mechanisms utilize embedded thermal sensors to collect fine-grained temperature information for monitoring the real-time thermal behavior of multi-core processors. However, embedded thermal sensors are very susceptible to a variety of sources of noise, including environmental uncertainty and process variation. This causes the discrepancies between actual temperatures and those observed by on-chip thermal sensors, which seriously affect the efficiency of DTM. In this paper, a smoothing filter-based Kalman prediction technique is proposed to accurately estimate the temperatures from noisy sensor readings. For the multi-sensor estimation scenario, the spatial correlations among different sensor locations are exploited. On this basis, a multi-sensor synergistic calibration algorithm (known as MSSCA) is proposed to improve the simultaneous prediction accuracy of multiple sensors. Moreover, an infrared imaging-based temperature measurement technique is also proposed to capture the thermal traces of an advanced micro devices (AMD) quad-core processor in real time. The acquired real temperature data are used to evaluate our prediction performance. Simulation shows that the proposed synergistic calibration scheme can reduce the root-mean-square error (RMSE) by 1.2 C and increase the signal-to-noise ratio (SNR) by 15.8 dB (with a very small average runtime overhead) compared with assuming the thermal sensor readings to be ideal. Additionally, the average false alarm rate (FAR) of the corrected sensor temperature readings can be reduced by 28.6%. These results clearly demonstrate that if our approach is used to perform temperature estimation, the response mechanisms of DTM can be triggered to adjust the voltages, frequencies, and cooling fan speeds at more appropriate times.

Design and performance of spectroscopic filter of rotational Raman temperature lidar for absolute measurement

Rotational Raman temperature lidar for absolute measurement is an important method to directly detect the atmospheric temperature profile by using active remote sensing technology. Compared with the rotational Raman temperature relative measurement, the absolute measurement can avoid the systematic error caused by the calibration process, but its high-precision requirements of rotational Raman spectroscopic filter restrict the development of absolute measurement technique for atmosphere temperature. In order to achieve the absolute measurement technique of rotational Raman temperature lidar, the fine resolution of single rotational Raman line and the effective suppression 60-70 dB for the elastic scattering signal are the key factors for directly retrieving the atmospheric temperature by using the relationship between the single rotational Raman line and temperature. Based on the operational principle of grating, a two-stage parallel multi-channel Raman spectroscopic filter with one-order blazed grating and fiber Bragg grating is designed, and the parameters and optical path structure of the core cascade device (micron-level fiber array) are optimized. The optical path of the primary spectroscope is simulated, the wavelength difference between the rotational Raman lines of adjacent even rotational quantum numbers of nitrogen molecule (N2) gradually decreases from 0.4506 nm to 0.4475 nm. Compared with the average of approximately 0.4494 nm, its floating interval is -0.0012-+0.0019 nm, and the maximum centrifugal distortion of the rotational Raman spectra is approximately 0.0031 nm, which means that the centrifugal distortion ratio is 0.69%. Under the different values of incident angle , the diffraction position difference between adjacent rotational Raman lines varies from 124.43 m to 125.51 m, with a variation interval of -0.57-+0.51 m compared with a fixed value of 125 m. In order to test the matching consistency between rotational Raman spectra and the multi-channel fiber array, and to obtain the out-of-band suppression and channel coefficient of each fiber channel, an experimental system which consists of a first-order blazed grating, a convex lens and a fiber array is set up, and the atmospheric echo signal is simulated by using a broadband light-source and a semiconductor laser (LD). The experimental results show that the channel coefficient of the rotational Raman channels of the primary spectroscope is above 0.75, and the maximum deviation between the measured wavelength of extracted spectrum and the theoretical value is approximately 0.0398 nm, which means the the deviation degree is 8.86%. Each channel can provide more than 27 dB effective suppression to elastic scattering signal, and then by combining with the second spectroscope of fiber Bragg grating, the suppression at least is up to 62 dB. Therefore we can fine extract single rotational Raman line of even rotational quantum number.

CEA’s Optical Pyrometry Technique for Non-Contact Temperature Measurement in High Temperature Surroundings

CEA’s Optical Pyrometry Technique for Non-Contact Temperature Measurement in High Temperature Surroundings

Analysis of infrared temperature measurement for flue gas shielding metal surface using Source Multi-Flux method

The infrared temperature measurement technique has been applied in various fields with the development of charge coupled device. In the problem of metal surface temperature measurement, if the surface is covered by participating media, the traditional infrared temperature measurement technique will lead to intolerable measurement errors. In this work, the infrared temperature measurement problem was solved by the source multi-flux method. On this base, the impact of the flue gas thickness and surface temperature on the apparent temperature measured by the charge coupled device was analyzed. Furthermore, the corresponding experimental system was set up. And the experimental results were found to have a good agreement with the simulated results. Finally, the idea of modification for the infrared temperature measurement by inverse method was proposed.

Noncontact localized internal infrared radiation measurement using an infrared point detector

The techniques for temperature measurement within the human body are important for clinical applications. A method for noncontact local infrared (IR) radiation measurements was investigated deep within an object to simulate how the core human body temperature can be obtained. To isolate the IR light emitted from a specific area within the object from the external noise, the radiating IR light was detected using an IR point detector, which comprises a pinhole and a thermopile positioned at an imaging relation with the region of interest within the object. The structure of the helical filament radiating IR light inside a light bulb was thermally imaged by scanning the bulb in two dimensions. Moreover, this approach was used to effectively measure IR light in the range of human body temperature using a glass plate placed in front of the heat source, mimicking the ocular fundus.

Tangential System of Thomson Scattering for Tokamak T-15

Two systems of Thomson scattering diagnostics, with vertical and tangential probing, are used in the D-shaped plasma cross section in tokamak T-15. The tangential system allows measuring plasma temperature and density profiles along the major radius of the tokamak. This paper presents the tangential system project. The system is based on a Nd:YAG laser with wavelength of 1064 nm, pulse energy of 3 J, pulse duration of 10 ns, and repetition rate of 100 Hz. The chosen geometry allows collecting light from ten uniformly spaced points. Optimization of the registration system has been accomplished. The collected light will be transmitted through an optical fiber bundle with diameter of 3 mm and quartz fibers (numerical aperture is 0.22). Six-channel polychromators based on high-contrast interference filters have been chosen as spectral equipment. The radiation will be registered by avalanche photodiodes. The technique of electron temperature and density measurement is described, and estimation of its accuracy is carried out. The proposed system allows measuring the electron temperature with accuracy not worse than 10% within the range of 50 eV to 10 keV on the pinch edge over the internal contour, from 20 eV to 9 keV in the plasma central region, and from 2 eV to 400 eV on the pinch edge over the outer contour. The estimation is made for electron density of not less than 2.6 × 1013 cm–3.

Temperature measurement techniques for gas and liquid flows using thermographic phosphor tracer particles

Temperature measurement techniques for gas and liquid flows using thermographic phosphor tracer particles

Perancangan Sensor Suhu Menggunakan Metode Interpolasi Lagrange Berbasis Serat Optik Berstruktur Sms (Singlemode-Multimode-Singlemode)

In this research, a temperature measurement technique was developed using fiber optic structured SMS and OTDR. Where in optical fibers singlemode-multimode-singlemode (SMS) and Optical Time Domain Reflectometer (OTDR) has been widely used for various sensors in detecting damage to the building earlier. Thereafter, calculations are performed using Borland Delphi's Lagrange Interpolation method 7. Characteristics of each of the fiber-optic fiber sensor structures that have been fabricated using multimode optical fibers with lengths of 5.5 cm, 6 cm, 6.5 cm and 7 cm and with use its operating wavelength is 1310 nm. Testing rangesuhusebesar 37oC - 67oC with every temperature rise of 10oC.Berdasarkan research results, multimode length 5.5 cm there is a graph increase with R2 of 93.7%. The increase in temperature, the loss of power generated greater. While the multimode length 6 cm, 6.5 cm, and 7 cm indicate that there is a decrease graph, for multimode length 6 cm with R2 equal to 97,7%, for multimode length 6,5 cm with R2 equal to 99,7%, for long multimode 7 cm with R2 99.2%. While based on result of calculation by Lagrange Interpolation method for suhuberstruktur SMS sensor based on result of calculation using Lagrange Interpolation method with different multimode length have same data regularity compared to temperature sensor structured SMS based on measurement result. For example, as long as 7 cm long multimode yield R2 of 99.2% for the measurement result and yield R2 of 99.3% for the calculation result.

Comparison of Measurement Techniques for Temperature and Soot Concentration in Premixed, Small-Scale Burner Flames

Optical and intrusive measurement techniques for temperature and soot concentration in hot reacting flows were tested on a small-scale burner in fuel-rich, oxygen-enriched atmospheric flat flames produced to simulate the environment inside an entrained flow reactor. The optical techniques comprised two-color pyrometry (2C-PYR), laser extinction (LE), and tunable diode laser absorption spectroscopy (TDLAS), and the intrusive methods included fine-wire thermocouple thermometry (TC) and electrical low pressure impactor (ELPI) particle analysis. Vertical profiles of temperature and soot concentration were recorded in flames with different equivalence and O2/N2 ratios. The 2C-PYR and LE data were derived assuming mature soot. Gas temperatures up to 2200 K and soot concentrations up to 3 ppmv were measured. Close to the burner surface, the temperatures obtained with the pyrometer were up to 300 K higher than those measured by TDLAS. Further away from the burner, the difference was within 100 K. The TC-derived t...

Development of Gas Dynamic Probe for High Total Temperature Measurement in High Speed Flow

Total temperature measurement in high speed and high temperature exhaust of air breathing engines like scramjet, ramjet and turbojets with afterburner is a challenging problem. The temperature of such hot gases is approximately 2000-2200 K. Conventional technique of temperature measurement by thermocouple suffers oxidation, doesn’t withstand aerodynamic load, and lacks robustness. Unconventional technique like optical method is expensive. These limitations have withheld the temperature measurement in high speed high temperature exhaust streams. Present work describes the design and development of a water cooled gas dynamic probe for total temperature measurement of high speed and high temperature gases. The probe consists of two choked nozzles in series. The hot flow is cooled after passing through the first nozzle, in a small settling chamber, using a heat exchanger. The flow from settling chamber is accelerated to Mach 1 in second nozzle. Using gas dynamic relations and measured parameters, the incoming flow total temperature is obtained. The probe has been calibrated for probe constant at total temperature range of 1200 to 1700 K at inlet Mach number 2. Probe constant varies proportional to the square of incoming flow total temperature. First restriction with C-D nozzle gave higher probe constant value than convergent nozzle.

Temperature measurement techniques for spray foam applications

Experiments were conducted to investigate the accuracy of thermocouple configurations in measuring temperatures within spray foam insulation products during application. Measurements of this kind are important for assessing products from the standpoint of thermal performance and safety. The response times of heating and cooling in air were first analyzed for several thermocouple configurations. The second phase of the investigation consisted of instrumenting five 2″×6″ wood frame cavities sheathed with a 2′ by 2′ piece of oriented strand board.A method is presented for instrumenting specimens in a way that is minimally thermally invasive, which leads to temperature results that can be trusted as highly accurate. The thermocouple type recommended for this application is insulated Type K 36 gauge, joined via welding. Larger wire gauges result in significantly underestimated temperatures, by as much as 30°C. In combination with thermocouple types with higher thermal conductivity of wires, this underestimation can reach as much as 60°C. The potential inaccuracies are particularly pronounced due to the low thermal mass and low thermal conductivity of spray foam insulation.

Measurement and prediction of cutting temperatures during dry milling: review and discussions

Higher rate of production and better surface quality are major driving forces for modern machining systems. Higher cutting speeds can be used to achieve higher production rates. The generation of heat puts a limit on cutting speeds, thus reducing production rates. Almost all energy spent in machining operations is converted into heat. The plastic deformation of metals during machining is concentrated in a narrow zone and thus very high temperature is expected in this zone. These high temperatures are responsible for reduction in tool life and degradation of surface quality. The complex coupling between plastic deformation and temperature fields is an area of research for many years. The techniques like numerical, analytical and experimental were used for the prediction of the cutting temperatures accurately. Milling is one of the most versatile machining processes used in modern industries. As the industries are focusing more on reducing the use of cutting fluids because of their harmful effects to the operators and environment, dry milling is used as an alternative. Measurement and prediction of the cutting temperature during milling is challenging because of the variation in the high-speed rotating cutter and chip thickness. In this paper, the literature on experimental measurement of the cutting temperatures and prediction of cutting temperatures using numerical, analytical and experimental techniques for dry milling operations is reviewed. The methodology used for modelling and the novelty in the work are highlighted. Initially, a brief review of the temperature measurement techniques is taken to bring out their relative merits and demerits. The paper is aimed to highlight the latest work in this field and also, the areas needed to be addressed are discussed.