The development of an indirect measurement model for electro thermal furnace and its implementation in a reconfigurable architecture are the main issues of this article. The proposed measurement system is based on the system model, the principle of conservation of energy and the laws of thermodynamics are applied to build a model of the thermal system where the Kalman theory is applied for filtering and prediction of the temperatures inside of a resistive furnace. Three setup are established to evaluate the performance of the indirect measurement system: off-line implementation of the...
XVIII IMEKO World Congress · TC12 · 2006 · Download
This work deals with the dynamic thermal conductivity (λ) measurements by hot wire method. This measurements are performed at unstationary state conditions (short time). Very thin (0.05 mm) manganin wire is supplied by DC electrical power and produces a thermal impulses which pass through the testing sample. Dynamics of this process depends on the type of the sample material. Temperature, electric power and time elapsed during the process are measured parameters from which thermal conductivity could be calculated. Measurement results are compared with those gained by the standard guarded hot...
XVIII IMEKO World Congress · TC12 · 2006 · Download
Manuel Antonio Pires Castanho, Rudinei de Brito Maciel
The purpose of this paper is to present the results of a bilateral interlaboratory comparison (ILC)[1] between the Mechanical Metrology Laboratory - IPT and Metrology Laboratory - Ecil. Both laboratories are accredited by Brazilian Calibration Net (RBC). In this program eight temperature artifacts have been calibrated in the range of –40°C to 1100°C. The artifacts are 02 thermocouples, 02 platinum resistance thermometers and 04 liquid in glass thermometers.
XVIII IMEKO World Congress · TC12 · 2006 · Download
A comparison of some defining temperature fixed-points on the ITS-90 was carried out at the National Institute of Standards using four calibrated SPRTs. The comparison was performed using large and small sealed cells from two different sources. The large cells, namely set1 cells and taken as reference cells were realized using the same technique used with the small cells (set2). The main task is to study the set2 cells and the possibility of using them instead of the large size (reference) cells. Measurements showed good results and some agreement between the two sets. The differences...
XVIII IMEKO World Congress · TC12 · 2006 · Download
Francisco Santos, Rafael Cantalice, Raimundo Freire, Will Almeida, Elmar Melcher
In this paper presents two microsensors structures compatible with microelectronic technologies that are analyzed for application in radiometers. The first structure is formed by one resistor that is made by doping a monocrystalline silicon substrate with boron. The second is a polysilicon resistor doped with phosphorous, over a silicon dioxide (SiO 2 ). The analysis is made by mathematical modeling of these devices, numeric simulation and graphics to obtain the better thermal-electrical characteristic of microsensor material. We choose the best microsensor structure with the increase...
XVIII IMEKO World Congress · TC12 · 2006 · Download
Antonio Carlos de Barros Neiva, Emerson dos Reis, Caio Glauco Sanchez
The main purpose of this work is to present the manufacturing, calibration and validation of a system for wet and dry bulb temperature measurements obtained on a new psychrometer. The calibration has lead to the adjustment of the appropriate psychrometer coefficient for the developed psychrometer, as a function of the wet bulb temperature, which fits best with experimental data, obtained on the range from 34% to 87% RH and 15°C to 30°C. Another set of experimental points on this range was used for evaluation of the psychrometer uncertainty. An electronic hygrometer was calibrated...
XVIII IMEKO World Congress · TC12 · 2006 · Download
This paper describes characterization of 1-T dew point generator developed at Laboratory for Process Measurement (LPM) self. Present operating range of generator is from -7°C to 18°C dew point range. The air flows through saturator in closed loop and is controlled with regulated flow meters. Air saturation degree is determined by measuring the temperature deviations between saturator air outlet and liquid in saturator. Thermometers are connected to the resistance bridge, which is in turn connected to the computer for data acquisition. The main design features of the 1-T generator are...
XVIII IMEKO World Congress · TC12 · 2006 · Download
The problem of measurements of the thermal resistance (R th ) of monolithic switched regulators (MSR) is considered in the paper. A new method of measuring this thermal parameter is proposed and the proper measuring set is presented. The results of measurements of R th of the considered devices are compared with the similar results obtained with two other known methods.
XVIII IMEKO World Congress · TC12 · 2006 · Download
In this paper computerized system for high temperature measurements of superficial properties has been presented. The process of superficial properties determination is based on digital image processing and analysis algorithms. Particular attention has been paid to adaptive thresholding algorithm with a local iterative threshold selection. Algorithm was elaborated to segment images obtained from the measurement process. Moreover, results of proposed algorithm have been presented. In the final stage of the paper difficulties appearing during high temperature measurements have been outlined....
XVIII IMEKO World Congress · TC12 · 2006 · Download
Sergio Libanio Campos, José Luiz Fernandes, José Alberto Reis Parise
The present paper describes a simulation model for the operation of an automotive air conditioning system subjected to typical mechanical failures. A review identified the most common mechanical failures in automotive A/C systems. Simple mathematical models of two of the most common of these failures were developed and introduced in a simulation model of the vapor compression cycle. Simulated components of the cycle, operating trouble-free or under failure, included the compressor and the condenser. The evaporator, thermal expansion valve, filter-dryer, hoses and connections are also sources...
XVIII IMEKO World Congress · TC12 · 2006 · Download