In Situ Two-Thermocouple Sensor Characterisation using Cross-Relation Blind Deconvolution with Signal Conditioning for Improved Robustness

Thermocouples are one of the most widely used temperature measurement devices due to their low cost, ease of manufacture and robustness. However, their robustness is obtained at the expense of limited sensor bandwidth. Consequently, in many applications signal compensation techniques are needed to recover the true temperature from the attenuated measurements. This, is turn, necessitates in situ thermocouple characterisation. Recently the authors proposed a novel characterisation technique based on the cross-relation method of blind deconvolution applied to the output of two thermocouples simultaneously measuring the same temperature. This offers a number of advantages over competing methods including low estimation variance and no need for a priori knowledge of the time constant ratio. A weakness of the proposed method is that it yields biased estimates in the presence of measurement noise. In this paper we propose the inclusion of a signal conditioning step in the characterisation algorithm to improve the robustness to noise. The enhanced performance of the resulting algorithm is demonstrated using both simulated and experimental data

Low-cost smart solutions for daylight and electric lighting integration in historical buildings

Research have shown that the correct integration of daylight and electric lighting reduces the energy use in buildings, while improving visual comfort. Smart shading systems, especially those electrically controlled, play an important role to control solar radiation. Similarly, smart and dimmable/tunable lighting can help to adjust the artificial light to the real users' needs. This paper presents preliminary results of an ongoing living lab study investigating how artificial lighting systems can be integrated with shading systems, placing human comfort at the heart of the study and yet saving energy. A manually controlled, commercial and low-cost smart system integrating two motorized shading devices and six dimmable LED luminaires with a different selection of CCT were installed in a private office in a historical building. Indoor and outdoor lighting conditions and energy consumption associated to the lighting system are constantly monitored to assess how the people use shading and lighting upon varying the boundary conditions.. Preliminary results highlight that users prefer to maximise daylight on the work plane as well as they generally use both shading and electric lighting systems in response to boundary conditions that cause serious discomfort

Low-cost smart solutions for daylight and electric lighting integration in historical buildings

Research have shown that the correct integration of daylight and electric lighting reduces the energy use in buildings, while improving visual comfort. Smart shading systems, especially those electrically controlled, play an important role to control solar radiation. Similarly, smart and dimmable/tunable lighting can help to adjust the artificial light to the real users' needs. This paper presents preliminary results of an ongoing living lab study investigating how artificial lighting systems can be integrated with shading systems, placing human comfort at the heart of the study and yet saving energy. A manually controlled, commercial and low-cost smart system integrating two motorized shading devices and six dimmable LED luminaires with a different selection of CCT were installed in a private office in a historical building. Indoor and outdoor lighting conditions and energy consumption associated to the lighting system are constantly monitored to assess how the people use shading and lighting upon varying the boundary conditions.. Preliminary results highlight that users prefer to maximise daylight on the work plane as well as they generally use both shading and electric lighting systems in response to boundary conditions that cause serious discomfort

Discretization Method of Continuous-Time Dynamic Linear Model

The article presents a new discretization method of a continuous-time linear model of sensor dynamics. It can be useful to reduce measuring errors related to the inertia of the sensor. For example it is important in the measurement of rapid processes as temperature changes in combustion chambers, or for shortening the time needed to establish the sensor readings in a transition state. There is assumed that sensor dynamics can be approximated by linear differential equation or transfer function. The searched coefficients of equivalent difference equation or discrete transfer function are obtained from Taylor expansion of a sensor output signal and then on the solution of the linear set of equations. The method does not require decomposition of sensor transfer function for zeros and poles and can be applied to the case of transfer function with zeros equal to zero. The method was used to compensate the dynamics of sensor measuring fast signals. The Bode characteristics of a compensator were compared with others derived using classical methods of discretization of linear models. Additionally, signals in time were presented to show the dynamic error before and after compensation

FIBRE OPTIC COUPLED, INFRARED THERMOMETERS FOR PROCESSES INCURRING HARSH CONDITIONS

This study undertook the development and testing of fibre optic coupled infrared thermometers (IRTs) that could substitute for thermocouples in harsh conditions that would affect contact temperature measurements deleteriously. The IRTs have been configured without photodiode cooling and signal chopping but achieved low minimum measurable temperatures, fast responses and good sensitivities. IRTs were configured with mid-wave infrared (MWIR) and short-wave infrared (SWIR) photodiodes, to measure over different temperature ranges. The thermometers had small footprints, therefore could be installed into constrained spaces and not cause interference with the process. The MWIR thermometers were substituted for thermocouples in high temperature conditions in end milling tool temperature measurements and reactive electrochemical conditions in Lithium-ion cell temperature measurements. The conditions into which the fibre optics were embedded would lead to inaccurate measurements from thermocouples, whereas the fibre optic and remotely positioned IRT offered immunity against these errors. Calibration drift is a major problem that afflicts thermocouple temperature measurements. There has been progress towards addressing this weakness with improved thermocouples. The SWIR thermometer used a zero drift operational amplifier to minimise offset voltage, drift and noise. The IRT was coupled to a sapphire fibre optic probe that had tin deposited onto the core to form an integral fixed point temperature calibration cell. This low drift IRT provided an increment towards creating a drift-free, self-calibrating IRT that would substitute for thermocouples with integral calibration capabilities. The feasibility of substituting thermocouples with embedded fibre optics coupled to IRTs has been demonstrated and potential improvements of these thermometers have been identified

Simulating Switchable Glazing with EnergyPlus: An Empirical Validation and Calibration of a Thermotropic Glazing Model

Adaptive transparent building envelope technologies could play a significant role in decreasing energy use in buildings and providing a more comfortable indoor environment. In order to evaluate these potentials in an economic and accurate manner, it is essential to have numerical models and simulation tools which correctly reproduce the behaviour of such components at the building level. This paper presents and discusses the empirical validation of models for thermo-tropic glazing, a specific adaptive transparent glazing, by means of a whole building performance simulation tool, EnergyPlus. Moreover, this study highlights the differences between two modelling approaches (EnergyPlus built-in and EMS models) and experimental data. Negligible differences are noted between the two modelling approaches, even though the models do not completely agree with experimental data unless a model calibration is performed. The EMS modelling approach could be successfully extended to other dynamic glazing technologies that do not have a builtin model available in EnergyPlus, provided that an accurate thermo-optical characterisation of the dynamic glazing is available

An Evaluation of Thermocouple Reconstruction Techniques

Temperature measurements can be difficult to obtain across many different harsh environments such as engine combustion chambers, engine exhaust temperatures, and explosion fireballs. While there are alternate methods to measure fluid temperature such as laser measurements, acoustic measurements, and camera imaging techniques, these methods can often be expensive, difficult to implement, and not able to see within the environment. Thermocouples are popular sensors because they are cheap and easy to implement across a wide range of applications and can measure temperature in areas where other methods cannot reach or see. However, while these sensors are very popular and versatile, they do have some disadvantages, mainly, the response time. When the testing environment becomes harsh, the thermocouple size increases so that the sensor can survive. Unfortunately, when the thermocouple size increases, so does the time that it takes to sense the gas temperature. For this research, the environment will mimic an explosive environment with very fast temperature rise times that will require quick sensor response. This will not be achievable with a single thermocouple; so, multiple thermocouples will be used. This research focuses on evaluating past multi-thermocouple reconstruction techniques to determine which available method is the most accurate and feasible to implement. Of the methods researched, this work has found that a frequency domain method proposed by Forney and Fralick provides temperature estimates as accurate as 0.5% off the average steady state temperature with an average percent error of 5%