Comparative Analysis of Water and Oil Media on Temperature Stability in PID Control-Based Digital Thermometer Calibrator

Digital thermometers are measuring instruments needed to perform temperature measurement actions and must be calibrated periodically according to standard measurement methods. The purpose of developing this tool is to add PID control to the calibration media where PID control aims to regulate the stability of the temperature setting to be achieved. This is achieved by studying and evaluating the effect of temperature stability on the heater and LM35DZ temperature sensor. This research method uses the Arduino Nanosystem for data processing and PID system control. The LM35DZ temperature sensor on the heater is regulated by a 2 Channel SSR module using a PID system then the temperature generated by the heater will be read by the LM35DZ and displayed on the LCD. The results of this study, digital thermometer calibrator measurements have been successfully carried out by comparing 3 digital thermometers with different brands, namely Omron 343F, Omron 245, and ThermoOne. The difference in error values in oil media is 3-4% and in water media 2-4% with the value of time stability in water media for 3-3.3 minutes and in oil media for 1-2 hours. With this comparison of calibration media, it is hoped that it can help in measuring temperature with better and more effective results. find methods, results, conclusions

Frost susceptibility of granular materials

In this thesis work to improve the Transport and Road Research Laboratory (TRRL) frost heave test is described along with a new indirect method of predicting the frost susceptibility of granular material. To determine the optimum TRRL test conditions temperatures in the Nottingham University cold room and prototype Self Refrigerated Unit (SRU) were automatically monitored. In a typical trial several thousand temperatures were recorded. These were reduced to just three independent parameters, each of which quantified a particular feature of the temperature regime. Temperature fluctuations in the water bath of the prototype SRU were excessive and so an improved Mk3 unit was developed . Road sub-base aggregates covering a wide variety of geological types and grading were tested. These had the same heave after 250 hours freezing in the Mk3 SRU and the cold room, at least within the working range. Rigorous statistical analyses revealed that frost susceptibility could be judged with equal precision after only 96 hours freezing. The variability of heave was the same in both units. This variability was attributed to intrinsic differences between nominally similar specimens. It is intended that a 96 hour Mk3 SRU, frost heave test will be specified in a new British Standard. The indirect method is based on the suction/moisture content characteristics of granular soils. These were determined using the osmotic suction technique although the specimen preparation procedure had to be improved to accommodate the hard, coarse aggregates. For all the materials tested, the volumetric moisture content at suction of pF2.5 (ϴ2.5) was strongly correlated with heave in the TRRL test. Calculations revealed that, for the TRRL test conditions, pF2.5 is a suction which must occur in the zone between the terminal ice lens and the limit of ice penetration. It is thought that ϴ2.5 reflects the overall permeability of this frozen fringe

Enhancement of panel radiator based hydronic central heating system using flow pulsation

Enhancing the heat output of the hydronic central heating system in buildings can play a major role in reducing energy consumption and CO2 emission. The main aim of this PhD research is to investigate the effect of pulsed flow input on the energy consumption of panel radiators in hydronic central heating systems and the user indoor comfort defined by ASHRAE standard 55 and EN ISO 7730. The research covers thermal performance of panel radiator and the indoor comfort. The work was performed using dynamic control modelling, CFD and experimental testing to prove the concept. Results from the mathematical and CFD modelling of the hydronic radiator with pulsed flow using various frequencies and amplitudes showed that 20% to 27% of energy saving can be achieved compared to the constant flow while maintaining the same radiator target surface temperature of 50oC as recommended by the BS EN442. The indoor comfort results were also achieved as recommended by international standards including CO2 concentration at 1000PPM±50PPM, relative humidity at 50±9%, comfort temperature at 20±1.6oC, air velocity of below 0.15m/s and draught risk parameters of less than 15%. The numerical results agreed well with experimental results with maximum deviation of radiator temperature output of ±4.1%, indoor temperature ±2.83% and energy saving of ±1.7%. The energy saved due to the pulsed flow is attributed to the enhancement of the radiator heat transfer performance that leads to higher heat output at lower average mass flow rate of the hot water

Fundamentals of heat measurement

Various methods and devices for obtaining experimental data on heat flux density over wide ranges of temperature and pressure are examined. Laboratory tests and device fabrication details are supplemented by theoretical analyses of heat-conduction and thermoelectric effects, providing design guidelines and information relevant to further research and development. A theory defining the measure of correspondence between transducer signal and the measured heat flux is established for individual (isolated) heat flux transducers subject to space and time-dependent loading. An analysis of the properties of stacked (series-connected) transducers of various types (sandwich-type, plane, and spiral) is used to derive a similarity theory providing general governing relationships. The transducers examined are used in 36 types of derivative devices involving direct heat loss measurements, heat conduction studies, radiation pyrometry, calorimetry in medicine and industry and nuclear reactor dosimetry

Engine thermal management with model predictive control

The global greenhouse gas CO2 emission from the transportation sector is very significant.To reduce this gas emission, EU has set an average target of not more than 95 CO2/km for new passenger cars by the year 2020. A great reduction is still required to achieve the CO2 emission target in 2020, and many different approaches are being considered. This thesis focuses on the thermal management of the engine as an area that promise significant improvement of fuel efficiency with relatively small changes. The review of the literature shows that thermal management can improve engine efficiency through the friction reduction, improved air-fuel mixing, reduced heat loss, increased engine volumetric efficiency, suppressed knock, reduce radiator fan speed and reduction of other toxic emissions such as CO, HC and NOx. Like heat loss and friction, most emissions can be reduced in high temperature condition, but this may lead to poor volumetric efficiency and make the engine more prone to knock. The temperature trade-off study is conducted in simulation using a GT-SUITE engine model coupled with the FE in-cylinder wall structure and cooling system. The result is a map of the best operating temperature over engine speed and load. To quantify the benefit of this map, eight driving styles from the legislative and research test cycles are being compared using an immediate application of the optimal temperature, and significant improvements are found for urban style driving, while operation at higher load (motorway style driving) shows only small efficiency gains. The fuel consumption saving predicted in the urban style of driving is more than 4%. This assess the chance of following the temperature set point over a cycle, the temperature reference is analysed for all eight types of drive cycles using autocorrelation, lag plot and power spectral density. The analysis consistently shows that the highest volatility is recorded in the Artemis Urban Drive Cycle: the autocorrelation disappears after only 5.4 seconds, while the power spectral density shows a drop off around 0.09Hz. This means fast control action is required to implement the optimal temperature before it changes again. Model Predictive Control (MPC) is an optimal controller with a receding horizon, and it is well known for its ability to handle multivariable control problems for linear systems with input and state limits. The MPC controller can anticipate future events and can take control actions accordingly, especially if disturbances are known in advance. The main difficulty when applying MPC to thermal management is the non-linearity caused by changes in flow rate. Manipulating both the water pump and valve improves the control authority, but it also amplifies the nonlinearity of the system. Common linearization approaches like Jacobian Linearization around one or several operating points are tested, by found to be only moderately successful. Instead, a novel approach is pursued using feedback linearization of the plant model. This uses an algebraic transformation of the plant inputs to turn the nonlinear systems dynamics into a fully or predominantly linear system. The MPC controller can work with the linear model, while the actual control inputs are found using an inverse transformation. The Feedback Linearization MPC of the cooling system model is implemented and testing using MathWork Simulink®. The process includes the model transformation approach, model fitting, the transformation of the constraints and the tuning of the MPC controller. The simulation shows good temperature tracking performance, and this demonstrates that a MPC controller with feedback linearization is a suitable approach to thermal management. The controller strategy is then validated in a test rig replicating an actual engine cooling system. The new MPC controller is again evaluated over the eight driving cycles. The average water pump speed is reduced by 9.1% compared to the conventional cooling system, while maintaining good temperature tracking. The controller performance further improves with future disturbance anticipation by 20.5% for the temperature tracking (calculated by RMSE), 6.8% reduction of the average water pump speed, 47.3% reduction of the average valve movement and 34.0% reduction of the average radiator fan speed

Investigation of rim seal exchange and coolant re-ingestion in rotor stator cavities using gas concentration techniques

Gas turbine engine performance requires effective and reliable internal cooling over the duty cycle of the engine. Understanding the effectiveness of cooling flows when making life predictions for rotating components subject to the main gas path temperatures is crucial. A test facility has been developed at the University of Sussex incorporating a two stage turbine designed to support a European funded research project with the objective of enhancing the understanding of interactions between main annulus gas paths and secondary air systems. This thesis describes the specific contribution of the author to the research conducted at the test facility. Non-invasive gas seeding and concentration measurement techniques together with hot geometry displacement measurements have been developed to meet three distinct objectives: to determine inter-stage seal flows between rotor disc cavities; to provide data to quantify rim seal exchange flows between rotor stator cavities and the main annulus gas path for both bulk ingestion and egress conditions; and, to provide data to quantify the re-ingestion of cooling air egressed into the main annulus gas path. Detailed knowledge of these flows is vital to understanding the flow structures within rotor stator cavities and to optimise coolant delivery methods. Experimental results are presented for a number of cooling flow supply geometries and flow rates. The gas concentration measurement techniques developed and the results obtained are compared to traditional measurements as well as numerical simulations carried out by research project partners. This work develops the measurement techniques of rotor stator cavity flows and provides data suitable for the validation of improved thermo-mechanical and CFD codes, beneficial to the engine design process

Residential house wall thermal performance

Rapid urbanisation due to global economic development and population growth necessitate the expansion of cities and towns with new buildings and associated energy requirements. The floor space area and volumetric dimension of modern residential houses are increasing at a constant rate in most developed countries including Australia. Therefore, the energy consumption for ongoing heating and cooling is also increasing. The increasing energy consumption leads to greater greenhouse gas emissions. In household consumption, around 40% of the total energy is used for space heating and cooling. Hence, the reduction of energy use for space heating and cooling is paramount for energy conservation, energy security and reduction of greenhouse gas emissions. A substantial amount of energy required for heating and cooling is lost through the house wall systems. Despite the importance of house wall systems for energy efficiency, little research has been undertaken on energy efficient house wall systems made of combined thermal masses and insulation materials that can be used and adapted for variable climate conditions with minimal design changes and cost. Therefore, the main objective of this research is to undertake a thermal performance study of two house wall systems (one conventional and the other a new design) with single and double glazed windows for variable climate conditions in order to develop an optimal energy efficient house wall system with minimal material modification and cost. Additionally, a thermal performance model for the optimal house wall systems is also to be developed for use in variable climate conditions

Diffusion and Viscosity Coefficients of Binary Non-Electrolyte Liquid Mixtures

The Taylor Dispersion Technique has been applied to the measurement of mutual diffusion coefficients for liquid mixtures at elevated pressures. The systems studied were toluene plus n-hexane and toluene plus acetonitrile over the temperature range from 273 to 348 K and up to 25 MPa. The density and viscosity for the same mixtures have been measured from 298 to 373 K and up to 500 MPa. A self-centering falling body viscometer was used for the viscosity measurements, and densities were measured with a bellows volumometer. High pressure densities are also reported for the ternary mixture of n-octane, i-octane and oct-1-ene. Measurements were also made of the mutual diffusion coefficient of benzene and eight fluorinated benzenes at trace concentration in n-hexane from 213 to 333 K, at atmospheric pressure. The results have been used to make a rigorous test of current theoretical and empirical relationships. The Tait equation fits the density data within 0.2%. The trace mutual diffusion coefficient data are satisfactorily accounted for on the basis of the rough hard-sphere model and the high pressure viscosity coefficient results are successfully correlated using a method based on consideration of hard-sphere theory. The Grunberg and Nissan equation satisfactorily reproduces the mixture viscosity data, with parameter G dependent on temperature, pressure and concentration. An important development in the correlation of dense fluid transport properties on the basis of hard-sphere model is described, whereby diffusion and viscosity coefficients are considered simultaneously. This should lead to more reliable prediction methods for transport coefficients of dense fluids and fluid mixtures