This thesis describes an investigation into the operation and performance of internal combustion engines boosted by an electric supercharger (eSC) in combination with a turbocharger. Engine downsizing offers one of the most effective ways to meet increasingly demanding CO2 reduction targets set for the automotive vehicles. The addition of a turbocharger has enabled significant downsizing but the loss of torque at low engine speeds remains a key barrier to further downsizing. A known solution to this problem is to additionally boost the engine using a supercharger. However, until recently, this was very difficult to implement economically on engines with modest engine power suitable for small to medium sized vehicles due to the low air mass flow rates for such engines. Now, a new turbo-machinery innovation, the high forward swept TurboClaw compressor, allows significant boosting to be done at low flow rates yet with moderate compressor shaft speeds. Since this compressor can be driven at a moderate speeds, the electric motor which drives for the electric supercharger (eSC) is more affordable. The research objective was to assess this new eSC system be means of a theoretical and experimental investigation. There are two possible combinations in terms of whether the (eSC) goes before the turbocharger (ETC), or after (TEC). Employing the eSC after turbocharger generally has the advantage of broadening the eSC map, towards higher-mass flows since a denser air exits the turbo-compressor as the turbocharger provides boosted air to the system. This augments the overlap of the two operating maps for the two devices. However the real benefit of eSC in each layout depends on the engine (baseline). In this research ETC and TEC produce basically the same torque increase; the real eSC benefit is at low speed where the nominal maximum torque is recovered for all the range. However since the current drawn from the battery is a key factor for this application, the investigation shows that the thermodynamic power requested by eSC is less than 1.5kW for ETC layout while this value is 2.5kW for TEC layout. Therefore ETC layout was chosen as the final configure to be implemented on the selected vehicle for the dyno test purposes since it requires less power. Theoretical models for the engine, turbocharger and TurboClaw eSC including electric motor were created and validated. The system of all components was designed including control system and strategy. A key result showed that the eSC was found to boost the torque of a 1.0 litre turbocharged engine by 125% and 58% for 1000 rpm and 1200 rpm respectively.

Magnetic nanofluid (MNF) is one special kind of nanofluid which possesses both magnetic and fluid properties. Nowadays, extensive attention has been focussed on development of thermal applications. Investigations of magnetic hyperthermia are emerging as a new frontier in studies of cancer therapy. The theory of treatment is based on the fact that magnetic nanoparticles produce heat under an AC magnetic field via a mechanism called magnetic losses. Facing with the present technical limits and growing demands for safe treatment, researchers have realized the advantage of assembling superparamagnetic nanoparticles (SMNP) into colloidal clusters for effective heating at low field intensity and frequency. In contrary to the isolated particles, the magnetic losses of the clusters are affected by inter-particle dipole interactions. The role of dipole interactions is complex and contradictory findings have been reported. Understanding the role of dipole interactions is the key to optimizing the clusters for efficient hyperthermia heating. Magnetic nanofluids have also been proven to be a highly thermally conductive working fluid. The dispersed SMNPs enable control over the fluid’s thermal physical properties, flow and heat transfer processes via an external magnetic field. The main challenges include how to improve the applicability of theoretical models on predicting thermal physical properties and interpreting the role of particle migration during a convective heat transfer process. Numerous results suggested that their anomalous physical properties should be attributed to particle aggregation since it changes the effective particle concentration and generates thermal percolation paths. Also, the rate of particle migration is heavily dependent of the size of aggregates. Therefore, it is necessary to study the effect of colloidal stability on thermal physical properties and convective heat transfer enhancement of the magnetic nanofluid. At the beginning of this doctoral research project, we investigated the effect of dipole interactions on hyperthermia heating cluster composed of multi SMNPs by time-quantified Monte Carlo simulation. The cluster’s shape is characterized by treating it as an equivalent ellipsoid. When the shape is highly anisotropic such as in chain and cylinder, dipole interactions not only facilitate the magnetization process but also impede the demagnetization process by aligning the individual moments to the cluster’s morphology anisotropy axis. Thus, the heating capability of chain and cylinder clusters are superior to non-interacting particles at the most angles between the field direction and morphology anisotropy axis. At high field intensity, the influence of dipole interactions on magnetic losses will be reduced to a minimum once the cluster loses its morphology anisotropy (i.e. cube or sphere); the probability to obtain improved heating becomes very low. Then, experimental and theoretical works were conducted together to find out how to improve the heating ability of anisotropic-less clusters at lower field intensity and frequency. Hydrophobic Fe3O4 nanoparticles were assembled into sphere-like clusters using the emulsion droplet evaporation method. The hydrodynamic size of the cluster was controlled within the range of 70 – 140 nm. An induction heating system equipped with an Optic-fiber thermometer was set up to test the heating efficiency of as - prepared Fe3O4 clusters with different size. Meanwhile, standard Monte Carlo simulation was performed to study the contribution of dipole interactions at different sizes. The findings suggested that if one expects anisotropic-less clusters to heat better, he should reduce the cluster’s size so that the clusters are in forms of dimer and/or trimers or use SMNP with high magnetization and magneto-crystalline anisotropy. Finally, a stable and surfactant-free magnetic nanofluid was prepared for study of convective heat transfer enhancement. Ethylene glycol and water mixture was selected as the base liquid, which is often used for cooing an automotive engine. The surfaces of Fe3O4 nanoparticles were modified with citric acid to make the colloidal stability sensitive to the pH of the particle suspension. It was found that the density and specific heat of obtained MNF can be interpreted well by mixing theory and thermal equilibrium model respectively. After the colloidally stability was optimized, the MNF exhibited Newtonian behavior. The viscosity barely changed with the shear rate despite variances in particle concentration and temperature. A modified Krieger and Dougherty model was used to explain the relationship between the size of aggregates and viscosity. Meanwhile, we found that the thermal conductivity can be predicted by the Maxwell model, which presumes the nanofluid has common features with a solid–liquid mixture. At last, it was demonstrated that the convective heat transfer coefficient of our MNF was 10 % higher than that of base liquid at transition and turbulent flow.

This thesis describes the development and validation of a new computational procedure for the calculation of thermal transmittance (U-value) of existing building elements from the measurement of surface heat flux, and surface and nearby air temperatures. The U-value plays a key role in the determination of the final energy consumption of a dwelling, and, as in the current political scenario reducing carbon emissions is a growing concern, obtaining accurate and quick measurements of thermal transmittance is of particular relevance to the precise representation of the energy performance of the building sector. The calculation method developed is an extension of the RC network, a model based on the discretisation of building elements in resistors and capacitors in analogy with electrical circuits. The advances proposed in this work extend the discrete RC networks to a model based on the full heat equation, with continuous, spatially varying thermal prop- erties. The solution algorithm is inserted in a Bayesian framework that allows the reformulation of the problem in terms of probability distributions. Two solution schemes have been confronted: Markov Chain Monte Carlo and Ensemble Kalman Filters approximation. The model proposed has been validated on synthetic data, laboratory data collected in an environmental chamber on a solid and cavity wall, and in-situ data collected in 3 different locations (2 solid walls and 1 insulated steel frame construction). The results show that the model offers an improved characterisation of the heat transfer through the building elements, furthermore, the algorithm can be used to analyse different wall constructions without the necessity of changing the structure of the model, as opposed to the standard RC networks, and, finally, it offers the practical advantages of the uncertainty reduction on thermal transmittance (from 14-25% to 7-10%) and a diminution of the necessary monitoring period from a minimum of 3 days to 1 day or less. These advantages, in turn, benefit the building performance evaluation on different levels: in first instance, the practicality of measuring thermal transmittance in-situ is improved, thus making it easier to monitor the actual envelope performance and, secondly, the uncertainty reduction on the U-value leads to important reductions on the uncertainty surrounding the energy consumption predictions associated with a dwelling.

The work includes summaries of the mechanics of wear in sliding systems under light loading, and severe wear mechanisms under metal cutting conditions. Applications of different wear mechanisms to cutting tool wear, and the problems associated with defining cutting tool life and failure criteria are discussed. Applications of dimensional analysis to the metal cutting problem are presented and include sections on: tool temperature, tool life/cutting speed relationships, tool life/temperature and temperature/time relationships, Colding's three dimensional tool life equation and.an analysis of the Taylor constant. The development of empirical cutting tool life equations is reviewed and includes Taylor type relationships, equations based on the concept of the chip equivalent and Colding's tool life equation. The effectsof cutting conditions, tool geometry, tool material and workpiecematerial on cutting tool life are considered. The fundamentals of sawing are outlined and the variations of modern power hacksaw and bandsaw machines discussed. This section includes a description of modern saw blades and saw blade nomenclature. A comprehensive review of previous work carried out on both the power hacksaw and bandsaw operations shows the present state ofknowledge in this field. The experimental work based on an adaptation of Colding's three dimensional tool life equation forms the first thorough investigation of bandsaw blade wear and its effects on cutting rates and economics. Relationships between the wear rate of the band and relevant parameters such as band speed, machine load and geometry of the workpiece are shown. Wear rate and cutting rate have been expressed in terms of a cutting constant, which defines the penetration of the teeth and its decay with use. A computer based simulation of the bandsaw operation has been developed and used to investigate the influence of relevant engineering parameters on productivity and cutting economics. The data obtained from the simulation model has been used to determine cutting rates and costs of bandsaw operations using constant feed rate and constant thrust load principles. The data is based on tests carried out on workpiece material classified as difficult to cut and trends obtained are believed to be typical of those that would beobtained when cutting the more common materials. For the firsttime, direct comparisons are made between carbon blades and high speed steel bi-metal blades under various bandsaw conditions, and the bandsaw and power hacksaw operations are directly compared. The investigation results in the following conclusions. The bandsaw operation may be a low cost, high cutting rate operation when high speed steel bi-metal blades are used under optimised operating conditions. High speed steel bi-metal blades should be preferredto carbon. A bandsaw machine operating with constant feed rate is superior to one operating with a constant thrust load system. A reduction in the total cost per cut can usually be obtained by optimising feed rates at the expense of blade life. The bandsaw operation can be as economical as the power hacksaw operation whilst achieving a higher cutting rate.

Published work concerning the influence of tooth geometry on hacksaw blade performance has been reviewed. By testing standard and modified hacksaw blades the author has shown that, contrary to previous belief, pitch is not a parameter which affects blade performance. Furthermore experimental evidence is presented to show that gullet size and shape significantly affect blade performance. The author proposes that restriction of chip flow by the gullet causes very inefficient metal removal. This is supported by examination of hacksaw chips, and a theoretical model has been developed to show how rapidly cutting forces increase when the chip is restricted from flowing. Two testing procedures have been developed to examine chip formation in the gullet. The first procedure employs video equipment to show chip formation and cutting forces simultaneously on one VDU, during cutting with single hacksaw teeth. This test is of limited use due to the slow cutting speeds employed. The second procedure, also using single teeth but cutting at realistic speeds, was capable of testing any tooth/gullet geometry cutting any material. The test results confirmed that restriction of chip flow by the gullet produces inefficient cutting. It has been shown that a particular tooth/gullet geometry can only cut efficiently over a limited range of feeds and workpiece lengths. The author has developed a method for accurately predicting sawing rates from the single tooth data gathered. The information gathered from the single tooth tests has enabled the author to isolate the most important aspects of tooth geometry affecting blade performance, and as a result, a new tooth design has been developed which performs better than the standard tooth.

This thesis is the summary of the research work that has been carried out by the author on the development of methods of optimum gear design and shaft design for gear boxes, and the integration of the methods into one software package together with parametric layout drawing. The objective of the optimum gear design is to minimise the gear centre distance with a fixed aspect ratio of pinion, when power capacity requirement is given. Although power capacity is dependant upon many factors, the optimum gear design method has used module, numbers of teeth, and helix angle as the significant variables. The power capacity rating is calculated by AGMA standards and the optimum design method is based on a study of the numerical behaviour of the AGMA power capacity rating and transformation of the gear design constraints into direct limiting boundaries on design variables. Numerical example tests show that the method is efficient and effective in finding the global minimum centre distance design. The shaft component design method is based on established theories for reaction calculation, bearing life rating, shaft stress calculation and shaft failure criterion. However, the layout of the gear box is defined by a unique system using vectors connecting shaft and gear centres. The gear design and shaft design methods are implemented in an integrated software package and a well defined data organisation provides the basis for data sharing. The definition of layout by centre vectors also serves as the reference frame around which to draw the layout by parametric programs. The design results of the software package are obtained by parametric programs from a data file based on the same data organisation. Parametric programs for individual shaft, bearing, and gears are written to draw the components and main dimensions such as centre distances, component axial positions, gear sizes and bearing sizes are shown on the layout. The contribution to knowledge by this investigation is mainly in the gear design area, viz., the study of the numerical behaviour of AGMA standards in relation to gear geometry and the development of the efficient and effective algorithm for the optimum gear design. The descriptive layout definition by centre vectors is also a novel feature.

This work is concerned with track spring components manufactured by Pandrol from a SiMn alloy in the quenched and tempered condition. For many years low to medium carbon based spring steel has been manufactured via an oil quench temper route producing components with suitable mechanical and microstructural properties. The current problem facing the spring manufacturer with the traditional heat treatment route involve a number of technical issues including a sensitivity to temper embrittlement and susceptibility to stress corrosion cracking. In addition, economic factors and component handling problems led Pandrol to seek solutions via the manufacturing process and materials selection. A programme of research was therefore proposed to identify a possible replacement alloy system and production route which could exclude the costly tempering operation and instil a degree of production control. The initial program of work involved the examination of several alloy systems based loosely around three separate microstructures, i.e. a fully pearlitic, bainitic and martensitic microstructure. In turn, each alloy was examined and assessed with respect to their suitability for the industrial application given their mechanical properties. From the initial research, a selected number of promising alloy systems were examined further, namely a chromium molybdenum alloy, salt bath quenched to produce a bainitic microstructure, a water quenched low carbon chromium and low carbon boron martensitic type alloy. The low carbon boron alloy was considered the most promising, with similar mechanical properties in both the plain bar and clip form compared to the existing Pandrol alloy. However, concern was raised over the amount of plastic deformation (permanent set) suffered by a clip component whilst in service. In response to this, the use of cold work was examined to further strengthen the microstructure with notable success. On identifying several possible alternative alloy systems to replace the existing oil quenched and tempered variant, the second stage of this research work concentrated on understanding the degree and type of microstructural strengthening involved on each particular alloy system. The effect of plastic deformation in each alloy type was also thoroughly investigated via transmission electron microscopy / true stress strain analysis and an attempt was made to relate microstructural changes to obtained mechanical properties. In addition the work hardening characteristics of the tempered microstructure were investigated, and compared to the straight through hardened variants. Qualitative Transmission Electron Microscopy studies confirmed that dislocation density/mobility played a crucial role in determining the work hardening rate. This project has studied the phenomena of work hardening in body centred cubic materials in the through hardened and untempered condition. A series of novel alloys have been developed with strengths equal to or above an oil quenched and tempered counterpart. However, these new alloys do not require a temper treatment thereby removing the risk of temper embrittlement. A clearer understanding of the work hardening characteristics has been developed through an assessment of the work hardening coefficient of these material variants.

No description available.

Master of Science / Department of Biological & Agricultural Engineering / Ajay Sharda / In the agriculture industry, in-field efficiency of tractors is critical information for operators and producers. Properly matching tractor to implement using real-world tractor performance characteristics is the primary factor that effects in-field efficiency. Currently, tractor testing is primarily conducted in a controlled lab environment to quantify attributes such as power take-off (PTO) power and fuel consumption. However, in-field quantification of these attributes is necessary to gain a full understanding of the machine’s performance. Therefore, this study was conducted with two primary objectives: 1) develop a data acquisition system to measure real-time tractor performance at varying machine states during field operations, and; 2) evaluate the performance of tractors individually and compared to each other. Studies were conducted to test multiple different sized tractors with varying implements used in a specific crop production cycle; these tractors included two smaller 71 HP machines, a 90 HP and a 100 HP machine. The primary performance comparison goals were to evaluate the performance efficiency differences between a cabin and open station machine of the same size, and to evaluate the differences in performance between two similarly sized machines. A custom data acquisition (DAQ) system developed comprises of a torque sensor, flow meter, and GPS to acquire target performance parameters using a National Instruments cRIO system. The PTO torque sensor and fuel flow meter were tested and validated in a controlled lab using a PTO dynamometer and fuel scale. Validation field studies conducted showed that the DAQ system captured real-time performance parameters; strong correlation was observed between power, speed, and fuel consumption.   Using the real-time data allows for a better understanding of the relationship between machine and implement, as well as a more thorough understanding of the effect of terrain and crop load on fuel consumption and PTO power. The peak torque values through the implement drivetrain and their frequencies coupled with the average breakdown of power consumption by the implement gives the manufacturer and producer the opportunity to modify usage trends or design, respectively. Spatial fuel consumption data on a tractor by tractor basis allows varying machines to be compared directly based on their efficiency. Testing of the two smaller tractors took place on the same day in a uniform field. While the data did not indicate any difference between open station and cabin machines, strong correlation was observed between both operating speed and PTO mode selection and performance efficiency. The testing of the two larger tractors was done on sequential cuts of alfalfa on the same field; to account for this, bales were geotagged and weighed to produce a forage density map. Data from testing yielded two main results; the first being that the fuel consumption rate of each tractor and operation can be accurately predicted using an equation using PTO power and operating speed as variables. The equation that defines the fuel consumption for the swathing operation predicts the fuel consumption within 10% over 75% of the time in both sized machines. Data recorded by the DAQ system yields the information necessary to give the manufacturer a thorough understanding of how machines and implements interact with each other, as well as how external factors effect machine performance.

The main objective of this research is to enhance the performance of a solar powered Micro Gas Turbine (MGT) by exploring suitable methods to be applied to the turbomachinery components to increase their efficiency and improve the predictability of their performance over the operating range of the MGT. A novel idea of reducing turbine rotor friction losses through adding riblets to the rotor hub was explored thoroughly. Computational Fluid Dynamics (CFD) has been used to study the effects of those features at design point conditions of the MGT. Riblets with different height and spacing have been examined to determine the riblet geometry where the maximum drag reduction is achieved. To improve the predictability of performance of the turbomachinery components of the MGT over the operating envelope, a prediction methodology was developed during this research which used a combination of CFD and empirical correlations to account for losses that are not included in the CFD model. It was found that riblets reduce the cross-stream motion of the low momentum fluid flow near the hub surface of the rotor passage, and separate the streamwise vortex from interaction with the hub surface. The maximum drag reduction was found to occur with riblets of a relative height of 2.5% with respect to the rotor inlet blade height. The performance prediction method was successfully applied to a radial turbine and centrifugal compressor designed for a 6 kWe solar powered MGT. A purpose-built test rig was built and the actual performance map for the turbine was achieved while running it using warm compressed air from an external air supply. The comparison between the actual and the predicted data revealed a good match between both results, which indicates the validity of the demonstrated performance prediction method.