Octane requirement increase arising from the use of lead free fuel

Lead in petrol has been identified as a health hazard and attempts are being made to create a lead-free atmosphere. Through an intensive study a review is made of the various options available to the automobile and petroleum industry. The economic and atmospheric penalties coupled with automobile fuel consumption trends are calculated and presented in both graphical and tabulated form. Experimental measurements of carbon monoxide and hydrocarbon emissions are also presented for certain selected fuels. Reduction in CO and HC's with the employment of a three-way catalyst is also discussed. All tests were carried out on a Fiat 127A engine at wide open throttle and standard timing setting. A Froude dynamometer was used to vary engine speed. With the introduction of lead-free petrol, interest in combustion chamber deposits in spark ignition engines has ben renewed. These deposits cause octane requirement increase or rise in engine knock and decreased volumetric efficiency. The detrimental effect of the deposits has been attributed to the physical volume of the deposit and to changes in heat transfer. This study attempts to assess why leaded deposits, though often greater in mass and volume, yield relatively lower ORI when compared to lead-free deposits under identical operating conditions. This has been carried out by identifying the differences in the physical nature of the deposit and then through measurement of the thermal conductivity and permeability of the deposits. The measured thermal conductivity results are later used in a mathematical model to determine heat transfer rates and temperature variation across the engine wall and deposit. For the model, the walls of the combustion cylinder and top are assumed to be free of engine deposit, the major deposit being on the piston head. Seven different heat transfer equations are formulated describing heat flow at each part of the four stroke cycle, and the variation of cylinder wall area exposed to gas mixture is accounted for. The heat transfer equations are solved using numerical methods and temperature variations across the wall identified. Though the calculations have been carried out for one particular moment in the cycle, similar calculations are possible for every degree of the crank angle, and thus further information regarding location of maximum temperatures at every degree of the crank angle may also be determined. In conclusion, thermal conductivity values of leaded and lead-free deposits have been found. The fundamental concepts of a mathematical model with great potential have been formulated and it is hoped that with future work it may be used in a simulation for different engine construction materials and motor fuels, leading to better design of future prototype engines.

A detailed design study of leaching and ancillary processes in the hydrometallurgical extraction of iron from iron bearing feedstocks

A systematic survey of the possible methods of chemical extraction of iron by chloride formation has been presented and supported by a comparable study of :feedstocks, products and markets. The generation and evaluation of alternative processes was carried out by the technique of morphological analysis vihich was exploited by way of a computer program. The final choice was related to technical feasibility and economic viability, particularly capital cost requirements and developments were made in an estimating procedure for hydrometallurgjcal processes which have general applications. The systematic exploration included the compilation of relevant data, and this indicated a need.to investigate precipitative hydrolysis or aqueous ferric chloride. Arising from this study, two novel hydrometallurgical processes for manufacturing iron powder are proposed and experimental work was undertaken in the following .areas to demonstrate feasibility and obtain basic data for design purposes: (1) Precipitative hydrolysis of aqueous ferric chloride. (2) Gaseous chloridation of metallic iron, and oxidation of resultant ferrous chloride. (3) Reduction of gaseous ferric chloride with hydrogen. (4) Aqueous acid leaching of low grade iron ore. (5) Aqueous acid leaching of metallic iron. The experimentation was supported by theoretical analyses dealing with: (1) Thermodynamics of hydrolysis. (2) Kinetics of ore leaching. (3) Kinetics of metallic iron leaching. (4) Crystallisation of ferrous chloride. (5) Oxidation of anhydrous ferrous chloride. (6) Reduction of ferric chloride. Conceptual designs are suggested fbr both the processes mentioned. These draw attention to areas where further work is necessary, which are listed. Economic analyses have been performed which isolate significant cost areas, und indicate total production costs. Comparisons are mode with previous and analogous proposals for the production of iron powder.

Phosphorus bearing minerals in iron ores and their possible benefication

Modern electron optical techniques together with X-ray and mineralogical examination have been used to study the occurrence and form of phosphorus bearing minerals in iron ores. Three ores have been studied - Bahariya and Aswan from Egypt and Frodingham ironstone from U.K. The iron in the Bahariya iron ore is mainly as hematite and goethite. The gangue minerals are halite, gypsum, barytes, quartz and calcite. Iron content is between 49.8 to 63.2% and phosphorus 0.14 to 0.34%. The phosphorus occurs as very fine particles of apatite which are distributed throughout the ore. Removal of the phosphorus would require very fine grinding followed by acid leaching. Aswan iron ore is an oolitic iron ore; the iron content between 41-57% and phosphorus content 0.1 to 2.9%. It is mainly hematitic with variable quantities of quartz, apatite and small amount of clay minerals. In the oolitic iron ore beds, apatite occurs in the hematite matrix; filling in the pores of the oolithic surfaces, or as matrix cementing the ooliths with the hematite grains. In sandstone claybeds the distribution of the apatite is mainly in the matrix. It is suggested that the liberation size for the apatite would be -80 m and flotation concentration could be applied for the removal of apatite from Aswan ore. Frodingham ironstone occurs in the lower Jurassic bed of the South Humberside area. The average iron content is 25% and the phosphorus is 0.32%. Seven mineral phases were identified by X-ray; calcite, quartz, chamosite, hematite, siderite, apatite, and chlorite. Apatite occurs as very fine grains in the hematite and chamosite ooliths; as matrix of fine grains intergrown with chamosite and calcite grains; and as anhedral and sub rounded grains in the ooliths (8-28 m). It is suggested that two processes are possible for the dephosphorisation; the Flox process or a reduction roast followed by fine grinding, magnetic separation, and acid leaching.

Foreign direct investment and corruption

In the last few decades, the world has witnessed an enormous growth in the volume of foreign direct investment (FDI). The global stock of FDI reached US$ 7.5 trillion in 2003 and accounted for 11% of world Gross Domestic Product, up from 7% in 1990. The sales of multinational enterprises at around US$ 19 trillion were more than double the level of world exports. Substantial FDI inflows went into transition countries. Inflows into one of the region's largest recipient, the Russian Federation, almost doubled, enabling Russia to become one of the five top FDI destinations in 2005-2006. FDI inflows in Russia have increased almost threefold from 13.6% in 2003 to 35% in 2007. In 2003, these flows were twice greater than those into China; whilst in 2007 they were six times larger. Russia's FDI inflows were also about 2.5 times greater than those of Brazil. Efficient government institutions are argued by many economists to foster FDI and growth as a result. However, the magnitude of this effect has yet to be measured. This thesis takes a Political Economy approach to explore, empirically, the potential impact of malfunctioning governmental institutions, proxied by three indices of perceived corruption, on FDI stocks accumulation/distribution within Russia over the period of 2002-2004. Using a regional data-set it concentrates on three areas relating to FDI. Firstly, it considers the significance, the size and the sign of the impact of perceived corruption on accumulation of FDI stocks within Russia. Secondly, it quantifies the impact of perceived corruption on the volume of FDI stocks simultaneously estimating the impact of the investment in public capital such as telecommunications and transportation networks on FDI in the presence of corruption. In particular, it addresses the question whether more corrupt regions in Russia are also those that could have accumulated more of FDI stocks, and investigates whether those 'more corrupt' regions would have had lower level of public capital investment. Finally, it examines whether decentralisation increases or decreases corruption and whether a larger extent of decentralisation has a positive or negative impact on FDI (stocks). The results of three studies are as follows. Firstly, along with market potential, corruption is found to be one of the key factors in explaining FDI distribution within Russia between 2002 and 2004. Secondly, corruption on average is found to be related to FDI positively suggesting that it may act as speed money: to save their time foreign direct investors might be willing to bribe the regional authorities so to move in front of the bureaucratic lines. Thirdly, although when corruption is controlled for, the impact of the latter on unobservable FDI is found to be on average positive, no association between FDI and public investment is observed with the only exception of transportation infrastructure (i.e., railway). The results might suggest therefore that it is possible that not only regions with high levels of perceived corruption attract more FDI but also that expansions in public capital investments are not accompanied by an increase of the volume of FDI (stocks) in regions with high levels of corruption. This casts some doubt on the productivity of the investment in public capital in these regions as it might be that bureaucrats may prefer to use these infrastructural projects for rent extraction. Finally, we find decentralisation to have a significant and positive impact on both FDI stock accumulation and corruption, suggesting that local governments may spend more on public goods to make the area more attractive to foreign investors but at the same time they may be interested into extracting rents from foreign investors. These results support the idea that the regulation of FDI is associated with and facilitated by a larger public sector, which distorts competition and introduces opportunities for rent-seeking by particular economic and political factors.

The prediction and control of transients in thyristor values

This thesis describes an investigation of methods by which both repetitive and non-repetitive electrical transients in an HVDC converter station may be controlled for minimum overall cost. Several methods of inrush control are proposed and studied. The preferred method, whose development is reported in this thesis, would utilize two magnetic materials, one of which is assumed to be lossless and the other has controlled eddy-current losses. Mathematical studies are performed to assess the optimum characteristics of these materials, such that inrush current is suitably controlled for a minimum saturation flux requirement. Subsequent evaluation of the cost of hardware and capitalized losses of the proposed inrush control, indicate that a cost reduction of approximately 50% is achieved, in comparison with the inrush control hardware for the Sellindge converter station. Further mathematical studies are carried out to prove the adequacy of the proposed inrush control characteristics for controlling voltage and current transients during both repetitive and non-repetitive operating conditions. The results of these proving studies indicate that no change in the proposed characteristics is required to ensure that integrity of the thyristors is maintained.

Fast pyrolysis of biomass in a circulating fluidised bed reactor

The objective of this work was to design, construct, test and operate a novel circulating fluid bed fast pyrolysis reactor system for production of liquids from biomass. The novelty lies in incorporating an integral char combustor to provide autothermal operation. A reactor design methodology was devised which correlated input parameters to process variables, namely temperature, heat transfer and gas/vapour residence time, for both the char combustor and biomass pyrolyser. From this methodology a CFB reactor was designed with integral char combustion for 10 kg/h biomass throughput. A full-scale cold model of the CFB unit was constructed and tested to derive suitable hydrodynamic relationships and performance constraints. Early difficulties encountered with poor solids circulation and inefficient product recovery were overcome by a series of modifications. A total of 11 runs in a pyrolysis mode were carried out with a maximum total liquids yield of 61.50% wt on a maf biomass basis, obtained at 500°C and with 0.46 s gas/vapour residence time. This could be improved by improved vapour recovery by direct quenching up to an anticipated 75 % wt on a moisture-and-ash-free biomass basis. The reactor provides a very high specific throughput of 1.12 - 1.48 kg/hm2 and the lowest gas-to-feed ratio of 1.3 - 1.9 kg gas/kg feed compared to other fast pyrolysis processes based on pneumatic reactors and has a good scale-up potential. These features should provide significant capital cost reduction. Results to date suggest that the process is limited by the extent of char combustion. Future work will address resizing of the char combustor to increase overall system capacity, improvement in solid separation and substantially better liquid recovery. Extended testing will provide better evaluation of steady state operation and provide data for process simulation and reactor modeling.

A study on the flow characteristics of an industrial radiant tube burner

The thesis presents an experimentally validated modelling study of the flow of combustion air in an industrial radiant tube burner (RTB). The RTB is used typically in industrial heat treating furnaces. The work has been initiated because of the need for improvements in burner lifetime and performance which are related to the fluid mechanics of the com busting flow, and a fundamental understanding of this is therefore necessary. To achieve this, a detailed three-dimensional Computational Fluid Dynamics (CFD) model has been used, validated with experimental air flow, temperature and flue gas measurements. Initially, the work programme is presented and the theory behind RTB design and operation in addition to the theory behind swirling flows and methane combustion. NOx reduction techniques are discussed and numerical modelling of combusting flows is detailed in this section. The importance of turbulence, radiation and combustion modelling is highlighted, as well as the numerical schemes that incorporate discretization, finite volume theory and convergence. The study first focuses on the combustion air flow and its delivery to the combustion zone. An isothermal computational model was developed to allow the examination of the flow characteristics as it enters the burner and progresses through the various sections prior to the discharge face in the combustion area. Important features identified include the air recuperator swirler coil, the step ring, the primary/secondary air splitting flame tube and the fuel nozzle. It was revealed that the effectiveness of the air recuperator swirler is significantly compromised by the need for a generous assembly tolerance. Also, there is a substantial circumferential flow maldistribution introduced by the swirier, but that this is effectively removed by the positioning of a ring constriction in the downstream passage. Computations using the k-ε turbulence model show good agreement with experimentally measured velocity profiles in the combustion zone and proved the use of the modelling strategy prior to the combustion study. Reasonable mesh independence was obtained with 200,000 nodes. Agreement was poorer with the RNG  k-ε and Reynolds Stress models. The study continues to address the combustion process itself and the heat transfer process internal to the RTB. A series of combustion and radiation model configurations were developed and the optimum combination of the Eddy Dissipation (ED) combustion model and the Discrete Transfer (DT) radiation model was used successfully to validate a burner experimental test. The previously cold flow validated k-ε turbulence model was used and reasonable mesh independence was obtained with 300,000 nodes. The combination showed good agreement with temperature measurements in the inner and outer walls of the burner, as well as with flue gas composition measured at the exhaust. The inner tube wall temperature predictions validated the experimental measurements in the largest portion of the thermocouple locations, highlighting a small flame bias to one side, although the model slightly over predicts the temperatures towards the downstream end of the inner tube. NOx emissions were initially over predicted, however, the use of a combustion flame temperature limiting subroutine allowed convergence to the experimental value of 451 ppmv. With the validated model, the effectiveness of certain RTB features identified previously is analysed, and an analysis of the energy transfers throughout the burner is presented, to identify the dominant mechanisms in each region. The optimum turbulence-combustion-radiation model selection was then the baseline for further model development. One of these models, an eccentrically positioned flame tube model highlights the failure mode of the RTB during long term operation. Other models were developed to address NOx reduction and improvement of the flame profile in the burner combustion zone. These included a modified fuel nozzle design, with 12 circular section fuel ports, which demonstrates a longer and more symmetric flame, although with limited success in NOx reduction. In addition, a zero bypass swirler coil model was developed that highlights the effect of the stronger swirling combustion flow. A reduced diameter and a 20 mm forward displaced flame tube model shows limited success in NOx reduction; although the latter demonstrated improvements in the discharge face heat distribution and improvements in the flame symmetry. Finally, Flue Gas Recirculation (FGR) modelling attempts indicate the difficulty of the application of this NOx reduction technique in the Wellman RTB. Recommendations for further work are made that include design mitigations for the fuel nozzle and further burner modelling is suggested to improve computational validation. The introduction of fuel staging is proposed, as well as a modification in the inner tube to enhance the effect of FGR.

Ash control methods to limit biomass inorganic content and its effect on fast pyrolysis bio-oil stability

This research investigates specific ash control methods to limit inorganic content within biomass prior to fast pyrolysis and effect of specific ash components on fast pyrolysis processing, mass balance yields and bio-oil quality and stability. Inorganic content in miscanthus was naturally reduced over the winter period from June (7.36 wt. %) to February (2.80 wt. %) due to a combination of senescence and natural leaching from rain water. September harvest produced similar mass balance yields, bio-oil quality and stability compared to February harvest (conventional harvest), but nitrogen content in above ground crop was to high (208 kg ha.-1) to maintain sustainable crop production. Deionised water, 1.00% HCl and 0.10% Triton X-100 washes were used to reduce inorganic content of miscanthus. Miscanthus washed with 0.10% Triton X-100 resulted in the highest total liquid yield (76.21 wt. %) and lowest char and reaction water yields (9.77 wt. % and 8.25 wt. % respectively). Concentrations of Triton X-100 were varied to study further effects on mass balance yields and bio-oil stability. All concentrations of Triton X-100 increased total liquid yield and decreased char and reaction water yields compared to untreated miscanthus. In terms of bio-oil stability 1.00% Triton X-100 produced the most stable bio-oil with lowest viscosity index (2.43) and lowest water content index (1.01). Beech wood was impregnated with potassium and phosphorus resulting in lower liquid yields and increased char and gas yields due to their catalytic effect on fast pyrolysis product distribution. Increased potassium and phosphorus concentrations produced less stable bio-oils with viscosity and water content indexes increasing. Fast pyrolysis processing of phosphorus impregnated beech wood was problematic as the reactor bed material agglomerated into large clumps due to char formation within the reactor, affecting fluidisation and heat transfer.

CFD modelling of the fast pyrolysis of biomass in fluidised bed reactors. Part B: Heat, momentum and mass transport in bubbling fluidised beds

The fluid–particle interaction inside a 150 g/h fluidised bed reactor is modelled. The biomass particle is injected into the fluidised bed and the heat, momentum and mass transport from the fluidising gas and fluidised sand is modelled. The Eulerian approach is used to model the bubbling behaviour of the sand, which is treated as a continuum. Heat transfer from the bubbling bed to the discrete biomass particle, as well as biomass reaction kinetics are modelled according to the literature. The particle motion inside the reactor is computed using drag laws, dependent on the local volume fraction of each phase. FLUENT 6.2 has been used as the modelling framework of the simulations with the whole pyrolysis model incorporated in the form of user-defined function (UDF). The study completes the fast pyrolysis modelling in bubbling fluidised bed reactors.

CFD modelling of the fast pyrolysis of biomass in fluidised bed reactors: modelling the impact of biomass shrinkage

The fluid–particle interaction and the impact of shrinkage on pyrolysis of biomass inside a 150 g/h fluidised bed reactor is modelled. Two 500 View the MathML sourcem in diameter biomass particles are injected into the fluidised bed with different shrinkage conditions. The two different conditions consist of (1) shrinkage equal to the volume left by the solid devolatilization, and (2) shrinkage parameters equal to approximately half of particle volume. The effect of shrinkage is analysed in terms of heat and momentum transfer as well as product yields, pyrolysis time and particle size considering spherical geometries. The Eulerian approach is used to model the bubbling behaviour of the sand, which is treated as a continuum. Heat transfer from the bubbling bed to the discrete biomass particle, as well as biomass reaction kinetics are modelled according to the literature. The particle motion inside the reactor is computed using drag laws, dependent on the local volume fraction of each phase. FLUENT 6.2 has been used as the modelling framework of the simulations with the whole pyrolysis model incorporated in the form of user defined function (UDF).

Computational modelling of the impact of particle size to the heat transfer coefficient between biomass particles and a fluidised bed

The fluid–particle interaction and the impact of different heat transfer conditions on pyrolysis of biomass inside a 150 g/h fluidised bed reactor are modelled. Two different size biomass particles (350 µm and 550 µm in diameter) are injected into the fluidised bed. The different biomass particle sizes result in different heat transfer conditions. This is due to the fact that the 350 µm diameter particle is smaller than the sand particles of the reactor (440 µm), while the 550 µm one is larger. The bed-to-particle heat transfer for both cases is calculated according to the literature. Conductive heat transfer is assumed for the larger biomass particle (550 µm) inside the bed, while biomass–sand contacts for the smaller biomass particle (350 µm) were considered unimportant. The Eulerian approach is used to model the bubbling behaviour of the sand, which is treated as a continuum. Biomass reaction kinetics is modelled according to the literature using a two-stage, semi-global model which takes into account secondary reactions. The particle motion inside the reactor is computed using drag laws, dependent on the local volume fraction of each phase. FLUENT 6.2 has been used as the modelling framework of the simulations with the whole pyrolysis model incorporated in the form of User Defined Function (UDF).

Gas-fired radiant heaters

This dissertation covers four areas of particular interest for the successful application of radiant heating in industrial environments. In it the author tackles the problem of how to predict the thermal comfort produced both by single heaters and also systems of heaters; proposes a method for modelling the mechanisms by which heaters interact with the buildings in which they are installed, in the static and dynamic cases; explores techniques for measuring the radiation produced by heaters; and presents experiments concerned with finding the temperatures and power balances prevailing during normal operation. It is contended that, whilst the generally accepted guides for sizing and operating space heating plant were a good first approximation, there are intrinsic subtleties arising from the fact that the primary mode of heat transfer in this instance is radiative. These nuances are concerned with how best to maximise the heat transfer from the heat source to the heated object; the placement of heaters within a system; and an assessment of the various techniques and strategies involved in controlling a radiant heating system. The conclusions reached are that: if sized and controlled correctly radiant heating systems offer considerable operational advantages over other types of space heating systems in certain applications, in terms of both economy and controllability. The efficacy of radiant heating systems is affected primarily by the control strategy implemented; secondarily, by the structure of the building into which it is installed; and only marginally by all other factors.

Flow and pressure drop on the shellside of cylindrical heat exchangers

This work presents pressure distributions and fluid flow patterns on the shellside of a cylindrical shell-and-tube heat exchanger. The apparatus used was constructed from glass enabling direct observation of the flow using a dye release technique and had ten traversable pressure instrumented tubes permitting detailed pressure distributions to be obtained. The `exchanger' had a large tube bundle (278 tubes) and main flow areas typical of practical designs. Six geometries were studied: three baffle spacings both with and without baffle leakage. Results are also presented of three-dimensional modelling of shellside flows using the Harwell Laboratory's FLOW3D code. Flow visualisation provided flow patterns in the central plane of the bundle and adjacent to the shell wall. Comparison of these high-lighted significant radial flow variations. In particular, separated regions, originating from the baffle tips, were observed. The size of these regions was small in the bundle central plane but large adjacent to the shell wall and extended into the bypass lane. This appeared to reduce the bypass flow area and hence the bypass flow fraction. The three-dimensional flow modelling results were presented as velocity vector and isobar maps. The vector maps illustrated regions of high and low velocity which could be prone to tube vibration and fouling. Separated regions were also in evidence. A non-uniform crossflow was discovered with, in general, higher velocities in the central plane of the bundle than near the shell wall._The form of the isobar maps calculated by FLOW3D was in good agreement with experimental results. In particular, larger pressure drops occurred across the inlet than outlet of a crossflow region and were higher near the upstream than downstream baffle face. The effect of baffle spacing and baffle leakage on crossflow and window pressure drop measurements was identified. Agreement between the current measurements, previously obtained data and commonly used design correlations/models was, in general, poor. This was explained in terms of the increased understanding of shellside flow. The bulk of previous data, which dervies from small-scale rigs with few tubes, have been shown to be unrepresentative of typical commerical units. The Heat Transfer and Fluid Flow Service design program TASC provided the best predictions of the current pressure drop results. However, a number of simple one-dimensional models in TASC are, individually, questionable. Some revised models have been proposed.

Fin spacing interaction in fluidized bed heat exchangers

The work presented in this thesis is concerned with the heat transfer performance of a single horizontal bare tube and a variety of finned tubes immersed in a shallow air fluidized bed. Results of experimental investigations with the bare tube indicate that the tube position in the bed influences its performance narticularly where fine bed materials are used. In some cases the maximum heat transfer is obtained with the tube in the particle cloud just above the dense phase fluidized bed - a phenomenon that has not been previously observed. This was attributed to the unusual particle circulation in shallow beds. The data is also presented in dimensionless correlations which may be useful for design purposes. A close approximation to the bare tube data can be obtained by using thetransient heating of a spherical robe and this provides a valuable way of accumulating a lot of data very rapidly. The experimental data on finned tubes shows that a fin spacing less than twenty times the average particle diameter can cause a significant reduction in heat transfer due to the interaction which takes place between the particles and the surface of the fins. Furthermore, evidence is provided to show that particle shape plays an important part in the interaction with spherical particles being superior to angular particles at low fin spacing/particle diameter ratio. The finned tube data is less sensitive to tube position in the bed than bare tubes and the best performance is when the tube is positioned at the distributor.A reduction in bed depth decreases the thermal performance of the finned tube but in many practical installations the reduction in pressure drop might more than comnensate for the reduced heat flux. Information is also provided on the theoretical uerformance of fins and the effect of the root contact area between the fins and the tube was investigated.

Heat transfer from molten materials to liquids

An apparatus was designed and constructed which enabled material to be melted and heated to a maximum temperature of 1000C and then flooded with a pre-heated liquid. A series of experiments to investigate the thermal interaction between molten metals (aluminium, lead and tin) and sub-cooled water were conducted. The cooling rates of the molten materials under conditions of flooding were measured with a high speed-thermocouple and recorded with a transient recorder. A simplified model for calculating heat fluxes and metal surface temperatures was developed and used. Experimental results yielded boiling heat transfer in the transition film and stable film regions of the classic boiling curve. Maximum and minimum heat fluxes were observed at nucleate boiling crisis and the Leidenfrost point respectively. Results indicate that heat transfer from molten metals to sub-cooled water is a function of temperature and coolant depth and not a direct function of the physical properties of the metals. Heat transfer in the unstable transition film boiling region suggests that boiling dynamics in this region where a stationary molten metal is under pool boiling conditions at atmospheric pressure would not initiate a fuel-coolant interaction. Low heat fluxes around the Leidenfrost point would provide efficient fuel-coolant decoupling by a stable vapour blanket to enable coarse mixing of the fuel and coolant to occur without appreciable loss of thermal energy from the fuel. The research was conducted by Gareph Boxley and was submitted for the degree of PhD at the University of Aston in Birmingham in 1980.