Browsing by Author "Probert, S. D."
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Item Open Access The appraisal of three gas-fired small-scale CHP systems.(Cranfield University, 1997-10) Riley, J. M.; Goffin, Keith; Probert, S. D.The research in this thesis has undertaken a technical. economic and environmeiital appraisal of three gas-fired, small-scale Combined Heat-and-Power (CHP) systenlýý together with a study of the UK's electricity supply industry (ESi) and CHP market. The purpose of each system is to attempt to utilise more of the heat and/or electricitY output from the CHP unit. Within the non-technical research area, t hree scenarios for the evolution of the ES1 have been developed to help establish llow changes to forces acting within the industry, might affect the development of the UK CHP market. New applications of several strategic management, alialysis tools were used to develop and select the following scenarios: (i) 'N-ewa nd reduced ('02 limits set by the Climate Control Conference + stricter environmental legislatioil, (ii) Changes to the Pool mechanism for pricing electricity. (iii) Business as usual. It was concluded that in isolation scenarios I and 3 would aid the expansion of the, CHP market, whereas scenario 2 is likely to hinder it. The selection of the scenarios and the implications for the ESi and CHP market are supported by the opinions of 'industry specialists', which were solicited in a survey specifically undertaken for this study. The investigation into the first of the three technical systems involves the substitution of two separate CHP units in place of a single larger unit. The intention is to operate the larger of the two CHP units at maximum output to satisfy the base heat-load and to use the second unit for meeting peak loads. The results for five test-cases were produced via a newlY-developed predictive model, and indicated that it is possible, for one of the case studies considered, to achieve shorter pay-back periods when using the double-unit - with a higher availability of 9.5% - rather than the single-unit system. In the other two cases (where CHP is a viable economic option), longer pay-back periods ensue by the installation of the twounit rather than the single-unit system. The operation of the two-unit system call potentially increase energy-utilisation from the CHP units at one of the other sites'. Furthermore, the proposed system can offer, in some cases, significant secondarý' benefits, which could encourage a potential investor in the technology. These benefits include the increased heat- an d-elect ri city output, increased availability from the system, back-up from the secondary unit if one unit fails. The second system determines the viability of an integrated small-scale CHP and TES system. Another predictive model was developed and tested on five test -case",. It was found that there is insufficient potential for the system and that the pot(, iitial is limited by the following factors (i) CHP-sizing methodology, (ii) the relat IvCIN, high capital cost for TEs hardware and installation, (iii) the relatively low econwilic value attributed to heat and (iv) the availability of IoN%-pricedo ff-peak electricitv. An industrial case study provided a rare and useful operational exainple of tlic proposed system and the findings indicated that the heat-store could reduce i he energy and monetary expenditures by up to 2.8/7c of the site's annual gas usage. displacing approximately 30 tones Of C02 emissions each year. Howe\-er, becauýw of the high financial cost of the TES components and installation. the pay-back period produced would rarely be acceptable to a prospecti\-e investor. except in exceptional circumstances. Finally, the viability of an integrated CHP/absorption chiller systeni was in\-(, stigated. The effectiveness of these types of systems are dependent on several factors, namely: the source-water temperature from the hot-engine CHP unit - for a high cop - and the cooling load at the site, the cooling demand at the site and the temperature of the cooling water. A first-stage predictive model was developed to determine the initial appropriateness of the installation of the integrated system at a local hospital for the first time. The indications were that the cooling demand was too low and the surplus waste-heat from the CHP unit insufficient to make the system viable at the site. A second working-system was studied with a full ('02 investigation undertaken. The intention was to compare the total C02 emissions for the integrated CHP and absorption chiller system with those for a similarl. y sized vapour-compression system. The results indicate that the installed systc1l) will produce 0.30kgCO2/kWhcoolth compared with 0.27 kg and 0.32kg for two different types of vapour compression systems at design conditions. If the CHP heat output is increased - to supply all of the heat required by the absorption chiller - then the proposed system can displace up to 0.06 kgC02 per kWhcoolth at design conditions and 0.10 kgC02 per kWh of cooling delivered for lower cooling water temperatures. This represents a reduction of 22% and 40% respectively, when compared with the vap our- compressions system.Item Open Access Bio-remediation of a sludge containing hydrocarbons(Elsevier, 2007) Ayotamuno, M. J.; Okparanma, R. N.; Nweneka, E. K.; Ogaji, S. O. T.; Probert, S. D.Bio-augmentation has been used as a bio-remediation option for hydrocarbon-contaminated, oily-sludge restoration. This sludge was obtained from the Bonny-Terminal Improvement Project (BTIP) for Bonny Island, near Port Harcourt, Nigeria. Its total hydrocarbon-content (THC) was 69,372 mg/kg of sludge. Three treatment reactors (X, Y and Z) and one control reactor (A) were charged with 1500 g of oily sludge and 250 g of agricultural soil (i.e. an oily sludge to soil ratio of 6:1), the mixture homogenized and allowed to settle for seven days before various CFUs were added to reactors X, Y and Z. Reactor A did not receive any bio-preparation. The agricultural soil served both as a nutrient and a microbe carrier. With regularly scheduled mixing and watering, the THC reduction in the oily sludge varied between 40.7% and 53.2% within two weeks as well as between 63.7% and 84.5% within six weeks of applying the bio-remediation. The CFU counts of the added bio-preparation varied between 1.2 × 1212 and 3.0 × 1012 CFU/g of sludge and decreased to 7.0 × 1011 CFU/g of sludge by the end of the sixth week. The pH of the degrading sludge fluctuated between 6.5 and 7.8 during the same period. When compared with the performance of the indigenous microbes in the control sample, the added bio-preparation evidently increased the THC reduction rate in the oily sludge.Item Open Access Bioremediation of a crude-oil polluted agricultural-soil at Port Harcourt, Nigeria.(Elsevier, 2006-11) Ayotamuno, M. J.; Kogbara, R. B.; Ogaji, S. O. T.; Probert, S. D.A combination of treatments, consisting of the application of fertilizers and oxygen exposure, was evaluated in situ during a period of six weeks. Conditions of a major spill were simulated by sprinkling crude-oil on experimental cells containing agricultural soil. The remedial treatments were then applied and the soil characteristics analyzed after set periods. Soil physicochemical parameters, such as moisture content, pH value, electrical conductivity as well as organic-carbon and total-nitrogen contents, showed distinct variations with time. The total heterotrophic-bacteria (THB) count in all the treatment cells increased with time. The control cell, O (which was not treated) indicated no signs of remediation within the study period. The hydrocarbon losses (50–95%) experienced in the five other treatment-cells revealed the effectiveness in degrading the hydrocarbon contaminant. The results of this study indicate that the application of increased concentrations of nutrients (by the application of fertilizers) lead to greater rates of biodegradation of petroleum-polluted agricultural soils.Item Open Access Development and implementation of preventive-maintenance practices in Nigerian industries.(Elsevier, 2006-10) Eti, Mark C.; Ogaji, S. O. T.; Probert, S. D.A methodology for the development of PM using the modern approaches of FMEA, root-cause analysis, and fault-tree analysis is presented. Applying PM leads to a cost reduction in maintenance and less overall energy expenditure. Implementation of PM is preferable to the present reactive maintenance procedures (still prevalent in Nigeria.Item Open Access Energy-efficient cooking systems, food preparation facilities, and human diets(Cranfield University, 1987-07) Newborough, Marcus; Probert, S. D.; Batty, W. J.This thesis aims at identifying the opportunities for saving energy, which are available to those working within the final link of the UK food system (i. e. at, or in relation to, the points of consumption). Substantial prospective savings exist, because relatively little attention has, as yet, been given to energy-thrift in food-preparation facilities. Within the food-service industry, cooking systems are characterised by high thermal capacities, excessive external surface temperatures and poorly-designed control systems. Catering staff, who use such appliances, are rarely trained to use energy wisely when preparing foods, and kitchens (and their associated dining facilities) tend to be designed without sufficient regard to energy-thrift. Similar problems prevail in domestic kitchens, but to a lesser extent because the cooks there usually pay (or contribute towards) the fuel bills. However, manufacturers still provide household appliances, which are unnecessarily energy-profligate. Furthermore most people have insufficient knowledge of the nutritional suitabilities and the primary-energy costs of their diets. Thus a major educational need exists, which must be satisfied if industrialised food systems are to become more energy efficient. This thesis attempts to make a contribution to this requirement, by analysing cooking systems, food-preparation facilities, kitchen operatives, and human diets from an energy-thrift perspective. Long-term savings (i. e. those achieved as a result of implementing the recommendations within a 15-year period) of approximately £1O p. a. (at 1987 prices) are predicted, although this could be increased substantially if Britons adopt more energy-efficient, yet nutritionally-balanced, diets.Item Open Access Farm mechanization leading to more effective energy-utilizations for cassava and yam cultivations in Rivers State, Nigeria(Elsevier Science B.V., Amsterdam., 2006-12-01T00:00:00Z) Nkakini, S. O.; Ayotamuno, M. J.; Ogaji, S. O. T.; Probert, S. D.Surveys have been conducted, under the auspices of the Ministry of Agriculture and Agricultural Development Projects (ADPs), in the 23 local-government areas of the Rivers State, Nigeria. A structured questionnaire, personal visits to farms and interactions with information repositories were used. The quantities of energy consumed by tractors used in activities associated with the growing of cassava and yam crops in those areas were compared with traditional operations, using just manual labour. Within the period of 1986–2004, the total energy utilizations in the production of these crops, in the 23 local government areas, were 2738.87 and 33.5 MJ for tractor-power and traditional-manual operations, respectively. The tractorization intensity (TI) dropped from 0.352 hp/ha in 1986 to 0.345 hp/ha in 2004. This result was below the presently advocated 0.5 hp/ha for agricultural operations in order to increase crop production. This study identified the causes of this shortfall and recommended, at least for the short- term future, that farm industrialization of all sectors should be subsidizeItem Open Access Gas-turbine diagnostics using artificial neural-networks for a high bypass ratio military turbofan engine(Elsevier Science B.V., Amsterdam., 2004-08-01T00:00:00Z) Joly, R. B.; Ogaji, S. O. T.; Singh, R.; Probert, S. D.The Tristar aircraft, operated by the Royal Air Force, fly many thousands of hours per year in the transport and air-to-air refuelling roles. A large amount of engine data is recorded for each of the Rolls-Royce RB211-524B4 engines: it is used to aid the maintenance process. Data are also generated during test-bed engine ground-runs after repair and overhaul. In order to use recorded engine data more effectively, this paper assesses the feasibility of a pro-active engine diagnostic-tool using artificial neural networks (ANNs). Engine-health monitoring is described and the theory behind an ANN is described. An engine diagnostic structure is proposed using several ANNs. The top level distinguishes between single-component faults (SCFs) and double-component faults (DCFs). The middle-level class includes components, or component pairs, which are faulty. The bottom level estimates the values of the engine-independent parameters, for each engine component, based on a set of engine data using dependent parameters. The DCF results presented in this paper illustrate the potential for ANNs as diagnostic tools. However, there are also a number of features of ANN applications that are user-defined: ANN designs; the number of training epochs used; the training function employed; the method of performance assessment; and the degree of deterioration for each engine-component's performance parameter.Item Open Access Heat exchanger design in a hot-water store(Cranfield University, 1991-09) Mote, R. T.; Probert, S. D.The behaviour of natural convective buoyancy-driven flows within a hot-water store due to the forced passage of colder water through the heat-exchanger's pipe are reviewed in the light of recent advances in experimental throughout the literature. The exchanger designs, for natural unworkable for the engineer complication arises because the heat exchanger are sensitive to and numerical studies, reported empirical development of heat convection problems, are often with a specification. The heat transfer performance of the the initial boundary conditions of the problem, ranging from the initial charged temperature of the water in the insulated tank of a fixed dimensíon, to the physical properties of the heat-exchanger's pipe. It was concluded that an improvement in the heat transfer performance can be derived by determining the optium length and the orientation of the heat-exchanger's arrangement. Further benefits are derived by correlating the thermal convective behaviour, within the hot-water store, with the forced passage of colder water through the heat exchanger's pipe. A convective flow model, based upon the experimental results, is described to advance the heat exchanger design principles in the situation of transient natural convection. Assumptions employed in the experimental work confirm that realistic and reasonable results can be obtained from the thermal analysis of the vertical cylindrícal store in two-dimensions.Item Open Access Impact of corporate culture on plant maintenance in the Nigerian electric-power industry(Elsevier, 2006-04) Eti, Mark C.; Ogaji, S. O. T.; Probert, S. D.Comparisons have been made of modern maintenance-practices, i.e. in the more developed economies, with what occurs in Nigeria. Significant differences arise due to variations in corporate culture, pertinent learning opportunities and effectiveness of strategic planning. The managerial implications of these divergences are discussed. A systematic, total productive-maintenance (TPM) approach needs to be adopted to allow corporate changes to be implemented at a rate commensurate with each organization's evolving culture. This paper advocates that maintenance should be managed better, in each organization, so as to cultivate a sense of ownership in the operators. Also autonomous maintenance-teams, consisting of operators, engineers and managers, should be set up with the aims of improving personnel competence and equipment performance.Item Open Access Implementing total productive maintenance in Nigerian manufacturing industries(Elsevier, 2004-12) Eti, Mark C.; Ogaji, S. O. T.; Probert, S. D.Remarkable improvements have occurred recently in the maintenance management of physical assets and productive systems, so that less wastages of energy and resources occur. The requirement for optimal preventive maintenance using, for instance, justin-time (JIT) and total quality-management (TQM) techniques has given rise to whathas been called the total productive-maintenance (TPM) approach. This study explores the ways in which Nigerian manufacturing industries can implement TPM as a strategy and culture for improving its performance and suggests self-auditing and bench-marking as desirable prerequisites before TPM implementation.Item Open Access Local involvement in harnessing crude oil and natural gas in Nigeria(Elsevier, 2006-11) Nwosu, H. U.; Nwachukwu, I. N.; Ogaji, S. O. T.; Probert, S. D.Abstract Vast financial investments have been made in the upstream crude-oil and natural-gas (CONG) sector in Nigeria, but have not resulted in significant benefits for most Nigerians. The associated major activities, e.g., exploration, drilling, production, well intervention and service provision remain primarily controlled and managed by foreign multi-national companies. Only minor contracts have been awarded to local contractors. Several factors, ranging from locally inadequate finance being available, corrupt local operators, lack of technical expertise and the conflicting attitudes of multi-national operators and local contractors have contributed to this. Yet, numerous opportunities are increasingly available for indigenous entrepreneurs and local contractors. To achieve good public relations, sustainability and better economic performances, a wiser balance between globalisation and localisation is needed! This study considers the impedances to achieving greater indigenous inputs to the CONG sector, with recommendations proffered with respect to what could be done to alleviate them.Item Open Access Modelling of Air Movements in Rooms(Cranfield University, 1979-04) Nevrala, D. J.; Probert, S. D.The assessment of room air movements, in all but elementary cases, relies on investigations using either full-size mock-ups or scaled models. Temperature considerations severly limit the maximum geometric scale factor. A solution is offered by which accurate predictions of the air flows in full-size air-conditioned rooms may be obtained from observations. made with small models if certain criteria are satisfied. The maximum geometric scale-factor can be increased to 8.5, while limiting the maximum working temperature in the model to 100°C, by replacing the convective currents with wall jets of a similar velocity profile, volume flow, momentumfl ux and heat content. A further improvement may be achieved if the scale-factor adopted for the jet nozzle is smaller than the geometric scale-factor. This approach can lead to scale-factors exceeding 11.8. Theoretical studies have shown the replacement of convective currents by plane jets is feasible. In the course of the study, detailed investigations of areas important for the aimsof the project but where there is a dearth of relevant information, were undertaken. To test the validity of predictions and to establish necessary empirical factors, a range of measurements of convective currents and their replacement jets were'carried out. The results showed that a virtual identity of maximump rofile velocity, momentumfl ux and volume flow at the replacement cross-section could be achieved. Based on measured empirical factors, a simple procedure, valid for the majority of practical applications, by which replacement jets can be calculated directly from convective surface parameters is given. Thus, the aim of this study, namely the worthwhile use of a small model which can be constructed cheaply, has been achieved.Item Open Access Optimal heat transfer design for district-heating and cooling pipelines in air-filled cavities(Cranfield University, 1986-04) Babus'Haq, Ramiz F.; Probert, S. D.; Shilston, M. J.District-heating and/or cooling systems are gradually becoming popular all over the world for heating and/or cooling of large premises. Current conventional practice for the DHC underground distribution networks is to place the supply and the return pipelines side-by-side in air-filled trencRe's. However, t present investigation has shown that by optimising the location of the pipelines, the thermal insulation provided by the air around the pipes can be maximised. This is achieved by placing the hot pipeline above the cold one, the exact position depending upon the temperatures involved. For most purposes, it is recommended that the displacement ratio for the hot pipe is to be at -0.7 or -0.08 and that of the cold pipe at 0.05 or 0.67 for district heating or cooling respectively [i. e. the hot and cold pipes being placed in the upper and lower halves of the trench respectively]. Each chapter is presented in such a way that it can be read independently of the others as far as possible.Item Open Access Petrochemical industry in Nigeria: a performance appraisal(Elsevier, 2004-09) Eti, Mark C.; Ogaji, S. O. T.; Probert, S. D.For any country, having a large indigenous petrochemical-producing industry tends to lead to raised prosperity, improved average standard-of-living for the population and the introduction of associated modern-technology locally. However, such benefits in Nigeria have as yet not been forthcoming to significant extents. This project reviews what needs to be done in the industry to achieve these desired improvements.Item Open Access Petroleum contaminated ground-water: Remediation using activated carbon.(Elsevier, 2006-11) Ayotamuno, M. J.; Kogbara, R. B.; Ogaji, S. O. T.; Probert, S. D.Ground-water contamination resulting from the leakage of crude oil and refined petroleum products during extraction and processing operations is a serious and a growing environmental problem in Nigeria. Consequently, a study of the use of activated carbon (AC) in the clean up was undertaken with the aim of reducing the water contamination to a more acceptable level. In the experiments described, crude-oil contamination of ground water was simulated under laboratory conditions using ground-water samples collected from existing hand-dug wells at Eagle Island, Port Harcourt, Nigeria. Different masses of the absorbent (i.e., activated carbon) were then added to the samples of ground water. The so treated water samples were left to equilibrate for 7 days, after which the total petroleum hydrocarbon (TPH) contents of the samples were measured. Adsorption isotherms were derived for the two forms of activated carbon used, namely granular activated-carbon (GAC) and powdered activated-carbon (PAC). Results of the TPH analyses showed that activated carbon is an excellent means for the stripping-off of the contaminant: there were decreases in contaminant concentration from an initial concentration of 9304.70 mg/l to average final concentrations of 361.00 and 12.37 mg/l, that is, 96% and 99.9% resulting from the same amounts of GAC and PAC applications respectively. The results of this study revealed that the powdered form of AC would be very effective in the remediation of petroleum-hydrocarbon contaminated ground water and its use is therefore recommended.Item Open Access Prolonging the lives of buried crude-oil and natural-gas pipelines by cathodic protection(Elsevier, 2007-09) Lilly, M. T.; Ihekwoaba, S. C.; Ogaji, S. O. T.; Probert, S. D.In Nigeria, a major problem is the corrosion of the external surfaces of such pipelines, which are not usually adequately safeguarded during construction. A cathodic protection system should be applied to the pipeline before this period.Item Open Access Reducing the cost of preventive maintenance (PM) through adopting a proactive reliability-focused culture.(Elsevier, 2006-11) Eti, Mark C.; Ogaji, S. O. T.; Probert, S. D.The economic and political realities of the 1990s forced managers to reverse long-standing organizational cultures in order to reduce costs and energy expenditures in their organisations. For instance, these can be achieved, with respect to maintenance, by replacing a reactive repair-focused attitude by a proactive reliability-focused culture. Thereby far less (i) human effort is expended and (ii) energy would be wasted, both of which lead to increased profitability.Item Open Access Reliability of the Afam electric power generating station, Nigeria(Elsevier, 2004-03) Eti, Mark C.; Ogaji, S. O. T.; Probert, S. D.Today’s economic climate requires that each industry aim at achieving maximum production capability while minimizing capital investment e.g. in the maintenance function. This means finding ways to maximize equipment reliability and up-time and extend plant and equipment life through cost effective maintenance. This paper surveys the performance of gas turbine plants in Afam Thermal Power Station. The findings show that the impact of lost generation (through non-availability) exceeded within a few years, the initial purchase price of the power plants and associated equipments.Item Open Access Solar energy applications in the Yemen Arab Republic(Cranfield University, 1986) Al-Motawakel, M. K.; Norton, Brian; Probert, S. D.; McVeigh, J. C.It is indeed seldom that a specialised subject can be considered independently. Usually it is allied to and embodied in a systematic sequence of principles, and its field is generally an integral part of a reflection of some broader conception. This is especially true of this thesis, which is concerned with the climatic environmental influences on regional architecture. In the process of evolving the passive solar aspects, theoretical considerations yielded some interesting details and solutions. Examples studied showed a great variety of design principles. Thus as the material grew it suggested an entity -a theme itself. Cont/d.Item Open Access Some aspects of the use of water-filled heat stores in gas-fired central-heating systems(Cranfield University, 1986-04) Tanton, D. M.; Probert, S. D.Water-filled heat stores present a convenient, relatively inexpensive means of optimising the use of diminishing gas stocks for the central-heating of buildings. The British Gas Corporation recently launched a series of central-heating units with storage, for use in the domestic sector, whose benefits include: - reduced boiler size, more efficient boiler operation, load-levelling at the hours of peak gas demand. This thesis is divided into three parts. Part I examines the inherent advantage of a with-storage, domestic, central-heating system over a conventional system, by means of two simple computer-simulation programs. A minimum efficiency advantage of about 5% is anticipated; the variation of this advantage with the values of certain key parameters has been assessed. Part II is an interim report of a full-scale field trial in the commercial sector; a large (3.3m3) store was fitted in the heating system of a London school, and its performance during the first weeks of its operation is presented here. Returning to the domestic sector, Part III presents a study of the use of two integral heat exchangers in the storage vessels of the above domestic units, whereby hot water can be drawn instantaneously. An attempt to optimise this domestic hot-water facility has been made.