Vehicle engines—Fuel consumption and air pollution

Vehicle engines—Fuel consumption and air pollution

BOOK REVIEWS Vehicle Engines--Fuel Consumption and Air Pollution, edited by M. S. Janota. Peter Peregrinus Ltd, 1974, £5.50. The objective of this bo...

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BOOK REVIEWS

Vehicle Engines--Fuel Consumption and Air Pollution, edited by M. S. Janota. Peter Peregrinus Ltd, 1974, £5.50. The objective of this book is to question the apparent supremacy of the internalcombustion engine for vehicle propulsion, and to examine critically the possible contenders. The book comprises a collection of eleven papers presented during a conference held at Queen Mary College, London, in April, 1973, in an attempt to provide scientific information and assessment on the vitally-important topics of fuel consumption and air pollution, and so counteract the half truths and emotions that blossom in the journalistic field. A statement of the energy-environmental problems comprises Part 1 (papers 1 and 2), whereas Parts 2 (papers 3 to 6) and 3 (papers 7 to 9) deal with engines based respectively on non-steady and continuous combustion. Part 4 looks at the possibilities of electrical engines for vehicles. The first paper presents a severe indictment of the private car, and just achieves a balance by mentioning in one sentence the real advantages it also offers, thus highlighting the crucial problem of weighing pros against cons. The second paper rightly criticises the savage legislation that followed the adoption of the Californian problem as a political hobby-horse, which has triggered a worldwide over-reaction, and develops further the editor's theme that environmental protection so often conflicts with fuel conservation that clear-cut choices are not always forthcoming. It is imperative, therefore, that the adverse effects of exhaust products be proved significant over and above those of natural sources before adopting energyintensive solutions. Paper 3, on the spark-ignition engine, concentrates largely on the hang-on devices proposed to oxidise incompletely-burnt products. Since most of these result in increased fuel consumption, poor driveability and/or susceptibility to lead, 237 Applied Energy (2) (1976)--O Applied Science Publishers Ltd, England, 1976 Printed in Great Britain

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the paper emphasises the wisdom of channelling such research effort into tackling the problem at source, i.e. to develop engines to operate on weaker fuel mixtures, to achieve more uniform mixture distribution, to burn more completely within the cylinders, and to do all these things over many years of engine life, rather than to adopt a panic hang-on afterthought philosophy. Paper 4, on diesel engine emissions, highlights the inaccuracies of some measuring instruments ( + 15 ~ !). As in spark-ignition engines, combustion swirl can be helpful in reducing emissions, although the reasons are complex, and the increased heat loss to coolant demands a larger radiator. The effectiveness but complication of variable injection timing is well covered, and discussion of such design features as turbocharging, aftercooling ~ind pilot injection shows that, in many cases, the concentrations of NOx are reduced at the expense of increases in CO and HC, together with loss of power. Paper 5 covers the interesting concept of the differential compound engine, comprising a diesel engine, compressor and turbine linked through an epicyclic gear, the whole unit having an inbuilt flexibility and low levels of CO, NOx and smoke compared with its turbocharged diesel competitor, but suffering from a high gear loss of up to 30 hp. The short paper 6 on the rotary combustion engine is marred by generality, but the problems of dynamic sealing are clearly outlined when the subject eventually develops. Most attention is given to the Anidyne engine which appears as an attractive concept, despite its retention of some reciprocating motion, although its promise of low pollution has yet to be achieved. Paper 7 covers the automotive gas turbine (i.e. below 250 hp), and argues in favour of the regenerative version, which can bring the mileage per gallon above comparable levels for piston engines. The two main areas requiring development are pinpointed as increases in combustion inlet temperature, which entail improved metallurgy, and in part-load efficiency, which might be met by systems of variable geometry (i.e. air proportioning) and/or alternative transmission. Paper 8 outlines the inherent advantages of the Stirling engine, and presents neatly the various configurations. Possibilities of the automotive application of the Rankine cycle are given in paper 9. Again, low pollution and high part-load efficiency are claimed, but fuel economy is unattractive except for low-speed city driving. The two final papers on electric cars outline the various methods of electrochemical conversion and the wide range of cells under consideration or development. As a long-term proposal, short-range battery-powered vehicles may be suited to the initial and final phases of a long journey, in conjunction with fixed power lines built into the main trunk routes. Although the general situation is seen to be disappointing, the electric car does not pollute, and its wider adoption may follow further development in batteries and/or fuel cells. As in all books of this type, a collection of authors provides the advantages of

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expertise in the diverse fields, but the disadvantages of lack of uniformity in style and the absence of close control over repetition or gaps. However, the book closes with a concise summary by the Editor in Part 5. It is still difficult to predict the most promising challenger to the conventional vehicle engine, but the simple table provided, together with Table 4 in paper 5, help to review clearly the present stateof-the-art with each system. Curiously, for a book of 1974 vintage, SI units have been ignored. A fair crop of minor printing faults has been overlooked, and tighter editing could have reduced the number of pages slightly from 154. On the whole, the book should provide very useful guidelines as technology gears itself to attempt the right selection of.alternative systems for vehicle propulsion in the future. E. M. GOODGER

Energy and Humanity, edited by M. W. Thring and R. J. Crookes (Mankind and the Engineer Series, Vol. 2), Peter Peregrinus Ltd, 1974, 200 pp., paper-bound. £5.50. This volume is the second in a series intended for professional and student engineers concerned with the impact of their activities on society. Unlike the first volume, 'Machines--Masters or Slaves of Man ?' by M. W. Thring, the present book is a multi-author collection of papers based on a conference held at Queen Mary College in September, 1972. Excluding the introductory and concluding sections by Thring, the book is divided into three main parts. Part I, 'Energy Supplies--Resources and Hazards' is a survey of (mainly) fossil fuels and nuclear energy, and the environmental hazards associated with their utilisation. Included here is an interesting paper by J. R. Tagg on wind generators. Other papers in this section must be categorised as rather conventional reviews of energy resources/reserves, presenting information available in more up-to-date publications. At a time when many people accept that political, social and economic factors dominate in determining the availability of adequate supplies of energy, such information is of limited value, especially in the context of the present book. Conventional estimates of future demand for energy are similarly becoming increasingly academic in view of the unpredictability of OPEC's future price demands, and the paucity of information on the price-elasticity of demand for energy. The papers on pollution from energy utilisation are also open to criticism as being conventional technical presentations. In the context of the present book one could wish for an exploration of the social and economic factors associated with energy-generated pollution and its control. Even on the technical side, the selection of topics seems eclectic; in particular thermal pollution--which is probably the ultimate global limitation on per capita energy utilisation--is given little attention. Yet already it is a problem on a local and regional scale.