536 



NATURE 



[December 23, 1920 



Domestic Fires and Fuels. 



'"PHE Air Pollution Board — a sub-committee 

 •*■ appointed by the Manchester Corporation in 

 191 5 to study the smoke nuisance — initiated an 

 investigation of the domestic coal fire by Mrs. 

 M. W. Fishenden. In 1917-18 the Department 

 of Scientific and Industrial Research made grants 

 in aid of the work, and now the Fuel Research 

 Board has, with the concurrence of the Man- 

 chester Board, published the results, ^ expressing 

 the opinion that "the investigation into the effi- 

 ciency of the open fire has yielded a collection of 

 carefully ascertained data, from which it is be- 

 lieved that a new departure, can be made in deal- 

 ing with the whole question of the use of smoke- 

 less solid fuel in domestic fires." 



It is even yet not sufficiently recognised how 

 grave an offender is the domestic coal fire in the 

 production of the smoke nuisance in regard not 

 only to the quantity, but also to the quality of 

 smoke, although this was shown by Prof. J. B. 

 Cohen many years ago. The Manchester Board was 

 doubtless right in basing the work, as the chair- 

 man, Mr. E. D. Simon, points out in his intro- 

 ductory summary, on a scientific study of the 

 domestic grate, about which an astonishing lack 

 of precise information was found. If fires could 

 be rendered more efficient, it was argued that a 

 reduction in coal consumption and in the corre- 

 sponding smoke production would automatically 

 follow. It was hoped at first to draw up a stand- 

 ard of efficiency in fireplaces which might be en- 

 forced by local by-laws. This hope, however, proved 

 illusory, as will be shown later. Determinations 

 were first made of the "radiant efficiency" as the 

 most important property of coal fires of different 

 types— i.e. the proportion of the heat of com- 

 bustion of the fuel which was radiated into the 

 room. Here Mrs. Fishenden was able to start 

 with the methods already elaborated for the 

 study of gas fires by a joint committee of the In- 

 stitution of Gas Engineers and the University of 

 Leeds. It was found possible to adapt the so- 

 called "Leeds test" to the more difficult problem 

 of the solid fuel fire. The figures given are for 

 the total radiation of heat from lighting to dying 

 out, although from the point of view of the users 

 of a fire the heat evolved in the early period and 

 at the end is of little value. This emphasises the 

 fact that solid fuel fires are less satisfactory for 

 intermittent use or for short periods. 



The results obtained were unexpected. The 

 grates examined did not differ much in radiant 

 efficiency. Fed with ordinary bituminous house 

 .coal from the Yorkshire Haighmoor (not " Haigh- 

 Tnore ") seam, all gave figures between 20 ana 

 24 per cent. The superior radiant efficiency of 

 the grates of modern construction proved to be 

 -a myth. How is this to be reconciled with the 

 common experience that the newer fires appear to 

 g-ive more warmth in the room for less coal? It 



1 "The Coal Fire. A Resi-arch by Mrs M. W. Fishenden for the 

 Manchester Corporation Air Pollution Boar^." Fuel Research Board. 

 Special Report No. 3. Pp. 112. (H.M. Stationery Office.) Price 4*. net. 



NO. 2669, VOL. 106] 



seems to be due to the constriction of the opening 

 into the flue, which prevents the flow of an ex- 

 cessive quantity of heat-conveying air into the 

 chimney. Strong draughts are avoided, and com- 

 fortable conditions in the room can, therefore, be 

 maintained by a smaller consumption of fuel. More- 

 over, massive iron bars and cheeks with their cool- 

 ing action are avoided ; fireclay is substituted so 

 as to promote the maintenance of a small fire, 

 while the fuel burns more slowly and more com- 

 pletely. The draught below the fire can be re- 

 stricted, and that in itself puts a great check on 

 the fire. 



The advantages are thus real, but not in the 

 direction which is popularly supposed. It was 

 shown that the mere removal of the bars from a 

 grate has only a negligible effect on the radiant 

 efficiency of a fire. Of course, the ventilating 

 effect of the fire is reduced if the opening to the 

 flue is lessened, but this seems generally to be 

 an advantage. Here one looks expectantly, but 

 vainly, for measurements of the ventilating' efi'ect 

 of the newer types of grates. Mrs. P'ishenden's 

 measurements were made on an old-fashioned grate 

 provided with an adjustable flue damper. With 

 unrestricted draught it was found to move up the 

 chimney as much as 25,000 cub. ft. per hour, 

 although by regulation of the damper this was 

 reduced to one-tenth. Such measurements on the 

 new types of fire would have been specially valu- 

 able for the comparison of different systems of 

 domestic heating. In domestic architecture in this 

 country heating and ventilation go together. 

 There seems to be no practical alternative to the 

 chimney flue, simple, cheap in upkeep, and auto- 

 matic in action, for the ventilation of smaller 

 houses. The recognition of this led to careful 

 measurement of the ventilating action of gas fires 

 by the joint committee of the Institution of Gas 

 Engineers and the L' Diversity of Leeds, and 

 similar measurements for modern coal grates 

 would be very valuable. 



The experiments on different fuels burnt in the 

 same grate are specially interesting. When burning 

 coal, the radiant efficiency was found to be 24 per 

 cent. With anthracite the figure was 27 per cent. 

 With dry gas coke 285 per cent, of the heat was 

 radiated, but this advantage over coal was lost if 

 more than 10 per cent, of moisture was present. 

 Two dry cokes produced by low-temperature car- 

 bonisation radiated respectively 31 and 34 per 

 cent, of their heat, but here again the pres- 

 ence of moisture was found to have a deleterious 

 effect. Briquettes of coal proved relatively in- 

 efficient with only 19 per cent, radiation. The 

 figures point a moral to producers of coke— i.e. the 

 desirability of preventing the degradation of an 

 excellent fuel by excessive moisture, although 

 there are technical difficulties in eliminating 

 moisture altogether. The results for low-tempera- 

 ture coke are striking, and "confirm the fact 

 accepted by all smoke-abatement reformers that it 

 is exceedingly desirable that a fuel of this nature 



