From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
The pros and cons of using glycerine as a non-freezing agent in motorcar engine cooling systems.
| Identifier | ExFiles\Box 151\3\ scan0002 | |
| Date | 3rd December 1912 | |
| W/TGr 3-12-12 X/435 GLYCERINE AND ENGINE COOLING. AT first sight it may not be evident what relation there is between the useful and household preparation named glycerine and the cooling of a motorcar engine, and it is only when the susceptibility of the water circulation system to the wiles of the frost fiend is taken into account that an explanation is found. If it could be done without it, it is questionable whether anyone would go out of their way to bother about the stuff, with its sticky and other generally nasty characteristics. True, it has some repute as a medium for keeping rain spots off the windscreen, but in this case we have merely to deal with an imperceptible film and not half a gallon or so, as in the case of the water circulation. As a non-freezing mixture the generally advised proportion of 20 per cent. of glycerine added to the circulation water is found to be as effective as anything, and at the same time it is harmless both to metal and the human economy. The latter advantage cannot be claimed for some of the chemical mixtures which may have none the less useful non-freezing properties. The drawback inherent in glycerine is that it does to an appreciable extent reduce the heat-absorbing and radiating value of the water, a drawback which would in any case be inherent in any non-freezing mixture with the exception of alcohol and water. This reduction of the heat-absorbing value is, perhaps, more a theoretical than practical one, otherwise more would have been heard of it. In the case of an engine which runs fairly close up to boiling point, however, one would not be surprised if the glycerine mixture broke down the narrow margin of safety and kept the water at boiling point. The only remedy then available is to reduce the strength of the mixture by trial to a value which will suit the engine. That the mobility or ease of flow of the water is lessened by adding glycerine will be obvious, and in a thermo-syphon system of circulation the rate of flow, under the most favourable conditions, is a very small one. It cannot be expected, then, that with a diminished amount of heat-charged fluid passing through the radiator every minute, it will keep down to normal temperature. Summing up the effect of the admixture of glycerine on the cooling efficiency of an engine's circulation system, it is safe to say that some reduction is bound to take place. In the majority of cases it is not of practical importance and in some cases it is. The question can only be settled by experience in individual cases. It must be kept in mind that when glycerine mixture is needed most the atmospheric conditions and the much colder air passing through the radiator have a compensating effect in keeping down the temperature to a workable figure. H. {Arthur M. Hanbury - Head Complaints} | ||