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).
Page from a report on radiator efficiency, comparing the effects of rapid versus sluggish water circulation on heat dissipation.
| Identifier | ExFiles\Box 178\1\ img027 | |
| Date | 15th February 1926 guessed | |
| - 11 - Again, suppose the car with the rapid circulation could be made to boil with an atmospheric temperature of 10°C. The difference in temperature between the radiator and atmosphere at this point would be 100 + 85 / 2 - 10 - or 82.5°C. With the sluggish circulation it was 60°C. Our experiments have shewn that the heat dissipating capacity of a radiator is proportional to the difference in temperature between the mean radiator temperature and the atmosphere. Heat units dissipated rapid circulation 82.5 -------------------------------------- --- Heat units dissipated sluggish circulation 60 ∴ Percentage increase in radiator efficiency due to increased circulation is 37.5% in this case, irrespective of increased conductivity due to rapid water flow. It is therefore clear that even a slight restriction in the water circulation of an engine may have disastrous effects upon its cooling capabilities. The drop across the R.R. radiators is not very great shewing that there is little to be gained from increasing the rate of water circulation. At full throttle, with a road speed of 30 or 40 m.p.h., the drop across the Phantom radiator is about 8°C, the Silver Ghost 10°C, when the top water temperature in each case is about 85°C or the optimum running temperature. contd. | ||