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).
Technical analysis of how increasing water flow through the radiator core affects engine overheating and critical atmospheric temperature.
| Identifier | ExFiles\Box 178\1\ img026 | |
| Date | 15th February 1926 guessed | |
| - 10 - (2) A rapid flow of water through the radiator core increases (a) The amount of heat the core can dissipate when the car is on the point of over-heating. (b) The critical atmospheric temperature of the car, or the atmospheric temperature at which it will overheat under any given set of conditions. (b) is the natural result of (a), being brought about as follows. Suppose a car, with a given circulation of water, has a drop of 60°C across the core when the liquid round the cylinder heads is boiling, and that this over-heating occurs at full throttle with an atmospheric temperature of 10°C. Then the mean difference in temperature between the radiator core and the atmosphere is 100 + 40 / 2 - 10 = 60°C when the cooling water boils. Now suppose the circulation of water in this car is quadrupled - then the drop across the matrix will be approximately one-quarter of the previous figure or 15°C. As the amount of heat given out by the engine remains the same, the mean difference in temperature between the atmosphere and radiator will remain the same to cope with this heat i.e. 60°C. Therefore, the mean radiator temperature must be (60° + 10°) or 70°C as before, and the top temperature 70 + 15 / 2 = 77.5°C. Now it will be apparent that whereas the car with the sluggish circulation was boiling, the system with the increased water flow will still be (100 - 77.5°C) or 22.5° off boiling, or in other words, its critical atmospheric temperature has been raised from 10°C to 32.5°C. contd. | ||