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).
Analysis of engine cooling curves and factors affecting heat transfer based on Newton's Law of Cooling.
| Identifier | ExFiles\Box 24\4\ Scan279 | |
| Date | 21th November 1924 guessed | |
| -2- circulation in this way being maintained normally by the pump. Top and bottom water temperatures and atmospheric readings were taken at fixed intervals throughout the run until the mean radiator temperature fell to 40°C. Both way readings were taken in each case and the tests carried out on a straight stretch of road to eliminate the effect of wind. In order to discover whether these cooling curves followed Newtons Law θ1 = θ2 e -at. where θ2 = starting temp θ1 = temp. after any time t a = heat transfer co-efficient log θ, where θ1 is the difference between the mean radiator temp. and atmospheric, was plotted against the time taken to reach this temp. t. The result was almost a straight line at the higher radiator temps. but a curve with a definitely increasing slope after the mean radiator temp. fell below 70°C. The reason for this was found to be - (a) That the crankcase estracted heat from the system at the beginning of each run, due to its not following the water temperature when this was rapidly brought up to 90°C. (b) That turning the engine over to circulate the water generated heat which was imparted thereto in a constant quantity throughout the test. Tests were actually made to discover the behaviour of the crankcase and the mechanical efficiency of the engine being the factor 'B' was established. These two factors tend to compensate each other at the higher temperatures. contd :- | ||