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 evaporatively cooled system for a Phantom I engine in an armoured car.
| Identifier | Morton\M5\ img054 | |
| Date | 30th April 1932 | |
| ~~By~~ from Lr.{Mr Ellor} c. Hs{Lord Ernest Hives - Chair}/Gib. GIB 84195? EVAPORATIVELY COOLED SYSTEM. PHANTOM I ENGINE IN ARMOURED CAR. Attached is a copy of the calibration of the hot well pump. It will be seen from the figures that the capacity at all engine speeds is greatly in excess of the condensate it has to deal with under operational conditions except at the very low engine speeds. Under these conditions the engine will merely be ticking over and the amount of condensate will be very small. Tests have been carried out with the same inlet and delivery heads as obtain on the car, but the surrounding pressures were atmospheric. When operating with the engine there will be a pressure in the condenser which will tend to increase the delivery. It will be noted that at speeds above 2300 R.P.M. the rate of delivery decreases with an inlet temperature of 100°C. This is a characteristic of all hot well pumps when working under inlet temperature conditions corresponding to the vapour pressure, and is due to the tendency to produce a depression inside the pump as the speed increases beyond the critical figure, thus reducing volumetric efficiency. Although the calibration indicates that the pump is adequately large to deal with the condensate, we must make quite sure that the separation in the header tank is good, as any excess of water passing from the header tank with the steam has to be dealt with by the hot well pump. A check on this cannot be carried out in a direct manner owing to the internal arrangement of the steam feed to the condenser, but we propose to couple up the inlet pipe to the water main and observe whether any water is carried back into the steam pipe which will then collect in the hot well. Also a glass level pipe will be fitted to observe the working level in the tank to check adequacy of expansion space. We think that all non return valves can be eliminated as the hot well system is self-contained and providing the delivery outlet is placed above the cold filling level in the tank there is no possibility of draining the system into the condenser. I think the modifications we have agreed upon to the distribution of steam at the base of the condenser will permit the letter to function satisfactorily. | ||