Electromotive Division Engines

Cleveland Diesel Engine Division Work on Stirling engines at the Electromotive Division was not well documented but useful information about this activity can be compiled from the various references listed above, principally Heffner (1966), Percival (1967), Mattavi el al. (1969) and Percival (1974).

Work on heavy, high-power Stirling engines apparently started at the Cleveland Diesel Engine Division of General Motors about 1958. Cleveland Diesel had supplied the majority of submarine engines during the Second World War and had strong connections with the U.S. Navy. In addition, they were builders of heavy diesel engines for locomotives and surface vessels. Their interest in Stirling engines was for use as an alternative to diesel engines for submarines, river and harbour work boats, and for locomotive propulsion. The Cleveland Diesel Engine-Division was dissolved in 1962 and the Stirling engine project was transferred to the Electromotive Division at LaGrange, Illinois.

Large marine engine

The first substantial project was the design and construction of a four cylinder 265 kW (360 hp) engine designated the Model 4-S1210 and shown in f ig. 13.8. This was basically four 65 kW (90 hp) Philips rhombic-drive engines compiled in an in-line arrangement on a common crankcase and with a common air preheater hood. The engine was constructed at Philips and, at the Electromotive Division, was fitted with a modified locomotive generator. Both units were mounted on a monstrous bed plate said to be equal to 15 per cent of the engine generator weight (Schab 1964). The engine weight was 3175 kg (7000 lb), the generator weight 2721 kg (60001b) and the total system was 6895 kg (15 200 lb). With a nominal power rating of 295 kW (400 hp) the specific weight was therefore 23.4 g/W (3S lbs per horsepower)! The unit was put together in a crash program to demonstrate the low noise and vibration characteristics. It was delivered to the Navy and the noise characteristics were evaluated (Schab 1964) with favourable results but with no great enthusiasm.

In addition to the noise evaluation studies, the performance of the engine was separately evaluated by Loftus (1964) principally with hydrogen. but also with helium as the working fluid. The engine achieved a maximum power of 265 kW (360 hp) at 1500 revolutions per minute with a hydrogen pressure of 13.8MN/ni: (20001b per sq in). Maximum eiliciencies in the range of 28 per cent were observed at 150(1 revolutions per minute and a power output of 205 kW (275 hp). On test, the engine experienced numerous operational difficulties and ran for only about 5(J hours. Loftus concluded the engine was feasible for operation where

Cleveland Diesel Engine Division

Fid. 13.8. MckIcI Type 4-S1210 380 lip four-cvlindcr rhombic-drive engine (after He finer

Fid. 13.8. MckIcI Type 4-S1210 380 lip four-cvlindcr rhombic-drive engine (after He finer

'extreme quietness and presumed adaptability' for low-grade fuels were of importance. However, 'the fuel economy... is 10-15 per cent poorer than would be expected in a diesel engine of similar size and speed'. In retrospect ii is difficult to avoid the feeling that this unit did more harm than good to Navy interest in Stirling engines. What a pity that a proper level of time and effort was not expended to produce a fully developed machine for Navy evaluation. It is understood that the unit was finally consigned to the Smithsonian Institution in Washington, D.C.

Hcfiner (1966) in his paper includes photographs of a single-cylinder Type 1-S1050 65 kW (90 hp) engine and a two-cylinder Type 2-S1210 130 kW (180 hp) engine, both attributed to Electromotive but little is known about these engines. They were most likely both rhombic-drive engines used basically for component development in dynamometer work.

Vee engine with variable phase angle

In 1965 the Electromotive Division built and tested a four-cylinder 295 kW 1400 hp) engine using four Type S1050 cylinder assemblies (Percival 1974). It was intended as an eight-cylinder vee engine but for test work only one bank of four cylinders was constructed. A photograph of the unit was given by Percival (1967). This engine was remarkable not only for its size but, principally, because the method of power control was by variation of the phase angle between volume variations in the compression and expansion spaces. Each of the four cylinders contained a conventional piston and displacer bul the four displacers and the four pistons were connected to different crankshafts. Phasing between the two shafts was maintained by a sun-and-planet gear system at the rear oí the engine. The phase angle between compression and expansion spaces could be readily varied by simple rotation of the sun gear thereby increasing or decreasing power as required. Sufficient rotation of the sun wheel resulted in zero and then negative power so that, in fact, the engine reversed in rotation. Response was virtually instantaneous and reversal could be obtained in little over one revolution. This facile reversal of the direction of rotation was the principal attraction of the engine for use in tugs and other marine coastal vessels requiring high manoeuverability. big. 13.9 contains the calculated forward and reverse characteristics of this engine, reproduced from Percival (1974). 1 he figure appears to refer to output per cylinder.

In 1967 Electromotive Division began construction of a double-acting version of a displacer engine, called the 'W" model, having one double-acting pistion and two displacers operating in separate cylinders. The engine had a power output of 105 kW (140 hp) but no other details of this engine were given by Percival (1974).

Drive phase angle (degrees)

Fig. 13.9. Forward and reverse characteristics of the Electromotive four-cylinder variable-phasc-anele Stirling engine (calculated; alter Pereival 1974).

Solar Stirling Engine Basics Explained

Solar Stirling Engine Basics Explained

The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

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