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The efficiency of internal combustion engines depends on several factors, the most important of which is the expansion ratio. For any heat engine the work which can be extracted from it is proportional to the difference between the starting pressure and the ending pressure during the expansion phase.
Phosphorus is a key anti-wear component in motor oil and is usually found in motor oil in the form of zinc dithiophosphate (ZDDP). Each new API category has placed successively lower phosphorus and zinc limits, and thus has created a controversial issue of obsolescent oils needed for older engines, especially engines with sliding (flat/cleave ...
For a heat engine, thermal efficiency is the ratio of the net work output to the heat input; in the case of a heat pump, thermal efficiency (known as the coefficient of performance or COP) is the ratio of net heat output (for heating), or the net heat removed (for cooling) to the energy input (external work). The efficiency of a heat engine is ...
Even when aided with turbochargers and stock efficiency aids, most engines retain an average efficiency of about 18–20%. [53] However, the latest technologies in Formula One engines have seen a boost in thermal efficiency past 50%. [54] There are many inventions aimed at increasing the efficiency of IC engines.
Engines with higher efficiency have more energy leave as mechanical motion and less as waste heat. Some waste heat is essential: it guides heat through the engine, much as a water wheel works only if there is some exit velocity (energy) in the waste water to carry it away and make room for more water. Thus all heat engines need cooling to operate.
The choice of working fluids is known to have a significant impact on the thermodynamic as well as economic performance of the cycle. A suitable fluid must exhibit favorable physical, chemical, environmental, safety and economic properties such as low specific volume (high density), viscosity, toxicity, flammability, ozone depletion potential (ODP), global warming potential (GWP) and cost, as ...
To clarify further the role of the coupling between heat-release fluctuations and pressure fluctuations in producing and driving an instability, it is useful to make a comparison with the operation of an internal combustion engine (ICE). In an ICE, a higher thermal efficiency is achieved by releasing the heat via combustion at a higher pressure ...
These engines were designed to have a total-loss lubrication system, with the motor oil held in a separate tank from the fuel in the vehicle, and not pre-mixed with it as with two-cycle engines, but mixed within the engine instead while running. Castor oil was often used because it lubricates well at the high temperatures found in air-cooled ...