What are the factors which affect the fuel efficiency of CNG?
In the first place let us list the energy content of the fuels you mention. Using units of MJ per kilogram, the net heating values of petrol, diesel, LPG and NG are about 45, 43, 46, and 44; the net heating value does not include the heat in the water vapour of the combustion products. If you look up the gross heating values – which do include this, the values are different (higher). So the differences between the fuels are not large. But the values will also vary quite a lot depending on the composition of the fuel – particularly for NG and LPG. We now need to consider the way in which different engines use the fuels – in particular the efficiency. The engine thermal efficiency is a function of many different factors but perhaps the most important one is the engine compression ratio. The higher the compression ratio the higher is the theoretical and also the actual efficiency. The maximum compression ratio (CR) different fuels can tolerate in fact defines the efficiency. Since diesel
In the first place let us list the energy content of the fuels you mention. Using units of MJ per kilogram, the net heating values of petrol, diesel, LPG and NG are about 45, 43, 46, and 44; the net heating value does not include the heat in the water vapor of the combustion products. If you look up the gross heating values – which do include this, the values are different (higher). So the differences between the fuels are not large. But the values will also vary quite a lot depending on the composition of the fuel – particularly for NG and LPG. We now need to consider the way in which different engines use the fuels – in particular the efficiency. The engine thermal efficiency is a function of many different factors but perhaps the most important one is the engine compression ratio. The higher the compression ratio the higher is the theoretical and also the actual efficiency. The maximum compression ratio (CR) different fuels can tolerate in fact defines the efficiency. Since diesel u
In the first place let’s list the energy content of the fuels you mention. Using units of MJ per kilogram, the net heating values of petrol, diesel, LPG and NG are about 45, 43, 46, and 44; the net heating value does not include the heat in the water vapor of the combustion products. If you look up the gross heating values – which do include this, the values are different (higher). So the differences between the fuels are not large. But the values will also vary quite a lot depending on the composition of the fuel – particularly for NG and LPG. We now need to consider the way in which different engines use the fuels – in particular the efficiency. The engine thermal efficiency is a function of many different factors but perhaps the most important one is the engine compression ratio. The higher the compression ratio the higher is the theoretical and also the actual efficiency. The maximum compression ratio (CR) different fuels can tolerate in fact defines the efficiency. Since diesel us
