The Development of Variable Specific Heat Charts and Graphs,and their Application to Internal Combustion Motor Problems

Abstract

The paper describes the development of a method of investigation, both analytical and graphical, into problems relating to internal combustion motor design and performance.

The authors have provided a chart, together with auxiliary graphs, by means of which theoretical indicator diagrams may be constructed for any internal combustion engine cycle under conditions of variable specific heat. It may also be used for studying any indicator diagram obtained under test conditions.

The main feature of the chart is the provision of means to enable it to be used for any hypothetical or initial conditions encountered in practice. It has been so generalized as to enable it to be used, not only for the examination and construction of indicator diagrams involving expansion down to atmospheric pressure or to the initial compression volume, but to any degree.

The auxiliary graphs provide a means whereby the thermal efficiency, mean effective pressure, and other essential quantities may more easily and readily be calculated than has previously been possible.

To illustrate the method of using the charts and graphs, examples have been worked out for the dual combustion cycle, the Diesel cycle and the constant volume cycle.

Get full access to this article

View all access options for this article.

References

David

W. T.

Leah

A. S.

1940 Proc. I. Mech. E., vol. 143, p. 289, “Fuel Economy in Petrol Engines”.

Hershey

R. L.

Eberhardt

J. E.

Hottel

H. C.

1936 S.A.E. Journal, vol. 39, p. 409, “Thermodynamic Properties of the Working Fluid”.

Rogers

1947 Phil. Magazine, vol. 38, p. 134, “The Derivation of Variable Specific Heat Expressions for Thermal Efficiency and Calorific Value of Working Fluid, for use in Internal Combustion Engine Design”.

Tizard

H. T.

Pye

D. R.

1923–4 Proc. Inst. Automobile Eng., vol. 18, part 1, p. 1, “The Character of Various Fuels for Internal Combustion Engines”.

Walker

W. J.

1917 Phil. Magazine, “Thermodynamic Cycles with Variable Specific Heat of Working Substance”.

1920 Proc. I. Mech. E., p. 1235, “Thermodynamic Cycles in Relation to the Design and Future Development of Internal Combustion Engines”.

1926 Proc. Inst. C.E., Selected Engineering Papers No. 33, “A Standard Cycle for all types of Internal Combustion Motors”.

1944. Phil. Magazine, vol. 35, 7th Series, p. 680, “Temperature, Pressure, and Specific Volume Changes of a Gas Mixture under Dissociation and Re-association Conditions, with Combustion following the Straight Line Law P = mV + n”.