Mollier Diagram Research Articles

Note on the Effect of Hydrogen/Carbon Ratio of Fuel on the Validity of Mollier Diagrams for Internal Combustion Engines

T possibility of using a Mollier diagram or its equivalent in investigating the various cycles of internal combustion engines has recently been pointed out. Like the steam engineer, the automotive engineer can, by the use of graphs representing the thermodynamic properties of the working fluid in the engine at any state, solve many problems in internal combustion engines without going into the tedious computations which formerly characterized these solutions.

A Mollier Diagram for the Internal-combustion Engine.

Summary Quantitative calculations of the effects of flame propagation and of piston movement on the temperatures attained in the various parts of on Otto-cycle engine charge during combustion are made relatively simple by the use of a Mollier diagram of the properties of the combustion products of octane and air. The method is applied to a consideration of the effect of spark advance on the temperature attained ahead of the flame front, and it is concluded that the results are significant in studies of engine knock.

The Condensation of Flowing Steam Part I—Condensation in Diverging Nozzles

Abstract The authors discuss the apparatus and method used in determining the point of condensation in diverging nozzles. The discussion is restricted to nozzles with very short throats and with angles of divergence greater than 2 deg. As a primary result of the work described, the authors locate the Wilson line for continuously expanding steam at the 4.5 per cent moisture line on the Mollier diagram. Condensation points and sizes of steam droplets are discussed for various pressure and temperature conditions before expansion and for various back pressures.

Undercooling in Steam Nozzles

Abstract This paper deals primarily with the effect of wall roughness on the flow of steam in nozzles; and secondarily with drop growth and the occurrence of initial condensation. It was found that roughness of the nozzle walls caused a retardation of steam flow and resulted in the Wilson line’s occurring at the 3.2 per cent moisture line on the Mollier diagram instead of at the 3.7 per cent moisture line as was found for a nozzle with smooth walls. In a specially designed nozzle drop growth was accomplished as evidenced by the complete visible spectrum which resulted from the scattering of light by the expanding steam in this nozzle. Photographs of the condensation region show that condensation is not occurring at any point previous to where the eye sees it. These researches indicate that the location of the Wilson line on the Mollier diagram depends entirely upon the rate of change of velocity of the steam, and, therefore, cannot be fixed for all conditions. In accordance with this fact it is suggested that the term “Wilson line” is a misnomer and should be replaced by the more appropriate one of “Wilson zone.”

The steam-turbine expansion line on the Mollier diagram, and a short method of finding the reheat factor

Report issued by the Bureau of Standards over the Mollier diagram. The steam-turbine expansion line on the diagram is discussed. This report includes tables, and illustrations.