Specific heat reduced correction

Edmister (1948) published a generalized plot showing the isothermal pressure correction for real gases as a function of the reduced pressure and temperature. His chart, converted to SI units, is shown as Eigure 3.2. Edmister s chart was based on hydrocarbons but can be used for other materials to give an indication of the likely error if the ideal gas specific heat values are used without corrections. 

In the first iteration, a reduction in the length and diameter successfully corrected most discrepancies except those of the outlet pressure and the residence time. To meet the latter specification, the diameter was further reduced. Simultaneously, the inlet pressure had to be increased to account for the resulting increase in pressure drop. Furthermore, as the heat transfer area decreased with diameter, the radiant temperature must also increase to supply a constant total heat input. 

If engineering departments calculated heating curves specifically for their furnaces and loads, they would be able to determine correct specifications for the furnace to meet their specific needs. In addition, when required to reduce costs, they could be aware of the results and inform plant management of the limitations imposed on the... 

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