Heat capacity of N-pentane liquid at elevated pressures

Abstract

Experimental heat capacity data have been obtained for n-pentane in the liquid region for temperatures from 140° to 300°F and pressures between ^00 and 3,000 psia by using a flow calorimeter system, The apparatus consisted of a calorimeter and constant temperature bath through which the fluid is circulated at a steady rate. The volumetric flow rate is measured with a turbine flowmeter and digital counter. The electrical energy to the main calorimeter heater is applied by a D.C. power supply, The heat capacity of the fluid is calculated from the fluid temperature rise, the mass flow rate, and the energy input. The heat capacity data for n-pentane are estimated to be accurate to within 1%. The experimental values have been compared with those resulting from density and enthalpy data for the substance and those calculated from generalized correlations for the heat capacity departure of non-polar fluids. The experimental data agree most closely with the values derived from the experimental density data (maximum deviation of approximately 3%). and are consistent with experimental data for the heat capacity of the saturated liquid. The generalized correlation presented by Edmister for the prediction of heat capacity values of normal fluid has been tested with experimental data for methane, nitrogen, propane, and n-pentane. The predicted values do not show good agreement with experimental results. More reliable prediction method is to be developed.