Influence of microadditive of carbon dioxide on the kinetics of boiling-up of superheated w-pentane

The effect of a low-boiling impurity (CO2 gas <1.5% mol) on the kinetics of boiling-up of superheated n-pentane in a vertical glass tube have been studied by high-speed video (2050 fps). The method of continuous pressure decrease from 2.00 to 0.10 MPa (in the temperature range of 100.2-145.1 °C), as well as the method of measuring the lifetimes of superheated liquids at 0.10 MPa (90.2-134.1 °C) have been used. The inner surface of the tube has two visible defects, one of which defines the boundary of the attainable superheat. After degassing the system, the defects of tube cease to play an appreciable role, the active centers are redistributed. The temperature of the attainable superheat increases from the initial value by 20 °C in tests with gas and by 10 °C in subsequent tests without it. The result obtained may be related to physical gas adsorption on the glass surface during the process of evacuation of the system.

Superheating Limit of Hydrocarbons Based on a Generalized Dieterici Equation of State

A new three-parameter Dieterici type equation of state is employed for studying the high-temperature thermodynamic characteristics of hydrocarbons. This generalized equation of state differs from the known Dieterici equation of state by a modified attractive term. That is, a new thermodynamic similarity parameter is introduced in the attractive term of the Dieterici equation of state. The parameters of the equation of state are determined through the experimental values on the critical-point parameters of hydrocarbons. The equation of state is presented in the reduced form, from which follows the single-parameter law of corresponding states. The proposed equation of state gives the value of maximum attainable superheat for hydrocarbons of about 0.887 to 0.894 times the critical temperature. The new three- parameter generalized Dieterici equation of state offers an acceptable compliance with experimental results of maximum attainable superheat of hydrocarbons.