Decomposition by film boiling heat transfer of glycerol

Abstract

In this paper, a simple method is presented to transform saturated liquid glycerol into a gaseous fuel mixture containing hydrogen (H2), carbon monoxide (CO), methane (CH4), ethylene (C2H4), and ethane (C2H6). It is based on glycerol decomposition within the vapor film of the film boiling regime of multiphase heat transfer on a horizontal tube. In film boiling, a thin gas layer of predominantly glycerol vapor surrounds the tube and decomposes as the gases flow in the film under the influence of buoyancy. The decomposition products are removed in the form of bubbles percolating through the liquid pool and their contents are chemically analyzed to determine the decomposition products and their fractional amounts.The glycerol boiling curve and critical heat flux were measured to determine the operational domain for decomposition which is between glycerol's minimum film boiling temperature and an upper value dictated by material considerations of the tube that supports the vapor film. The results show that 95% of the gases produced by decomposition of glycerol are themselves viable as a fuel. Decomposition of glycerol is a multistep process initiated by radical species in the product stream. Key reactions are identified by a sensitivity and pathway analysis. An optimal thermal efficiency and corresponding temperature for conversion corresponding to the experimental design is suggested for conversion by film boiling at atmospheric pressure.