Proceedings of the Second International Energy 2030 Conference,
November 4-5, 2008, Abu Dhabi, UAE

Energy Efficient Polymers for Seawater Heat Exchangers

Patrick Luckow
The University of Maryland, USA

Avram Bar-Cohen
The University of Maryland, USA

Peter Rodgers
The Petroleum Institute, UAE

Juan Cevallos
The Petroleum Institute, UAE

Abstract
The present study explores the thermofluid characteristics of a seawater-methane heat exchanger that could be used in the liquefaction of natural gas on offshore platforms. The compression process generates large amounts of heat, usually dissipated via plate heat exchangers using seawater as a convenient cooling fluid. Such an application mandates the use of a corrosion resistant material. Metals such as titanium, expensive in terms of both energy and currency, are a common choice. The “total coefficient of performance,” or COP_T [1], which incorporates the energy required to manufacture a heat exchanger along with the pumping power expended over the lifetime of the heat exchanger, is used to compare conventional metallic materials to thermally conductive polymers. The thermofluid characteristics of heat exchangers built of high thermal conductivity polymers are analyzed, for conditions typically seen by ADGAS. It assumes a 1 year service life for a typical plate heat exchanger, though heat exchangers operating in such corrosive environments may have far shorter service lives. In this study the hot natural gas is represented by 90 ºC methane and 35 ºC seawater is used as the coolant. Gas is flowing through the heat exchanger at 10 m/s, and water at 0.5 m/s. Analytical models were used to calculate the heat transfer rates and the required pumping power, as well as additional metrics, over a range of fin spacings, wall thicknesses, and thermal conductivities.