Hawaii Geothermal Project : a parametric study of a vertical heat exchanger designed for geothermal power plant application

Abstract

The preliminary design of a vertical, counterflow, shell and tube heat exchanger for use in a binary fluid power cycle is presented. The heat exchanger is to be part of a representative geothermal power plant generating 10 MW utilizing geothermal brine at 350°F with isobutane as the working fluid. The computational procedure for determining heat transfer coefficients, tube lengths, number of tubes, and pressure drops is outlined. Detailed in graphical form are results of a parametric study showing how these four parameters are affected by changes in turbine inlet temperature, tube diameter, tube pitch, isobutane velocity, scale thickness, pinch point temperature difference, and system pressure.