Thermal Analysis and Pressure Loss Modeling for an Optimized Heat Exchanger Used in a Recuperated CO2 Power Cycle

Abstract

A simple recuperated cycle is studied and optimized in this paper. Geometrical parameters for a novel recuperator design are then optimized to minimize area density. The recuperator is where the s-CO2 is analyzed and simulated for both hot and cold sides. The design of the cycle is obtained through a study of a 100 MW net power output s-CO2 cycle, where this cycle features a turbine inlet temperature of 1023 K. The main objective of this paper is to couple a recuperated cycle with a heat exchanger. This is done through Pareto optimality to study the tradeoffs between conflicting variables. The geometry of the heat exchanger features two inlet headers attached to semirectangular channels. The thermal analysis used is based on one-dimensional finite enthalpy method, where discretization is made by equal heat transferred per element. In addition, pressure drops are calculated at both sides of main heat exchanger body. Optimized cycle based on practical parametric assumptions reveals an efficiency of 45.8% and specific power of 132.1 kJ/kg. Best design reveals channel side length of 7 mm with surrounding solid sidewall thickness of 1 mm. Pressure drops for the proposed design are 4.8% and 0.6% of the initial pressure for the hot and the cold sides, respectively. Overall length of the heat exchanger is found to be 10.7 m with an effectiveness of 96.2% and an area density of 363 m2/m3.