Design of Compact Condensers Enabled by Additive Manufacturing

Condensers are essential components in heat pump, refrigeration, and Rankine cycles, as well as a variety of industrial and chemical processes. However, condensation at low vapor qualities is characterized by poor heat transfer coefficients, requiring large surface areas to achieve complete condensation. This adds volume and weight to the condenser, resulting in high material costs, difficulty of transportation, and the need for a large space to house the condenser.
Novel designs for condensers that take advantage of the capabilities of metal additive manufacturing are developed to achieve enhanced heat transfer and reduce the volume of water-cooled condensers. Specifically, tube size, spacing, and the number of tubes are tailored and varied along the condensation length to yield high heat transfer rates at all stages of condensation while maintaining low pressure drops. A genetic algorithm is used to optimize the size, number, and spacing of tubes at many points throughout the condensation process. Under the same operating conditions, this genetic algorithm results in a condenser ~90% smaller than one manufactured with conventional methods.
A technique to periodically drain liquid condensate from the working fluid channels, thereby minimizing the thermal resistance presented by the condensed liquid film, is introduced and evaluated for condensers with representative heat duties of 50 kW and 2.4 GW. This technique achieves a reduction in condenser length of 8.3% to 9.4% for the 2.4 GW case, but an increase in length is found for the 50 kW case due to a corresponding decrease in mass flux. Thus, this drainage option should be employed in cases with high initial mass flow rates of the condensing fluid. The design methods and insights gained from this work will guide the development of additively manufactured compact condensers.