(732f) Development and Demonstration of Novel Thermal Technologies for Enhanced Air - Side and Two - Phase Performance of Cpi - Relevant Heat Exchangers

"Almost every process in the chemical process industries (CPI) involves heat transfer. Georgia Tech (GT), the University of Illinois at Urbana Champaign (UIUC), and Heat Transfer Research Inc. (HTRI) are working on an integrated RAPID project to develop, test, and demonstrate, in a testbed industrial condenser, novel air- and process-side heat transfer technologies developed at the laboratory scale at GT. The goal is to improve air- and process-side thermal performance, by using autonomously fluttering reeds on the air side, and ultrasound transducers on the process side, to significantly improve energy utilization, and reduce footprint, weight, and cost. These technologies help overcome limitations of previous passive, geometrically complex designs burdened with significant flow losses, and can be incorporated into new and existing equipment.

Laboratory work at GT has focused on demonstrating 20-30% (air- and process-side) enhancement. On the air side, GT has explored reed geometries, materials, and array configurations leading to two-fold heat transfer enhancement with minimal pressure drop penalty. On the process side, GT has investigated modulation frequency, power, and array configurations for ultrasound transducers leading to complete condensation, thereby allowing significantly reduced condenser length, mass, and volume. We have addressed challenges associated with durability/insertion of reed arrays and ultrasound transducer placement. Air-side work at UIUC has pointed the way to use of a streamwise series of reeds and has developed computational tools to scale the GT laboratory results to pilot-scale demonstration at HTRI. Process-side models account for interface shape, bubbles in the liquid phase, and drops in the vapor phase. Work at HTRI incorporates the reed and ultrasound technologies into a pilot-scale condenser, and measurements are under way to quantify performance under real-world conditions, including air- side flow maldistribution. Process economics work at GT accounts for capital and utility costs, and provides upper bounds on fabrication and installation costs below which the new technologies are economically viable. This work shows how the new technologies can increase throughput when improved heat transfer de-bottlenecks a process, and how one can eliminate equipment that would be needed for recirculation and phase disengagement of incompletely condensed fluid when improved condenser performance so allows.

These novel heat transfer approaches have the potential to transformatively enhance performance of a broad class of heat exchangers across many CPI applications. They also have the potential to enable new applications, including natural gas upgrading by cryogenic distillation, multifunctional modules, and utilization of renewable bioproducts, as well as integration of multiple processes (e.g., separation and heat transfer for binary and multi-component liquids, for which ultrasound has demonstrated the capability to produce an atomized mist enriched in one component). Higher energy efficiency and energy productivity allow for new trade-offs between reduced footprint/mass (and hence lower capital cost), and higher throughput (allowing for de-bottlenecking). The potential for swap-in/swap-out retrofit is particularly attractive."