Session: K10-03: MULTI-SCALE MULTI-PHASE HEAT TRANSFER EQUIPMENT II

Paper Number: 140789

140789 - Additively Manufactured Water-Cooled Condenser Heat Exchanger With R134a 

Abstract: 

Additive manufacturing (AM) enables the creation of complex geometries, making it advantageous for heat exchangers that incorporate three-dimensional structures that enable high heat transfer and low pressure drop. This paper describes the design, fabrication, and testing of a 5-kW AM condenser heat exchanger. The condenser heat exchanger is configured in a cross-counter flow arrangement. The working fluids are fresh water at an inlet temperature of 25°C, and R134a at 35°C that is a saturated vapor at the inlet and saturated vapor at the exit. The water flow rate is 40 L/min and has a Reynolds number of 4,100. The refrigerant has a flow rate of 108 kg/hr and has a Reynolds number of 18,000 at the inlet (saturated vapor) and 4,900 at the exit (saturated liquid). The AM condenser heat exchanger was fabricated from AlSiMg in a powder bed AM process and has overall dimensions of 260 mm X 235 mm X 39 mm. The heat exchanger was designed by creating a hierarchical segmented model that allows for thermodynamic properties, heat transfer, and pressure drop to be calculated at each location along the length of the flow. Both the water side and the refrigerant side are designed with three-dimensional fins that extend into the flow, increasing the heat transfer surface area and decreasing the channel cross-section. The modeling allows for the fin design to be selected such that the thermal resistances are matched on the water side and the refrigerant side, in order to achieve higher heat transfer and a compact design. The water side fins consist of three dimensional “T” shapes that are arranged in wavy strips in the flow direction, demonstrating a three-dimensional geometry that enhances the heat transfer and that is only manufacturable with AM. The AM condenser heat exchanger achieves a power density of 2.1 MW/m³, which is higher than commercially available shell-and-tube heat exchangers that have a power density of around 0.9 MW/m³. Additionally, Full 3D CFD simulations are used to validate the hydraulic flow and thermal performance with an accuracy higher than 95% for the water pressure drop and 94% for the heat exchange capacity. The heat exchanger was modeled and tested across a range of flow rates and inlet conditions, resulting in a full performance map across variable water flow rates.

Presenting Author: Omar Zaki University of Illinois Urbana-Champaign

Presenting Author Biography: Omar received his BSc with High Honors from Cairo University in 2019 while being the valedictorian of his class. He also received his MSc from Cairo University in Mechanical Engineering with a focus on heat transfer and air conditioning. Before joining UIUC, Omar worked on research projects with entities such as ORNL, KAUST, and UNIDO related to HVAC&R applications. His research mainly focused on heat transfer and air conditioning applications both on a component level and on a system level. Currently, his research at UIUC with Professor King and Professor Miljkovic is concerned with applying additive manufacturing technology to heat transfer applications to achieve higher performance when compared with conventional heat exchanger technologies.

Authors:

Omar Zaki University of Illinois Urbana-Champaign
Robert S. Stavins University of Illinois Urbana-Champaign
Mario Wezel Creative Thermal Solutions
Andrew Musser Creative Thermal Solutions
Stefan Elbel Creative Thermal Solutions
Nenad Miljkovic University of Illinois Urbana-Champaign
William P. King University of Illinois Urbana-Champaign