Rotary Heat Exchanger Design for Indirect Dry Cooling in Power-Plants using High Fidelity

Sumanta Acharya, Illinois Institute of Technology

Usage Details

The project aims at developing economically viable indirect dry cooling system that utilizes a recirculating high surface-area mesh heat exchanger with encapsulated phase-change materials (EPCM). In the proposed innovation, the rotary heat exchanger is used to dissipate heat from a water-cooled steam surface condenser with negligible water loss to the environment. Hot water exiting the condenser is cooled by melting phase change materials embedded in thin hydrophobic polymer shells/tubes that are interconnected to form a mesh like structure. The tubes are mounted on rotary systems that continuously circulate them out of water into the air-side flow path, using the technology developed for rotary pre-heaters. As ambient air passes across the meshes, the phase change materials solidify and rejects the heat to the air. The solidified structures then travel back to the hot water side to complete the cycle. The tube modules will be designed to have high heat capacity, high heat transfer coefficient for both air and water, large surface area, low pressure drop and hence low cost. The proposed research has the following advantages (1) It will be cost effective model compared to the conventional cooling towers (2) It has no significant water dissipation, which leads to low water loss. (3) It will achieve power production efficiency similar to wet cooling towers.  

Our research objective mainly focus on understanding the air-side and water-side flow features and heat transfer. We will simulate air and water flow over tubes of different size, shape, spacing and obtain the required pressure drop and heat transfer characteristics. This investigation will help us to optimize the heat exchanger tube bundles for enhanced air-side and water side heat transfer, reduced pressure drop and high COP.  Additionally, for the water side, we have to account for water column break-up, droplet impact and roll off. These challenges are quite significant from the numerical viewpoint. These calculations, both on the air side and water side, will provide the appropriate pressure drop correlations and heat transfer coefficients for design optimization. Our final goal is to build up a prototype simulator for the entire rotating heat exchanger and optimize it for the highest thermal performance.