DESIGN, FULL-SCALE TESTING, AND ANALYSIS OF AN INNOVATIVE NATURAL-CONVECTION-DRIVEN HEAT-RECOVERY HEAT-EXCHANGER FOR SPACE-CONDITIONING APPLICATIONS

The temperature of water in large water reservoirs remains essentially constant at approximately 60-degrees-F throughout the year and theref ore is attractive for space-conditioning applications. The energy exch ange with the water reservoir is accomplished through a heat exchanger . In the present work, two heat-recovery heat exchangers were designed using a simplified computer model. Design-1, which used smooth tubes, was tested at a flooded abandoned mine vein at Scranton, Pennsylvania . The subsequent design, which used the spirally fluted tubes, was tes ted at the Ohio State University (OSU) and at a lake in Lackawanna Sta te Park in Pennsylvania. A more detailed thermal hydraulic model was d eveloped for the analysis of these heat-recovery heat exchangers. The data obtained at OSU and Lackawanna were analyzed using the thermal hy draulic model to develop a correlation for natural convection. Finally , using this correlation, it was found that the design with spirally f luted tube clearly offers advantages in terms of reduced size of the h eat exhanger for a given heat duty.