Minewater heat recovery project. Final technical report -- Research overview

This report describes the work carried out for the development of a downhole bundle heat exchanger for heat recovery from mine water. The temperature of water flowing through mine shafts remains essentially constant at approximately 60 F throughout the year. Therefore, it is warmer than the working fluid in the heating season and colder than the working fluid in the cooling season. In addition, it is available at zero fuel cost, thus making it an ideal candidate for space-conditioning applications. The heat transfer performance of the heat exchanger in a constant temperature water reservoir was studied and experimentally evaluated by installing the heat exchanger in the mine water shafts at Scranton, Pennsylvania and also subsequently at the Ohio State University and the lake at Lackawanna State Park. All these sites provided a stationary water column for installing a heat exchanger, where heat exchange through natural convection could be obtained. Depending on the requirements of the system cycle the heat exchanger could either function on the heating or cooling modes of operation. In tests, spanning over a period of many months, the performance of the downhole bundle heat exchanger was evaluated for both cooling and heating modes of operation