Abstract

Due to rising energy costs and increasing concerns of green house gas emissions, much research is being conducted to develop a means of efficiently converting low grade thermal energy into useable energy in the form of mechanical work or electrical power. One such technology is an Organic Rankine Power cycle (ORC). One difficulty in utilizing an ORC to harness low-grade thermal energy is the transfer of heat from the source to the working fluid of the power cycle. Micro channel heat exchangers are capable of achieving extremely high rates of heat transfer and are good candidates for application in and ORC.

This thesis provides experimental validation of a computer model used to design single pass cross flow microchannel heat exchangers for use in ORC's. A model ORC was constructed and used to test the performance of the boiler and condenser, both of which were designed by the computer model. The performance of the heat exchangers was calculated using the effectiveness method and the log mean temperature method, also the overall rate of heat transfer and pressure drop were calculated for the heat exchangers. The average accuracy of the total heat transfer in the boiler was 29.9%. The average accuracy of the total heat transfer in the condenser was 8.9%. A major contributor to the inaccuracy found in the boiler model was the inability to determine the phase of the refrigerant around the saturation point due to limitation in the data acquisition system.