Design and Applications of a Cross Flow Heat Exchanger

Heat Exchangers are one of the most effective ways to test, analyze and calculate heat transfer for experimental purposes. The purpose of this project is to design and test a cross flow heat exchanger (CFHX) with filtered air flow to allow students to gain hands-on learning on Heat Transfer concepts. The air filter ensures virtually no fouling on the fin area and other areas of the heat exchanger. Additionally, the CFHX is expected to be an improvement on the current DLMX CFHX used in the laboratory allowing: the selection of desired water temperatures and flow regimes and the computational collection of data. The final design included temperature, pressure, flow rate, and differential pressure sensors that connect to a Data Acquisition (DAQ) system and NI LABVIEW software. After proper calibration of the sensors, experiments were conducted to test for pressure drop on the air side and overall heat transfer across the system with and without an air filter. The theoretical values showed a pressure drop of 70 Pa and 120 Pa for air flow velocities of 2.98 m/s and 4.86 m/s, respectively, which corresponded to the speed settings of the fan. These settings result in the overall heat transfer rates were 492.4 W and 707.6 W for corresponding laminar and turbulent flow regimes. The results indicate a pressure drop across the heat exchanger including an air filter and the theoretical values were consistent with experimental values. Overall, the CFHX can be an improvement since it allows for the automatic collection of data and the ability to experiment with different flow regimes and temperatures.