Analysis of Ground Coupled Heat Exchanger Efficiency Brett Walsh Master of Engineering In Mechanical Engineering Rensselaer Polytechnic Institute at Hartford

Introduction/Background Improve the efficiency of heating, ventilation and air conditioning (HVAC) systems. A ground coupled heat exchanger can be used in either a heating or cooling mode by taking advantage of a “near constant” ground temperature. The “near constant” ground temperature can be used as either a heat sink to remove heat to cool a building or as a heat source to heat a building.

Problem Description Analyze the efficiency of a ground coupled heat exchanger in an effort to optimize an already efficient design. Analysis will be performed for a ground coupled heat exchanger that utilizes the following –Open and/or Closed loop –Single or multiple passes –Multiple fluids Calculations will be performed to determine the outlet temperature and efficiency based on varying inlet and exterior temperatures.

Methodology/Approach This study will use an analytical and numerical approach to analyze the efficiency of a ground coupled heat exchanger. Heat transfer analysis will involve the use of conservation of energy, the heat transfer rate equation, and the evaluation of the total thermal resistance between the two fluids (i.e., between the air or other fluid and the ground). The two common methods: –Log Mean Temperature Difference (LMTD) –Effectiveness-NTU (ε-NTU) LMTD method will be used to optimize the various ground coupled heat exchangers designs and analyze their efficiency.

Resources Required The resources required for the complete of this project are including, but not limited to, the use of the following textbooks: –Introduction to Thermodynamic and Fluids Engineering –Convective Heat and Mass Transfer –Fundamentals of Engineering Thermodynamics –Transport Phenomena Microsoft Office and COMSOL Multiphysics will be used for analysis, post processing, and compilation.

Expected Outcome The expected outcome for this project is have a complete analysis of a ground coupled heat exchanger that utilizes an open and/or closed loop, that is either a single or multiple pass heat exchanger and that uses of different fluids in the system. This analysis will be used to determine what is the optimal ground coupled heat exchanger design based on the efficiency of the system.

Milestones/Deadlines DeadlineMilestone 9/30Complete Project Proposal 9/30Start COMSOL simuation 10/7Complete Open Loop – Single Pass Calculation for Air 10/9Complete Open Loop – Multiple Pass Calculation for Air 10/14Complete Closed Loop – Single Pass Calculation for Air 10/16Complete Closed Loop – Multiple Pass Calculation for Air 10/18Analyze/Compare Calculations for Air 10/20Post Process First Progress Report 10/21Complete First Progress Report 10/26Complete Open Loop – Single Pass Calculation for Second Fluid 10/28Complete Open Loop – Multiple Pass Calculation for Second Fluid 11/2Complete Closed Loop – Single Pass Calculation for Second Fluid 11/3Complete Closed Loop – Multiple Pass Calculation for Second Fluid 11/4Analyze/Compare Calculations for Second Fluid 11/11Complete Second Progress Report 11/18Complete COMSOL Simulation 11/26Analyze/Compare COMSOL Simulation with Calculation Performed for the Two Other Fluids 12/2Complete Final Draft 12/16Complete Final Report