AN OPERATING PERFORMANCE STUDY TO ADAPT RETScreen METHODOLOGY TO TREATED WASTEWATER SOURCE HEAT PUMP SYSTEM

A ground source heat pump system (GSHP) is a heating and air-conditioning system where a ground source is used as a heat source and sink. Potential ground sources include groundwater, surface water, and ground. A GSHP has several advantages over other heat pump systems, such as an air-source heat pump, because it has higher heating and cooling efficiency, more energy savings, and lower CO2 emissions. A treated wastewater source heat pump (TWSHP) system is similar to a GSHP system, but the TWSHP system relies on a treated wastewater source, which means that the source temperature is variable. A TWSHP is more convenient and offers greater cost savings; the TWSHP system avoids the costs associated with pumping, grouting, and drilling because the treated wastewater is already available at the surface. RETScreen is a software product that provides a methodology to study the feasibility of installing a constant-temperature source GSHP system. Advantages of using RETScreen include it is tested, valuable, readily available, and free. If design of a variable-temperature source TWSHP system can take advantage of RETSceen methodology, it would bring a tremendous help for TWSHP applications. This paper presents a case study to test whether a TWSHP system can take advantage of RETSceen methodology. The approach involves an assessment of TWSHP system operating performance under variable source temperatures. Results show that a TWSHP system can take advantage of RETSceen methodology for a variable source temperatures span over a certain range. In this study the heating temperature ranged from 9 to 16 ℃ and the cooling temperature ranged from 11 to 22℃. Keywords: treated wastewater source heat pump; RETScreen methodologyM.S. in Environmental Engineering, July 201