Heat pumps at drinking water utility building

Abstract

Consulta en la Biblioteca ETSI Industriales (8999)

In the United States each person consumes about 70 million BTUs each year in the residential sector, a tendency that is constantly growing because of technology and society growth (EIA, 2011). The United States department of energy (USDOE, 1988) reported that heat pumps are energy efficient devices that can provide heating and cooling in residential and industrial buildings and also in households. According to Bernier (2006) they offer many advantages such as decreased space needs, higher efficiencies, lower maintenance costs etc. and that is why they have been implemented in many regions throughout the United States as well as in many European countries. However, their use is many times hindered due to the high initial costs relative to conventional heating air conditioning ventilating systems (HVAC), technologies that are widely known and have been used for many years. The purpose of this thesis is to analyze the performance, economic feasibility, and greenhouse gas emission reduction of implementing heat pump devices in drinking water plants for heating and cooling needs inside the building. The proposed system is similar to groundwater heat pumps (described in an upcoming section) but instead of groundwater the heat pump relies on drinking water that has been treated in the plant and it is ready for its use. Groundwater has one main advantage because it is at a constant temperature year round (NRC, 2005) which gives the heat pump system stability in its behavior. Moreover, it is at a higher temperature than air in winter, and at a lower temperature than air in summer, which makes it an excellent candidate for heat transfer purposes in the refrigeration cycle. The four cases studies described in this work examine medium and high efficiency heat pumps installed in existing plants and new plants. Because drinking water is readily available after its treatment, the cost of drilling and grouting is avoided and this high quality water also avoids most of the problems related to quality of water such as scaling or fouling. This system gives a return of investment that is in all cases lower than six years. emissions are reduced by about 50 per cent because the use of a much more efficient device produces less for each kWh of heating or cooling delivered in the building.