Silje Marie Smitt, PhD, NTNU (associated PhD)

The hotel sector features high thermal demands, often realised through processes that advance the global warming effect. Excessive energy use within the hotel sector in cold climates is primarily due to the thermal energy production of domestic hot water, space heating and cooling. Heat pump systems satisfy these criteria by reducing energy consumption and operational costs related to thermal energy production. The application of natural and environmentally friendly refrigerants, such as CO₂, has gained much attention as an approach to reduce greenhouse gas emissions from refrigeration, air-conditioning, and heat pump systems. The focus of my research has been to investigate potential, design and control strategies for “all-in-one” CO₂ heat pump and chiller units with thermal storage for the hotel sector. This research work includes a large-scale investigation of the market potential of integrated CO₂ systems within the Nordic hotel sector, an in-depth performance evaluation of an integrated CO₂ hotel unit, and, finally, numerical evaluations of designs and control strategies to enhance performance.