Utilizing outdoor temperatures in cold climates for household refrigeration and cooling applications
Kim, Viacheslav (2025)
Kandidaatintyö
2025
School of Energy Systems, Energiatekniikka
Kaikki oikeudet pidätetään.
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2025080180638
https://urn.fi/URN:NBN:fi-fe2025080180638
Tiivistelmä
Improving the energy efficiency of household refrigeration systems is an important step toward reducing electricity consumption, environmental impact, and long-term operating costs. This thesis investigates the potential benefits of utilising naturally cold outdoor air as a heat rejection source for the condenser in residential refrigerators.
A dynamic simulation model of a residential refrigerator was developed in Simulink, based on a residential refrigeration model provided by MathWorks(2023). The model was modified to include a dual-condenser setup with supervisory valve control, allowing the system to switch between indoor and outdoor heat rejection. Several simulations were conducted, comparing system performance under different outdoor temperatures. Performance metrics such as compressor mechanical power, ON/OFF cycle frequency, duty time, and energy consumption were extracted and analysed.
The results show that using outdoor air for condenser cooling can significantly reduce compressor workload. At 10 °C, mechanical energy use dropped by 27% compared to the baseline 25 °C indoor case. Lower ambient temperatures led to even more reduced energy consumptions up to 90%, however those conditions are not as common in the world and have their complications.
This work contributes to the target of the European Union to reduce energy consumption of refrigerators to 114 kWh/year per unit by 2030 by demonstrating practical methods for improving refrigeration efficiency. The findings suggest that combining outdoor cold utilisation offers a promising pathway to further energy reductions in residential cooling systems.
A dynamic simulation model of a residential refrigerator was developed in Simulink, based on a residential refrigeration model provided by MathWorks(2023). The model was modified to include a dual-condenser setup with supervisory valve control, allowing the system to switch between indoor and outdoor heat rejection. Several simulations were conducted, comparing system performance under different outdoor temperatures. Performance metrics such as compressor mechanical power, ON/OFF cycle frequency, duty time, and energy consumption were extracted and analysed.
The results show that using outdoor air for condenser cooling can significantly reduce compressor workload. At 10 °C, mechanical energy use dropped by 27% compared to the baseline 25 °C indoor case. Lower ambient temperatures led to even more reduced energy consumptions up to 90%, however those conditions are not as common in the world and have their complications.
This work contributes to the target of the European Union to reduce energy consumption of refrigerators to 114 kWh/year per unit by 2030 by demonstrating practical methods for improving refrigeration efficiency. The findings suggest that combining outdoor cold utilisation offers a promising pathway to further energy reductions in residential cooling systems.