Multi-function thermal system with natural refrigerant for a wide temperature range

Highlights: • An integrated cooling and heating system with natural refrigerants is proposed. • The system can cover −50 to 160 °C with cooling, heating and steam supply. • The optimal recovery ratio is selected according combined system COP. • Economic and environmental analysis of several heating systems is conducted. -- Abstract: The Multi-function thermal system with wide temperature range (−50 °C to 160 °C) is proposed. As the cooling also belongs to a type of thermal energy supply, the proposed system can output several integrated heat source at the same time, named Multi-function thermal system finally. It is composed of refrigeration, heat recovery, vapor generation and vapor boosted systems for industry applications where cooling, heating and steam are required simultaneously. To validate the system feasibility and application effect, the proposed system was demonstrated in a poultry slaughtering plant with the temperature range of −40 °C to 125 °C. The NH₃ refrigeration system can maintain temperature at −40 °C. The condensing heat is recovered by the NH₃ heat pump system to produce 60 °C and 80 °C hot water. A sensible heat recovery system is added to heat the hot water from 80 °C to 90 °C. The 80–90 °C stored water is heat source for water vapor heat pump system to produce 125 °C steam. The system design, equipment selection and load matching strategy are introduced in detail. To further investigate the features of Multi-function thermal system, economic analysis compared with other methods is conducted. Results show that although the initial investment of integrated system is larger, the energy saving effect is remarkable and pollutant emission is less.