Abstract
The objective of the present work is the investigation of a novel polygeneration system for power, refrigeration and heating production at two temperature levels. The present system uses CO2 as the working fluid, which is an environmentally friendly fluid. The total configuration is a combination of a transcritical refrigeration cycle coupled to a Brayton cycle with recompression, which is fed by a biomass boiler. The examined system, at nominal operating conditions, produces refrigeration at 5 °C, and heating at 45 °C and 80 °C. Additionally, the system can be converted into a trigeneration system where the two heating outputs are produced at the same temperature level. The system was studied parametrically by changing the following seven critical parameters: turbine inlet temperature, high pressure, medium pressure, heat exchanger effectiveness, refrigeration temperature, heat rejection temperature and high heating temperature. In nominal operating conditions, the system energy and exergy efficiencies were 78.07% and 26.29%, respectively. For a heat input of 100 kW, the net power production was 24.50 kW, the refrigeration production was 30.73 kW, while the low and high heating production was 9.24 kW and 13.60 kW, respectively. The analysis was conducted with a developed model in Engineering Equation Solver.
Highlights
Renewable energy utilization is an important weapon for tackling critical energy problems such as fossil fuel depletion, global warming, increasing energy demand and increasing electricity prices [1,2,3]
The objective of the present work is the investigation of a novel polygeneration system for power, refrigeration and heating production at two temperature levels
The total configuration is a combination of a transcritical refrigeration cycle coupled to a Brayton cycle with recompression, which is fed by a biomass boiler
Summary
Renewable energy utilization is an important weapon for tackling critical energy problems such as fossil fuel depletion, global warming, increasing energy demand and increasing electricity prices [1,2,3]. The concept of using renewable energy sources to feed polygeneration systems is a viable and environmentally friendly solution for future sustainable systems. Another important aspect of these systems is their use of environmentally friendly working fluids, which are usually natural fluids such as CO2, NH3, propane and butane [6]. These fluids present some limitations, which are related to performance, toxicity and flammability. There are alternative working fluids (not natural) that have zero ODP and a not so high GWP (
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