Work

Investigation of heat recovery in CO2 refrigeration cycles for supermarkets: A mechanism for determining optimal discharge pressure

Year: 2025

Type: article

Abstract: The benefit of two-stage heat recovery compared to one-stage heat recovery is not deeply investigated in CO 2 refrigeration systems with heat recovery in supermarkets. Moreover, the optimum discharge pressure respecting the thermodynamic principles governing the heat recovery heat exchangers, has not been defined. This study addresses this research gap combining existing knowledge of the pinch point in CO 2 heat pump gas coolers and supermarket refrigeration systems with heat recovery. This novel approach leads to more accurate control and design inputs for the commercial refrigeration industry. Key findings of the study in a Swedish supermarket show that two-stage heat recovery, compared to one-stage, improves the Seasonal Performance Factor for heat (SPF) by 17 %, with the refrigeration cycle’s annual energy savings reaching up to 4 % in cold climates. Additionally, heat export capabilities to district heating networks are explored, demonstrating a 25 % efficiency improvement with a two-stage configuration instead of a one-stage configuration. Moreover, increasing the discharge pressure by less than 5 bar compared to the optimum value can reduce the total required UA-value of the heat recovery heat exchangers by 45–48 %, with a maximum SPF penalty of 2.8 %

Source: Applied Thermal Engineering

DOI: 10.1016/j.applthermaleng.2025.126728

Author: Sotirios Thanasoulas

Institution: KTH Royal Institute of Technology

Language: English

Topic: Refrigeration and Air Conditioning Technologies

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Climate action, Responsible consumption and production, Affordable and clean energy

Open Access status: hybrid

Estimated APC paid: $3,660