Experimental investigations to maximize efficiency of CO2 vapor compression systems
CO2 is an environmentally friendly and cost-effective replacement for synthetic refrigerants used in refrigeration and heat pumps systems. Hence, the installation of CO2 refrigeration system is expected to increase in the coming years. In this project, we will experimentally verify methods to maximize the efficiency of CO2 refrigeration systems
Background
Vapor compression systems using CO2 as refrigerant gained ground in some of the most energy intensive refrigeration and heat pump applications, such as: supermarkets, ice rinks, food processing industries and hot water production for small and large scale. The number of CO2 vapor compression systems is expected to further accelerate in the coming years due to the implementation of the EU F-gas regulations, which ban installing systems with HFC’s in many application areas. The rapid increase of CO2 installations has also led to development of several solutions to increase the efficiency of the CO2 vapor compression system control. Some of these features are: overfeeding of evaporators, heat recovery, integrated air conditioning, geothermal integration, ejector and liquid ejector, and mechanical sub-cooling. These energy efficiency solutions must be refined and verified through experimental investigations
In this project we are experimentally investigating a number of these energy efficiency solutions using the facilities at the laboratory if the energy technology department at KTH. The laboratory has a 4-room climate chamber which can be maintained at two temperature levels of -10 and -35 0C. The climate chamber is cooled using a CO2 booster system equipped with two level heat recovery unit, two phase ejector, option for mechanical sub-cooling. Additionally, the lab is equipped with a CO2 test rig that can be used a cascaded system along with the cooling system of the climate chamber to independently test methods for overfeeding the evaporator and liquid ejector. These facilities will be used to experimentally investigate various energy efficiency solutions of CO2 vapor compression systems in this project
Aim and objectives
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Experimentally evaluate features to maximize the energy efficiency of CO2 vapor compression systems
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Experimentally evaluate at least 4 methods of overfeeding the evaporators
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Investigate the heat recovery function of the system for the applications of space heating
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Experimentally verify performance of the ejector and liquid ejector, domestic hot water, and exporting heat to district heating
Project partners
KTH
Advansor AB
Danfoss AB
Green & Cool
HB products
Huurre Sweden AB
ICA Fastigheter AB
IWMAC Operation Center
LU-VE Sweden AB
Svensk Energi & Kylanalys
Funding is provided by Energimyndigheten.
Timeframe: 2022-2025
Researchers
