Heat pumping technologies for refrigeration, air conditioning, and heating applications are expected to have greater role in our future energy systems, which means that more efficient and environmentally friendly systems will be needed.
An efficient refrigeration and heat pump system will have to be equipped with the most efficient and cost effective components. They should also be working with environmentally benign refrigerants.
The local and global actions that have been taken to protect the environment in the past decades forced the refrigeration and heat pumping industry to go through transition periods when it comes to the refrigerants that can be used. This created an increased and continuous need of research on refrigerants in the past 2-3 decades, therefore, several projects at the division have been investigating the use of natural refrigerants such as propane, isobutane, ammonia, and carbon dioxide in heat pumping and refrigeration systems. Refrigerants with very low global warming potential have also been extensively investigated. The division has also been at the forefront in publishing thermo-physical and performance characteristics data of heat transfer fluids, which are also referred to as secondary fluids or brines.
With new refrigerants and higher demand on efficiency new highly efficient compressors, heat exchangers, and expansion devices need to be developed. With new system solutions the use of non-conventional components such as expanders, gas ejector, and liquid ejector have been emerging, which also have been investigated within different research projects. The research on components at the divisions is strongly supported by the in-house competence in heat transfer, modelling, and laboratory infrastructure.
The research conducted in this area covers:
Heat exchangers
Fluids (refrigerants and secondary fluids)
Compressors
Projects
Related research projects at the division during the last ten years:
Propane in residential heat pumps
Ammonia in small scale residential heat pump
Carbon dioxide in commercial refrigeration
Heat transfer fluids (secondary fluids)
Low global warming potential refrigerants
Heat exchangers for minimum charge propane, isobutane, and ammonia systems
Compressors for ammonia and propane heat pumps
Alternative secondary fluids for indirect refrigeration systems
The secondary fluid is a complex mixture which also contains pH adjusting agents, antioxidants, anti-foaming agents, stabilizers, colorants, etc. These additives can stabilize and improve the fluid performance but also affects the thermophysical properties. Secondary fluid is water-based solutions of organic or inorganic substances (such as alcohols, glycols and salts) used in various indirect refrigeration systems and heat pumps. The advantages of the indirect refrigeration systems are: low refrigerant charge, low risk of refrigerant leakage, the fact that the primary refrigerant system is localized in the machine room, easy and precise control, no oil recovery problems, refrigerants like ammonia and hydrocarbons can be used; easy maintenance, no technical limitations on the distance between refrigeration and machine room, plastic pipes can be used and that it will be longer intervals between defrost periods when air cooling due to more uniform frost formation.
The overall objective of this project is to develop a structured method to approach the challenge of better understanding the techniques and potential for capacity control in Heat pump systems with a focus on Ground Source Heat Pump (GSHP) systems.
Digitalization and IoT technologies for Heat Pump systems
In the last decades digital technologies became widely used in energy end-use sectors and digital solutions have been driving dramatic changes in the society. In the years to come, Heat Pumps will become connected devices
participating in the Internet of Things (IoT).
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
Smart Control Strategies for Heat Pump Systems (completed)
A new perspective for improving the heat pump system performance can be given by the development of enhanced system control strategies able to achieve a considerable increase of the system Seasonal Performance Factor together with a reduction of operation and maintenance costs.
Tank to Grave Management of new Low-GWP Refrigerants (Hantering av nya låg-GWP köldmedier från installation till destruktion)
The project “Tank to Grave Management of new Low-GWP Refrigerants” is a project funded within the Termo program (heating and cooling for future energy systems), the 5th funding call (contributing to a Sustainable Energy System through Heating and Cooling) by the Swedish Energy Agency.
