The refrigeration industry is increasingly concerned by designing low refrigerant charge systems to comply with the existing restrictions for new refrigerants, while ensuring that heat pumps using the alternative refrigerant can be at least as energy efficient as the conventional ones. In particular the heat exchangers have a relevant role because most of the charge stays into their volume. In order to optimally design heat exchangers for heat pumps, it is important to analyse in detail the heat transfer mechanisms at component level, but also to consider the integration of the component within the system.
The involved research groups work on these topics and strive to continuous innovation in the field.
The research group Flexible Heat Pumps and Cooling Systems (, belonging to the Mechanical Engineering Department and located at the KU Leuven campus in Geel and linked to the research activities in Energyville, has a wide experience in Heat pump technology and system modelling.

The project aims to propose a novel approach to design (parts of) compact heat exchangers(HX) in a heat pump (HP) in which the design freedom provided by additive manufacturing techniques is exploited. To this end, detailed flow and heat transfer models are composed to improve the component design, while taking into account the system level to ensure optimal system performance. 

The main research objective of this project is the reduction of the refrigerant charge in the heat exchangers by means of design innovation.

The PhD candidate will be responsible to setup a heat pump model with a detailed representation of the heat exchangers. A special focus will be on the evaporator and the problem of frosting formation in air source heat pumps. Laboratory testing will be required to analyse this phenomenon. Interactions with other PhD students involved in the project and responsible for other tasks will be requested.


  • Master Degree (MEng or MSc degree or equivalent) in a relevant field for the project content (mechanical engineering, energy engineering or related subjects), where the student distinguished him/herself for the good results achieved.
  • Proficient knowledge of English. The English proficiency test scores accepted by KU Leuven are the TOEFL certificate, IELTS certificate, and Cambridge C1 Advanced (CAE) or C2 Proficiency (CPE) certificate, check on
  • Experience with programming languages is considered beneficial (software that can be used in the project: Python, Matlab, Modelica)
  • Willingness to cooperate in an open and multi-disciplinary environment, creative mind set and ability to take initiatives

We offer a 4 year contract as PhD student within a collaborative project at KU Leuven. The contract can start after October the 1st 2022 (to be agreed). The candidate will attain a PhD degree reflecting skills in modelling, design and testing of heat exchangers and heat pumps using natural refrigerants.

PhD scholarship: