Thesis Work – Experimental and Numerical Investigation of Sub-Cooled Droplets Injected into a Steam Environment

Are you a student looking to apply your knowledge to real-world solutions that support the energy transition? With us, you will have the opportunity to complete your thesis project close to the business, working alongside experienced specialists and tackling challenges where your ideas and perspectives can make a real difference. 

About the Thesis Work

The Fluid Dynamics Team within Energy Transfer & Environment (YRLE) at Vattenfall Research & Development is a multidisciplinary group working with fluid flow challenges across Vattenfall’s operations, from hydropower and offshore wind to nuclear energy.

Subject / Assignment

Heat transfer in multiphase flows is a complex phenomenon involving interactions between liquids, gases, and solids. A key application is spray cooling of steam in pressurized water reactors (PWRs), where droplets interact with hot steam and surrounding surfaces.

As part of the AdTherM Competence Centre and its research on multiphase flows, you will:

• Perform CFD simulations in OpenFOAM using different flow, turbulence, spray, droplet, and thermodynamic models.
• Evaluate simulation results against experiments conducted at Vattenfall’s laboratory in Älvkarleby.
• Investigate steam condensation, spray-wall interaction, and heat transfer mechanisms.
• Contribute to the validation and improvement of existing heat transfer models used in industry.
• Have the opportunity to participate in experimental work, including studies using a new miniature test rig and high-speed infrared imaging of droplet behavior in hot saturated steam.

The long-term objective is to improve the accuracy of computational models for multiphase heat transfer processes relevant to the energy industry.

Goal / Purpose

The thesis aims to build understanding of state-of-the-art computational models for:

• Multiphase flows
• Droplet dynamics
• Steam condensation
• Spray-wall interactions
• Heat transfer processes

You will gain hands-on experience in both advanced CFD modelling and experimental validation within a cutting-edge research environment.

We are looking for a student who are about to complete their academic studies and are eager to apply their knowledge in a real-world setting through a thesis project at Vattenfall. You are someone who shares our values and identifies with our principles: Active, Open, Positive and Safety. 

• Master's student in Mechanical Engineering, Engineering Physics, or a related field.
• Thesis scope: 30 ECTS credits (approximately 6 months).
• Strong communication skills in English.

• Start date: January/February 2027 or by agreement
• Location: University (local), Älvkarleby, Solna
• Application – one file containing your CV and a copy of your transcripts
• Application deadline: 2026-10-18
• Contact person and supervisor at Vattenfall:

Eric Lillberg, eric.lillberg@vattenfall.com, +46 (0)70 5372994

Nicolas Edh nicolas.edh@vattenfall.com, +46 (0)70 6522790

Kristian Angele kristian.angele@vattenfall.com, +46 (0)70 6398731

Diversity and Inclusion – In Everything We Do

At Vattenfall, we value being Active, Positive, Open, and Safety-conscious. We are looking for employees who share our vision and can contribute to strengthening our company culture. We believe that diversity helps build a more successful and attractive company, and we strive to be role models in diversity and inclusion. Vattenfall actively works to ensure that all employees have equal opportunities and rights, regardless of age, ethnic or cultural background, gender identity, religion or belief, sexual orientation, or disability. Read more about how we work with diversity and inclusion here.

Vattenfall is part of Sweden’s critical infrastructure, and many of our positions are therefore classified from a security perspective. If this position is security-classified, a security screening will be conducted prior to employment in accordance with the Swedish Security Protection Act.

Vattenfall is a leading European energy company serving approximately 12 million customers and employing around 21,000 people. We believe there is a way to build a future where everyone can choose fossil-free ways to move, make, and live.