The Solar Thermal Energy Research Group has recently welcomed three students from Eindhoven University of Technology in the Netherlands: Job ten Hacken, Roel Hazelhof and Tijn van Rooij. These three masters students in Mechanical Engineering are doing a three-month internship at STERG.

Job’s project under the supervision of Prof Jaap Hoffmann at STERG, aims to measure the contact resistance between crushed rock particles found in packed rock beds. This includes designing an experimental setup. To achieve this, he says: “I have designed an experimental setup where two cylindrical rock samples are stacked onto each other, one of the rocks is heated and the other one is cooled, creating a heat flux between them. During the experiment, temperatures will be measured at different locations within the rocks by inserting thermocouples in small holes drilled in the rocks. An important aspect of the experiment is minimizing heat loss, as it will significantly impact the results. The temperature data collected will allow me to calculate the thermal contact resistance between the rocks.”

In his free time, Job enjoys going to the gym, road cycling, playing piano and spending time with friends. Another passion of his is skiing, which he looks forward to doing during the Christmas Holidays. In the coming months, Job intends to learn more about the South African culture and explore the country.

 

Roel’s project is also under the supervision of Prof Jaap Hoffmann. Regarding his research, he says: “I will be conducting research on the behaviour of fluid flow through a rock bed in the transitional regime between laminar and turbulent flows. The rock bed is used to store heat as part of the late Prof. Kruger’s Sunspot cycle. An important parameter of heat transfer between the fluid and the rocks is the behaviour of the flow between the rocks. To this end, we want to gain more insight in how the flow develops in the transitional regime experimentally. I will try to achieve this using Particle Imaging Velocimetry: this means that my project entails designing a see-through rock bed and a flow circuit that allows for the imaging of the velocity fields in the body of the flow. Using the results of this future numerical models can be validated and understood better.”

In his spare time, Roel thoroughly enjoys socialising, whether it be by grabbing a drink, watching sport or attempting a new hobby. During his stay, Roel intends to learn more about the South African culture and explore the country.

 

Tijn’s research under the supervision of Prof Craig McGregor at STERG, focusses on the behaviour of bricks under high temperatures in a molten salt bath and simulating the thermal energy storage of concentrating solar power (CSP) plants. Tijn expands upon his research by stating: “Molten salt is quite expensive, so combining it with rocks could be a potential solution. However, a major challenge with rocks is a phenomenon known as ratcheting (this happens when the reactor expands more than the rocks, and since the rocks are thrown in randomly, they shift slightly downward after expansion. When the reactor cools and contracts, it ends up smaller at the top than the bottom). My work involves investigating a structural setup using bricks as a possible solution, ensuring they remain inert when immersed
in molten salt for extended periods. Additionally, I’m working on developing a 3D model of the bricks to explore optimal properties and how voids within the bricks may impact performance.”

Outside of his research, Tijn enjoys running and recently participated in the Chapman’s Peak Marathon. He is also an avid football fan, including both watching and playing the sport. Tijn expands upon his hobbies by stating: “When I’m not running or on the field, I enjoy going out with friends and playing games (I know, quite basic, right?). I love backpacking and travelling. Last year, I spent six months in Central and South America.” Tijn intends to explore South Africa during his stay and has his sights set on Southeast Asia next year.

 

Credit: Benjamin Gardiner and Leigh van der Merwe