Technical University of Denmark: Students realize big cost saving in DTU’s refrigeration system

As part of their undergraduate programme, Jonas Sønder Nielsen and Adam Mark Berman have prepared a model of one of DTU’s refrigeration systems. More specifically, a model of a plant used to cool the water in one of DTU’s fish pens.

“The model formed part of an assignment in a course on which we learned to develop and use digital models. We were made aware that it might be interesting in this connection to take a closer look at the refrigeration system in the fish pen. DTU’s Campus Service—which is responsible for maintenance and operation of the University—was keen on the idea and gave us access to data from the refrigeration system, and we were subsequently allowed to perform our own measurements,” says Jonas Sønder Nielsen.

Based on data, the two students built a digital model of the refrigeration system. Such a model is typically used to optimize operations, but it obviously requires that you first validate the model so that it corresponds to reality.

“When we started performing our measurements to ensure validation, we quickly discovered that something was completely wrong. However, it wasn’t our model that was wrong, but the refrigeration system that used far more power than it should,” says Adam Mark Berman.

Originally, it was intended that the surplus heat from the cooling system would be distributed internally in DTU’s district heating system, but—due to an undersized water circulation pump—this never happened. The surplus heat was instead cooled down by DTU’s central refrigeration system and was—in other words—wasted.

Improvement potential has been realized
At the end of the course, Jonas Sønder Nielsen and Adam Mark Berman handed in a report in which they described their model in detail and pointed out two possible improvement potential scenarios. One scenario was to optimize the current refrigeration systemso that it does not consume more power than necessary. The second scenario was to invest in a new water circulation pump with such a large capacity that the surplus heat can be utilized in DTU’s district heating system.

The report was sent to, among others, Mechanical Engineer Emil Dybro Jacobsen, who was the two students’ contact person in DTU’s Campus Service.

“It’s a brilliant technical report. However, we’re particularly excited about the conclusions and calculations that show great opportunities for cost savings. Immediately afterwards, we had the pump repaired according to the instructions in the report, which entailed, among other corrections, a new temperature sensor and changes to a valve plate so that it now consumes much less power,” says Emil Dybro Jacobsen.

“We will also soon be buying and installing a new water circulation pump that can utilize the surplus heat. This is fully in line with our work to ensure sustainable solutions thoroughout campus. It also makes sense financially. The students’ calculations showed that the investment will have a recoupment period of just 3-4 months and result in a cost saving of around DKK 350,000 annually.”

Campus Service would like to collaborate with students
Emil Dybro Jacobsen emphasizes that Campus Service is always interested in collaborating with students on specific projects based on the University’s buildings and technology.

Jonas Sønder Nielsen and Adam Mark Berman have been very enthusiastic about the course ‘Simulation of thermal systems’, which they recommend other students to take.

“It’s a course on the methodology and principles behind modelling, which is not only relevant in relation to thermal energy, but can also be used in many other contexts. It’s by far the best course we’ve taken at DTU. Not least because it offers an opportunity to perform assignments that are not only theoretical, but can be applied and make a difference in the real world,” says Jonas Sønder Nielsen.

However, the two students find it puzzling that there is not a greater range of courses offered in thermal energy, especially in the MSc programmes.

“This is not least remarkable in the current situation, where society demands engineers with knowledge of heat pumps and thermal energy systems, which are an important element in the green transition. Hopefully, it will have an impact on the number of courses before long,” says Adam Mark Berman.