The next steps towards changing the heating system in our device have been made. The currently used heating system is based on the conduction of heat through a shelf under which a heating mat is placed to the product. In the prototype device, the product drying process will be based on the application of heat by means of microwaves. Below we present the preliminary numerical results of a freeze dryer equipped with three magnetrons emitting microwaves towards the product. The magnetrons were placed on three sides of the chamber, namely the upper and side walls.
Recently, the activities of the project team have focused on developing the concept of a prototype of a freeze dryer equipped with microwaves and a new cooling system.
The proposed ideas for a new device geometry are based on the following modifications:
- internal evaporator with microwave membrane
- the use of the position of the zigzag-shaped shelves
After selecting a new refrigerant, it is time to redesign the refrigeration system, i.e. select the appropriate components, including the shape and length of the evaporator. The FrostWave team decided to move from an external evaporator (coil) to a microchannel evaporator located inside the chamber. In parallel with these activities, steps relating to a method for applying microwave heating have been taken.
The FrostWave team has just started working on the concept of a new device!
The first changes will concern the cooling system. A major step will be to switch from the current synthetic refrigerant with a relatively high GWP (Global Warming Potential) to a natural working fluid. Thanks to the analysis carried out by the NTNU team, two potential substitutes for the currently used refrigerant were identified, namely R290 (propane) and R1270 (propylene).
On October 27, part of the SUT team visited the Zespół Szkół Łączności im. prof. Stanisława Fryzego in Gliwice. The purpose of the visit was to familiarize high school students with what research groups operating at the Silesian University of Technology do, and thus what they themselves would have the opportunity to do in the near future by joining our ranks. As part of the promotional presentation, prof. Jacek Smołka and MSc.
On Saturday, October 9, 2021, we had the pleasure to participate in the 16th edition of the Scientists' Night of the Silesian University of Technology. During the visit to the SUT laboratory, our guests could learn a bit about the freeze-drying of food and get acquainted with our experimental rig. Thank you for visiting us and we hope to meet you next year at the next edition of the Scientists' Night!
We are pleased to announce that the freeze dryer has been successfully equipped with high-class Endress + Hauser sensors. Additional equipment allows for accurate measurement of pressure and flow of the working fluid in the cooling system. Due to the dimensions of the sensors, the SUT team prepared a special table on which they were placed. In addition, the data acquisition system has been expanded with additional modules that support the devices described above.
After a series of successful experiments conducted in SUT laboratory, in the next step, the lyophilisator will be equipped with high-quality pressure and flow sensors for comprehensive monitoring of the refrigeration cycle. For that reason, the device left SUT laboratory and will be modified at FrostX workshop, where high-class Endress+Hauser sensors will be installed in the refrigeration cycle.
Based on the geometric model of the computational domain shown in the figure below
a simulation model of the lyophilisation process is currently being developed. The computer code generated in the Matlab package is then coupled (at each time step) with the code generated in the Ansys / Fluent package. The obtained numerical results are also compared with the results of thermal measurements.
SINTEF & NTNU are organising The 15th IIR-Gustav Lorentzen Conference on Natural Refrigerants in 2022. Two members from the SINTEF and NTNU teams of our project are actively involved in organisation of this conference. Prof. Trygve M.