Dynamic equation-based thermo-hydraulic pipe model for district heating and cooling systems

Simulation and optimisation of district heating and cooling networks requires efficient and realistic models of the individual network elements in order to correctly represent heat losses or gains, temperature propagation and pressure drops. Due to more recent thermal networks incorporating meshing decentralised heat and cold sources, the system often has to deal with variable temperatures and mass flow rates, with flow reversal occurring more frequently. This paper presents the mathematical derivation and software implementation in Modelica of a thermo-hydraulic model for thermal networks that meets the above requirements and compares it to both experimental data and a commonly used model. Good correspondence between experimental data from a controlled test set-up and simulations using the presented model was found. Compared to measurement data from a real district heating network, the simulation results led to a larger error than in the controlled test set-up, but the general trend is still approximated closely and the model yields results similar to a pipe model from the Modelica Standard Library. However, the presented model simulates 1.7 (for low number of volumes) to 68 (for highly discretized pipes) times faster than a conventional model for a realistic test case. A working implementation of the presented model is made openly available within the IBPSA Modelica Library. The model is robust in the sense that grid size and time step do not need to be adapted to the flow rate, as is the case in finite volume models.status: publishe

Ion beam techniques for nuclear waste management

An automated CO2 gas handling and injection system was developed. It is designed to dilute CO2 samples with blank gas in a mixing volume. The system is intended to be used for the characterization and quantification of 14C content in reactor graphite with accelerator mass spectrometry. A 100 kV accelerator system was developed to measure samples with high 14C content, to test the gas injection system and to measure the 3H content from gaseous releases of reactor graphite. Additionally, the Tandetron model 4130 was purchased from the Max-Planck Institute for Biogeochemistry Jena (Germany) and a concept was developed for installation at the accelerator building of the University of Cologne. With the new 3 MV system, new isotopic ratio measurements and ion beam techniques for material analysis can be performed. The system will be used for nuclear waste management measurements of isotopes, e.g. 3H, 14C, 36Cl, 41Ca and 55Fe, which are difficult to measure with other techniques

Ion beam techniques for nuclear waste management

An automated CO2 gas handling and injection system was developed. It is designed to dilute CO2 samples with blank gas in a mixing volume. The system is intended to be used for the characterization and quantification of 14C content in reactor graphite with accelerator mass spectrometry. A 100 kV accelerator system was developed to measure samples with high 14C content, to test the gas injection system and to measure the 3H content from gaseous releases of reactor graphite. Additionally, the Tandetron model 4130 was purchased from the Max-Planck Institute for Biogeochemistry Jena (Germany) and a concept was developed for installation at the accelerator building of the University of Cologne. With the new 3 MV system, new isotopic ratio measurements and ion beam techniques for material analysis can be performed. The system will be used for nuclear waste management measurements of isotopes, e.g. 3H, 14C, 36Cl, 41Ca and 55Fe, which are difficult to measure with other techniques