Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

In the present work, a charge-sensitive numerical model under extit{Matlab} environment is developed to simulate the blood bank refrigerators line of extit{B Medical Systems}, a Luxembourg-based pioneer in the medical equipment industry, specialising in research, development and the manufacturing of professional refrigerators, freezers and solutions for safe transport and management of blood and vaccines.\

A particular focus is given on the capillary tube modelling. In the case of small-scale units, the refrigerant flow inside the capillary tube is choked, which results in the settlement of a maximum mass flow rate in the system along with a critical pressure level. The detection and computation of these critical conditions are of utmost importance for the cooling system performance simulation. A dichotomy-like algorithm is self-implemented for the capillary tube. 

The numerical simulation of cool-down and stable running conditions tests is carried out. The different modelling assumptions led to convergence issues for the cooling system model, mostly due to an improper refrigerant charge prediction in the heat exchangers. This model being highly implicit, large tolerances on the residuals had to be implemented to achieve convergence. It results that the proper simulation of the heat exchangers is of utmost importance for a charge-sensitive model.\

An experimental simulation of a specific refrigerator is also carried out. 
The experimental and numerical results comparison put into light the difficulty to accurately model the temperature spatial distribution inside the cabinet and their evolution through time.

thermodynamic --- refrigeration --- Ingénierie, informatique & technologie > Energie

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

This master thesis reports the contributions made to the RenewBat project during the end-of-study internship. The project focused on building and operating a 10kWe-scale thermally integrated and reversible ORC-based Carnot battery demonstration plant con- nected to the district heating of the University of Liège.
This type of system can be built with different architectures. The first part of this work justifies the technological choices made on the basis of previous laboratory experiments and the literature. The sizing and selection of components are also described. This sum- mary will help the scientific contributors to better grasp the project, and will provide a basis for discussion on the design of similar systems.
A significant part of this work consists in rigorously redefining the project’s objectives and the requirements needed to achieve them. Ultimately, the system will have to be fully automated and meet industry requirements, so that the results can make a significant contribution to the research field. The KPIs that can be achieved and that will contribute to the maturity of the technology are identified. Possible improvements to optimize these KPIs over the duration of the project are outlined.
Based on the architectural choices and the constraints defined by the project objectives, the final design is proposed. Particular attention is paid to circuits sizing to maximize components and overall system performance. Opperability and safety constraints are also taken into account. Sensors are discussed in order to minimize costs while enabling optimal control, which will be the key to achieving the best system performance.
An original off-design modeling method is proposed for the system. This development follows the control requirements identified. Particular attention is paid to auxiliary con- sumptions (water pumps, dry cooler), the efficiency of electric motors, and the physical limits of components, so that the results obtained correspond to a realistic system imple- mented in a significant environment. This model is used to identify tests to be carried out during system installation to obtain data that cannot be collected once the demon- stration plant is operational. In the medium term, it will provide a basis for fine-tuning the system. In the long term, once the model is fully calibrated, the KPIs can be extrap- olated to cover the entire operating range of the system, enabling control optimization.
The final results of the project will be used to assess the benefits of the technology for identical configurations and power levels. Application to cases varying in one of these two characteristics is not trivial, however, and will require additional modeling work. A systematic methodology for selecting suitable cases for Carnot batteries integrating waste heat recovery in industry is proposed.

Ingénierie, informatique & technologie > Energie

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

This thesis aims at developing, optimizing and controling a hybrid solar microgrid for rural electrification and heat supply in sub-Saharan Africa. The considered system includes PV, Parabolic Trough Collectors, Organic Rankine Cycle and LPG generator, as well as chemical battery storage and thermal energy storage. The work focuses on multiple aspects of the ongoing development of solar hybrid microgrids for the rural electrification of remote areas in Lesotho. These aspects range from very specific improvements (the mechanical design of a high expansion ratio expander) to the more global evaluation of their impact once included into a complex micro-grid system. Special attention has also been paid to the links between thermal and electrical demands.

The main contributions of this thesis are:
- The mechanical design of a high expansion ratio scroll expander, involving drawing, machining and assembly of the parts. 
- The detailed model of an organic Rankine cycle with the purpose of evaluating the improvement brought by the high expansion ratio scroll expander and mapping the ORC performance.
- A building model developed to predict the thermal loads of a health clinic in rural communities of Lesotho. The developed lumped-parameter model can be used for various building typologies and communities. The model is designed to be as generic and simple as possible, and contrasts with the data-intensive models generally proposed in the literature.
- The gathering of monitoring and weather data relative to a health clinic in Lesotho, and their use for the calibration of the building model.
- A microgrid model built by interconnecting all of its subcomponent models. A rule-based control strategy is developed, accounting for interactions between thermal and electrical loads, and dispatching heat and power flows of each component in order to cover the demand while minimizing the fuel consumption.
- A particle-swarm optimization model used to optimize the microgrid under different cost assumptions and control strategies

The above models prove that the system performs better with the developed high expansion ratio expander. The maximum output power of the ORC is increased by 33 %, and the fuel consumption of the microgrid is reduced by 25 %.

For the studied community of Ha Nkau in Lesotho, the determined optimal system infrastructure is composed of PV (65 kW) and batteries (259 kWh) only, and the optimum control strategy achieves a levelized cost of electricity of 0.202 USD/kWh. Fuel consumption is mainly due to the burner, which supplies all the thermal load because no other heating system is selected by the optimization.

modeling --- optimization --- microgrid --- rural electrification --- ORC --- scroll expander --- heat supply --- control --- rule based control --- Lesotho --- Ingénierie, informatique & technologie > Energie