Two-phase expansion is the process where a fluid undergoes a pressure drop through or in the liquid–vapor dome. This operation was historically avoided. However, currently it is studied for a multitude of processes. Due to the volume increase in volumetric expanders, a pressure drop occurs in the fluid resulting in flashing phenomena occurring. These phenomena have been studied before in other processes such as two-phase flows or static flash. However, this has not been extensively studied in volumetric expanders and is mostly neglected. Even if data has shown this is not always neglectable depending on the expander type. The thermal non-equilibrium occurring can be modeled on different principles of flashing flows, such as the mixture model, boiling delay model, and homogeneous relaxation model. The main application area in current literature for volumetric two-phase expansion machines, is in low-temperature two-phase heat-to-power cycles. These cycles have shown benefit over classic options if expanders are available with efficiencies in the range of at least 75%. Experimental investigation of expanders in two-phase operation, though lacking in quantity, has shown that this is an achievable goal. However, the know-how to accomplish this requires more studies, both experimentally and in modeling techniques for the different phenomena occurring within these expanders. The present work provides a brief but comprehensive overview of the available experimental data, applicable flashing modeling techniques, and available models of volumetric two-phase expanders.

In this work, a proof of concept design for a poultry meat farm is studied. The design aims to be climate-neutral and energy-flexible by applying different technologies such as PV panels, PVT panels, BEO field, and high and low-temperature heat pumps. In order to size these systems, the farm's required heating, cooling power and (de)humidification rate has to be estimated, which is the focus of the current paper. For this purpose, a model was created in the Python environment. Based on the building's current design, expected weather conditions throughout a model year, and the required conditions for the chickens' well-being, the heating and cooling loads are calculated. The analysis does not yet take into account which technology is used to supply the heat as the sizing will be done based on the results of this analysis. In addition to the 'standard' climate requirements, some pens will be used to study the behaviour of the chickens during alterations in the temperature and humidity of the pen. These tests are predefined and the HVAC installation should be able to handle these test conditions as well. The results of the model can be used as a guideline to size the different HVAC systems. However, as the model is based on assumptions and simplifications, a sensitivity analysis was performed as well. This analysis shows that the conductive losses are small compared to ventilation and infiltration losses. The air changes per hour of the farm have a great impact on the total required heating and cooling power. Therefore, attention should be given to the air-tightness of the chicken pens to reduce the required installation size.

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