The manufacturers of household refrigerators and freezers (HHKG) are challenged to develop even more efficient appliances due to the high total energy demand of this sector worldwide. It is known from preliminary projects that the capillary tube used exclusively in HHKG does not operate the refrigeration process optimally in all operating states. As a result, efficiency increases of up to 10% in the energy consumption measurement are still possible if this component is adapted. Investigations of the previously unknown, alternative ΔT/m. control concept, which is implemented by the new geometrically self-adjusting expansion valve (SEEV), should succeed in providing functional proof of more efficient operation compared to the state of the art (capillary tube). At the component level, the SEEV will be constructed and functionally tested in the laboratory. At the system level, a selected HHKG with three different expansion valve variants (state of the art (capillary tube), the optimal operation (with adjustable micro expansion valve), and the new SEEV with ΔT/m. control) will be experimentally investigated in terms of energy consumption (steady state and transient), sensitivity to refrigerant charge and pull-down behavior. At the same time, simulation-based investigations are carried out on the three different expansion valve variants. The simulations provide a more detailed insight into the physical processes in the refrigeration cycle, allowing a better interpretation of the measurements and increasing the understanding of the behavior of the three expansion valve variants, which is especially important in the transient, controlled case. The simulation-based study requires modeling of additional components (frame heater, geometrically self-adjusting expansion valve, internal heat exchanger, adjustable micro expansion valve) for the existing 1D refrigeration cycle simulation model. Parameterization of the selected unit is also required. With the successful completion of the project, the determination and analysis of the optimal operation are done and form the basis for the investigation of further expansion valves and their control. Furthermore, the new models can also be used for a simulation-based analysis of the transient refrigeration circuit, which is controlled with the aid of an adjustable expansion valve and can make a valuable contribution to the development of HHKG. With the help of all the data obtained, the study, evaluation, and functional verification of the new SEEV with ΔT/m. control will be carried out
|Effective start/end date||2/01/23 → 1/07/24|
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