Search

In this paper, a robust fault diagnosis for a refrigerator compartment containing a quantity of ice using the bond graph (BG) approach is performed by linear fractional transformations (LFTs). The BG model describes heat transfers supported by the amount of ice placed in the refrigerator compartment, as well as a water container. The LFT modeling of BG elements offers advantages from the point of view of structural analysis and data processing implementation. We have introduced four faults, which consist of ice temperature rise, water leakage, insulation failure at the hot walls of the refrigerator and an increase of the internal temperature due to poor door sealing. The faults are in the form of additional heat fluxes. The simulation results show the effectiveness of the proposed method for detecting and localizing faults. In addition, the lack of door sealing has the most influence on the temperatures in the internal cooling space, water, and ice compared to the other faults.

This paper aims to prove the efficiency of using the naturally free and abundant cold airflow to improve the cooling inside a household refrigerator and to reduce the energy consumption in Nordic and high altitude countries. The cold airflow is spread out in a cavity covering the side wall of the appliance. This cavity is also connected to the cold outdoor environment through inlet and outlet ducts. For that purpose, a pseudo bond graph (BG) model is proposed to model this installation. It represents the thermal transfers by forced convection in the cavity and the ducts with the ambient and outdoor surroundings. The internal air temperature is computed according to the evaporator temperature and the outside cold airflow that is also computed according to the outside temperature. The simulation results show that the cooling process was speeded up by about 39% and the duration of the compressor functioning was reduced by about 10[Formula: see text]h and 8[Formula: see text]min, which allows reducing the total energy use by 0.88[Formula: see text]kWh, and thus achieving an energy saving of about 34.61%. Experimental data of the outside airflow temperature in Canada during 28 hours in January 2017 are used in the model and allow an energy saving of about 40%.

The present paper studies the properties of observability and controllability using Bond Graph (BG) approach. It is especially applied to a pseudo BG model that describes the thermal transfers in a household refrigerator compartment exposed to an outdoor natural cold airflow. This latter is spread out in an installation, which consists of a cavity covering the side wall of the appliance and connected to inlet and outlet ducts through two openings. The study results show that the pseudo BG model is observable and controllable in time-varying (TV) systems using the concept of duality.

This paper proposes a pseudo bond graph model of thermal transfers by natural convection inside a household refrigerator. It has two inputs: the ambient temperature and the temperature at the level of the evaporator wall. The latter assesses the functioning of the compressor cycles. A performance comparison, with the experimental data, was carried out in order to verify the model, in which, real measurements are used to modulate the evaporator temperature source. The simulation results show the effectiveness of the proposed approach.