Near-Empty Refrigerator

Introduction

This model simulates the effect of adding hot food to a household refrigerator that is nearly empty. The flow of heat and the circulation of air, both within the refrigerator and between the refrigerator and the external environment, are modeled with components from the HeatTransfer library and the FluidHeatFlow library.

View the model diagram for this model.

This model should be compared with the HotFood model, which simulates the addition of hot food to a normally loaded refrigerator.

The other model in this example is DoorOpening, which simulates the effects of opening and closing the compartment doors.

Simulation

The model simulates the effect of a piece of hot food added at t=0 seconds to a refrigerator that is nearly empty, with only a small amount of fresh and frozen food stored in the compartments.

To simulate the model, follow the steps below:

• Click the button in the top-right corner.
• When the build is finished, click the Simulate button .

By default, the model is simulated over a period of 7200 seconds.

Visualization

After simulating the model, look at the displayed plot of the food and air temperatures in the refrigerator compartment. The plot looks like this:

You can see that the fresh food temperature increases by about 7 K, outside acceptable limits. The low thermal mass of the near-empty refrigerator also leads to excessively frequent thermostat switching, visible after t=5500 seconds.

By simulating the HotFood model, you can see the effect of adding hot food to a normally loaded refrigerator instead of a near-empty one:

You can see that, in the normally loaded refrigerator, the fresh food temperature increases by about 2 K, which is within acceptable limits.

Other Scenario

Try simulating the other model in this example, DoorOpening, to explore the effects of opening and closing the refrigerator and freezer compartment doors.

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