Simulation of Air fryer

This electric product is used for cooking and frying protein and vegetables. Its components include a food container, carrying handle of the container, temperature display, cooking instructions and the time the device stays on to show the cooking program, outer shell, hot air outlet vent on the back of the device. Among the internal components, we can mention the element with 1500 watts of heat flux and a fan with an approximate power of 30 watts for the circulation of hot air inside the air conditioner and its uniformity. The internal temperature of the “air fryer” in cooking mode is around 180 degrees Celsius, which is suitable for cooking and frying food.

Physical phenomena

The air around the element is heated through convection heat transfer (the contact of air molecules with the element).

Due to the presence of the fan, the flow and its circulation done with force convection. The hot air moves away from the element and spreads in the air compartment, and after heating the food, it is sucked again by the center of the fan and directed to the hot element through a radial jet.

The heat of the element is transferred to the surface of the food through radiation.

Design evaluation parameters by simulation

By using this simulation, the design done for this product is evaluated. There are design requirements aimed at high-quality baking and user safety, which are evaluated by simulation:

  1. The speed of the circulation flow around the food should be the speed allowed for cooking the product.
  2. Uniform distribution of temperature and speed should be maintained as much as possible around the food.
  3. The outer shell areas must have a temperature within the permissible range (of course, hand contact is not allowed for this range)
  4. The handle should have a temperature that can be tolerated by the skin of the hand.
  5. The average temperature of the chamber should be in the range of 180 degrees everywhere in the cooking chamber.

Description of the simulation model

This simulation is done with the aim of evaluating the design of the food tray and its position and the air guider (on the bottom of the cooking chamber). For this geometry, coupled model of fluid flow and heat transfer produces an extensive model with high computational volume.

Considering that the design of the tray and the air guider directly affect the air circulation pattern inside the chamber, at this stage we can skip the heat transfer modeling and only simulate the cold air flow inside the cooking chamber.

These cases are simplifications of the model and reduce the calculation time, and the results provide a good view of the design of the desired parts.

Therefore, in this simulation, the analysis of the cold flow inside the oven chamber is done with the k-w turbulent flow model, and the rotation of the fan is modeled with its frame motion. The number of 4320437 mesh cells was created for this analysis and the time solution was done in pseudo transient mode.

In this step, changes have been made in the geometry of the tray and its position, and simulations for two cases with and without an air guide have been performed and compared. The dimensions and optimal position of the tray were calculated using this simulation. Also, the proper fan speed was obtained.

The function of the simulation model

The simulation of the air flow inside the air fryer gives an overview of the flow circulation inside the chamber. By means of it, sensitive points in air circulation, obstacles and vortices can be identified. By changing the design of places that cause problems in the air flow, changing the design and re-simulating, it is possible to achieve an optimal design without the need to make a prototype and test in a laboratory.