Heat pump dryers can be used to dry oranges, generally speaking, oranges need to be dried at low temperatures to maintain their taste and quality. Here are some basic steps and temperature-setting suggestions:

1. Wash the oranges and slice them. Make sure each slice is the same thickness, this will help make the drying time more even.

2. Arrange the orange slices evenly on the dryer. Avoid stacking them so the air flows better.

3. Set the temperature of the heat pump dryer between 40°C and 50°C. This temperature range helps preserve the flavor and color of the oranges. If your dryer doesn’t have a temperature setting option, try setting it on the “low” setting.

4. Let the oranges dry in the dryer for 8-12 hours. The exact time depends on the thickness of the oranges and the model of dryer. It is recommended that you regularly check the dryness of your oranges to make sure they are not overly dry.

It is important to note that if the temperature of the heat pump dryer is too high, the oranges may become too dry and lose their taste and quality. So make sure you choose the correct temperature setting for your dryer and the thickness of your oranges.