Heat pump dryers can often be used to dry a variety of fruits and vegetables, including tomatoes. Here are the steps for drying tomatoes in a heat pump dryer:

1. Prepare the tomato: Choose a fresh ripe tomato, wash it, and cut it into slices or chunks of appropriate size.
2. Heat pump dryer setting: Set the temperature of the heat pump dryer to 40-60°C and the humidity to about 20-30%. If your dryer has multiple temperature and humidity settings, you can adjust them for the size and shape of your tomatoes.
3. Place the tomatoes: Place the processed tomatoes evenly on the drying tray of the heat pump dryer, try not to overlap or stack them together so that the hot air can circulate.
4. Drying time: The drying time of the heat pump dryer depends on the size and moisture content of the tomatoes, usually it takes 6-12 hours. During the drying process, the tomatoes can be turned or turned from time to time to ensure that they are evenly heated and dried.
5. Finish drying: When the tomatoes are completely dry, they can be taken out and placed in a ventilated and dry place to let them cool and shape. After that, store it in a dry, cool, and ventilated place to prolong the storage time.

It should be noted that the heat pump dryer should be kept clean and hygienic when drying tomatoes to avoid cross-contamination and bacterial growth. In addition, during the drying process, if any abnormality is found, such as deterioration or peculiar smell, the drying should be stopped immediately and the cause should be checked.