Going against the natural flow of heat and moving thermal energy from a low temperature to a high temperature is

The correct answer is "refrigeration".

Explanation:

Refrigeration is the process of rejecting heat from low temperature reservoir and transfers it to high temperature reservoir. Here, the heat is taken from the colder body and reject it to hotter body. The sink is at the lower temperature. The source is at the higher temperature.

In heat engine, the heat is transferred from high temperature reservoir to the low temperature reservoir. It is just opposite of the refrigeration.

Therefore, going against the natural flow of heat and moving thermal energy from a low temperature to a high temperature is refrigeration.