What is the general rule for evaporation temperature in a compression refrigeration system in relation to the cooled medium?

In a compression refrigeration system, the evaporation temperature plays a critical role in the efficiency and effectiveness of the cooling process. The general rule is that the evaporation temperature should be between 5°C (41°F) to 10°C (50°F) lower than the temperature of the medium being cooled. This temperature difference ensures that sufficient heat is absorbed from the medium, allowing for effective heat transfer and cooling.

When the evaporator absorbs heat from the cooled medium, it causes the refrigerant inside the evaporator to evaporate and absorb heat efficiently. If the evaporation temperature is too close to the temperature of the medium, there may not be enough heat transfer to allow for effective cooling, which could not only compromise performance but could also lead to issues such as higher energy consumption and prolonged cooling times.

Maintaining the evaporation temperature within the specified range ensures that there is an adequate temperature gradient for heat exchange, which is essential for the system's optimal functioning.