The digester outlet carries 1 Nm³/h of biogas at 35°C and approximately 47 g of water vapor. At points where this temperature value falls below, the water vapors in the biogas, which lose their ability to carry moisture, turn into water. First of all, this situation, which causes condensate formation in the lines, also creates the ground for many different problems at the later points of the process. Since hydrogen sulfide (H₂S) in biogas turns into sulfuric acid when it meets water, the problem is no longer just a condensate problem.

Biogas dehumidification systems, in other words, biogas chiller systems are used to prevent condensate and undesirable situations related to condensate. Chiller system general working principle; It is based on the collision of the closed circuit cooled liquid with the biogas in the heat exchanger. When the biogas, which comes to the heat exchanger at a temperature of approximately 35°C, comes into contact with the cooling liquid at a temperature of 2-5 °C, condensation occurs rapidly. The water vapor in biogas, which loses its ability to carry moisture very quickly, turns into water. Water is kept in the heat exchanger outlet separator and the biogas is sent to the gas engines in a dehumidified state. The world's leading gas engine manufacturers allow humidity up to certain limits in the engine gas supply. In cases where biogas chiller systems are not used and the gas engine is fed with high humidity, malfunctions and unplanned stops are inevitable.