KalinaKreisläufe

KalinaKreisläufe, also known as Kalina cycles, are a type of thermodynamic cycle that utilizes a working fluid mixture, typically a mixture of ammonia and water, to generate power. These cycles are a variation of the organic Rankine cycle and are particularly well-suited for applications involving low-temperature heat sources. The primary advantage of the Kalina cycle lies in its ability to achieve higher thermal efficiencies compared to traditional steam Rankine cycles when operating with these low-grade heat sources.

The operation of a Kalina cycle involves several key stages. First, the ammonia-water mixture is heated by the external heat source, causing the ammonia to vaporize more readily than the water due to its lower boiling point. This vapor-rich stream then expands through a turbine, producing mechanical work. After expansion, the working fluid is condensed, and the liquid-rich stream is pumped back to a higher pressure. A crucial component of the Kalina cycle is the solution heat exchanger, which preheats the liquid returning from the condenser using the hot liquid leaving the evaporator, thereby improving overall efficiency.

Kalina cycles find applications in various fields, including waste heat recovery from industrial processes, geothermal power generation, and solar thermal energy utilization. Their ability to efficiently extract energy from heat sources at temperatures as low as 80-150 degrees Celsius makes them a viable option for many decentralized power generation scenarios. While the complexity of managing a two-component working fluid can be a challenge, the potential for increased efficiency, especially in specific temperature ranges, makes the Kalina cycle an important technology in the realm of renewable and waste heat energy utilization.