A cascade system is an energy-efficient solution that is often used for larger heat demands or temperature differences. In this system, several heat pumps are connected and work together to provide the desired temperature level.
The operating principle of the cascade system
Multi-stage heat transfer: The primary (base) heat pump extracts heat from the ambient heat source (e.g. air , water or ground) and transfers it to an intermediate heat transfer medium.
This medium transfers heat to the second heat pump, which further increases the temperature or lowers it if cooling is required.
Increased temperature difference: Cascading operation allows the system to reach even very high or low temperatures without placing excessive load on a single heat pump.
Balanced load: Heat pumps work in coordination with each other so that no unit operates beyond its capacity, which increases the system's lifespan and efficiency.
Advantages
Higher efficiency: Each heat pump operates within an optimal range, which reduces energy consumption.
Handling larger temperature differences: Ideal for applications where extreme temperatures need to be achieved (e.g. in industrial processes).
Flexible scalability: The system can be easily expanded by adding additional heat pumps if the heat demand increases.
Reliability: If one heat pump fails, the other units can continue to operate, minimizing the risk of system downtime.
Reduced load on individual units: Even load distribution ensures a longer service life for the equipment.
Areas of application
Larger buildings: Heating and cooling of multi-storey residential buildings or office buildings.
Industrial facilities: During manufacturing processes where large temperature differences are required.
Commercial facilities: To meet the energy needs of shopping malls, hotels and hospitals.
Special cooling applications: For example in the food industry or for cooling data centers.
Example of how a cascade system works
Primary heat pump:
- It extracts 10°C of heat from the air or ground and heats it to 35°C.
Secondary heat pump:
- It heats the transfer medium preheated by the primary system to 60 °C, which is used by the heating system.
Cascade system vs. Simple heat pump
| Characteristic | Cascade system | Simple heat pump |
|---|---|---|
| Temperature range | Wider | Limited |
| Efficiency | Higher | Lower, in extreme conditions |
| System flexibility | Easily expandable | Fixed capacity |
| Equipment life | Longer | Shorter, due to higher load |
Challenges and factors to consider
Complexity: The design and installation of the system is more complicated than for a simple heat pump.
Initial cost: Requires a higher investment cost, although it may pay for itself in the long run through lower operating costs.
Maintenance: Using multiple heat pumps requires more complex maintenance.
Summary
A cascade system offers an efficient and flexible solution for larger heating or cooling needs. Although the initial installation costs may be higher, the energy efficiency and reliability of the system make it a worthwhile investment in the long run. A cascade system is particularly useful for industrial, commercial and larger facilities where high performance and scalability are essential requirements.