The compressor is the core component of a high-temperature heat pump (HTHP), enabling the supply of process heat at elevated temperature levels. It compresses the gaseous refrigerant, raising both its pressure and temperature. The mechanical energy required for this process is supplied by an electric motor. This thermodynamic step is essential for upgrading low-grade waste heat into useful heat at temperatures reaching up to 200 °C.

In industrial HTHP systems, piston and screw compressors are the most commonly used technologies:

• Piston compressors are well suited for applications with high temperature demands due to their ability to handle large pressure ratios.
• Screw compressors are particularly suitable for continuous operation under high temperature lift conditions and represent a cost-effective solution for standard refrigeration applications.

The choice of compressor type depends on specific process requirements, such as temperature, pressure, and volumetric flow rate.

Compressor efficiency has a major impact on the overall performance of the heat pump. An optimized compression process reduces energy consumption and increases the system’s coefficient of performance (COP). This results in lower operating costs, a reduced carbon footprint, and ultimately the most economical solution.

Modern HTHP compressors are designed for use with natural refrigerants such as ammonia (NH₃), propane (R290), isobutane (R600a), butane (R600), and pentane (R601). These refrigerants feature low global warming potential (GWP) and enable high discharge temperatures, making them particularly efficient and environmentally friendly.

In summary, the compressor is the heart of a high-temperature heat pump. Its design and efficiency are critical to the system’s overall performance and economic viability. Careful selection and proper sizing of the compressor are therefore key to the successful deployment of HTHPs in industrial applications.