Industrial Heat Pumps

An industrial heat pump uses external work, usually electricity, to move thermal energy from a lower-temperature source to a higher-temperature industrial process. It upgrades waste or ambient heat through a thermodynamic cycle, creating the temperature lift needed for useful heating rather than converting all its input electricity directly into heat.

Vapour-compression cycle

The most common design circulates a refrigerant through four repeating stages. The heat delivered equals the heat absorbed from the source plus the work supplied to the compressor.

• In the evaporator, low-pressure refrigerant absorbs heat from waste streams, air or water and vaporises.
• The compressor uses mechanical work to raise the vapour's pressure and temperature.
• In the condenser, the hot refrigerant releases heat to the industrial process and condenses.
• An expansion valve lowers the refrigerant's pressure and temperature before it returns to the evaporator.

Integration with industrial processes

Heat exchangers connect the cycle to both the heat source and the process requiring heat, generally without mixing the refrigerant with process materials.

• Recoverable heat may come from cooling water, effluent, exhaust streams or other low-grade waste heat.
• The upgraded heat can supply hot water, drying, evaporation, preheating or steam generation where the required temperature is technically achievable.
• Multistage or cascade systems can provide a larger temperature lift, but they require additional equipment and energy.

Efficiency and energy significance

Heating performance is measured by the coefficient of performance, defined as useful heat delivered divided by work input. It can exceed one because the system transfers source heat in addition to converting compressor work into heat.

• Performance generally falls as the difference between source and delivery temperatures increases.
• Industrial heat pumps can reduce direct fossil-fuel use by electrifying process heat and recovering energy that would otherwise be rejected.
• Their economic and environmental benefits depend on operating temperatures, utilisation, electricity supply, equipment efficiency and refrigerant management.