Performance
Performance figures only become comparable when their operating point, time period and electrical boundary are stated.
- Coefficient of performance (COP)
- Useful heating output divided by electrical input at a stated operating point and measurement boundary.
- Seasonal COP
- Useful heat delivered over a defined period divided by electricity used over the same timestamps and system boundary.
- Temperature lift
- The difference between refrigerant evaporating and condensing temperatures. It is normally wider than the difference between the plant source and sink temperatures.
- Part load
- Operation below the selected full-load duty. Capacity, power and COP can all change as compressors stage or vary speed.
- Turndown
- The range over which equipment can reduce output while maintaining acceptable control and operation.
Heat flows and integration
Source and sink descriptions should include temperature, quantity and timing rather than a name alone.
- Heat source
- The stream or environment from which the heat pump absorbs heat, such as condenser water, warm effluent or exhaust air.
- Heat sink
- The process or utility receiving useful heat, defined by its supply temperature, return temperature, load and schedule.
- Direct heat recovery
- Transfer of heat from a source to a sink through a heat exchanger without using a compressor to raise its temperature.
- Pinch analysis
- A process-integration method used to identify minimum external heating and cooling demand and suitable heat-recovery matches.
- Approach temperature
- The minimum temperature difference across a heat exchanger. Cold-side and hot-side approaches widen the lift seen by the refrigerant cycle.
Equipment and cycles
These terms describe common ways of extending temperature range, reusing vapour or operating several assets together.
- Mechanical vapour recompression (MVR)
- Compression of a process vapour so that it condenses at a higher pressure and temperature and its latent heat can be reused.
- Cascade system
- Two linked refrigeration cycles using different temperature levels, often selected when one cycle cannot cover the required lift efficiently.
- Desuperheating
- Recovery of high-temperature heat from refrigerant vapour before it condenses. The available quantity is usually smaller than total condenser heat.
- Hybrid system
- A heating arrangement in which a heat pump works with a boiler or another heat source for peaks, startup, outages or higher-temperature duties.
- System boundary
- The agreed set of useful outputs and electrical inputs included in a performance or savings calculation.
Sources
General technical explanation. No specific external source claims are made on this page.