Source-sink mapping for industrial heat pumps

Start with streams, not machines

List every material or utility stream that is cooled and every stream that is heated. For each one, record inlet and outlet temperature, flow, heat capacity, operating schedule and whether its temperature changes with production. A monthly utility bill cannot show whether a source and sink coincide.

Separate quantity from quality

Heat quantity is the recoverable power or energy. Heat quality is its temperature and stability. A large cooling load at 10°C may be less useful than a smaller continuous source at 45°C when the sink needs 80°C water.

• Plot source availability by temperature
• Plot sink demand by required supply and return temperature
• Mark hours of overlap
• Identify contamination and heat-exchanger boundaries
• Test direct recovery before adding a heat pump

Rank the matches

The first screening criterion is simultaneity, followed by temperature lift, annual hours and integration difficulty. Keep storage as a separate design option: it can bridge short timing differences but cannot compensate for a seasonal source and year-round sink.

Calculate stream duties consistently

For a liquid stream, thermal power is mass flow multiplied by specific heat capacity and usable temperature change. Water flowing at 20 kilograms per second and cooling by 10 K releases about 836 kW when a specific heat capacity of 4.18 kJ/kgK is used.

The usable temperature change may be smaller than the measured process change because the heat exchanger needs an approach and the process may impose a minimum return temperature. Vapour, condensing streams and moist air require latent heat to be included.

Build the matrix around time

Place sources down the rows and sinks across the columns. For each pairing, record source and sink temperatures, potential duty, distance, contamination boundary and hours of overlap. A colour or score can help screening, but retain the underlying values.

Use separate rows where one physical source has materially different modes. Refrigeration condenser heat during summer cold-store operation may not resemble winter performance. Combining them into one average hides the design case.

Do not optimise one pairing in isolation

Using the warmest source for a low-temperature sink may prevent it serving a more valuable high-temperature duty. Pinch analysis or a structured heat-recovery review can show how pairings interact across the plant.

The selected map should explain where each source goes when its preferred sink is unavailable. Rejection equipment, storage and backup remain part of the system even when they operate infrequently.