Pinch point analysis (also known as pinch analysis) is a systematic method for analysing and holistically optimizing energy use in industrial processes, taking into account both capital and operating costs. The goal is to align heat sources and heat sinks within the process in such a way that overall energy consumption – particularly for external heating and cooling – is minimised. A key element of the analysis is the so-called pinch point, which marks the narrowest point in the thermal energy flow, where the smallest temperature difference between a hot and a cold process stream occurs. A typical example of an industrial energy efficiency measure is the direct use of waste heat to preheat a cold process stream.

Relevance for high-temperature heat pumps

In the context of industrial heat pumps—particularly high-temperature heat pumps – waste heat streams that are otherwise unsuitable for direct use in process heating can be utilised, due to their low temperature. A comprehensive pinch analysis of all heat and cold streams in an industrial facility reveals where a heat pump can be integrated effectively. From an efficiency perspective, the waste heat should ideally be used directly by the heat pump, so that no temperature gradient arises and the pinch point is 0 K. If this is not feasible – for example, when waste heat is available in the form of exhaust air or flue gas – a water-based heat exchanger is typically used to transfer the heat to the heat pump. In this case, the temperature difference at the pinch point should be kept as small as possible in order to increase the system’s efficiency and thus the heat pump’s coefficient of performance (COP). By utilizing waste heat and providing process heat, both conventional heating and cooling demands can be reduced. This improves overall process efficiency and lowers CO₂ emissions.

Approach and analysis tools

The analysis is based on all relevant heat consumers and sources within the facility. Their temperature and heat load data are combined into so-called composite curves. These curves make it possible to determine the thermodynamically minimum heating and cooling demand, as well as potential energy savings. The composite curve – a temperature–heat flow diagram of the involved heat sources and heat sinks – shows where internal heat recovery between processes is feasible. In addition, the grand composite curve provides provides information on where external systems such as heat pumps can be most effectively deployed.

Benefits of pinch analysis

Pinch analysis is a key tool for the design and efficient integration of high-temperature heat pumps in industrial processes. It identifies the optimal integration point in the thermal process chain, thereby optimizing both energy efficiency and economic performance. Especially for large-scale industrial applications, pinch analysis is often a prerequisite for technically robust and economically viable solutions – and, in many cases, a requirement for eligibility under public funding schemes.