ZIMBA: Innovation in Action

04.11.2025

As industries across Europe seek smarter ways to recover and reuse low-grade waste heat, the ZIMBA project is pushing the boundaries of absorption heat pump design. Funded by the European Union’s Horizon Europe Research and Innovation Action (RIA) program, ZIMBA aims to develop a compact, high-performance Absorption Heat Transformer (AHT) system using ammonia/water refrigerant. Designed to deliver industrial heat starting at 110 °C and later scaling to 130 °C, the system supports broader energy system decarbonization and complements the integration of renewable energy sources.

At the heart of ZIMBA’s innovation are two core breakthroughs that address long-standing limitations in absorption heat pump systems and unlock new performance capabilities.

First, the integration of an innovative ejector working with ammonia-water mixture into the AHT cycle marks a major leap in system control and responsiveness. This enhancement improves system stability and operational flexibility. Traditional AHTs often suffer from narrow operating windows and performance fluctuations under varying load conditions. ZIMBA’s ejector-equipped design overcomes these limitations, enabling a wider range of capacities and more consistent thermal output. This makes the system highly adaptable to real-world industrial environments, where heat demands can shift rapidly.

Second, ZIMBA introduces a novel baseline AHT architecture that eliminates the need for a flash tank. By generating high-temperature vapor directly within the absorber, the system produces high-temperature vapor—up to 110 °C at 1.5 bar—directly within the absorber. This direct vapor generation simplifies the system layout and enhances overall efficiency. It also minimizes energy losses typically associated with flash tank operation, making the heat transformation process more compact and cost-effective.

In terms of performance, ZIMBA aims for an electrical Coefficient of Performance (COP) of up to 40, reflecting its potential for high energy efficiency in suitable industrial applications.

Together, these innovations represent a major step forward in absorption heat pump technology. By combining stable performance with efficient vapor generation, ZIMBA delivers a flexible and powerful solution for recovering and upgrading low-grade waste heat. Built with readily available components, the system is easy to deploy and supports a more sustainable, circular economy.

The project is coordinated by CEA and supported by a consortium of European research and industry partners—including Politecnico di Milano, CLAUGER, Eastern Switzerland University of Applied Sciences (OST), and AMIRES—and will run for four years.

ZIMBA is more than a technical upgrade—it’s a strategic contribution to Europe’s energy transition, helping industries reduce CO₂ emissions, improve energy efficiency, and move toward cleaner, more resilient heating solutions.