The project investigated a range of small‑scale heating solutions for a plastic injection‑molding plant and a university test facility. Four main boiler concepts were compared: an electric thermal‑oil boiler, a gas‑fired thermal‑oil boiler with 150 kWth, a larger gas‑fired boiler of 400 kWth, and a combined heat‑and‑power (CHP) unit that couples a 132 kWe/216 kWth CHP with a 150 kWth boiler. An additional variant added an air‑conditioning module. For each design the required investment, projected savings, and pay‑back period were calculated. The smallest electric boiler cost €236 000 and offered no direct savings, while the 150 kWth gas boiler required €724 000 (including a €492 000 gas line) and yielded €23 000 in annual savings with a pay‑back exceeding 25 years. The 400 kWth gas unit cost €758 000 and produced the same savings and pay‑back. The CHP‑boiler combination cost €909 000 and, after the removal of the CHP incentive, offered no savings. The CHP plus air‑conditioning variant required €1.074 million and delivered €50 000–90 000 in annual savings, giving a pay‑back of 5–9 years without subsidies. These figures were derived from a detailed economic model that also considered the installation of 15 machines and their connection to a thermal‑oil network. Earlier calculations without gas lines suggested pay‑backs of 5–9 years, but changes in feed‑in‑tariff policy, a jump in gas‑line costs from €200 k to €500 k, and a revised CHP law shifted the investment focus from consumers to suppliers, making the original plant location unfeasible.

The technical core of the study was a virtual coupling concept that separates generation from consumption. The University of Kassel built a scaled CHP test bench with a 50 kWe/81 kWth unit. The CHP’s exhaust heat is recovered through a high‑temperature heat exchanger (200–300 °C) delivering 19.8 kWth at 300 °C, while the remaining waste heat is released to the environment. The bench also features a motor‑driven cooling system that can adjust the exhaust air velocity. Experiments measured the temperature of the conveyor belt air above the test section as a function of exhaust velocity. Results showed that increasing the velocity from 0.05 m s⁻¹ to 0.10 m s⁻¹ lowered the belt temperature by about 2.1 K for a 600 mm wide opening with a 1.5 kW load, while further increases produced diminishing returns. From an economic standpoint, velocities above 0.10 m s⁻¹ were deemed inefficient. The bench also demonstrated that an optimized fresh‑air control scheme could reduce annual energy demand by 33 % (from 2 500 MWh to 1 678 MWh), with heating accounting for 51 % of the remaining consumption.

Collaboration involved the plastic‑molding company Junghans, the University of Kassel, and the research organization ROM. Junghans was initially intended to host the plant, but regulatory changes made this impossible. ROM performed simulation studies of the CHP system throughout the project. The University of Kassel supplied the test infrastructure and real‑time data transfer via an sFTP tool, enabling the virtual coupling of the plant’s injection‑molding machines with the CHP bench. The project ran over a three‑year period and was funded by German federal agencies, reflecting national interest in distributed energy generation and energy efficiency. The partnership combined industrial experience, academic research, and simulation expertise to evaluate the feasibility of small‑scale CHP and advanced thermal management in a manufacturing context.